calcium and vitamin d for vegans

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Calcium and Vitamin D

by Jack Norris, RD | Last updated: March 2013

Calcium and Vitamin D f or Vegans: Summarized! is an abridged, reader-friendly version of this article.

Contents

Recommendations Calcium Vitamin D

Calcium & Vegan Diets: Why the Fuss? Animal Protein & Osteoporosis

Epidemiological Studies Metabolic Studies

What Causes Osteoporosis? Calcium and Vitamin D Vitamin B12 and Bone Mineral Density

Research on Vegans Bone Mineral Density EPIC-Oxford Buddhist Nuns

Dangers of Calcium Supplements Calcium Absorption from Plant Foods Calcium Tips Conclusion on Calcium and Vegan Diets

Vitamin D Mild Vitamin D Deficiency and Health Problems Dietary Sources of Vitamin D Vitamin D Levels in Vegetarians Sunshine

Dark Skinned People Older People Tanning Beds Test Kit Vitamin D3 vs. Vitamin D2 Vitamin D Supplements and Meals Vitamin D2 in UV Treated Mushrooms Vitamin D in Fortified Foods

References

Recommendations

Calcium

The USA daily recommended intake for calcium is 1,000 mg for adults up to 50 years old, and 1,200 for adults over51 and older. The UK's recommended intake is 700 mg. Evidence to date does not indicate that vegans have lowercalcium needs than non-vegans. Only a few leafy greens are high in absorbable calcium: kale, mustard greens, bokchoy, turnip greens, collards, and watercress. If you are not eating at least 3 servings of those foods a day (oneserving is 1/2 cup cooked), then you need to be eating calcium fortified non-dairy milk (or another calcium-fortifiedfood), calcium-set tofu, or taking a calcium supplement of 250 - 300 mg/day to ensure you are getting enoughcalcium. Some research indicates that it is prudent to keep calcium intakes lower than 1,400 mg per day. Calciumsupplements are best taken with meals, especially for those people prone to kidney stones.

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Page 1 of 14Calcium and Vitamin D

13-Jun-13http://www.veganhealth.org/articles/bones


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Table 4. U.S. DRI for Calcium

AgeUS DRI

(mg)

0 - 6 mos 200

6 - 12 mos 260

1 - 3 yrs 700

4 - 8 yrs 1000

9 - 18 yrs 1300

19 - 50 yrs 1000

51 - 70 yrs (male) 1000

51 - 70 yrs (female) 1200

over 70 1200

14 - 18 pregnant/lactating 1300

19 - 50 pregnant/lactating 1000

While not found in many foods, vitamin D can be made by the action of sunlight (UV rays) on skin. S ince about2005, there has been a controversy in scientific circles about the ideal levels of vitamin D for preventing diseasewith some researchers suggesting amounts much higher than those recommended by the Institute of Medicine.Regardless of this debate (of which there are more details below), I have encountered many vegans, often fromsunny areas such as southern California, who have had extremely low levels of vitamin D. At least five weresuffering from fatigue or bone pain that improved upon vitamin D supplementation.

If your arms and face (or the equivalent amount of skin or more) is exposed to the following amounts of middaysun (10 am to 2 pm), without sunscreen, on a day when sunburn is possible (i.e., not winter or cloudy), then youshould not need any dietary vitamin D that day:

Light-skinned: 10 to 15 minutes Dark-skinned : 20 minutes

Elderly: 30 minutes (23)

On all other days, follow these recommendations:

Vitamin D Recommendations

Age US DRI VH.orga, b

0 - 12 mos 10 g (400 IU) 10 g (400 IU)

1 - 70 yrs 15 g (600 IU) 15 g (600 IU) to 25 g (1,000 IU)

over 70 20 g (800 IU) 20 g (800 IU) to 25 (1,000 IU)

pregnancy 15 g (600 IU) 15 g (600 IU) to 25 g (1,000 IU)

lactation 15 g (600 IU) 15 g (600 IU) to 25 g (1,000 IU)

aVeganHealth.org recommendations.bAmounts somewhat larger are considered safe, but it's best not to take morethan twice the recommendations without a doctor's supervision.

25 mcg (1,000 IU) is more than you can get from fortified foods or multivitamins; amounts that high are onlyavailable through vitamin D2-only supplements. Country Life makes one that is commonly available in naturalfoods stores in the U.S. and is fairly inexpensive. Deva makes one that can be ordered by mail. There isevidence that it can be harder to raise vitamin D levels using vitamin D2, the vegan version of vitamin D, and sowe suggest somewhat more than the RDA (as reflected in the table above). More on vitamin D2 vs. D3 below.There is also a vegan version of vitamin D3 made by Vitashine.

Calcium & Vegan Diets: Why the Fuss?

Americans are regularly being urged to consume more calcium inorder to prevent osteoporosis. It is practically impossible to meetthe recommendations without large amounts of cows' milk,calcium-fortified foods, or supplements.

Enter vegan diets. Because vegans do not eat dairy products,their calcium intakes tend to be low. The Dietitian's Guide toVegetarian Diets (2004) lists 45 studies that have surveyedvegetarians' calcium intakes in Appendix G. The daily calciumintakes in these studies are about:

Vegans: 500 - 600 mg

Lacto-ovo vegetarians: 800 - 900 mg

Non-vegetarians: 1,000 mg

Only one study included supplements. In it, daily calcium intakeswere: 840 mg (vegan males), 720 mg (non-vegetarian males),710 mg (vegan females), and 855 mg (non-vegetarian females).

The U.S. Dietary Reference Intakes (DRI) for calcium are listed inTable 4.

Animal Protein & Os teopor os is

As you can see above, the calcium intake of vegans tends to bequite a bit lower than lacto-ovo vegetarians, non-vegetarians, andthe DRI. Traditionally, the vegan community has responded tothis by saying osteoporosis is a disease of calcium loss from thebones, not a lack of calcium in the diet. This was based on twobits of evidence. The first bit is that ecological studies have shown that the countries with the highest intake of

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dairy products (northern Europe and the USA) have higher rates of hip fractures than do Asian and Africancountries where much less milk is consumed. This can be explained by the second bit of evidence which is thatstudies show that after ingesting animal protein, people urinate large amounts of calcium. Therefore, the thinkinggoes, calcium intake isn't important for preventing osteoporosis and vegans are protected due to the lack ofanimal protein in their diets.

Let's examine this evidence.

Epidemiological Studies

While it is true that Asian countries have lower rates of hip fractures than do higher dairy-consuming countries, itturns out that hip fracture rates can be misleading. The first prospective cohort study measuring clinicallydiagnosed vertebral fractures in an Asian population, the Hong Kong Osteoporosis Study, found that while hipfracture rates were lower in Hong Kong than Sweden, vertebral fracture rates were higher (7), as shown in thegraph below (or you can click here for an easier version to see):

The authors of the Hong Kong Osteoporosis Study state:

The observed ethnic differences in fracture incidences may be due to the fact that hip fracture riskwas affected by fall risk, whereas the risk of vertebral fracture mostly depends on bone strength.Despite the low hip fracture rate in our population, Hong Kong women had a higher prevalence ofosteoporosis [technical parenthetical deleted] than US Caucasian women (35.8% vs. 20%,respectively) and a similar prevalence of about 6% in Hong Kong and US Caucasian men.

In other words, at least in this group of people from Hong Kong, the Chinese don't have lower rates ofosteoporosis.

Here are some excerpts from a 2009 review of the epidemiological studies on protein and bone health:

Overall, there was very little evidence of a deleterious influence of protein intake on [bone mineraldensity (BMD)], with most cross-sectional surveys and cohort studies reporting either no influenceor a positive influence. Thus, 15 cross-sectional surveys found a statistically significant positiverelation between protein intake and at least one BMD site. However, 18 studies found nosignificant correlation between protein intake and at least one BMD site.

The cohort studies also identified little evidence of any deleterious influence of protein intake onbone. ...[N]o studies showed a significant increase in BMD loss with increased protein intake, andonly one study showed a significant decrease in BMD loss with increased animal and total proteinintakes."

Overall, the [seven] cohort studies indicated either a benefit or no effect of protein intake on hipfracture relative risk, with only one study reporting a significant increase in risk with increasinganimal protein intake and increasing animal to vegetable protein ratio. Three studies found adecreased relative risk of hip fracture with increasing animal, total, and vegetable protein intakes.

Two studies found no significant association of animal protein with fracture risk, whereas 2 studiesfound no association of total protein with fracture risk. Last, 2 studies found no relation betweenfracture risk and vegetable protein.

Metabolic Studies




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As mentioned above, there is a theory that protein increases osteoporosis by increasing a loss of calciumthrough the urine. The idea is that protein, especially through the sulfur-containing amino acids, increases theacid in the blood which, in turn, gets shuttled to the urine, increasing the renal acid load. In order to neutralizethat acid, calcium is used as a buffer and then urinated out with the acid.

There has been an enormous amount of research on protein and bone health and this view of protein causingosteoporosis has been refuted. Here are some of the main points of a 2012 literature review (28) of clinical trailson the subject:

Many clinical trials show that adding purified proteins to the diet increases calcium excretion through theurine. But when whole foods are eaten, this effect is not strong. And phosphorus, in which meat and dairy

are rich, counteracts the increase of calcium in the urine between 40 and 65%.

High protein diets increase acid excretion in the urine, but this can be handled by the body's acid buffersystem without the need for calcium.

In low-calcium, but not high-calcium diets, higher protein intakes probably increase calcium absorptionfrom the digestive tract causing an increase in calcium excretion in the urine.

Fruits and vegetables are beneficial to bone health, probably due to their high potassium and magnesiumcontent. This could cause confounding in protein studies because diets high in protein are often low infruits and vegetables.

There is some evidence that a beneficial effect of protein on bones is only seen when calcium intake andvitamin D status is adequate.

Maintenance of adequate bone strength and density with aging is dependent on adequate muscle masswhich is dependent on adequate intake of protein.

An increase in IGF-1 is most likely the mechanism for increased bone health with higher protein intakes.

They conclude:

Although HP [high protein] diets induce an increase in net acid and urinary calcium excretion, theydo not seem to be linked to impaired calcium balance and no clinical data support the hypothesisof a detrimental effect of HP diet on bone health, except in the context of inadequate calciumsupply.

Another 2009 meta-analysis found that among five well-designed studies measuring calcium balance, net acidexcretion was not associated with either decreased calcium balance or a marker of bone deterioration ( 48).

What Causes Osteoporosis?

If animal protein doesn't cause osteoporosis, what does?

Genetics likely play a strong role in osteoporosis, and, possibly related, estrogen levels in women. Among factorsthat can be controlled by lifestyle and diet, there has been evidence for the following:

Helps prevent:

Weight-bearing exercise throughout one's lifetime

Higher body weight

Adequate intake of calcium, vitamin D, vitamin K, phosphorus, potassium, magnesium, and boron

Contributes to:

High sodium and caffeine intake

Smoking

Too little protein

Excessive vitamin A (retinol, not beta-carotene)

Possibly vitamin B12 deficiency

Calcium and Vitamin D

Some background: When calcium levels in the blood drop, parathyroid hormone (PTH) is released. PTH causescalcium to be released from the bones, thus raising the low calcium levels in the blood. Osteoporosis may resultfrom chronically high levels of PTH. The conversion of 25-hydroxyvitamin D to calcitriol is also somewhatregulated by PTH levels (4). Calcitriol increases absorption of calcium and phosphorus (another majorcomponent of bones) from the intestines and decreases their excretion in the urine. In so doing, calcium levels inthe blood rise and PTH levels drop.

Research has shown that, on average, Americans are getting enough calcium. A 2003 report from the NursesHealth Study showed vitamin D to be more important than calcium intake for preventing hip fractures inpostmenopausal women (5). In 2007, a meta-analysis of prospective studies and randomized controlled trialsfound that calcium intake and calcium supplements were not associated with a lower risk for hip fractures (15).

Vitamin B12 and Bone Mineral Density




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Taking vitamin B12 might also be important for bone mineral density. Two studies have linked low B12 status invegetarians to poorer bone health.

A 2009 cross-sectional study from Slovakia compared lacto-ovo vegetarian women to omnivores. They foundthat the vegetarians' higher homocysteine levels (16.5 vs. 12.5 mol/l; 78% vs. 45% were elevated) and lowervitamin B12 levels (246 vs. 302 pmol/l; 47% vs. 28% were deficient) were associated with significantly lowerbone mineral density in the femur (34). Participants were not allowed to have been taking vitamin or mineralsupplements. The researchers did not measure calcium intake or vitamin D status.

Another 2009 cross-sectional study of German omnivores, lacto-ovo vegetarians, and omnivores, and Indianlacto-ovo vegetarians and omnivores found higher markers of bone turnover associated with low vitamin B12

status (34). The findings were no worse for the lacto-ovo vegetarians than the vegans, indicating that poor bonehealth can start with just moderate B12 deficiency. None of the participants were taking B12, calcium, or vitaminD supplements.

Research on Vegans

Bone Mineral Density

A number of small, cross-sectional studies have shown vegans to have the same or slightly lower bone mineraldensity as non-vegans (9-12, 13, 30). These studies were done on vegans who might not have gotten muchvitamin D and probably did not make an effort to get the recommended amount of calcium in their diet.

In 2009, researchers from Vietnam and Australia did a meta-analysis looking at the bone mineral density ofvegetarians (32). They concluded that "[T]here is a modest effect of vegetarian diets, particularly a vegan diet, on[bone mineral density], but the effect size is unlikely to result in a clinically important increase in fracture risk."

EPIC-Oxford (2007)

In 2007, the first study looking at vegan bone fracture rates was released (14). The EPIC-Oxford study recruited

57,000 participants, including over 1,000 vegans and almost 10,000 lacto-ovo vegetarians, from 1993 to 2000.They were asked to fill out a questionnaire to measure what they ate. About 5 years after entering the study, theywere sent a follow-up questionnaire asking if they had suffered any bone fractures.

After adjusting for age alone, the vegans had a 37% higher fracture rate than meat-eaters. After adjusting forage, smoking, alcohol consumption, body mass, physical activity, marital status, births, and hormonereplacement, the vegans still had a 30% higher fracture rate. Meat-eaters, fish-eaters, and lacto-ovo fracturerates did not differ in any of the analyses performed.

When the results were adjusted for calcium intake, the vegans no longer had a higher fracture rate. And amongthe group of subjects who got at least 525 mg of calcium a day (only 55% of the vegans compared to about 95%of the other diet groups), vegans had the same fracture rates as the other diet groups. The study didn't give theaverage calcium intake of those vegans, but it was possible to calculate that at a minimum, their average calciumintake was 640 mg.

The authors noted that fracture rates did not correlate with protein or vitamin D intake among the people in thisstudy. A separate analysis in EPIC-Oxford (20) showed that, among all participants (regardless of diet group),calcium intake was related to an increased fracture risk in women (relative risk 1.75 (1.33-2.29) for 1200 mg/day), but not in men.

Buddhist Nuns (Vietnam, 2011)

In 2011, a follow-up (49) of an earlier study on vegan Buddhist nuns (30) was released. After two years, thevertebrae of 88 vegans and 93 omnivores were examined using x-rays. Ten women (five vegans and fiveomnivores) had sustained a new vertebral fracture after two years; there was no significant difference betweenthe two groups.

Rates of bone mineral density (BMD) change were examined at the lumbar spine and femoral neck with a varietyof associations found. Lumbar BMD increased with age, lean body mass, and vegetable fat; and decreased withvegetable protein and steroid use. The authors suggested that the increase in BMD of the lumbar spine waspossibly due to osteoarthritis and, therefore, not a healthy phenomena.

As for the femoral neck, BMD increased with both lean and fat body mass; and decreased with age, animal fat,and ratio of animal protein to vegetable protein. This would indicate that animal protein had a negative impact onbone. To make this even a bit more complicated, the food questionnaires used by the researchers indicated thatthe vegans were only eating an average of 1,093 calories, 36 g of protein, and 360 mg of calcium per day. Theestimated energy requirement for women their age and size is about 1,600 calories which indicates that the foodintake of the vegans was possibly underestimated by one-third. The non-vegan nuns had intakes of 1,429calories, 62 g of protein, and 590 mg of calcium per day which seems more likely.

Ten fractures in 181 women in two years seemed high. The rate of vertebral fracture in women over 65 in HongKong and J apan is 594/100,000 person-years (30). The person-year fracture rate in this Buddhist nun studyworks out to be 2,762/100,000. That's obviously quite a bit higher, but it should be noted that the fractures in theBuddhist nun study were determined by giving an x-ray to each subject, rather than reporting a bone break, andwould likely find more fractures than the study determining the 594/100,000 rate.

In summary, compared to non-vegetarian Buddhist nuns, vegan nuns had a similar rate of vertebral fractures, butit appears that the rates for both groups were relatively high.

Some research has linked calcium supplements with an increased risk of cardiovascular disease. These studieshave mostly found a link in people getting well over the DRI for calcium (more info), and with the effect strongerin smokers. A 2013 study from Sweden found that there was no increased risk up to 1,300 mg of calcium per




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day, but a significantly increased risk for the group getting 1,400 mg per day (37). A 2012 study that examinedthe arteries of participants found no correlation with calcium supplements and calcification of the arteries inamounts up to 3,000 mg per day (58). To be safe, it might be best not to increase calcium intake higher than1,400 mg per day. People with chronic kidney disease should talk to their physicians about the costs andbenefits of calcium supplements.

There is some evidence that taking calcium supplements can increase the risk of kidney stones in people whoare genetically susceptible. However, taking calcium supplements with meals can actually reduce the risk ofcalcium-oxalate kidney stones, the most common form of stone.

Calcium Abs orption fr om Plant Foods

As a calcium dose increases, the percentage absorbed decreases. Beyond the size of the dose, the oxalate levelin a plant food is the main determinant of how much calcium can be absorbed. See Table 5 for the referencesand details for the following:

Studies have shown that calcium in fortified soymilk, bok choy, kale, and mustard greens is absorbed well.

Based on oxalate levels, the calcium in turnip greens should also be absorbed well.

Based on oxalate levels, the calcium in collards, broccoli, and watercress should be absorbed moderatelywell.

Studies have shown that the calcium in spinach and rhubarb is not absorbed well.

Based on oxalate levels, the calcium in beet greens should not be absorbed well.

Soy milk should be well-shaken to make sure the calcium has not settled to the bottom of the carton.

Table 5. Calcium in Selected Plant Foods

Food Servingsize

Ca

(mg)AOxalate

(mg)A, 65Absorption

rateCa absorbed

(mg)

Cow's milk 1 cup 300

Cow's milk 250 22%61 55

Cow's milk 200 28%60 55

Cow's milk 40 66%62 26

Soymilk - fortified 1 cup200-300

Soymilk - fortified 250 21%61 53

Soymilk - fortified 40 65%62 26

Tofu prepared with calcium salts(check label) 1/2 cup

120-850

Greens

Beet greens raw 1 cup 44 231

Bok choy cabbage, chinese (pak-choi), cooked, boiled, drained,shredded 1/2 cup 79 2063 40%63 32

Bok choy cabbage, chinese (pak-choi), raw, shredded 1 cup 74

Broccoli raw - chopped 1 cup 43 173

Broccoli cooked, boiled, drained -chopped 1/2 cup 31

Broccoli frozen, chopped, cooked,boiled, drained 1/2 cup 30

Collards frozen, chopped, cooked,boiled, drained 1/2 cup 179

Collards cooked, boiled, drained,chopped 1/2 cup 133

Collards raw - chopped 1 cup 52 162

Kale raw - chopped 1 cup 90 13




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Kale frozen, cooked, boiled,drained, chopped

1/2 cup 90 40%59 36

Kale cooked, boiled, drained,chopped 1/2 cup 47

Mustard greens frozen,cooked, boiled, drained,chopped 1/2 cup 76 2263 40%63 30

Mustard greens raw, chopped 1 cup 58

Mustard greens cooked,boiled, drained, chopped 1/2 cup 52

Rhubarb frozen, cooked, withsugar 1/2 cup 174 41763 9.263 16

Spinach, cooked, boiled,drained, without salt 1/2 cup 122 29160 5.1%60 6

Spinach raw 1 cup 30 291

Turnip greens frozen, cooked,boiled 1/2 cup 125

Turnip greens raw, chopped 1 cup 105 28

Turnip greens cooked, boiled,drained, chopped 1/2 cup 99

Watercress raw, chopped 1 cup 41 105

Other

Almonds dry roasted, wholekernels 1/4 cup 92 21%E, 66 19

Hummus commercial 2 tablespoon 11

Molasses 1 tablespoon 41

Navy beans mature seeds,cooked, boiled 1/2 cup 63

Refried beans canned,vegetarian 1/2 cup 42 17%E, 66 7

Tahini from roasted andtoasted sesame seed kernels 1 tablespoon 64 21%E, 66 13

ACalcium and oxalate amounts do not match the amounts used in the absorption study servings.Calcium to oxalate ratios in the studies were used to determine the oxalate amounts listed in the tablebased on the calcium amounts listed in the USDA Nutrient Database for the common serving size.EEstimated

Calcium Tips

Many non-dairy milks are now fortified with calcium, vitamin D, and/or vitamin B12. Many orange juicesare fortified with calcium.

Calcium supplements can inhibit iron absorption if eaten at the same time. (4).

In addition to the calcium in the leafy greens listed on the right, leafy greens also contain vitamin K, whichis good for bones.

The Daily Value for calcium on food labels is 1,000 mg. Therefore, if a food label says it has 25% of thedaily value, it means it has 250 mg of calcium per serving.

Conclus ion on Calcium and Vegan Diets

There is no reason to think that vegans are protected from osteoporosis more than other diet groups, and theyshould strive to meet calcium recommendations. Although it is possible to meet the calcium recommendations byeating greens alone (see chart below), the average vegan probably will not meet recommendations withoutdrinking a glass of fortified drink each day, eating calcium-set tofu, or taking a 250 - 300 mg supplement (inaddition to eating an otherwise balanced diet). Although it is important to get enough calcium, do not get morethan 1,400 mg of calcium per day.




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Table 12. Average Vitamin D Levels in EPIC-Oxford36

Diet nmol/l

Non-Veg 76.4

Pesco 74.3

Lacto-Ovo 66.9

Vegan 55.9

Adjusted for season and year of blood sample collection and age.

Table 11. Average Vitamin D Levels in Adventist Health Study -221

Diet Whites(nmol/l) Blacks(nmol/l)

Non-Veg 78.6 51.5

Partial Vegb 77.3 52.6

Vegetariana 76.8 48.7

aIncluded lacto-ovo-vegetarians and vegans. | bIncluded semivegetarians (ate meat and fish


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Sunshine

For many years, people thought that extra amounts of vitamin D made by the sun during the summer could bestored in the body and used during the winter. But it is important to remember that these days many of us spendvery little time in the sun without sunscreen.

On average, it appears that most people, including vegans, are sustaining vitamin D levels over the winter thatthe Institute of Medicine considers healthy. In some cases, they are not.

For example, in a 2000 experiment, vegans in Finland were not able to maintain healthy levels of vitamin Dduring the winter (8). A follow-up study found an increase in lumbar spine density in 4 out of the 5 vegans who

took 5 g (200 IU) per day of vitamin D2 for 11 months (3). A dose of 5 g (200 IU) per day was also required tokeep vitamin D levels above 40 nmol/l (16 ng/ml) in Ireland during the winter (27).

It should be noted that the American Academy of Dermatology urges people not to get vitamin D via sunshinebecause of the increased risk of cancer (38). That said, not all researchers recommend complete avoidance ofthe sun.

According to Dr. J acqueline Chan, increasing the surface of the skin exposed to the sun proportionatelydecreases the amount of time needed in the sun to produce the same amount of vitamin D. The duration of thesun exposure should be no more than about half the amount of time it takes for the skin to turn pink (38). Dr.Chan also says that in order to make vitamin D, "The sun must shine directly on skin without being blocked bysunscreen, glass and most plastics. Glass and most plastics block UVB, the part of the spectrum that convertspro-vitamin D3 but allow passage of UVA which contributes to skin cancer." (38)

Dark Skinned People

An article in USA Today,Your Health: Skin co lor matters i n the vitamin D debate (updated 4/19/2009),quotes vitamin D researcher Dr. Michael Holick as saying:

"Though someone in Boston with pale skin can get adequate vitamin D by exposing their arms and legs tothe sun for 10 to 15 minutes twice a week in the summer, someone with the darkest skin might need twohours of exposure each time[.]"

This was the most specific statement I could find by a vitamin D researcher on how much sun a dark-skinnedperson needs to produce adequate vitamin D. As Holick notes in the article, this much sun is impractical andcould cause skin cancer. While dark-skinned people have lower rates of skin cancer than whites, they are morelikely to get diagnosed past the time that the cancer can be cured.

It is probably best for dark-skinned people to rely on vitamin D supplements rather than exposing themselves tothe sun for more than a few minutes at a time. Monitoring vitamin D levels, if possible, would be ideal for knowingif supplements are needed.

Older People

Elderly people need 30 minutes a day of direct sunlight in order to produce adequate vitamin D ( 23).

A 2009 study from Ireland of people aged 64 years or older showed that 5 mcg (200 IU) per day was needed to

keep most of the participants' vitamin D levels above 40 nmol/l (16 ng/ml) over the winter (based on the lowerstandard deviation; 22).

The abstract of a 1982 study indicates that a daily dose of 11.2 g (450 IU) of vitamin D2 was able to increasevitamin D levels in elderly subjects (24)

Tanning Beds

Some tanning beds can produce vitamin D with the type of UV rays they emit, but most do not. Experts generallyrecommend against using tanning beds to produces vitamin D because of their inefficiency and an increased riskof skin cancer. Click here for more information on tanning beds, vitamin D, and skin cancer.

Test Kit

The Vitamin D Council has partnered with ZRT Labs to make a discounted take-home vitamin D test kitavailable (for $65 as of April 2010).

Vitamin D3 vs. Vitamin D2

There are two types of vitamin D supplements:

Vitamin D3 - cholecalciferol

Derived from animals (usually from sheep's wool or fish oil). It is the form of vitamin D produced inthe skin when exposed to UV rays.

There is now a brand of vegan vitamin D3 on the market, manufactured by Vitashine (more info).

Other companies claim to produce a vegan D3 but none have been verified to my satisfaction or bythe UK Vegan Society (more info).

Vitamin D2 - ergocalciferol

Obtained by exposing yeast (18) or mushrooms to UV rays.

The original version of vitamin D used to treat cases of rickets.




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Some vitamin D blood tests only measure vitamin D3, so make sure that if you're taking vitaminD2, any blood test you get can measure D2. (More information at Mayo Clinic.)

There has been a long-running debate on whether vitamin D3 supplements are more effective than vitamin D2.The research has been trickling in since 1998, and in 2012 a thorough meta-analysis by Tripkovic et al. waspublished making some things clear (53):

In large boluses of 50,000 IU or more, vitamin D3 is much more effective than D2 at raising andmaintaining vitamin D levels.

In daily amounts of 1,000 to 4,000 IU per day, vitamin D3 is somewhat better than D2 at raising vitaminD3 levels.

There are some things to consider regarding this research, but first we need some background on vitamin D.

Vitamin D2 and D3 are not biologically active. Once ingested or created in the skin, in order to becomebiologically active, they have to be converted to the hormone, calcitriol. The first step in this process is for theliver to convert the vitamin into 25-hydroxyvitamin D, also known as 25(OH)D. When we talk about "vitamin Dlevels" going up or down, we are talking about the 25-hydroxyvitamin D. Then, when the body senses a need formore calcitriol, the kidney converts 25-hydroxyvitamin D into calcitriol.

Throughout this process, the part of vitamin D that distinguishes D2 from D3, also known as theside chain, staysattached to the molecule. So, calcitriol is either calcitriol-D2 or calcitriol-D3, and to our knowledge there is nodifference in biological activity. However, there is a theory that once converted into calcitriol and then degraded,the calcitriol-D3 can be retroconverted back into 25-hydroxyvitamin D3, but the D2 version of calcitriol cannot beretroconverted or cannot be at nearly the rate of D3. This could explain why infrequent, large boluses of vitaminD2 quickly disappear from the system the vitamin D is converted to calcitriol, used, and then degraded withoutreplenishing the 25-hydroxyvitamin D.

There are some other things to consider about the research comparing D2 to D3, the most important of which isthatvitamin D2 is probably adequate for most people. Even though D3 might increase vitamin D levelssomewhat better than D2, D2 still increases the levels well into and beyond the range that is considered optimalby the Institute of Medicine.

Additionally, much of the research is done on people who already have adequate vitamin D levels. For example,in one of the more recent studies that was included in the meta-analysis mentioned above, a 2011 study byBinkley et al. (54), the average vitamin D levels started out above 72 nmol/l (29 ng/dl) which is well aboveadequate levels of 50 nmol/l (20 ng/ml) recommended by the Institute of Medicine. It could very well be that atlevels this high, the degrading of the vitamin D2 is of no concern (unless someone goes a long time withoutbeing able to replenish stores).

All studies in the meta-analysis used vitamin D doses much higher than the DRI of 600 IU per day. At dosescloser to the DRI, in people who have low vitamin D levels, it's possible that vitamin D2 and D3 might be virtuallyindistinguishable in their ability to raise vitamin D back to healthy levels.

Finally, there is some anecdotal evidence. Although I have heard from some vegans who have had a hard timeraising their vitamin D levels using D2, many others have succeeded. For example, in J une 2010, a vegan whohad been diagnosed with vitamin D deficiency wrote me saying that his weekly 50,000 IU of vitamin D2prescribed by his doctor for 12 weeks succeeded in raising his vitamin D levels from 32.5 nmol/l (13 ng/ml) in

J anuary to 180 nmol/l (72 ng/ml) in May. For long-term maintenance, his doctor recommended 1200 IU per day. Iheard from another person in December 2010 who raised her levels from 30 to 67 nmol/l (8.1 to 27 ng/ml) with4,000 IU of vitamin D2 per day for 2 months.

For those vegans whose vitamin D levels do not respond well to vitamin D2, there is a vegan vitamin D3supplement available from Vitashine, mentioned at the top of this section.

For historical purposes and because some people might want more details, I have left in the research Ipreviously discussed regarding D2 vs. D3 directly below, but I have already hit the important points above andyou can click here to skip t his research .

Dr. J acqueline Chan sums up the studies on vitamin D2 vs. D3, "Treatment for most of the studies finding D2to be less effective than D3 were extremely large boluses given only once, whereas in studies finding themequally effective, the treatment was daily amounts between 400 and 2,000 IU (38)." More recently, a studywas published in which large boluses were given repeatedly, on a weekly basis, and D3 increased vitamin Dlevels more than did D2 (25). Details on this study are provided below, and it does not change my view thatvitamin D2 taken consistently should be adequate for most people.

In a 2011 study from Germany, 28,000 IU of vitamin D2 was fed to subjects either in the form of a supplementor from mushrooms, one time per week for four weeks. Vitamin D levels increased from 34 to 57 nmol/l in themushroom group, and from 29 to 58 nmol/l in the supplement group. The placebo group's vitamin D2 levelsdecreased over the course of the study (2).

In a 2004 study by Armas et al. (17), subjects were given one dose of 50,000 IU of vitamin D2 or vitamin D3.Vitamin D2 was absorbed just as well as vitamin D3. However, after three days, blood levels of 25(OH)Dstarted dropping rapidly in the subjects who were given vitamin D2, whereas those who received vitamin D3sustained high levels for two weeks before dropping gradually.

Similarly, a 2011 study by Heaney found that a weekly dose of 55,000 IU of vitamin D3 raised vitamin D levelssignificantly better than did a weekly dose of 48,000 IU of vitamin D2 (25). The differences in the amountsgiven were not enough to explain the discrepancy between the increases in vitamin D3. However, some thingsshould be noted. 25(OH)D levels for the D2 group started out at 76.5 nmol/l (30.6 ng/ml), while those in the D3group started out with levels at 65.0 nmol/l (26.0 ng/ml). In other words, both groups were already replete




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(according to the Institute of Medicine). The 25(OH)D levels in the D2 group increased to about 130 nmol/l (50ng/ml) over the course of the study. Finally, two of the authors have financial ties to BTR Group, Inc., amanufacturer of Maximum D3. That is not to say that any data was fudged, just that financial ties can possiblybias one's perspectives.

Trang et al. (19) (1998) found that a daily dose of 4,000 IU of vitamin D3 for two weeks was 1.7 times moreeffective in raising 25(OH)D levels (which increased 22.5 5 nmol/l (9.0 2 ng/ml)) than 4,000 IU of vitaminD2 (which increased levels 10.5 5 nmol/l (4.2 2 ng/ml)).

Holick et al. (18) (2007) found that a daily dose of 1,000 IU of vitamin D2 over 11 weeks increased 25(OH)Dlevels from 42 to 67 nmol/l (16.9 to 26.8 ng/ml). Vitamin D3 increased levels similarly, from 49 to 72 nmol/l

(19.6 to 28.9 ng/ml). It took 6 weeks for 25(OH)D levels to plateau on that regimen. The study was conductedin Boston and started in February.

Glendenning et al. (39) (2009) compared 1,000 IU of D2 vs. D3 in people with vitamin D insufficiency who hadhip fractures. After three months, those who supplemented with D3 had a 31% or 52% (depending on howthey were measured) greater increase in 25(OH)D levels than those supplementing with D2. However,parathyroid hormone levels (which can cause bone loss) did not differ between groups, leading theresearchers to question whether the difference in 25(OH)D levels were of biological importance.

Gordon et al. (40) (2008), treated 40 infants and toddlers with vitamin D deficiency. Each were assigned toone of three 6-week regimens: 2,000 IU oral vitamin D2 daily, 50,000 IU vitamin D2 weekly, or 2,000 IUvitamin D3 daily. At the end of the trial, participants' 25(OH)D levels went from an average of 42.5 to 90 nmol/l(17 to 36 ng/ml), and there were no significant differences between treatment groups.

Thatcher et al. (41) (2009) gave children with rickets one oral dose of 50,000 IU of vitamin D2 or D3. Afterthree days, 25(OH)D levels rose from approximately 50 to 72 nmol/l (20 to 29 ng/ml) for both groups. Calcitriol(the actual vitamin D hormone) levels also increased similarly in both groups (by about 70%), however,calcium absorption did not increase, leading the researchers to conclude the rickets were not caused byvitamin D deficiency. This should not be a surprise since the baseline average level of 50 nmol/l (20 ng/ml) of

25(OH)D should be adequate to prevent rickets.

Biancuzzo et al. (42) (2010) tested changes in 25(OH)D from a daily dose of 1,000 IU of vitamin D2 or D3from either orange juice or supplement capsules for 11 weeks at the end of winter. The placebo groupreceived nothing and their 25(OH)D levels decreased slightly. The average 25(OH)D levels of the other fourgroups (D2 from orange juice, D2 from capsules, D3 from orange juice, D3 from capsules) went up about 25nmol/l (10 ng/ml) with no significant differences between groups.

Vitamin D Supplements and Meals

Because vitamin D is a fat soluble vitamin, taking vitamin D supplements with foods that contain fat mightincrease absorption.

A 2010 study explored this (50). A group of people diagnosed with vitamin D deficiency had been prescribedsupplements (some D2 and some D3) and were being monitored by the Cleveland Clinic Foundation BoneClinic. Some of these patients' vitamin D levels had not increased to desired levels. Patients with stubbornvitamin D levels were then instructed to take the vitamin D with meals. After 2 to 3 months of taking with meals,the average vitamin D level went from 30 to 47 ng/ml (75 to 117 nmol/l).

This study had no control group, so it is not clear that the vitamin D levels increased due to taking with meals. Itcould have been simply because their levels took longer to respond to supplements or because they wereexposed to more sunlight during the meal period (the time of year studied was not reported). It should also benoted that even though these subjects' vitamin D levels were more stubborn than other patients, their levels atthe beginning of the study were well above those recommended by the Institute of Medicine; the stubborn levelsmight have been a result of the body regulating vitamin D once it had reached an ideal level rather than aninability to absorb it.

Vitamin D2 in UV Treated Mushrooms

Food manufacturers are now creating large amounts of vitamin D2 in mushrooms by exposing them tocommercial ultraviolet light or direct sunlight (55, 56). The vitamin D is well-retained in the mushrooms over thecourse of the typical storage life of fresh mushrooms, up to two weeks (55, 57). This vitamin D is effective inimproving vitamin D status and no different from a vitamin D2 supplement (2).

Vitamin D in Fortified Foods

The Daily Value for vitamin D is 10 mcg (400 IU). Therefore, if a food label says it has 25% of the dailyvalue, it means it has 2.5 mcg (100 IU) per serving.

Vitamin D fortified soy, almond, or rice milk normally has 2-3 mcg (80-120 IU) per cup.

References

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2. Urbain P, Singler F, Ihorst G, Biesalski HK, Bertz H. Bioavailability of vitamin D from UV-B-irradiated buttonmushrooms in healthy adults deficient in serum 25-hydroxyvitamin D: a randomized controlled trial. Eur J Clin Nutr. 2011Aug;65(8):965-71. doi: 10.1038/ejcn.2011.53. Epub 2011 May 4. | link




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3. Outila TA, Lamberg-Allardt CJ . Ergocalciferol supplementation may positively affect lumbar spine bone mineral densityof vegans. J Am Diet Assoc 2000 Jun;100(6):629.

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6.Statistically significant means that the finding had at least a 95% likelihood of not being due to random chance. At least95% is the level necessary to be considered a true association.

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8. Outila TA, Karkkainen MU, Seppanen RH, Lamberg-Allardt CJ . Dietary intake of vitamin D in premenopausal, healthyvegans was insufficient to maintain concentrations of serum 25-hydroxyvitamin D and intact parathyroid hormone withinnormal ranges during the winter in Finland. J Am Diet Assoc. 2000 Apr;100(4):434-41.

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13. Parsons TJ , van Dusseldorp M, van der Vliet M, van de Werken K, Schaafsma G, van Staveren WA. Reduced bonemass in Dutch adolescents fed a macrobiotic diet in early life. J Bone Miner Res 1997 Sep;12(9):1486-94.

14. Appleby P, Roddam A, Allen N, Key T. Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford. Eur J Clin Nutr. 2007 Dec;61(12):1400-6. Epub 2007 Feb 7.

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16. Schwalfenberg G. Not enough vitamin D: health consequences for Canadians. Can Fam Physician. 2007 May;53(5):841-54.

17. Armas LA, Hollis BW, Heaney RP. Vitamin D2 is much less effective than vitamin D3 in humans. J Clin EndocrinolMetab. 2004 Nov;89(11):5387-91.

18. Holick MF, Biancuzzo RM, Chen TC, Klein EK, Young A, Bibuld D, Reitz R, Salameh W, Ameri A, Tannenbaum AD.Vitamin D2 is as effective as vitamin D3 in maintaining circ ulating concentrations of 25-hydroxyvitamin D. 2008Mar;93(3):677-81. Epub 2007 Dec 18.

19. Trang HM, Cole DE, Rubin LA, Pierratos A, Siu S, Vieth R. Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2. Am J Clin Nutr. 1998 Oct;68(4):854-8. (Abstract)

20. Key TJ , Appleby PN, Spencer EA, Roddam AW, Neale RE, Allen NE. Calcium, diet and fracture risk: a prospectivestudy of 1898 incident f ractures among 34 696 British women and men. Public Health Nutr. 2007 Nov;10(11):1314-20.

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22. Cashman KD, Wallace JM, Horigan G, Hill TR, Barnes MS, Lucey AJ , Bonham MP, Taylor N, Duffy EM, Seamans K,Muldowney S, Fitzgerald AP, Flynn A, Strain J J , Kiely M. Estimation of the di etary requirement for vi tamin D in free-living adults >=64 y of age. Am J Clin Nutr. 2009 May;89(5):1366-74.

23. Reid IR, Gallagher DJ , Bosworth J . Prophylaxis against vitamin D deficiency in the elderly by regular sunlightexposure. Age Ageing. 1986 J an;15(1):35-40. (Abstract only.)

24. Toss G, Andersson R, Diffey BL, Fall PA, Larko O, Larsson L. Oral vitamin D and ultraviolet radiation for t heprevention of vitamin D deficiency in the elderly. Acta Med Scand. 1982;212(3):157-61. (Abstract only.)

25. Heaney RP, Recker RR, Grote J , Horst RL, Armas LA. Vitamin D(3) is more potent than vitamin D(2) in humans. J ClinEndocrinol Metab. 2011 Mar;96(3):E447-52. Link

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27. Cashman KD, Hill TR, Lucey AJ , Taylor N, Seamans KM, Muldowney S, Fitzgerald AP, F lynn A, Barnes MS, HoriganG, Bonham MP, Duffy EM, Strain J J , Wallace J M, Kiely M. Estimation of the di etary requirement for vitamin D inhealthy adults.Am J Clin Nutr. 2008 Dec;88(6):1535-42.

28. Calvez J , Poupin N, Chesneau C, Lassale C, Tom D. Protein intake, calcium balance and health consequences. EurJ Clin Nutr. 2012 Mar;66(3):281-95. | link

29. Kerstetter J E, O'Brien KO, Insogna KL. Dietary protein, calcium metabolism, and skeletal homeostasis revisited.Am J Clin Nutr. 2003 Sep;78(3 Suppl):584S-592S. Review.

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31. Bow CH, Cheung E, Cheung CL, Xiao SM, Loong C, Soong C, Tan KC, Luckey MM, Cauley J A, Fujiwara S, Kung AW.Ethnic difference of clinical vertebral fracture risk. Osteoporos Int. 2011 Apr 2. [Epub ahead of print] (Abstract) Link




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32. Ho-Pham LT, Nguyen ND, Nguyen TV. Effect of vegetarian diets on bone mineral density: a Bayesian meta-analysis. Am J Clin Nutr. 2009 Jul 1. [Epub ahead of print] PubMed PMID: 19571226.

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34. Krivosikova Z, Krajcovicova-Kudlackova M, Spustova V, Stefikova K, Valachovicova M, Blazicek P, Nemcova T. Theassociation between high plasma homocysteine levels and lower bone mineral density in Slovak w omen: theimpact of vegetarian diet. Eur J Nutr. 2009 Oct 7.

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36. Crowe FL, Steur M, Allen NE, Appleby PN, Travis RC, Key TJ . Plasma concentrations of 25-hydroxyvitamin D in meateaters, fish eaters, vegetarians and vegans: results from the EPIC-Oxford study. Public Health Nutr. 2011 Feb;14(2):340-6. Link

37. Michalsson K, Melhus H, Warensj Lemming E, Wolk A, Byberg L. Long term calcium intake and rates of all causeand cardiovascular mortality: community based prospective longitudinal cohort study. BMJ . 2013 Feb 12;346:f228. | link

38. Vitamin D Update for Nutrition Professionals. Chan J . Vegetarian Nutrition. Volume XVIII, Number 1 and 2, 2009:1.

39. Glendenning P, Chew GT, Seymour HM, Gillett MJ , Goldswain PR, Inderjeeth CA, Vasikaran SD, Taranto M, MuskAA, Fraser WD. Serum 25-hydroxyvitamin D levels i n vitamin D-insufficient hip fracture patients aftersupplementation with ergocalciferol and cholecalciferol. Bone. 2009 Nov;45(5):870-5. Epub 2009 J ul 23. (Abstract)

40. Gordon CM, Williams AL, Feldman HA, May J , Sinclair L, Vasquez A, Cox J E. Treatment of hypovitaminosis D ininfants and toddlers. J Clin Endocrinol Metab. 2008 J ul;93(7):2716-21. Epub 2008 Apr 15.

41. Thacher TD, Obadofin MO, O'Brien KO, Abrams SA. The effect of vitamin D2 and vitamin D3 on intestinal calciumabsorption in Nigerian children with rickets. J Clin Endocrinol Metab. 2009 Sep;94(9):3314-21. Epub 2009 Jun 30.

42. Biancuzzo RM, Young A, Bibuld D, Cai MH, Winter MR, Klein EK, Ameri A, Reitz R, Salameh W, Chen TC, Holick MF.Fortification of or ange juice with vitamin D(2) or vitamin D(3) is as effective as an oral supplement in maintainingvitamin D status in adults. Am J Clin Nutr. 2010 Jun;91(6):1621-6. Epub 2010 Apr 28.

43. Urashima M, Segawa T, Okazaki M, Kurihara M, Wada Y, Ida H. Randomized trial of vitamin D supplementation toprevent seasonal influenza A in schoolchildren. Am J Clin Nutr. 2010 May;91(5):1255-60. Epub 2010 Mar 10. Link

44. Holick MF, Chen TC. Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr. 2008Apr;87(4):1080S-6S. Review. Link

45. Manson J E, Mayne ST, Clinton SK. Vitamin D and prevention of cancer--ready for prime time? N Engl J Med. 2011Apr 14;364(15):1385-7. Link

46. Toner CD, Davis CD, Milner J A. The vitamin D and cancer conundrum: aiming at a moving target. J Am Diet Assoc.2010 Oct;110(10):1492-500. Link

47. The American Academy of Dermatology. Position Statement on Vitamin D. Amended by the Board of DirectorsDecember 22, 2010. Link

48. Fenton TR, Lyon AW, Eliasziw M, Tough SC, Hanley DA. Meta-analysis of the effect of the acid-ash hypothesis ofosteoporosis on calcium balance. J Bone Miner Res. 2009 Nov;24(11):1835-40. Link

49. Ho-Pham LT, Vu BQ, Lai TQ, Nguyen ND, Nguyen TV. Vegetarianism, bone loss, fracture and vitamin D: alongitudinal study in Asian vegans and non-vegans. Eur J Clin Nutr. 2011 Aug 3. [Epub ahead of print] Link

50. Mulligan GB, Licata A. Taking vitamin D with the largest meal improves absorption and results in higher serum levelsof 25-hydroxyvitamin D. J Bone Miner Res. 2010 Apr;25(4):928-30. Link

51. Strhle A, Waldmann A, Koschizke J , Leitzmann C, Hahn A. Diet-dependent net endogenous acid load of vegan dietsin relation to food groups and bone health-related nutrients: results from the German Vegan Study. Ann Nutr Metab.2011;59(2-4):117-26. Link

52. Herrmann W, Obeid R, Schorr H, Hbner U, Geisel J , Sand-Hill M, Ali N, Herrmann M. Enhanced bone metabolism invegetarians--the role of vitamin B12 deficiency. Clin Chem Lab Med. 2009;47(11):1381-7. | link

53. Tripkovic L, Lambert H, Hart K, Smith CP, Bucca G, Penson S, Chope G, Hyppnen E, Berry J , Vieth R, Lanham-NewS. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematicreview and meta-analysis. Am J Clin Nutr. 2012 J un;95(6):1357-64. | link

54. Binkley N, Gemar D, Engelke J , Gangnon R, Ramamurthy R, Krueger D, Drezner MK. Evaluation of ergocalciferol orcholecalciferol dosing, 1,600 IU daily or 50,000 IU monthly in older adults. J Clin Endocrinol Metab. 2011 Apr;96(4):981-8.| link

55. Kalaras MD, Beelman RB, Elias RJ . Effects of postharvest pulsed UV light treatment of white button mushrooms(Agaricus bisporus) on vitamin D2 content and quality attributes. J Agric Food Chem. 2012 J an 11;60(1):220-5. | link

56. Simon RR, Phillips KM, Horst RL, Munro IC. Vitamin D mushrooms: comparison of the composition of buttonmushrooms (Agaricus bisporus) treated postharvest with UVB light or sunlight. J Agric Food Chem. 2011 Aug 24;59(16):8724-32. | link

57. Roberts J S, Teichert A, McHugh TH. Vitamin D2 formation from post-harvest UV-B treatment of mushrooms (Agaricusbisporus) and retention during storage. J Agric Food Chem. 2008 J un 25;56(12):4541-4. | link

58. Samelson EJ , Booth SL, Fox CS, Tucker KL, Wang TJ , Hoffmann U, Cupples LA, O'Donnell CJ , Kiel DP. Calciumintake is not associated with increased coronary artery calcification: the Framingham Study. Am J Clin Nutr. 2012 Dec;96(6):1274-80. | link

59. Heaney RP, Weaver CM. Calcium absorption from kale. Am J Clin Nutr. 1990 Apr;51(4):656-7. | link




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60. Heaney RP, Weaver CM, Recker RR. Calcium absorbability from spinach. Am J Clin Nutr. 1988 Apr;47(4):707-9. | link

The oxalate content of spinach was calculated measured in this study to be 200 mg of Ca per 477.5 mg of oxalate. 1/2 cupof boiled spinach contains 122 mg of calcium per the USDA database and would, therefore contain

61. Zhao Y, Martin BR, Weaver CM. Calcium bioavailability of calcium carbonate fortified soymilk is equivalent to cow'smilk in young women. J Nutr. 2005 Oct;135(10):2379-82. | link

62. Tang AL, Walker KZ, Wilcox G, Strauss BJ , Ashton J F, Stojanovska L. Calcium absorption in Australian osteopenicpost-menopausal women: an acute comparative study of fortified soymilk to cows' milk. Asia Pac J Clin Nutr. 2010;19(2):243-9. | link

63. Weaver CM, Heaney RP , Nickel KP, Packard PI. Calcium Bioavailability from High Oxalate Vegetables: Chinese

Vegetables, Sweet Potatoes and Rhubarb. J ournal of Food Science. 1997 May;62(3):524-5. | link

64. Kenney J J . Diet and Kidney Stones. Originally posted 4/01/2002. Accessed 3/26/2013. | link

65. Oxalic Acid Content of Selected Vegetables | link. Gives amounts of oxalate in 100 g of the raw, unprepared food(according to correspondence with the USDA Nutrient Data Library 05/13/2013).

66. Weaver CM, Plawecki KL. Dietary calcium: adequacy of a vegetarian diet. Am J Clin Nutr. 1994 May;59(5Suppl):1238S-1241S. | link

Also Revi ewed

Aloia J F, Patel M, Dimaano R, Li-Ng M, Talwar SA, Mikhail M, Pollack S, Yeh J K. Vitamin D intake to attain a desiredserum 25-hydroxyvitamin D concentration. Am J Clin Nutr. 2008 J un;87(6):1952-8.

Dawson-Hughes B. Racial/ethnic considerations in making recommendations for vitamin D for adult and elderlymen and women. Am J Clin Nutr. 2004 Dec;80(6 Suppl):1763S-6S.

Fairweather-Tait SJ , J ohnson A, Eagles J , Ganatra S, Kennedy H, Gurr MI. Studies on calcium absorption from milk usinga double-label stable isotope technique. Br J Nutr. 1989 Sep;62(2):379-88. | link

Freedman BI, Wagenknecht LE, Hairston KG, Bowden DW, Carr J J , Hightower RC, Gordon EJ , Xu J , Langefeld CD,Divers J . Vitamin d, adiposity, and calcified atherosclerotic plaque in african-americans. J Clin Endocrinol Metab.2010 Mar;95(3):1076-83. Epub 2010 Jan 8. (Abstract)

Harris SS. Vitamin D and African Americans. J Nutr. 2006 Apr;136(4):1126-9. PubMed Abstract.

Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ . Human serum 25-hydroxycholecalciferol response toextended oral dosing with cholecalciferol. Am J Clin Nutr. 2003 J an;77(1):204-10.

Houghton LA, Vieth R. The case against ergocalciferol (vitamin D2) as a vitamin supplement. Am J Clin Nutr. 2006Oct;84(4):694-7.

This paper argued that vitamin D2 should not be used for fortification or supplementation. The authors state:

"Vitamin D2, if given in high enough doses, prevents infantile rickets and is capable of healing adult osteomalacia.However, the inefficiency of vitamin D2 compared with vitamin D3, on a per mole basis, at increasing 25(OH)D is nowwell documented, and no successful clinical trials to date have shown that vitamin D2 prevents fractures (19 - 21, 47)."

But references 19-21 were not studies looking at whether D2 prevents fractures. They include references 19 (Trang etal.) and 17 (Aramas, et al.) cited above, as well as this study:

Mastaglia SR, Mautalen CA, Parisi MS, Oliveri B. Vitamin D2 dose required to rapidly increase 25OHD levels inosteoporotic women. Eur J Clin Nutr. 2006 May;60(5):681-7.

Their final citation was a book on vitamin D from 1985, and though I'm not certain, I'm skeptical that it includes anystudies comparing D2 and D3's affects on bone fractures:

Norman AW, Schaefer K, Grigoleit H-G, Vaamonde J , eds. Vitamin D, chemical, biochemical and clinical update.Berlin, Germany: Walter deGruyter, 1985;3-12

Romagnoli E, Mascia ML, Cipriani C, Fassino V, Mazzei F, D'Erasmo E, Carnevale V, Scillitani A, Minisola S. Short andlong-term variations in serum calciotropic hormones after a single very large dose of ergocalciferol (vitamin D2)or chol ecalciferol (vitamin D3) in the elderly. J Clin Endocrinol Metab. 2008 Aug;93(8):3015-20. Epub 2008 May 20.


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