BY

EHAB ABUSINNA

VITAMIN D DEFICIENCY

VITAMIN D

Fat-soluble vitamin

Sources Foods

Naturally found in very few foods

Added to many foods on the market

Supplements Sunlight

A QUICK REVIEW OF VITAMIN D METABOLISM

Vitamin D3 (cholecalciferol) is made in sun-exposed skin,or can be absorbed in the diet or as a supplement.

liver Vitamin D3 is converted into 25-OH vitamin D (calcidiol) in the liver. IIt can also be taken as an oral supplement.This is the form of the hormone we test for in the blood.

kidney 25-OH-vitamin D is converted to 1,25-OH vitamin D (calcitriol)

in the kidney. This is the active form of the hormone.

METABOLISM OF VITAMIN D

ACTION OF VITAMIN D

Vitamin D is a steroid hormone that primarily acts to increase transcription of vitamin D responsive genes primarily in the small intestine These genes mediate increased absorption of

calcium and phosphorous in the gut However, there is evidence that other cell

types express the vitamin D receptor Vitamin D plays a role in maintaining normal

neuromuscular function and immunity There is some evidence that vitamin D

regulates apoptosis, cell proliferation and inflammation as well

Involved in cellular growth, differentiation and apoptosis

Simulates insulin secretion

Modulates the immune system.

Reduces inflammation

Muscle development

VITAMIN D DEFICIENCY

Vitamin D deficiency causes osteomalacia in which bone mineralization is defective In children this causes rickets. A common presenting

syndrome is bowing of the legs In adults this causes fragility of the bones which can lead

to fractures

Other symptoms of vitamin D deficiency include diffuse body aches and muscle weakness

VITAMIN D DEFICIENCY

oSubclinical deficiencyoSilent epidemic.oPresent in approximately 30% to 50% of the general

population.oMore prevalent in elderly, women of child bearing age and

infants.oOften unrecognized by clinicians.oMay contribute to development of osteoporosis &

increased risk of fractures related to falls in the elderly.

CAUSES

Inadequate sun exposure Sunscreen Pigmented skin Aging (older than 65 years) Winter season

Decreased absorption Bowel bypass surgery Crohn’s disease Celiac disease Fat and cholesterol absorption inhibitors

OTHER CAUSES

Breastfeeding

Liver failure

Chronic renal disease

Medications; Steroids decrease half life of vitamin D. Dilantin, Phenobarbital, and Rifampin can induce hepatic p450 enzymes to accelerate the catabolism of vitamin D.

RISK FACTORS FOR VITAMIN D DEFICIENCY

Female gender

Age > 50

Minimal sun exposure

Dark skin

Fat malabsorption

Obesity

RISK FACTORS

Individuals older than 50 years

Nursing home residents

Individuals with non-vertebral or hip fractures

Individuals with kidney disease

Individuals with low bone mass or osteoporosis

Individuals with a history of falls

Breastfed infants

ASSOCIATED CLINICAL CONDITIONS

Muscle Weakness and Falls Proximal muscle weakness Chronic muscle aches Myopathy Increase in falls

Risk of osteoporosis may be reduced with adequate intake of vitamin D and calcium.

Studies support the concept that vitamin D at doses between 700 and 800 IU/d with calcium supplementation effectively increase hip bone density and reduced fracture risk, whereas lower vitamin D doses may have less effect.

BONE DENSITY AND FRACTURES

MODERN DAY INTEREST

Vitamin D & metabolites Significant role in calcium homeostasis & bone

metabolism

Deficiency Rickets in children Osteomalacia in adults

Rickets ? rare in most developed populations

Vitamin D supplementation is associated with a lower risk of autoimmune diseases.

In a Finnish birth cohort study of 10,821 children, supplementation with vitamin D at 2000 IU/d reduced the risk of type 1 diabetes by approximately 78%, whereas children who were at risk for rickets had a 3-fold higher risk for type 1 diabetes.

In a case-control study of 7 million US military personnel, high circulating levels of vitamin D were associated with a lower risk of multiple sclerosis.

Similar associations have also been described for vitamin D levels and rheumatoid arthritis.

AUTOIMMUNE DISEASE

Low intake of vitamin D and calcium has been associated with an increased risk of non-Hodgkin lymphomas, colon, ovarian, breast, prostate, and other cancers.

The anti-cancer activity of vitamin D is thought to

result from its role as a nuclear transcription factor that regulates cell growth, differentiation, apoptosis and a wide range of cellular mechanisms central to the development of cancer. These effects may be mediated through vitamin D receptors expressed in cancer cells.

Vitamin D is not currently recommended for reducing cancer risk

ROLE IN CANCER PREVENTION

VITAMIN D AND CANCER

Roles in prevention of Colon cancer Breast cancer

Role in Reproductive Health Vitamin D deficiency early in pregnancy is associated with

a five-fold increased risk of preeclampsia.

Role in All Cause Mortality Researchers concluded that having low levels of vitamin

D (<17.8 ng/mL) was independently associated with an increase in all-cause mortality in the general population.

Vitamin D deficiency activates the renin-angiotensin-aldosterone system and can predispose to hypertension and left ventricular hypertrophy.

Additionally, vitamin D deficiency causes an increase in parathyroid hormone, which increases insulin resistance secondary to down regulation of insulin receptors and is associated with diabetes,

hypertension, inflammation, and increased cardiovascular risk.

ROLE IN CARDIOVASCULAR DISEASES

TYPE 2 DIABETES

Altered vitamin D and calcium homeostasis may play a role in development of type 2 diabetes

Low serum levels of 25(OH)D are associated with impaired pancreatic β cell function and insulin resistance

High calcium intake is inversely associated with body weight

SOURCES OF VITAMIN D

Sunlight (UV)

Intestinal absorption (only ~20%) Oily fish Fortified milk / bread / cereal

Supplements

DIETARY SOURCES

Natural sources of vitamin D include:

Fish liver oils, such as cod liver oil, 1 Tbs (15 mL) provides 1,360 IU

Fatty fish species, such as: Herring, 85 g (3 ounces) provides 1383 IU Catfish, 85 g (3 oz) provides 425 IU Salmon, cooked, 100 g (3.5 oz]) provides 360 IU Mackerel, cooked, 100 g (3.5 oz]), 345 IU Sardines, canned in oil, drained, 50 g (1.75 oz), 250 IU Tuna, canned in oil, 85 g (3 oz), 200 IU Eel, cooked, 100 g (3.5 oz), 200 IU

A whole egg, provides 20 IU

Beef liver, cooked, 100 g (3.5 oz), provides 15 IU

FOOD SOURCES OF VITAMIN D

3 oz smoked salmon = 583 IU

3 oz light tuna, canned in oil = 229 IU

1 large, whole egg = 29 IU

FORTIFIED SOURCES

Some of the dietary sources: Fortified milk (100 IU/8 oz) Cheeses and yogurt Fortified cereals

DIETARY SUPPLEMENTS

Calcium Carbonate or citrateDose dependent absorptionTwo doses per day

Vitamin D

D2 or D3

D3 is best

TAKE HOME MESSAGE

There is considerable evidence to support vitamin D deficiency screening and supplementation in elderly individuals at risk for osteoporosis, falls and fractures.

Do all age, racial, geographic groups require the same vitamin D levels for general health?

Is widespread supplementation of vitamin D safe in all populations?

Would supplementation benefit younger people? Is it possible that some people have low calcidiol

levels, but adequate calcitriol levels and thus no adverse consequence to “low” vitamin D?

CONSEQUENCES OF VITAMIN D DEFICIENCY

o Reduced intestinal absorption of calcium & phosphorus

o Hypophosphataemia precedes hypocalciaemia

o Secondary hyperparathyroidism

o Bone demineralisation

o Osteomalacia / rickets

True or False. Vitamin D is not necessary for Calcium to be absorbed

in the body.

True or False Vitamin D is not necessary for Calcium to be absorbed

by the body.

WHERE DO WE GO FROM HERE?

o Routine screening

o Rectify deficiency / insufficiency

o Maintain levels through a patient-specific combination of diet, supplementation, and sun exposure

RECOMMENDATIONS

o Annual testing of 25(OH)D

o Consider time of year in testingo Lowest levels generally towards end of winter, early

spring

GOALS IN MAINTAINING VITAMIN D LEVELS

o Prevent disease of deficiency – rickets, osteomalaciao Prevent complications of insufficiency – impaired calcium

absorption and increased bone resorptiono Minimize risks of future disease – cancer,

cardiopulmonary diseases, diabetes, other immune-related diseases

VITAMIN D OVERVIEW

o It is a fat soluble vitamin.o Not just a vitamin it is a prehormoneo Found in some food and made in the body after

exposure to UV rayso Major biological function is to maintain normal

blood levels of Ca and Po4o Other tissues like macrophages, prostrate tissue

also have vit D receptor

CONCLUSION

o Commoner than we think!

o Can be prevented:o Promote awareness, especially in high-risk groupso Sun-exposure

o Safe, 10-15 minutes per day (longer with darker skin)

o Adequate intake of fortified products in diet

THANK YOU