superfoods or supermyths?

Nutrition @ DEAKIN

Superfoods or Supermyths?Associate Professor Tim Crowe

School of Exercise and Nutrition SciencesDeakin University

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tim.crowe@deakin.edu.au@CroweTimwww.thinkingnutrition.com.au

Nutrition @ DEAKIN

What is a ‘Superfood’?• Describes a food with a

high phytonutrient content(antioxidants, fibre, selenium,omega-3s etc.) that mayconfer health benefits

• Has no meaning among nutrition scientists• No legal definition of the term• More an over-used marketing tool• Most of the foods are fruits or vegetables

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Common ‘Superfoods’• Blueberries• Pomegranates• Wheatgrass• Goji• Noni• Mangosteen• Açai

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• Broccolli• Garlic• Pumpkin seeds• Tea• Soy• Coconut oil• Spirulina

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Goji Berry• Lycium barbarum or wolfberry, widely grown in Asia,

though most marketing focusses on Tibetan cultivars• Most research is in cellular and animal studies with

extrapolation made to humans• Claims relate to anti-cancer activity, aging, vision,

insulin resistance and infertility• Few clinical trials of any methodological quality in

humans – most only show improvements in anti-oxidant markers and subjective feelingsof ‘well-being’

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Goji• Common claims they have the highest level of

vitamin C of all plants (claims up to 500-times an orange!): completely false as has same vitamin C content as an orange

• “18 amino acids”• “Life extension” claims

• Can interfere with blood-clotting medications and increase bleeding risk

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• Cherry-sized purple berry fruit of the acai palm• Lab studies suggest it may have anti-cancer and anti-

inflammatory effects, as well as a possible use in treating heart disease

• No human studies on its health effects yet published• “Six times the antioxidant level of blueberries“• “It is a poster child of the power of the Internet to

promote products for which only limited phytochemical and pharmacological information is available” Heinrich M et al. Phytochemistry Letters 2011;4:10-21

Acai

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Noni• Lime-green Polynesian tropical fruit• Noni fruit and juice derivatives have shown

anti-tumour activity in rats and mice, but few clinical trials in humans

• Cancer patients given daily capsules containing noni fruit extract (not juice) no effect on tumour regression, but ↑ QoL Issell BF et al. J Clin Oncology 2005;23 (June 1 Supplement):8217

• Some evidence for ↓ post-operativenausea Prapaitrakool S et al. J Med Assoc Thai 2010;93:S204-9

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Wheatgrass• Claims: Blood cleanser and ‘detoxifier’

attributed to the 'natural plant enzymes‘and the chlorophyll content of the freshly-juiced grass

• Common claim that 30 mL shot of wheatgrass juice is nutritionally equivalent to a kilogram of vegetables is a complete myth – has similar nutrient content to broccoli and spinach

• Floret of broccoli, or tablespoon of spinach, contain more folic acid and vitamin C than 30 mL of wheatgrass juice

• Chlorophyll is not absorbed by the body, requires sunlight for activation, and its supposed high levels are no higher than other green vegetables

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Antioxidants

• Found in foods (especially fruit andvegetables) that protect the bodyfrom the harmful effects of free radicals

• Free radical damage linked to development of cancer, heart disease, Alzheimer’s and Parkinson’s, and is linked to the aging process

• Vitamins C, E and beta-carotene are the main vitamins with antioxidant properties are

• Other compounds also demonstrate antioxidant properties e.g. selenium and lycopene

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AntioxidantsTotal antioxidant capacity (TAC) measured using ORAC

(oxygen radical absorbance capacity) test

10Wu et al. J Agric Food Chem. 2004;52:4026-4037

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An Apple a Day

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Cost-Benefit Analysis• Five 30 mL serves of Noni Juice ($7.50) = 1 navel

orange• Five 30 mL serves of Goji ($10) = 1 red delicious apple• Three serves of Acai ($2) = 1 red delicious apple

On a serve-by-serve basis, many common fruits such as strawberries and apples, contain more antioxidants, and

are cheaper

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Why buy them?• Superfruit juices contain a range of nutrients, but

marketing spin vastly exaggerates their health benefits• Typically sold at high cost through multi-level marketing• Until better scientific evidence arises, cheaper and

wiser to get antioxidants from ‘traditional’ fruit and veg sourcesSince 1 July 2007, marketing of products as "superfoods" is prohibited in the European Union unless accompanied by a

specific medical claim supported by credible scientific research

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Eat your Fruit and Veggies• Hundreds of epidemiological studies linking F&V

consumption to ↓ risk of almost all major cancers• Effect not from one particular food, but a wide variety• ↑ F&V may decrease intake of more high-calorie foodsMechanism?• Antioxidants• Fibre• Polyphenols – antioxidant activity, inhibit cell

proliferation, phytoestrogenic activity• Isothiocyanates (cruciferous vegetables) – increase

solubilising and inactivating enzymes • Allium compounds (onions and garlic) – suppress DNA

synthesis, increase excretion14

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Proposed Mechanism of Action of Cruciferous Vegetables

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Top Foods to Consume

Literally thousands of natural chemicals in foods that can affect our health

There is no one ‘superfood’

Think ‘super diets’ instead

Should not focus on the effect of a single nutrient, but the total effect of food to health

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10. Yoghurt• Great source of calcium

• Low in fat and high quality protein

• Source of ‘good’ bacteria

• ‘Reduced-fat’ yoghurt may have more calories than regular yoghurt – check the labels!

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9. Lean Meat

• High-quality protein • Great source of zinc, iron and

vitamin B12• Choose lean cuts and grill or fry in a minimum

of oil and avoid charring• Eat less than 500 grams (cooked weight per

week)

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8. Dark Chocolate• Dark chocolate has typically 2-3 times

more cocoa as milk chocolate• Rich source of flavanols which are potent antioxidants• Clinical trials show it can

– ↓ blood pressure,– ↓oxidation of LDL-cholesterol– ↑blood flow (by causing relaxation of the muscles lining

blood vessel walls)– Improve the action of insulin

• Some evidence that regular eaters of cocoa- containing foods have lower rates of CVD

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7. Tomatoes

• Contain a powerful antioxidant – lycopene• Found in red/orange coloured fruit and veggies• May offer protection against prostate cancer

• Cooking makes the lycopene more available to the body (especially with a small amount of oil)

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6. Soy

• High-quality protein• Contains ‘isoflavones’ that have weak estrogen

activity• Lower breast cancer risk and good for post-

menopausal symptoms???• Soy found to lower LDL-cholesterol• Better evidence for soy than isoflavone supplements

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5. Tea

• Rich in flavonoids (a class of polyphenols that have antioxidant activity)

• May slow cancer growth and lower heart disease• Black and green tea both good, though greater

evidence for green tea for CVD• Some evidence of anti-depressant effects• Good source of ‘water’

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4. Nuts and Seeds• High in ‘good’ mono- and poly-

unsaturated fat• High in vitamin E• Good source of fibre and protein

• Associated with favourable body weight outcomes• Linked with CVD and diabetes protection

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3. Oats

• Good source of protein and B-groupvitamins and low in fat

• Great source of fibre (important for keeping blood sugar and cholesterol levels under control)

• Help with feelings of ‘fullness’ after a meal

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2. Fish• High in ‘omega-3’ fatty acids• Good sources: salmon, herring, sardines and

capsules• Edible bones for calcium• Offers protection against:

– Heart disease (stops blood from clotting, improves heart beat rhythm, lower blood fats)

– Rheumatoid arthritis (anti-inflammatory)– Mental health: depression, ADHD– Dementia , Alzheimer’s

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1. Cruciferous Vegetables

• Broccoli, cauliflower, turnips,Brussels sprouts, bok choy,cabbage, and radishes

• Broccoli: vitamins A, C, B group, and fibre

• Potent cancer protection: inactivate cancer-causing molecules and act as antioxidants

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