Tuesday, August 14, 2012

What's the Most Important Antioxidant?

That's a trick question. There isn't one! For over a generation scientists have told us that antioxidant status has a major role in the development of chronic diseases such as cancer and cataracts, diabetes and heart disease, high blood pressure, and, of course, obesity. Conventional wisdom, common sense, and many of our mothers have taught us to eat our vegetables and to avoid processed foods, but medical researchers have failed time and time again to find the “magic bullet” in plant foods that cures disease. Even more alarmingly,
in the 1990s, researchers even found that taking a single plant nutrient (beta-carotene for prevention of lung cancers in smokers) might cause more problems than it cures.

One reason for the disappointments in the clinical trials of single antioxidants may be that the protective effects of fruits and vegetables result from the action of lesser-known antioxidants combined in a kind of cocktail with better-known nutrients such as beta-carotene, vitamin C, vitamin E or coenzyme Q10.

The human body is not a grinding machine that churns all incoming nutrients on a list of antioxidants into a homogeneous soup. Its tissues, organs, cells, and macromolecules are organized in exquisite and practically infinite variation.

The mere fact that our bodies are composed of cells rather than a plastic baggie around a liquid soup requires that some part of our bodies rely on water-soluble nutrients and other parts rely on fat-soluble nutrients. Our bodies also contain proteins, which attract and use nutrients through a third electrostatic process. No single antioxidant is enough to support the entire body.

Another finding of relatively recent research is that antioxidants “recharge” each other. Laboratory research confirmed that vitamins C and E recharge each other, and consuming both vitamins is better than consuming just one. Scientists have also identified a recharging mechanism for lipoic acid and some of the more exotic forms of vitamin E.

Moreover, too much of one antioxidant can turn it into a pro-oxidant, a chemical acting in exactly the opposite way as desired. In healthy people, for instance, vitamin C is an antioxidant when it is consumed in quantities below about 170 mg a day and a pro-oxidant when it is consumed in quantities above 170 mg a day—although the vitamin continues to act as an antioxidant even when consumed in vastly greater quantities in bodies under stress.

Because antioxidants act in concert, our bodies do not require exact amounts. This is fortunate, because two plants grown in the same field in the same season typically have 2-15 percent variation in antioxidant content. The same plant foods grown at different times, stored in different ways, or originating in different countries or continents can have drastically different antioxidant content, on the order of 50 percent, sometimes more. It is never a good idea to rely on one food for all your requirements of antioxidants, any more than it is to rely on one antioxidant for treatment of a health condition.

This table is based on the work of researchers who looked specifically at the capacity of the antioxidant capacity of plant foods to act as antioxidant with regard to iron. There is a 100,000 percent difference between the highest and lowest antioxidant capacities of various plant foods.

Pomegranates, berries, fruits in the rose family (apples, cherries, strawberries), ginger, sunflower seeds, and walnuts have the highest antioxidant power. Generally speaking, the parts of plants involved in reproduction, that is, fruits and seeds, have the highest total antioxidant content, but processing seeds into grain products destroys antioxidants. The fact that a vegetable has a low antioxidant rating or is not on the list does not mean you should never eat it.

Carrots, for instance, have practically no antioxidant content, but the little antioxidant content they do have is almost entirely beta-carotene, for which they are a superior source. Tomatoes likewise are low in total antioxidant content, but they are terrific sources of lycopene.

Total Antioxidant Content of Selected Plant Foods (mmol/100 g)

Rose hips (dog rose) 39.46
Walnuts 20.97
Pomegranates 11.33
Crowberries 9.17
Blueberries (wild) 8.23
Blackcurrants 7.35
Strawberries (wild) 6.86
Cherries, sour 6.13
Sunflower seeds 5.39
Blueberries (cultivated) 3.79
Ginger 3.76
Dried fruit, apricots 3.24
Dried fruit, prunes 2.60
Chile peppers, Ancho 2.46
Kale 2.34
Strawberries (cultivated) 2.33
Buckwheat flour (whole grain) 1.99
Beets, red 1.98
Beans, fava 1.86
Red cabbage 1.86
Bell peppers, orange or yellow 1.85
Bell peppers, red or green 1.84
Grapes 1.45
Sesame seeds 1.21
Beans, pinto 1.14
Brussels sprouts 1.14
Oranges 1.14
Plums 1.14
Pineapples 1.04
Cherries, sweet 1.02
Dates 1.02
Lemons 1.02
Celery 0.85
Beans, soy 0.82
Papayas 0.82
Dried fruit, raisins 0.80
Potatoes, blue 0.80
Dried fruit, figs 0.76
Onions 0.69
Beans, black-eyed pea 0.65
Corn meal 0.60
Oats, steel-cut 0.60
Broccoli 0.58
Apricots, fresh 0.52
Wheat flour, whole wheat 0.49
Kaki/Sharon 0.43
Okra 0.41
Bean, mung 0.35
Lettuce 0.34
Bulgur 0.31
Tomatoes 0.31
Almonds 0.30
Apples 0.29
Turnips 0.29
Sweet potatoes 0.24
Cashews 0.23
Cauliflower 0.23
Rye flour 0.23
Wheat flour, white 0.23
Yucca 0.22
Pears 0.20
Cassava 0.17
Eggplant (Aubergine) 0.17
Manioc 0.17
Cantaloupes 0.15
Peas, English 0.12
Cabbage 0.10
Parsnips 0.09
Fennel 0.07
Cucumbers 0.05
s Carrots 0.04
Watermelon 0.04
Zucchini (Courgette) 0.02

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