Interesting article from The Paleo Diet:
Unfortunately, many environmental, lifestyle, and pathological situations can allow excess free radicals to accumulate. This results in oxidative stress that has been related to cardiovascular disease, cancer, and other chronic diseases that now account for a major portion of deaths1, 2.
Antioxidants fight the damaging effects of free radicals
Antioxidants are compounds that hinder oxidative processes, delaying or preventing oxidative stress. By slowing or preventing oxidation of other molecules, antioxidants stop damaging effects of free radicals2.
The systems that protect cells from free radicals use multiple types of antioxidants. These include glutathione, beta-carotene, vitamin A, vitamin C, vitamin E, selenium, and zinc. Enzymes, such as catalase, superoxide dismutase, and various peroxidases are also used.
For more than five decades, studies aimed at determining the causes of aging have focused on oxidative stress due to free radicals, and the connection between oxidative stress and dietary antioxidants3-6. Low levels of antioxidants, or inhibition of antioxidant enzymes can cause oxidative stress and may damage or kill cells.
Research into how antioxidants affect disease is increasing
The research on antioxidant biochemistry is expanding at a rapid pace. Recent publications have examined hypoxia-inducible genes that protect against free radicals7, and links between selenium-poor soils. Free radicals and male infertility have also been studied8.
Other studies have looked at Kashin-Beck disease in central China9, antioxidant supplementation during chemotherapy for breast cancer10, and timing of black currant extract consumption11.
Invitro studies of multiple antioxidants suggest wide antioxidant network between water- and fat-soluble antioxidant nutrients in a biological system, although more studies are needed12.
Antioxidants in fruits and vegetables have been linked to reduced risk of cardiovascular disease in a Swedish study13. Likewise, increased consumption of fruits and vegetables protects against stroke14. The important antioxidant properties of polyphenols15 in fruits and vegetables16, 17 will be an area to watch as science progresses.
Dietary supplementation with antioxidants may do more harm than good
Consumption of antioxidant supplements has become widespread. It is estimated that about one third of adults in developed countries consume antioxidant supplements18.
The past decade has produced a large number of studies that assessed both the costs and benefits of antioxidant supplementation. Unfortunately, this research has shown that dietary supplementation with antioxidants may do more harm than good19-22.
For example, a meta-analysis (a scientific review combining results of related research) of antioxidant studies found that supplementation with beta-carotene, vitamin A, and vitamin E did not increase lifespan23-27.
In fact, some reviews have suggested antioxidant supplementation may increase the risk of early death. For example, a meta-analysis of supplementation with beta carotene, vitamin A, and vitamin E suggested an increase in overall mortality among people taking supplements23.
Surprisingly, supplementation with vitamin C has been shown to decrease training efficiency28, cancel beneficial effects of exercise on insulin sensitivity29, and delay healing after exercise30. In addition, vitamin C supplementation did not decrease free radical damage to DNA31.
A recent meta-analysis of clinical studies that focused on vitamin E supplementation also showed increased overall mortality in those taking vitamin E26. It should be noted, however, that the importance of the antioxidant properties of vitamin E at the concentrations present in the body are not clear. It is possible that vitamin E is required in the diet for reasons unrelated to its ability to act as an antioxidant32.
Concentrated, pure antioxidants were not part of our ancestral diet
Our Paleolithic ancestors had no access to concentrated forms of pure antioxidants like those in modern supplements. They got all their vitamins (including antioxidants) and minerals from food they hunted or gathered, or, in the case of vitamin D, from sunlight33, 34.
Given our present knowledge about the apparent lack of benefit from consuming antioxidants as supplements, it is probably best to get antioxidants from fruits and vegetables, especially those grown organically in healthy soils35, 36.
The Paleo Diet is good source of antioxidants
Fortunately, we can still get antioxidants from the foods we eat. Research shows that, aside from vitamin D, it is possible to consume a nutritionally balanced diet from contemporary foods that mimic the food groups and types available during the Paleolithic37.
With its high consumption of fruits and vegetables, the Paleo Diet provides optimum levels of vitamins and minerals as well as antioxidants. In this diet, vegetable consumption is unlimited, and fruit consumption is only limited by certain conditions, such as excess weight, insulin resistance, hypertension, metabolic syndrome, diabetes, kidney disease, and cardiovascular disease. For those who may need to limit fruits with a high sugar content, a table of fruits and sugars is available on our website.
Many of the Paleo Diet foods supply antioxidants. Vitamin C is available in parsley, kiwi fruit, broccoli, persimmon, papaya, strawberry and citrus fruits. Asparagus, avocado, eggs, almonds, and spinach are good sources of vitamin E. Selenium can be obtained from Brazil nuts, walnuts, and lean meats. Lean meats and nuts are also good sources of zinc38.
Liver is a good source of pre-formed vitamin A. There are plant sources of beta carotene, but not of preformed vitamin A. Recent evidence indicates that the conversion of beta carotene to vitamin A in the liver is inefficient in humans.
The Paleo Diet, along with sun exposure and vitamin D supplementation, will optimize our health because it is our evolutionary heritage. Following the Paleo Diet, with its focus on lean meats, fruits and vegetables, along with a sensible exercise program, will go a long way toward alleviating the chronic diseases that plague our Western culture.
Next time, we’ll take a look at current research that suggests the gut-brain connection plays an important role in IBS patients suffering from psychiatric diseases. We’ll also show you how to make breakfast (without a grain-based product like cereal, a bagel, or toast) a healthy way to start the day.
