Nutritional Supplements: Too Much of a Good Thing
Perhaps more alarming to many of you is not the left side of the curve, but rather its right side. I realize that many of you may be taking high doses of B and antioxidant vitamins because you think they provide protection from cancer and heart disease. Nothing could be further from the truth, and in fact this practice will increase your risk of dying from cancer, heart disease and all causes combined. Except for fish oil and vitamin D, supplementation is a total waste of your time and money. It’s high time to dismantle the myth of nutrient supplementation as our guiding light to health and well-being and replace it with the truth of nutrient dense, “real” foods.24, 30
Folic acid supplementation and fortification
I have previously written an extensive blog post on folic acid supplementation. Starting in 1998 the U.S. Food and Drug Administration mandated that all enriched wheat flour was to be fortified with folic acid. Because most commercial wheat products (breakfast cereals, bread, cookies, cakes, crackers, doughnuts, pizza crust, hamburger and hotdog buns, wheat tortillas etc.) are made with enriched wheat flour, essentially the entire U.S. population began to consume folic acid in 1998. As I and others have pointed out this practice produced marginal reductions in neural tube defects, but moreover increased the risk for breast, prostate and colorectal cancers for the entire U.S. population.
Antioxidant Supplements do More Harm than Good
Of all the supplements people take, antioxidants are one of the most popular, particularly with seniors and cancer patients. The most commonly supplemented antioxidants are beta carotene, vitamin A, vitamin C, vitamin E and selenium. About 11% of the U.S. population supplement their diets with antioxidants on a daily basis, whereas this number rises to almost 20% in adults 55 years of age and older.27 A near universal perception with most antioxidant consumers is that these nutrients increase longevity and may prevent cancer, heart disease and whatever else ails them.34, 35 It goes without saying – more is almost always thought to be better.
Let’s examine the “U” shaped curve once again. If people are deficient in these nutrients, there is little doubt that health will suffer. On the other hand more is definitely not better. Biological systems, like our bodies operate optimally when nutrients are supplied to them in the ranges for which they were designed. If you underinflate a tire, your car performs poorly – if you overinflate it, the tire ruptures. Just like tires, our body’s natural defense against disease as well as the rate it ages is dependent upon just the right amount of antioxidants from our diet – not too little, but also not too much. I invoke the “U” shape curve and Paracelsus once again, “dose makes the poison.”
The idea behind antioxidant supplements is that they capture and inactivate free radicals. These are highly reactive particles formed within our tissues as byproducts of metabolism. Excessive free radicals may damage cells and tissues in many ways. In animal experiments, high free radical production can promote cancer, heart disease and premature aging. Our bodies use dietary antioxidants to disarm free radicals and thereby prevent damage to cells. We also manufacture antioxidants within our bodies which work together with dietary antioxidants to keep free radicals at bay.
An often overlooked fact when it comes to free radicals is that they are necessary components of normal body function and a healthy immune system. Free radicals are used by the immune system to destroy cancer cells, kill invading microorganisms and detoxify cells. If we overload our bodies with massive doses of antioxidants, these essential functions are impaired as normal free radical activity is suppressed. Alternatively, supra normal doses of antioxidant vitamins upset other delicate aspects of cellular machinery which can actually turn antioxidants into pro-oxidants and ultimately increase free radical activity.
In 1994 one of the first inklings that high doses of antioxidants may be harmful surfaced with the completion of the ATBC study, a randomized, placebo controlled experiment of 29,133 male smokers.2 The idea behind this experiment was to determine if beta carotene or vitamin E supplementation could reduce lung cancer incidence in this group of heavy smokers. Following 5 – 8 years of supplementation, the researchers were shocked – treatment with beta carotene actually increased lung cancer rates by 16 –18% and overall death rates by 8%. Further, the men taking vitamin E suffered more hemorrhagic stroke than those taking placebo pills.2 A similar randomized placebo controlled trial known as the CARET study had been on-going concurrently with the ATBC study. In the CARET trial smokers and former smokers received beta carotene (20 mg) in combination with high doses of vitamin A (25,000 I.U.) for an average of five years.31 The men who received the antioxidants experienced a 28 % greater incidence in lung cancer and a 17% higher death rate than those taking an inert placebo pill. The CARET trial was immediately stopped when the results of the ATBC trial were reported.
In the years since the ATBC and CARET trials, more convincing data have verified the harmful effects of antioxidant supplementation. A 2007 meta analysis of 67 randomized controlled trials studies involving 232,606 participants showed that supplementation with either vitamin E, beta carotene, or vitamin A increased overall death rates.5 In 2008, a large randomized controlled trial (The SELECT study) of vitamin E and selenium supplementation in 35,533 men was prematurely halted when it was discovered that these two antioxidants increased the risk for prostate cancer and type 2 diabetes.23 A large m eta analysis involving 20 randomized controlled trials and 211,818 subjects revealed antioxidant supplementation (beta carotene, vitamin A, vitamin C, vitamin E and selenium) did not protect against gastrointestinal cancer, but rather increased overall death rates.3
A series of recent meta analyses (combined results from many studies) show that high vitamin E intake may be particularly dangerous. Dr. Miller and colleagues at Johns Hopkins School of Medicine analyzed 19 randomized trials that included more than 136,000 subjects and stated, “High-dosage (> or =400 IU/d) vitamin E supplements may increase all-cause mortality and should be avoided.” 28 In a meta analysis of 118,765 people and 9 randomized controlled trials evaluating the effects of vitamin E on stroke, Dr. Schurks and co-workers at Harvard Medical School concluded, “In this meta analysis, vitamin E increased the risk for haemorrhagic stroke by 22% . . . indiscriminate widespread use of vitamin E should be cautioned against.”37
Even the once acclaimed and vaunted vitamin C may have little therapeutic value for cancer or heart disease. In The Physicians' Health Study, a randomized, placebo-controlled trial of vitamins E and C in 14,641 male doctors, the authors summarized, “. . . neither vitamin E nor C supplementation reduced the risk of prostate or total cancer. These data provide no support for the use of these supplements for the prevention of cancer in middle-aged and older men.”14 The situation for cardiovascular and vitamin C and other antioxidants appears to be the same as for cancer – they are a waste of your money as Dr. Bleys and colleagues have demonstrated in a meta analysis of 11 randomized controlled trials. His concluding remarks were as follows: “Our meta-analysis showed no evidence of a protective effect of antioxidant vitamin-mineral or B vitamin supplementation on the progression of atherosclerosis. . . Our findings add to recent skepticism about the presumed beneficial effects of vitamin-mineral supplementation on clinical cardiovascular endpoints.”7
Here’s one final point regarding vitamin C supplementation that may be of interest. If you are an athlete a series of recent human and animal experiments suggest that mega doses of vitamin C may have detrimental effects upon your performance.12, 15, 33 Surprisingly, supplementation with vitamin C may decrease training efficiency, cancel beneficial effects of exercise on insulin sensitivity, and delay healing after exercise. In addition, vitamin C supplementation did not decrease free radical damage to DNA that may occur following exercise18
These kinds of studies further cement the notion that fitness, vitality and well-being can never be achieved by single isolated nutrients, supplements or fortified foods. In fact, the available evidence conclusively shows these compounds are harmful by causing nutritional imbalances within our bodies.4, 6 The Paleo Diet has never been about supplements, but rather about real, wholesome living foods.
A closing thought. Supplementation can also be hazardous to our children’s health as well. A number of studies have demonstrated that multivitamin supplementation29 increases the risk for food allergies and asthma as do supplements of vitamin A, D, E and C.17, 22
Cordially,
Loren Cordain, Ph.D., Professor Emeritus
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