|Vitamins C and E, beta-carotene and selenium are considered to be the most important dietary antioxidants. Vitamin-C is water-soluble while vitamin-E is fat-soluble. Lycopene, for example, is a carotenoid antioxidant which is more abundant in the human body than beta-carotene and is a far stronger antioxidant. Coenzyme Q10 (ubiquinone) is another fat-soluble antioxidant. It is known that oxidative stress adversely effects the function of the lining of the blood vessels (endothelial function) and may lead to vascular damage leading to blood vessel & heart disease. We also know that oxidized Low Density Lipoprotein (LDL) Cholesterol increases vascular damage and increases heart attack risk. In theory antioxidants should be of benefit in preventing vascular damage. While there have been a large number of studies with varying results; all the well controlled outcome studies have failed to show a benefit of anti-oxidants in prevention of cardiovascular events.
This was advocated for many years to prevent heart disease. The HOPE Study looked at the benefit of Vitamin E versus ramipril (Altace) or placebo in the prevention of death, heart attack or congestive failure in high risk patients. After 4 years of treatment, there was a highly significant (almost 30%) reduction in death, heart attacks & stroke in those subjects taking ramipril; there was absolutely no benefit in those subjects on Vitamin E (400 i.u.) Ref: Heart Outcomes Prevention Evaluation (Hope) Study Investigators. Effects of ramipril and Vitamin E on cardiovascular and microvascular outcomes in people with diabetes mellitus. Lancet. 2000;355:253-259.
A naturally occurring anti-oxidant which it was felt could prevent cardiovascular disease. The Heart Protection Study of the Medical Research Council in Great Britain investigataed this in a well organized statistically significant study of 20,536 individuals at risk of a cardiovascular event. While a statin (cholesterol lowering drug), reduced cardiac end points by 37%, there was no benefit from treatment with beta carotene and other antioxidants. Ref: Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high risk individuals. A randomized placebo controlled trial. Lancet. 2002;360-7:7-22.
Scientists first discovered ALA in the 1950s, and recognized it as an antioxidant in 1988. It has been the subject of research around the world, some being done at the University of California, Berkeley by Dr. Lester Packer, a leading expert on antioxidants. It is readily synthesized in the body and is well absorbed from the diet through the stomach and intestines. Liver and yeast are especially good dietary sources of ALA. The body needs ALA to produce energy. It plays a crucial role in the mitochondria, the energy-producing structures in cells. The body actually makes enough ALA for these basic metabolic functions. This compound acts as an antioxidant, however, only when there is an excess of it and it is in the "free" state in the cells. But there is little free ALA circulating in your body, unless you consume supplements or get it injected. Foods contain only small amounts of it. ALA is believed to help deactivate cell-damaging free radicals in many bodily systems. Proof of clinical benefit is lacking.
Claims, Benefits: Prevents or treats many age-related diseases, from heart disease and stroke to diabetes and cataracts.
Bottom Line: This compound alpha-lipoic acid (ALA) is an antioxidant, in common with Vitamin E and Beta Carotene. While we know that oxidative stress plays a part in the development of cardiovascular disease and there are theoretical reasons why anti-oxidants could show benefit; there have been no well controlled statistically significant studies that have shown any advantage to using these compounds. For now, not enough is known to recommend it.
ALA is being studied in animals and in humans as a preventive and/or treatment for many age-related diseases. These range from heart disease and stroke to diabetes and Parkinson’s and Alzheimer’s disease, as well as declines in energy, muscle strength, brain function, and immunity. In Germany, it is already used to treat long-term complications of diabetes, such as nerve damage, thought to result in part from free-radical damage; there is also evidence that it can help decrease insulin resistance and thus help control blood sugar. Many studies have yielded promising results; others are still underway. There have been no valid controlled studies reported in humans.
Why it is still too soon to act
Though evidence has been accumulating, it is clear that the research on ALA is still in its early stages. Large, long-term, well-controlled studies on humans are needed. No one knows what dose should be used for what ailment. Most studies have used 100 to 600 milligrams a day, but higher doses have also been studied. Though ALA so far appears to be safe, the long-term effects of large supplemental doses are unknown. There may be a danger in too much of a good thing. In addition, while in Germany it is sold only by prescription and (like other supplements) is monitored by the government, in the U.S. & Canada you have no way of knowing what’s in the bottles.
The landmark study of the British Medical Research Council, Heart Protection Study (http://www.ctsu.ox.ac.uk/~hps/) on over 20,000 individuals at high risk of cardiovascular event, compared anti-oxidants, Vitamin E & Beta Carotene against a statin (cholesterol lowering drug). Again the anti-oxidants showed no benefit (though again no harm), while the cholesterol lowering strategies lowered heart attack, stroke and death substantially.