National Eye Institute AREDS Authors Advise AMD Patients To Continue Taking Supplements with 400 IU Vitamin E

Vitamin E has been in the spotlight lately, following a meta-analysis by Johns Hopkins researchers regarding its safety. Meta-analysis, a statistical method for combining results from smaller studies, is given only limited credence by many researchers. A number of experts strongly disagree with the conclusions drawn by Johns Hopkins researchers that 400 IU of vitamin E could be harmful. The study, widely criticized as flawed, found only a tiny adverse effect - less than ½ of one percent - and the NY Times reported that prominent Harvard and UC Berkeley statisticians found the analysis to be unpersuasive. Researchers who conducted the AREDS trial also issued a statement advising those concerned about their macular health to continue taking 400 IU of vitamin E, the level found to protect eyesight in that long-term clinical trial, along with other nutrients. The AREDS investigators believe that the evidence indicates 400 IU is safe. Learn more about this issue by clicking here. You can also read the statement from the AREDS researchers to participants of the study (on the American Academy of Opthalmology's website), by clicking here.

Each year the Office of Dietary Supplements (ODS) at the National Institutes of Health chooses exemplary papers that make a significant contribution to knowledge in the dietary supplement field. This year, the winning papers include research on supplements and bone health, cancer, cardiovascular health, inflammation and early development. Several of these papers were featured in previous issues (March, October) last year. Since cardiovascular disease remains the number one public health problem in the US, below are two studies in that category from the ODS bibliography.

Vitamins C & E Combo Slow Atherosclerosis

The Antioxidant Supplementation in Atherosclerosis Prevention (ASAP) study, a 6 year clinical trial, examined the effectiveness of vitamins C and E in preventing the progression of atherosclerosis or narrowing of the carotid arteries. The carotids are the main arteries in the neck that bring blood to the brain and eyes. The progression of plaque in these arteries was determined by measuring how much the inner wall has thickened. Smokers and non-smokers aged 45-69 years, were supplemented twice daily with either 137 IU vitamin E, 250 mg of vitamin C, a combination of both vitamins, or a placebo during the initial double-blinded 3 year period. For the next 3 years, those taking the supplements received only the combination.

After 6 years, the vitamin E and C combination reduced the progression of plaque overall by 26 percent. For men, the reduction was 33 percent. While progression was slowed by 14 percent in women, it did not reach statistical significance. The benefits were greater in people who had low blood levels of vitamin C at the start of the study. According to the results, reasonable doses of these antioxidant vitamins may reduce the progression of carotid atherosclerosis in healthy men with high blood cholesterol levels. A much longer study period would be needed to know whether these effects will translate into a lower rate of stroke. While the results from clinical trials on vitamin E in people who already have heart disease have been inconsistent, many studies link vitamin E with a lower risk of heart disease in healthy people.

Green Tea Extract Lowers Cholesterol

Population health studies also link tea consumption with a reduced risk for CVD. However, human intervention studies using tea or tea extracts have not shown an effect on cholesterol. This controlled trial was designed to look at the effects of a theaflavin-enriched green tea extract on lipid profiles in people with mild to moderately elevated cholesterol levels. Theaflavin is a component found in black tea, while green tea has a higher content of catechins. In this study, Chinese men and women, 18 or over, ate their usual diets and received either 375 mg theaflavin-enriched green tea extract (75 mg of theaflavins, 150 mg of catechins, and 150 mg of other tea polyphenols) or a placebo for 12 weeks.

The tea extract safely and significantly lowered total cholesterol, LDL cholesterol and the ratio of total cholesterol to HDL. Subjects receiving placebos experienced no change in cholesterol levels. These results suggest that a theaflavin-enriched green tea extract is well tolerated and may help reduce total and LDL cholesterol in Chinese adults with mild to moderately high cholesterol. The findings should be confirmed in populations consuming western-style diets, which have higher fat content than Chinese diets. For those who like to drink tea, both green and black teas are healthful.

References

1. Age-Related Eye Disease Study, AREDS Coordinating Center. Letter to AREDS participants, published on the American Academy of Ophthalmology Website (http://www.aao.org/aao/patient_ed/upload/Vitamin_E_Letter.pdf), November, 2004.
2. Salonen RM et al. Six-year effect of combined vitamin C and E supplementation on atherosclerotic progression: The Antioxidant Supplementation in Atherosclerosis Prevention (ASAP) study.Circulation 107:947-953, 2003.
3. Maron DJ et al. Cholesterol-lowering effect of a theaflavin-enriched green tea extract: A randomized controlled trial. Archives of Internal Medicine 163:1448-1453, 2003.