In the News: Vitamins B6, C, & D, and the Omega-3 Fats

Supplemental Vitamin B6 Needed by Many

One of the largest population-health studies to evaluate B6 levels reports that inadequate blood concentrations of this B-vitamin are much more common than previously believed (1). Deficiencies of B6 were thought to be relatively rare except among the elderly. B6 is needed for red blood cell formation, protein metabolism, normal immune function and cardiovascular health.

In the study, Tuft's researchers analyzed blood levels of the active form of B6 in a large sample of the population. Four groups were identified as being particularly deficient: women of childbearing age, men who smoke, Afro-American men, and people over 65.

Among the women, current and former users of oral contraceptives had significantly lower levels then men in the same age group. In fact, 75% of those who used oral contraceptives, but did not take B6 supplements, were deficient. According to the study authors, some population groups need supplemental B6 in order to achieve adequate status.

Review Supports Heart Benefits of Vitamin C

While popularly known as a vitamin that helps lessen the symptoms and length of colds, vitamin C may have heart benefits as well. A recent meta-analysis or review, which included 13 double blind trials, concluded that vitamin C at a minimum dose of 500 mg daily can lower elevated LDL cholesterol by an average 5% and triglycerides by nearly 9% (2).

While these reductions are very modest, they translate to an estimated 7% lower risk of coronary heart disease (CHD). The researchers stated that even small changes can have beneficial effects on the incidence of CHD, especially in light of the low cost and safety of supplemental vitamin C within the range of 500-1000 mg daily. vitamin C may work by protecting LDL from damage so that it can be recognized by receptors in the liver and removed from the circulation.

Good Vitamin D Status Seems Heart-Essential

Inadequate levels of vitamin D have been associated with an increasing number of health conditions, and experts are calling for higher-than-RDA intakes to achieve healthier blood levels of D. The findings from several new studies add to the mounting evidence that the current RDA for vitamin D is set far too low.

In the first study, investigators from Harvard's School of Public Health reviewed the medical records and blood samples of men with a history of heart attack or heart disease (3). They found that men with low vitamin D levels were over 100% more at risk of heart attack compared to men with sufficient levels. A doubling of vitamin D blood levels was associated with halving the risk of a heart attack.

A second study from the University of Graz in Austria produced similar results. Higher vitamin D blood levels were linked with both lower overall death rates and deaths from cardiovascular causes (4). The cardio-protective effects of this vitamin might range from improving the health of smooth muscles in the vascular system to reducing inflammation and blood pressure.

Omega-3s Lower the Risk for AMD

Finally, a higher intake of the omega-3 fatty acids EPA and DHA cut the risk of age-related macular degeneration (AMD) by up to 38%, according to a new review of 9 population-health studies (5). In analyzing these studies, which included roughly 88,900 participants, researchers from Australia found that higher intakes of EPA and DHA cut the risk of early AMD substantially. In terms of advanced AMD, getting more of these omega-3 fats yielded a 38% risk reduction. While we await the findings of AREDS-2, which is testing the effects of the omega-3 on AMD progression, it's wise to eat cold-water fish at least 2-3 times weekly.

References

1. Morris MS, et al. Trends of vitamin B6 status in US population sample. AJCN 87:1446-54, 2008.
   
2. McRae MP. Vitamin C supplementation lowers serum low-density lipoprotein cholesterol and triglycerides: a meta-analysis of 13 randomized controlled trials. J of Chiropractic Med 7:48-58, 2008.
   
3. Giovannucci E, et al. 25-hydroxyvitamin D and risk of myocardial infarction in men-a prospective study. Arch of Intern Med 168:1174-80, 2008.
   
4. Dobnig H, et al. Independent association of low serum 25-hydroxyvitamin D and 125-dihydroxyvitamin D levels with all-cause and cardiovascular mortality. Arch of Intern Med 168:1340-49, 2008
   
5. Chong EW-T, et al. Dietary n-3 fatty acids and fish intake in the primary prevention of AMD-A systematic review and meta-analysis. Arch of Ophthalmol 126:826-833, 2008.