Not Enough B-6?

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Updated on February 8, 2010

Researchers from Tufts University have found that people may not be getting enough vitamin B-6 with the current Recommended Daily Allowance of 2 milligrams. And that goes double for certain groups.

Vitamin B-6 plays an integral role in the formation of red blood cells, regulation of blood glucose, digestion of protein, and the function of the immune and nervous systems. The researchers tested plasma pyridoxal 5’-phosphate (PLP) levels as the primary measure of B6 status.

Corresponding author Morris and colleagues studied 7,822 blood samples of men and women ages one-year and older collected from the 2003-2004 National Health and Nutrition Examination Survey (NHANES). Vitamin B6 inadequacy was defined as a plasma PLP concentration less than 20 nmol/L. To the authors’ knowledge, the current study is the first large scale study to use plasma PLP concentrations to evaluate vitamin B6 status in free-living people of all ages. The investigators were also able to consider whether the current RDA guaranteed adequate vitamin B6 status because study participants were questioned about supplement use and two days’ worth of food intake. … Eleven percent of supplement users and nearly a quarter of non-users demonstrated plasma PLP blood levels of less than 20 nmol/L.

via Science Daily

The groups that showed low levels of PLP were primarily “women of reproductive age, especially current and former users of oral contraceptives, male smokers, non-Hispanic African-American men, and men and women over age 65.”

Women between the ages of 15-34 had much lower PLP measures overall when compared to men of the same age group. In fact, men fared pretty well. Other than the low PLP levels seen in non-Hispanic African-Americans, men didn’t show a drop in PLP after adolescence if they took supplements. Oral contraceptive use appeared to be a significant factor in the gender discrepancy and was associated with “extremely low plasma PLP levels.” Seventy-five percent of women who were currently using oral contraceptives but did not take supplements showed a vitamin B6 deficiency. Among those who had previously taken but discontinued oral contraceptives, 40 percent showed B6 deficiency. Because low levels of vitamin B6 are also associated with a rise in homocysteine, the researchers tested for homocysteine measures as well. Women who had previously taken oral contraceptives but were not currently using them showed higher homocysteine levels than those currently using oral contraceptives.

Interesting food for thought, eh? As you may know or may have guessed, we have our mumblings and grumblings about the RDA system. Frankly, we prefer to gauge our diet and supplementation to other standards that we feel more adequately address our nutritional needs and more effectively mitigate the factors of modern lifestyles. And, as this research clearly illustrates, sometimes the medications we must use or choose to take should have bearing on our decisions as well.

What does this study say to us? Well, those who used supplements fared better than those who didn’t; however, they should’ve fared better than they did. We wonder what kind of supplement(s) they’re taking and especially if they’re on a full B-complex.

Oral contraceptives, even after discontinuation of use, inherently come with certain nutritional consequences that should be monitored and mitigated with the oversight of a physician. Unfortunately (anecdotally speaking), many physicians don’t know about this connection, and many who do too often prescribe a single B6 supplement rather than a B-Complex.

Finally, the study underscores for us how important it is to assess the larger picture of your life and lifestyle in determining your nutritional needs. Stress? Urban living? Contraceptive use? Age? Fitness and training level? We always encourage talking with your doctor about all the factors of your life, not just the scripted questions and typical tests for your age group.