B-vitamins and homocysteine in Spanish institutionalized elderly.

Background: Hyperhomocysteinemia is an accepted risk factor for cardiovascular disease, and possibly also for cognitive impairment and dementia. It has also been proposed as a marker for the status of the B vitamins, which participate in the metabolism of homocysteine. Therefore, especially in the elderly, it is important to know the prevalence of high homocysteine (tHcy) levels and the influence that B vitamins have on them.
Material and Methods: 218 elderly of both sexes, aged 60-105, living in an elderly home in Granada (Spain), were screened for serum folate, red blood cell (RBC) folate, serum cobalamin (B12) (Abbott, IMx), holotranscobalamin II (Holo-TC II) (HoloTC RIA, Axis-Shield), methylmalonic acid (MMA) (MS-GC), total pyridoxine (B6) (HPLC), and total homocysteine (tHcy) (Abbott, IMx).
Results: Hyperhomocysteinemia (tHcy >12 pmol/L) was detected in 80.7%. Serum folate deficiency was severe (< or =4 ng/mL) in 19.3% and moderate (4-7 ng/mL) in 43.1%. In 14.2% of the elderly RBC folate was < or =175 ng/mL, and in 61.0% it was between 175-400 ng/mL. Vitamin B12, measured in serum (< or =200 pg/mL), was deficient in 15.8%, but if measured as Holo-TC II (< or =45 pmol/L), deficiency ranged up to 39.1%. MMA was high (> or =300 nmol/L) in 45.6%. Vitamin B6 (< 20 nmol/L) was low only in one person. In order to identify the factors that could predict tHcy levels, a multiple regression analysis was performed. Best results corresponded to the combination of log serum folate and log Holo-TC II, which gave values of R > 0.5. If analyzed independently, the highest correlation was with log serum folate (r = -0.290), followed by RBC folate (r = -0.263), Holo-TC II (r = -0.228), log B12 (r = -0.175), and log B6 (r = -0.078).
Conclusion: There is a high prevalence of vitamin B deficiency and hyperhomocysteinemia in the studied population. Our data confirm the influence of these vitamins, especially folate, on tHcy levels, but hyperhomocysteinemia cannot be used as the only diagnostic criterion to detect subclinical vitamin deficiency in elderly people, especially to detect vitamin B12 deficiency.