[Bioavailability of natural versus synthetic B vitamins and their effects on metabolic processes]. / Bioverfügbarkeit eines natürlichen versus eines synthetischen Vitamin-B- Komplexes und deren Auswirkungen auf metabolische Prozesse.

BACKGROUND: Owing to the widespread use of vitamin supplements to prevent and compensate for deficiencies, the equivalence of natural versus synthetic vitamins with respect to their bioavailability and metabolic influence is discussed controversially. METHOD: Thirty healthy female (n=22) and male participants (n=8) were investigated in a randomized, double-blind, cross-over study over a supplementation period of 6 weeks for each condition. The participants received a daily dose of a complex of the 8 natural B vitamins (group N), determined by the natural composition of quinoa seedlings, resp. synthetic B vitamins (group S), both corresponding to about 2.5 times the Recommended Dietary Allowance (RDA) of the national nutrition board. The primary criterion under investigation was changes in the blood levels of the individual B vitamins. Secondary criteria were the influence of both B complexes on homocysteine, antioxidant status, polyphenols, peroxide loading and peroxidase activity. RESULTS: Compared to baseline values, serum levels of all B vitamins measured increased: Vitamins B1 (N +23%; S +27%), B2 (N +14%; S +13%), B6 (N +101%; S +101%), B9 (N +86%; S +153%) and B12 (N +16%) were elevated at the end of the first supplementation period (p < 0.05), while serum levels of vitamins B1, B9 and B12 remained elevated compared to baseline even after the 2-week washout phase. During the second supplementation period, the vitamin concentrations in group N, with the exception of vitamin B1, could be increased once again (p < 0.05). In contrast, in group S only for vitamins B2 and B12 substantial increases (p < 0.05) were found. The influence of B vitamins on metabolic parameters such as homocysteine and polyphenols, which were markedly reduced, was also clearly measurable; however, total antioxidant capacity and peroxidase activity increased. The peroxide concentration remained almost unchanged in both groups. CONCLUSION: This clinical pilot study showed comparable bioavailability for both natural and synthetic B vitamins, with a 2.5-fold concentration of the RDA. Both vitamin B preparations showed a clear influence on metabolic parameters, whereas that of the natural B vitamins tended to have a slightly stronger effect than the synthetic analogues.

Influence of a complex micronutrient supplement on the immune status of elderly individuals.

Nutritional status is known to have profound effects on immune function and resistance to infections, particularly in the elderly. We investigated the effect of a complex micronutrient supplement in elderly people on the changes in some of the cellular components of the immune system, on lymphocyte function, and on the antibody response to influenza vaccination. One-hundred-six subjects aged 62 to 98 were randomly assigned to receive a complex micronutrient supplement or a placebo for three months. Subjects were vaccinated against influenza after eight weeks. Clinical parameters, lymphocyte subsets, in vitro lymphocyte activation, and influenza antibody titers were assessed at baseline and after 90 days of supplementation. A significant increase in total lymphocytes (p=0.034) and white blood cells (WBC) (p=0.03) in the supplemented group was observed. A shift from CD4+/CD45RO+ "memory" cells to CD4+/CD45RA+ "naïve" T-cells in favor of CD4+/CD45RA+ "naïve" T-cells took place. The group consuming additional micronutrients showed an increase in CD45RA+ subsets (p=0.032) compared to the control group. A decrease of total cholesterol (from 228.72 + or - 56.11 to 210.74 + or - 52.58, p=0.002) and low-density lipoprotein (LDL) (from 145.75 + or - 48.86 to 125.47 + or - 41.72, p<0.001) was observed. Influenza antibody titers showed no correlation with micronutrient intake. We conclude that supplementation with a complex micronutrient formulation increases the number of various types of immune cells and decreases total cholesterol and LDL in elderly people. No beneficial effect on specific antibody response to influenza vaccination was observed. Further research is needed to evaluate whether enhanced cellular immune responses decrease the incidence of infections in elderly people.