Effects of a nutritional supplement on the immune response and cytokine production in free-living Chilean elderly.

BACKGROUND: Immune response is impaired in the elderly. Our aim was to study the effects of a special nutritional formula on the immune response and response to influenza and pneumococcal vaccination in elderly subjects. METHODS: Sixty healthy subjects aged > or = 70 years, with a Mini Mental score > or = 22 were studied. Half of the subjects received a special nutritional formula (in addition to the regular diet) providing, among other nutrients, 480 kcal, 31 g proteins, 120 IU vitamin E, 3.8 microg vitamin B12, 400 microg folic acid, 10(9) cfu Lactobacillus paracasei (NCC 2461), and 6 g of fructo-oligosaccharides. At 4 months of follow-up, subjects were vaccinated against influenza and pneumococcus. Lymphokine production by mononuclear cells (PBMC), lymphocyte subpopulations, and natural killer cell (NK) activity were measured at baseline and 4 months of follow-up (before vaccination). Antibodies against influenza and pneumococcal antigens and flu-stimulated production of interferon gamma and interleukin-2 by PBMC were measured at 4 and 6 months. Skin response to 7 recall antigens and body composition were assessed at baseline and at 4 and 12 months. All infections occurring during the study period were recorded. RESULTS: NK activity increased in supplemented subjects and decreased in nonsupplemented individuals. Interleukin-2 production by PBMC and the proportion of T cells with NK activity decreased in controls and did not change in supplemented subjects. Supplemented subjects reported less infections than nonsupplemented individuals (in 13% and 22% of scheduled visits, respectively; p = .02). CONCLUSIONS: This nutritional supplement increased innate immunity and protection against infections in elderly people.

Hyperhomocysteinemia and endothelial function in young subjects: effects of vitamin supplementation.

BACKGROUND: The relationship between hyperhomocysteinemia and cardiovascular disease has not been totally elucidated. HYPOTHESIS: The study aimed to verify the association between hyperhomocysteinemia and endothelial dysfunction before and after modification of total homocysteine (tHcy) serum levels with vitamin supplementation in young male subjects devoid of any other cardiovascular risk factor. METHODS: Twenty hyperhomocysteinemic (tHcy > 15 [micromol/l) male volunteers (< or = 40 years) and 20 age-matched subjects with normal tHcy levels (tHcy < 13 micromol/l) were included. Exclusion criteria were smoking, hypertension, diabetes, vitamin ingestion, obesity, hypercholesterolemia, renal failure, and positive antiphospholipid antibodies. Serum tHcy, folate, vitamin B12 levels, activated protein C and S, protein C resistance, fibrinogen, prothrombin, thrombin, antithrombin III, and in vitro oxidation of low-density lipoprotein (LDL) particles were measured. Noninvasive ultrasound measurements of endothelium-dependent (EDD) and -independent dilatation (EID) of the brachial artery were performed. Each pair was then randomly assigned to receive a vitamin capsule (0.6 mg folic acid, 0.8 mg B12. and 2.0 mg B6) oran identical placebo during 8 weeks, in a double-blind study design. After the treatment phase, blood samples and vascular reactivity were repeated. RESULTS: Nine pairs of volunteers received vitamins and 11 received placebo. Hyperhomocysteinemic subjects had lower baseline serum levels of vitamin B12. Serum folate levels, antithrombotic function, in vitro LDL oxidation, and EDD were similar in all groups. After the vitamin supplementation, serum folic acid levels increased significantly both in normo- and hyperhomocysteinemic subjects, unlike vitamin B12, which increased only in the hyperhomocysteinemic individuals. Plasma tHcy decreased significantly in the supplemented groups. Treatment with vitamins was not associated with improvement in EDD or antithrombotic function. CONCLUSIONS: Mild hyperhomocysteinemia is not associated with endothelial dysfunction in young male subjects with no additional cardiovascular risk factors, and reduction of tHcy by vitamin supplementation does not modify EDD in this age group. In this sample, tHcy was more related to vitamin B12 than to folic acid status.

Effects of prebiotics on the immune response to vaccination in the elderly.

BACKGROUND: Prebiotics stimulate the growth of bifidogenic bacteria in the gut. The aim of this work was to assess the effects of a prebiotic mixture on the immune response in healthy elderly people. METHODS: Healthy free-living elderly people (age, > or = 70 years), receiving a nutritional supplement that provided 1.6 MJ, 15 g of protein, and 50% of vitamin daily reference values per day, were randomly assigned to receive a prebiotic mixture (6 g/d of a 70% raftilose and 30% raftiline mixture) or placebo (6 g of maltodextrin powder) for 28 weeks. At week 2 of the study, all subjects were vaccinated with influenza and pneumococcal vaccines. At weeks 0, 2, and 8 of the study, serum total proteins, albumin, immunoglobulins, saliva secretory immunoglobulin A (IgA), and serum titers of influenza A and B and pneumococcal antibodies were measured. At week 8, cultured peripheral monocyte cell secretion of interleukin-4, interferon-gamma, and lymphocyte proliferation, stimulated with phytohemagglutinin and influenza antigen, were measured. RESULTS: Sixty-six subjects were considered eligible for the study, and 43 (20 receiving prebiotics and 23 receiving placebo) were considered for final analyses on a per protocol basis. No changes in serum proteins, albumin, immunoglobulins, and secretory IgA were observed. Antibodies against influenza B and pneumococcus increased significantly from weeks 0 to 8, with no significant differences between groups. Antibodies against influenza A did not increase. No effects of prebiotics on interleukin-4 and interferon-gamma secretion by cultured monocytes were observed. CONCLUSIONS: No immunological effects of prebiotics were observed in this study.

Endothelial function in healthy younger and older hyperhomocysteinemic subjects.

OBJECTIVES: To compare endothelium-dependent vasomotor response in healthy younger and older subjects without classic cardiovascular risk factors, with high and normal fasting homocysteine (tHcy) levels. DESIGN: We compared endothelium-dependent vasodilatation, using ultrasound, in healthy younger (aged 18-40) and older (> or =70) people with normal (<13 micromol/L) and high (>15 micromol/L) tHcy levels. Exclusion criteria were smoking, personal history of cardiovascular disease, hypertension, chronic diseases, vitamin intake, obesity, abnormal serum lipids levels, and creatinine higher than 130 micromol/L. SETTING: Research laboratory. MEASUREMENTS: In addition to tHcy levels, serum folate and vitamin B12 levels were measured. RESULTS: We studied 17 younger and 12 older hyperhomocysteinemic subjects and respective aged-matched normohocysteinemic subjects. Endothelium-dependent vasodilatation was lower in the hyperhomocysteinemic older people (P <.01) than in all younger subjects and in normohomocysteinemic older people. Serum vitamin B12 levels were higher in younger and older normal controls. Folic acid levels were higher in younger controls and in both older groups. CONCLUSIONS: This study shows an effect of high circulating tHcy on vascular reactivity in older people. Because serum levels of tHcy are associated with nutritional status of vitamin B12 and folic acid, prospective studies are necessary to demonstrate the effects of a long-term nutritional supplementation with vitamins on vascular function and global cardiovascular risk.

The Chilean flour folic acid fortification program reduces serum homocysteine levels and masks vitamin B-12 deficiency in elderly people.

Hyperhomocysteinemia is considered a risk factor for cardiovascular disease and is prevalent in the elderly. Supplementation with folic acid, vitamin B-6 and B-12 lowers homocysteine levels. In January 2000, the Chilean government initiated a flour folic acid fortification program to decrease the occurrence of neural tube defects. The aim of this study was to evaluate the effect of this program on serum homocysteine and folate levels in elderly subjects after 6 mo. A total of 108 elderly people were studied. We measured serum folate, homocysteine and vitamin B-12 levels before the fortification started and 6 mo later. At baseline, folate deficiency (<6.8 nmol/L) was present in 1.8%, vitamin B-12 deficiency (<165 pmol/L) in 27.6% and hyperhomocysteinemia (>14 micromol/L) in 31% of the sample. Six months later, serum folate levels increased from 16.2 +/- 6.2 to 32.7 +/- 7.1 nmol/L (P < 0.001), homocysteine levels decreased from 12.95 +/- 3.7 to 11.43 +/- 3.6 micromol/L (P < 0.001) and vitamin B-12 levels were unchanged. Flour fortification with folic acid had a moderate lowering effect on homocysteine levels. Given that vitamin B-12 deficiency was more common than folate deficiency, it may be more appropriate to add vitamin B-12 to food, at least in foods for this age group.