1.
The effect of vitamin D supplementation on the gut microbiome in older Australians - Results from analyses of the D-Health Trial.
Pham, H, Waterhouse, M, Rahman, S, Baxter, C, Duarte Romero, B, McLeod, DSA, Ebeling, PR, English, DR, Hartel, G, O'Connell, RL, et al
Gut microbes. 2023;15(1):2221429
-
-
-
Free full text
-
Plain language summary
Microbiota are communities of microorganisms that co-exist with the host ecosystem in a specific environment. The term microbiome refers to the microbial genome. The aim of this study was to investigate the effect of supplementing older adults with 60,000 IU of vitamin D per month on the gut microbiome for a period of five years, using a subsample (n = 835) of participants recruited from the large population-based D-Health Trial. This study is based on a subsample from the D-Health Trial, which was a randomised, double-blind trial with two parallel arms. Participants were randomly allocated (1:1 ratio) to monthly doses of either 60,000 IU of cholecalciferol (vitamin D3) or matching placebo. Results showed that monthly doses of 60,000 IU vitamin D over 5 years did not alter the composition of the gut microbiome in a population that is largely vitamin D replete. Authors conclude that further investigation is required to examine whether non-bolus doses of vitamin D would influence the gut microbiome or whether vitamin D supplementation would be beneficial in populations with a higher prevalence of vitamin D deficiency.
Abstract
Observational studies suggest a link between vitamin D and the composition of the gut microbiome, but there is little evidence from randomized controlled trials of vitamin D supplementation. We analyzed data from the D-Health Trial, a randomized, double-blind, placebo-controlled trial. We recruited 21,315 Australians aged 60-84 y and randomized them to 60,000 IU of vitamin D3 or placebo monthly for 5 y. Stool samples were collected from a sample of 835 participants (417 in the placebo and 418 in the vitamin D group) approximately 5 y after randomization. We characterized the gut microbiome using 16S rRNA gene sequencing. We used linear regression to compare alpha diversity indices (i.e. Shannon index (primary outcome), richness, inverse Simpson index), and the ratio of Firmicutes to Bacteroidetes between the two groups. We analyzed between-sample (beta) diversity (i.e. Bray Curtis distance and UniFrac index) using principal coordinate analysis and used PERMANOVA to test for significant clustering according to randomization group. We also assessed the difference in the abundance of the 20 most abundant genera between the two groups using negative binomial regression model with adjustment for multiple testing. Approximately half the participants included in this analysis were women (mean age 69.4 y). Vitamin D supplementation did not alter the Shannon diversity index (mean 3.51 versus 3.52 in the placebo and vitamin D groups, respectively, p = 0.50). Similarly, there was little difference between the groups for other alpha diversity indices, the abundance of different genera, and the Firmicutes-to-Bacteroidetes ratio. We did not observe clustering of bacterial communities according to randomization group. In conlusion, monthly doses of 60,000 IU of vitamin D supplementation for 5 y did not alter the composition of the gut microbiome in older Australians.
2.
Relationship between vitamin D status and the vaginal microbiome during pregnancy.
Jefferson, KK, Parikh, HI, Garcia, EM, Edwards, DJ, Serrano, MG, Hewison, M, Shary, JR, Powell, AM, Hollis, BW, Fettweis, JM, et al
Journal of perinatology : official journal of the California Perinatal Association. 2019;39(6):824-836
-
-
-
Free full text
-
Plain language summary
The composition of the vaginal microflora can significantly impact both reproductive and neonatal health. Numerous studies support the important role for sufficient serum or plasma concentrations of 25-hydroxy vitamin D (25(OH)D) during pregnancy in preventing negative outcomes. The study’s hypothesis was that vitamin D status is associated with the vaginal microbiome. This study is an analysis of a sub-cohort from a randomised, placebo-controlled clinical trial of vitamin D supplementation of pregnant women who were enrolled during the first trimester of pregnancy and followed until delivery. Participants (n=387) were randomised and received supplement: 191 received 400 IU (control group) and 196 received 4400 IU (treatment group). Results show that women in both the control and treatment groups displayed higher circulating 25(OH)D concentrations with increasing gestational age. Furthermore, among women of African ancestry, there was a negative correlation between 25(OH)D and abundance of Megasphaera [type of anaerobic microflora]. Authors conclude that certain vaginal bacteria are associated with plasma 25(OH)D concentration.
Abstract
OBJECTIVE Evidence supports an inverse association between vitamin D and bacterial vaginosis (BV) during pregnancy. Furthermore, both the vaginal microbiome and vitamin D status correlate with pregnancy outcome. Women of African ancestry are more likely to experience BV, to be vitamin D deficient, and to have certain pregnancy complications. We investigated the association between vitamin D status and the vaginal microbiome. STUDY DESIGN Subjects were assigned to a treatment (4400 IU) or a control group (400 IU vitamin D daily), sampled three times during pregnancy, and vaginal 16S rRNA gene taxonomic profiles and plasma 25-hydroxyvitamin D [25(OH)D] concentrations were examined. RESULT Gestational age and ethnicity were significantly associated with the microbiome. Megasphaera correlated negatively (p = 0.0187) with 25(OH)D among women of African ancestry. Among controls, women of European ancestry exhibited a positive correlation between plasma 25(OH)D and L. crispatus abundance. CONCLUSION Certain vaginal bacteria are associated with plasma 25(OH)D concentration.
3.
Functional biochemical and nutrient indices in frail elderly people are partly affected by dietary supplements but not by exercise.
de Jong, N, Chin A Paw, MJ, de Groot, LC, de Graaf, C, Kok, FJ, van Staveren, WA
The Journal of nutrition. 1999;129(11):2028-36
-
-
-
Plain language summary
Elderly people are at risk of nutritional deficiencies for a variety of reasons including reduced appetite, increased medication, and alterations in the absorption and metabolism of vitamins and minerals with age. The aim of this study was to measure the influence of exercise, and supplementing the diet with vitamins and minerals, on indicators of nutritional and health status in frail elderly people. A 17-week randomised controlled trial was carried out on 145 frail elderly people living in the community. Participants were given either; 1) food products enriched with vitamins D, E, thiamine, riboflavin, B6, folic acid, B12, calcium, magnesium, zinc, iron and iodine; 2) an exercise programme; 3) both enriched food products and exercise programme; or 4) food products that had not been enriched and a social programme (the control group). At the end of the study, significant improvements in the blood levels of vitamins B6, B12, C and D were detected in the groups receiving the enriched food products compared to the controls. There was no additional benefit to be gained from exercise. The improvement in nutritional status did not appear to influence several other biological indicators of health, perhaps because these indicators were already within normal levels at the start of the study. Despite this, the authors concluded that long-term supplementation may help to maintain optimal vitamin and mineral levels in elderly people, and therefore reduce the chance of this population developing health problems related to malnutrition.
Abstract
A decline in dietary intake due to inactivity and, consequently, development of a suboptimal nutritional status is a major problem in frail elderly people. However, benefits of micronutrient supplementation, all-round physical exercise or a combination of both on functional biochemical and hematologic indicators of nutritional and health status in frail elderly subjects have not been tested thoroughly. A 17-wk randomized controlled trial was performed in 145 free-living frail elderly people (43 men, 102 women, mean age, 78 +/- 5.7 y). Based on a 2 x 2 factorial design, subjects were assigned to one of the following: 1) nutrient-dense foods, 2) exercise, 3) both (1) and (2) or 4) a control group. Foods were enriched with micronutrients, frequently characterized as deficient [25-100% of the recommended daily allowance (RDA)] in elderly people. Exercises focused on skill training, including strength, endurance, coordination and flexibility. Dietary intake, blood vitamin levels and nutritional and health indicators, including (pre)albumin, ferritin, transferrin, C-reactive protein, hemoglobin and lymphocytes were measured. At baseline, 28% of the total population had an energy intake below 6.3 MJ, up to a maximum of 93% having vitamin intakes below two thirds of the Dutch RDA. Individual deficiencies in blood at baseline ranged from 3% for erythrocyte glutathione reductase-alpha to 39% for 25-hydroxy vitamin D and 42% for vitamin B-12. These were corrected after 17 wk in the two groups receiving the nutrient-dense foods, whereas no significant changes were observed in the control or exercise group. Biochemical and hematologic indicators at baseline were within the reference ranges (mean albumin, 46 g/L; prealbumin, 0.25 g/L; hemoglobin, 8.6 mmol/L) and were not affected by any of the interventions. The long-term protective effects of nutrient supplementation and exercise, by maintaining optimal nutrient levels and thereby reducing the initial chance of developing critical biochemical values, require further investigation. Other indicative functional variables for suboptimal nutritional status, in addition to those currently selected, should also be explored.