Genome-wide association study in 79,366 European-ancestry individuals informs the genetic architecture of 25-hydroxyvitamin D levels

Vitamin D is a steroid hormone precursor that is associated with a range of human traits and diseases. Previous GWAS of serum 25-hydroxyvitamin D concentrations have identified four genome-wide significant loci (GC, NADSYN1/DHCR7, CYP2R1, CYP24A1). In this study, we expand the previous SUNLIGHT Consortium GWAS discovery sample size from 16,125 to 79,366 (all European descent). This larger GWAS yields two additional loci harboring genome-wide significant variants (P = 4.7×10-9 at rs8018720 in SEC23A, and P = 1.9×10-14 at rs10745742 in AMDHD1). The overall estimate of heritability of 25-hydroxyvitamin D serum concentrations attributable to GWAS common SNPs is 7.5%, with statistically significant loci explaining 38% of this total. Further investigation identifies signal enrichment in immune and hematopoietic tissues, and clustering with autoimmune diseases in cell-type-specific analysis. Larger studies are required to identify additional common SNPs, and to explore the role of rare or structural variants and gene-gene interactions in the heritability of circulating 25-hydroxyvitamin D levels.

Contribution of complementary food nutrients to estimated total nutrient intakes for urban Guatemalan infants in the second semester of life

Complementary foods (CF) are introduced earlier or later than appropriate in developing societies. They often contribute poorly to overall adequate micronutrient intake during the critical period for growth and development, which constitutes the period from 6 to 12 months of life. The objective of this study was to determine the contribution of the CF nutrients to the total estimated nutrient intake in infants in the second semester of life. Three non-consecutive 24-hour recalls interviews were conducted with mothers of 64 infants, aged 6-12 months on enrolment, from a convenience sample in a marginal urban settlement in Guatemala City. Retrospective recording of early introduction of pre- and post-lacteal feeding and introduction of first foods and beverages was included. Human milk intakes were estimated by a model based on assumptions that human milk plus CF exactly satisfied the infant's daily energy needs. The WHO/FAO Recommended Nutrient Intakes (RNI) were the standards for adequate nutrient consumption. Instances of exclusive breast feeding to 6 months were rare, with the introduction of CF earlier than recommended. Baby food in jars was mentioned most frequently as the first food offered. The contribution of CF increased with age through the second semester of life. CF contributed more of a nutrient than human milk in all instances. However,CF nutrient density for Ca, Fe, and Zn fell below international standard. Fortified sugar contributed excessive amounts of Vitamin A to the diets. We conclude that for most nutrients, intakes reached or exceeded recommendation levels, unusual within the CF experience in scientific literature.

No effect of fish oil supplementation on serum inflammatory markers and their interrelationships: a randomized controlled trial in healthy, middle-aged individuals

BACKGROUND

A high intake of n-3 polyunsaturated fatty acids (PUFAs), mainly present in fish, may be associated with decreased inflammation. Previous intervention studies on fish PUFA and inflammatory markers in healthy individuals did not analyze a broad spectrum of inflammatory cytokines, chemokines and cell adhesion molecules, or their interrelationships. Therefore, we determined the effects of fish oil supplementation on 19 serum inflammatory markers and their interrelationships in healthy, middle-aged individuals.

METHODS

Individuals (n=77) aged 50-70 years completed a randomized, double-blind placebo-controlled intervention study. Participants received 3.5 g/day fish oil (1.5 g/day total n-3 PUFA) (n=39) or placebo (high oleic sunflower oil) (n=38) for 12 weeks. Serum concentrations of 19 inflammatory markers were determined using a multiplex immunoassay before and after intervention. Changes in concentrations were analyzed using analysis of covariance and differences in patterns in inflammatory markers between the fish oil and placebo group were analyzed by principal component analysis.

RESULTS

Fish oil supplementation did not significantly affect serum concentrations of cytokines, chemokines or cell adhesion molecules as compared with placebo. However, there was a trend for all inflammatory markers to increase after fish oil supplementation. PCA did not result in markedly distinctive patterns of inflammatory markers for the fish oil and placebo group.

CONCLUSION

In conclusion, this 12-week randomized, double-blind placebo-controlled intervention trial did not show that 1.5 g/day n-3 PUFA significantly affected the serum inflammatory response in healthy individuals, nor did patterns of inflammatory markers. Thus, a healthy middle-aged population may not benefit from fish oil as an anti-inflammatory agent.