Vitamin D heritability and effect of pregnancy status in Vervet monkeys (Chlorocebus aethiops sabaeus) under conditions of modest and high dietary supplementation

Objectives The two objectives of the current study were to: 1) investigate the genetic contributions to variations in serum vitamin D concentrations under two dietary conditions (a standard monkey biscuit diet vs. a diet designed to model typical American consumption); and 2) explore the interaction of vitamin D with pregnancy status using a cohort of pedigreed female vervet/African green monkeys. Methods This study includes 185 female (≥3.5 years) vervet/African green monkeys (Chlorocebus aethiops sabaeus) from a multi-generational, pedigreed breeding colony. The 25(OH)D₃ concentrations were first measured seven to eight weeks after consuming a "typical American" diet (TAD), deriving 37, 18, and 45% of calories from fat, protein sources, and carbohydrates, and supplemented with vitamin D to a human equivalent of 1,000 IU/day. Vitamin D concentrations were assessed again when animals were switched to a low-fat, standard biscuit diet (LabDiet 5038) for 8 months, which provided a human equivalent of approximately 4,000 IU/day of vitamin D. All statistical analyses were implemented in SOLAR. Results Pregnancy was associated with reduced 25(OH)D₃ concentrations. Heritability analyses indicated a significant genetic contribution to 25(OH)D₃ concentrations in the same monkeys consuming the biscuit diet (h²=0.66, P=0.0004) and TAD (h²=0.67, P=0.0078) diets, with higher 25(OH)D₃ concentrations in animals consuming the biscuit diet. Additionally, there was a significant genotype-by-pregnancy status interaction on 25(OH)D₃ concentrations (P<0.05) only among animals consuming the TAD diet. Discussion These results support the existence of a genetic contribution to differences in serum 25(OH)D₃ concentrations by pregnancy status and emphasize the role of diet (including vitamin D supplementation) in modifying genetic signals as well as vitamin D concentrations.