Study suggests causal relationship between vitamin D deficiency and hypertension

Vitamin D (also known as calciferol) is a group of fat-soluble steroids that is said to be responsible for preventing rickets or osteomalacia through increased intestinal absorption of iron, calcium, zinc, magnesium, and phosphate. In recent years, however, there has been a significant improvement in the understanding of vitamin D's pleiotropic effects in multiple organ systems besides homeostasis. Receptors for the active form of vitamin D, 25-dihydroxyvitamin D, have been identified in most human tissues. Increased BP (called as hypertension) is a prevalent chronic disease and is considered a silent killer due to the absence of symptoms.

Several studies have shown an association between vitamin D deficiency and hypertension. However, improvements in blood pressure resulting from vitamin D supplementation have been inconsistent. There is no clarity on the relationship between vitamin D deficiency and hypertension. Considering this, Songcheng Yu, Department of Cardiology, First Affiliated Hospital of Zhengzhou University, Zhengzhou, China, and colleagues investigated the same in a family-based study.

The study included 1370 people from both vitamin D deficiency and hypertension families. Firstly, the researchers estimated the heritability of vitamin D deficiency using the Falconer method. Secondly, a family-based association test was used to screen SNPs (single nucleotide polymorphisms) of vitamin D metabolic and functional pathway genes associated with vitamin D deficiency. Further, the findings were verified in nuclear families with vitamin D deficiency. Finally, a family-based association test was applied to investigate the association between SNPs associated with vitamin D deficiency and hypertension.

The study yielded the following findings:

• The heritability of vitamin D deficiency was 50.4% in this family-based study.
• Allele C of rs3847987 was a risk factor for vitamin D deficiency (OR: 1.639).
• A family-based association of rs3847987 with hypertension was found in both additive and recessive models.
• Vitamin D deficiency was associated with hypertension (OR: 1.317).

The researchers wrote in their conclusion that "rs3847987 in the VDR gene was associated with hypertension and vitamin D deficiency. Therefore, vitamin D deficiency may be a causal factor for hypertension."

Reference:

Bai, L., Qu, C., Feng, Y. et al. Evidence of a causal relationship between vitamin D deficiency and hypertension: a family-based study. Hypertens Res (2022). https://doi.org/10.1038/s41440-022-01004-0