Genetic research and high blood pressure: what is the relationship with vitamin D deficiency?

IN BRIEF

• Numerous observational associations exist between low vitamin D levels and increased blood pressure; a prospective meta-analysis quantified this link in large populations. [1]
• Mendelian randomization studies report conflicting results: some find signs of a protective effect of higher 25(OH)D levels on blood pressure, while others do not detect a causal effect in the general population. [2][3][4]
• Systematic reviews and meta-analyses of randomized clinical trials generally show limited benefits of vitamin D supplementation as an antihypertensive therapy. [5]
• Large-scale clinical trials on cardiovascular outcomes provide mixed results: some show no clear reductions in cardiovascular events, while others suggest possible signals in subgroups or for specific outcomes. [7][8]
• Interpreting the data requires caution: observational associations, genetic evidence, and trial results do not always agree; uncertainties remain regarding dose, population, and possible non-linear effects. [2][4][5]

Abstract: what does science say?

The relationship between vitamin D deficiency (measured as 25-hydroxyvitamin D) and hypertension has been investigated using observational, genetic (Mendelian randomization), and experimental (clinical trials) approaches. Observational studies generally report an inverse association between 25(OH)D levels and the risk of hypertension, but these associations can be influenced by confounders such as obesity, physical activity, and sun exposure. Older Mendelian randomization studies suggested a possible causal effect, while larger and more recent studies have yielded inconclusive or null results, raising the hypothesis of non-linear effects or effects limited to subjects with severe deficiency. Randomized clinical trials and overall meta-analyses do not support the use of vitamin D as an antihypertensive drug in the general population, although they leave room for possible benefits in selected subsets. In summary: biological plausibility and observational studies justify further research, but there is no clinical consensus to recommend vitamin D supplementation solely for the prevention or treatment of hypertension.

Scientific evidence: observations, genetics, and trials

Observational evidence

Numerous cohort studies and prospective meta-analyses have documented an inverse association between 25-hydroxyvitamin D concentrations and the future risk of hypertension: in large population pools, higher 25(OH)D levels have been associated with a relative reduction in the risk of hypertension. However, observational data do not establish a causal relationship and can be influenced by factors that modify both vitamin D and blood pressure (e.g., body mass index, outdoor activity, diet, and chronic conditions). These limitations justify complementary methods for causal inference. [1]

Mendelian randomization: strengths and results

Mendelian randomization (MR) uses genetic variants associated with vitamin D levels as instruments to assess causal effects, reducing confounding and reverse causation. A large-scale MR study reported a relationship between genetic variants linked to vitamin D synthesis and a lower risk of hypertension, suggesting a possible causal effect in some contexts. However, subsequent MR studies, with more genetic variants and even larger samples, have reported conflicting or null results, and some recent works have found no evidence of a general causal effect of vitamin D on blood pressure. Such discrepancies may depend on the choice of genetic instruments, statistical power, and the presence of non-linear effects (an effect visible only in severely deficient individuals). [2][3][4]

Randomized clinical trials and meta-analyses

Evidence from randomized clinical trials (RCTs) is crucial for evaluating the effectiveness of supplementation. Systematic reviews and meta-analyses with individual patient data and trial data have shown, overall, negligible effects of vitamin D supplementation on blood pressure reduction in the general population. Some medium-sized intervention studies in people with hypertension or deficiency have yielded conflicting results, but large-scale analyses do not support supplementation as a universally effective antihypertensive strategy. It remains debated whether subgroups with severe deficiency might benefit. [5][6][7]

What it means in practice

Interpreting the evidence for the public

For the average person, the message is clear and cautious: low vitamin D levels are frequently associated with hypertension in observations, but routine supplementation to lower blood pressure is not supported by solid evidence for the entire population. Blood pressure control remains based on established measures (balanced diet, physical activity, salt reduction, weight management, and pharmacological therapies when indicated). Monitoring vitamin D status can still be useful for bone health or other clinical risks, but the decision to start supplementation must be personalized and discussed with a doctor. [5]

Who might benefit from particular attention

Individuals with risk factors for deficiency (limited sun exposure, very dark skin, malabsorption, kidney diseases, or conditions affecting vitamin D metabolism) may require evaluation and specific supplementation according to local guidelines. The effects of vitamin D on blood pressure might be more relevant in subjects with marked deficiency; however, the evidence of direct benefit on blood pressure reduction remains uncertain and should be evaluated on a case-by-case basis. [4][7]

Key takeaways

• Observations show an inverse correlation between 25(OH)D and hypertension, but correlation does not equal causality. [1]
• Genetic studies (Mendelian randomization) have yielded conflicting results: some suggest an effect, others do not; a non-linear effect might exist. [2][3][4]
• Randomized clinical trials and overall meta-analyses do not support the generalized use of vitamin D to lower blood pressure. [5]
• The decision to measure or supplement vitamin D should be based on individual clinical conditions, not solely on the intent to prevent or treat hypertension. [5][7]
• Further research is needed on doses, duration, deficient populations, and possible effects on specific cardiovascular events. [8]

Limitations of the evidence

Difference between observational studies and causal evidence: cohort studies identify associations but remain vulnerable to confounders and reverse causation; MR reduces some biases but relies heavily on the quality of genetic instruments and the assumption that SNPs act only through vitamin D. Clinical trials better control intervention and comparison, but often include subjects with wide variability in vitamin status, doses, and intervention duration, and sometimes are not designed to evaluate specific cardiovascular outcomes. Additional methodological limitations include insufficient statistical power for subgroups, variability in 25(OH)D measurements, and possible non-linear effects (benefits only below a certain threshold). All of this requires cautious interpretation and an integrated approach to the evidence. [1][2][5][4]

Editorial conclusion

The relationship between vitamin D and blood pressure remains an active and complex scientific topic. Observational signals and biological plausibility justify further studies, but the balance of available evidence does not authorize generalized recommendations for the use of vitamin D as an antihypertensive treatment. Clinical evaluation must remain individualized: correcting a documented deficiency is appropriate for general health reasons, while preventive use aimed exclusively at blood pressure reduction currently lacks solid experimental support. Progress in research (targeted trials on deficient populations, MR approaches with robust instruments, and non-linear analyses) will be crucial for defining future recommendations. [2][5][4][7]

Editorial note

This article was published in a previous version and updated according to scientific verification criteria and clarity of dissemination. The information provided is for informational purposes only and does not replace the advice of your treating physician; for diagnostic and therapeutic decisions, always consult a healthcare professional.

SCIENTIFIC RESEARCH

1. Kunutsor SK, Apekey TA, Steur M. Vitamin D and risk of future hypertension: meta‑analysis of 283,537 participants. Eur J Epidemiol. 2013;28(3):205-221. https://doi.org/10.1007/s10654-013-9790-2
2. Vimaleswaran KS et al. Association of vitamin D status with arterial blood pressure and hypertension risk: a mendelian randomisation study. Lancet Diabetes Endocrinol. 2014;2(9):719-729. https://doi.org/10.1016/S2213-8587(14)70113-5
3. Jiang X et al. Vitamin D and cause‑specific vascular disease and mortality: a mendelian randomisation study. BMC Med. 2019;17:160. https://doi.org/10.1186/s12916-019-1401-y
4. HUNT Study investigators. Serum vitamin D, blood pressure and hypertension risk in the HUNT study using observational and Mendelian randomization approaches. Sci Rep. 2024; (article). https://doi.org/10.1038/s41598-024-64649-6
5. Beveridge LA et al. Effect of Vitamin D Supplementation on Blood Pressure: A Systematic Review and Meta‑analysis Incorporating Individual Patient Data. JAMA Intern Med. 2015;175(5):745-754. https://doi.org/10.1001/jamainternmed.2015.0237
6. Pilz S et al. Effects of vitamin D on blood pressure and cardiovascular risk factors: a randomized controlled trial. Hypertension. 2015; (article). https://doi.org/10.1161/HYPERTENSIONAHA.115.05319
7. Manson JE; VITAL Research Group. Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease. N Engl J Med. 2019;380:33-44. https://doi.org/10.1056/NEJMoa1809944
8. Neale RE et al. Vitamin D supplementation and major cardiovascular events: D‑Health randomised controlled trial. BMJ. 2023;381:e075230. https://doi.org/10.1136/bmj-2023-075230

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