Writing in Nutrition Research, researchers from Harvard University and the University of Madrid suggested that randomized controlled trials are still needed to confirm clinical efficacy and optimal dosing but that, when combined, the dual use of magnesium and vitamin D may be a “reasonable approach” for people trying to lower blood pressure.
Only two published randomized controlled trials directly examined the combined effects of magnesium and vitamin D on blood pressure.
“Despite the well-established individual roles of magnesium and vitamin D in cardiovascular physiology, relatively few studies have examined their combined influence on blood pressure…” they wrote. “This gap highlights the need for integrative work such as the present review, which aims to synthesize and critically assess the available evidence to better characterize the potential synergy between these nutrients and determine whether combined insufficiency contributes meaningfully to blood pressure regulation.”
The work was funded by ALIMNOVA UCM Research group.
Two interconnected supplements
High blood pressure (BP), or hypertension, impacts millions of people and is the primary risk factor for cardiovascular diseases and related deaths worldwide. Hypertension is responsible for approximately 50% of all ischemic heart diseases and stroke events.
Healthy diets can reduce the risk of cardiovascular diseases. Diets like DASH are effective at lowering systolic blood pressure and diastolic blood pressure, but the researchers explained overall dietary recommendations for prevention and management of hypertension are not comprehensive.
Lifestyle changes and pharmaceuticals are typically used to manage hypertension, but a small, growing body of research suggests a role for supplementation.
“Magnesium plays a key role in many physiological functions and is linked to the prevention of major health conditions such as diabetes, osteoporosis and cardiovascular disease,” the researchers noted. “It is also necessary for activating vitamin D, which helps regulate calcium and supports vascular and overall heart health.”
They explained that magnesium supplementation may enhance magnesium balance by influencing the expression of genes participating in magnesium regulation, leading to potential cardioprotective effects.
Fat-soluble vitamin D has a role regulating blood pressure, too, influencing vascular growth, inflammation and fibrosis. Despite the reported benefits, clinical studies show mixed results for the hormone. Some trials report notable reductions in systolic and diastolic blood pressure in people with vitamin D deficiency while other studies show no significant reductions.
In combination, however, magnesium and vitamin D may influence the prevention of high blood pressure. Magnesium is a necessary cofactor for enzymes responsible for converting vitamin D into its active form. Together, adequate magnesium and vitamin D synergistically reduce peripheral vascular resistance, potentially promoting vasodilation and lowering blood pressure.
Study details
The researchers searched PubMed, ClinicalTrials.gov and the WHO trials registry for randomized clinical trials published in the past 15 years. They found only eight studies (systematic reviews, metanalysis, clinical trials) that evaluated the combined effects of magnesium and vitamin D supplementation on blood pressure, though they cited research depicting the individual roles each nutrient had on blood pressure.
Their analysis suggests the following:
- The supplement combination may improve the bioavailability and activation of vitamin D when there is adequate magnesium present.
- Research indicates insufficient magnesium and vitamin D during pregnancy may contribute to gestational hypertension and gestational diabetes.
- Both supplements have roles in endothelial function, vascular tone regulation and modulation of inflammation— all relevant to control hypertension. According to the review, research is still limited in this area.
- In one clinical trial, participants taking magnesium and vitamin D with baseline systolic blood pressure >132 mmHg experienced a significant reduction in that blood pressure.
- A Cleveland Clinic trial showed strong blood pressure reduction in elderly hypertensive participants receiving the supplement combination.
- The authors suggested that vitamin D, magnesium and possibly vitamin C could have potential as complementary strategies, although the evidence did not establish a synergistic effect.
“While [magnesium and vitamin D] are individually linked to cardiovascular health and blood pressure, evidence on their synergistic effects is scarce and presents a critical opportunity for future studies that clarify the underlying mechanisms, determine optimal dosages and explore potential interactions with other nutrients and lifestyle factors,” the researchers wrote.
They noted that the review offers insights into clinical practice and future research on integrative approaches to cardiovascular health.
Source: Nutrition Research. doi: doi.org/10.1016/j.nutres.2026.06.001. “Potential synergistic influence of magnesium and vitamin D supplementation on blood pressure reduction: a narrative review”. Authors: Montaña Cámara et al.
