Joëlle Schutten

Chapter 1 10 Food and nutrition surveys in the United States and Europe consistently show that dietary magnesium intake is insufficient. In the US, dietary magnesium intake is below the recommended daily allowance (RDA) and the estimated average requirement (EAR) in almost all age and sex groups 1. In fact, approximately 50% of the US population consumes less than the EAR of magnesium 2. A more recent study among post-menopausal women showed that approximately 75% had a magnesium intake below the RDA 3. Among Dutch adults, the proportion with intakes below the EAR is between 16 and 35% 4. Low consumption of vegetables, decreased magnesium content in vegetables compared to historic contents 5 and increased consumption of processed foods, which contain low amounts of magnesium have been identified as important contributors. Early signs of lowmagnesium intake include fatigue and muscle cramps 6,7. Lowmagnesium intake may also lead to an increased risk of cardiovascular disease (CVD) 8. As CVD is the leading cause of death globally 9, preventive measures to lower the risk of CVD are needed and may include adjustments in magnesium intake. At the same time, large well-designed randomized controlled trials (RCTs) addressing the potential effects of increased dietary magnesium intake (by means of supplementation) on cardiovascular health outcomes are lacking.To date, several clinical studies investigated effects of magnesium supplementation on blood pressure, however, showing inconclusive results 10–14. It has been suggested that these inconclusive results are the consequence of large differences in study populations, large differences in study durations and different magnesium formulations that were used. Interestingly, a meta-analysis that summarized the effect of magnesium supplementation on blood pressure found a reduction in blood pressure in a dose- and time-dependent manner, suggesting that studies with higher magnesium dosages and longer durations are more effective 15. Because magnesium has been suggested to antagonize calcification of soft tissues, including the vascular wall, from the perspective of vascular health magnesium supplementation may not only be of interest for reducing blood pressure, but also for improving arterial stiffness by reducing vascular calcification. The effect of magnesium supplementation on arterial stiffness, which is a validated marker of cardiovascular health 16, has rarely investigated, but Joris et al. recently found a significant reduction in arterial stiffness after 24 weeks of magnesium citrate supplementation 17. Magnesium in foods and supplements Magnesium can either be ingested via foods or via dietary supplements that contain magnesium. Foods that are high in magnesium include grains, (green) vegetables, nuts, and dairy products. When consuming an average portion of 200 g of spinach, the total

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