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In the news: Low vitamins D & K Up Mortality Risk; High GI Diet Increases CVD & Death

Follow-up: Low Vitamins K & D Ups Mortality Risk

The last issue of EduFacts examined the relationship between vitamins D and K2 : While vitamin D promotes calcium absorption, vitamin K directs calcium to bone and reduces the deposition of calcium in blood vessel walls and soft tissue. The findings of a newly published study(1) from medical researchers in the Netherlands lends weight to the importance of vitamins D and K status on clinical outcomes.

To explore the association of both plasma vitamin D and K concentrations with all-cause and cardio-vascular mortality in middle-aged individuals in the general population, the researchers studied 4,742 participants of the PREVEND Study. Vitamin D was measured by plasma 25-hydroxyvitamin D and vitamin K by uncarboxylated matrix GLA protein at baseline, and patients were categorized into adequate and insufficient levels of both vitamins and compared to reference values.

Combined low vitamin K and D status was present in 20% of participants and was associated with a greater risk (hazard ratio 1.46 ) of all-cause mortality over a 14+-year median follow-up. The combined association of low status for both vitamins was greater than the sum of low vitamin D and K status alone, indicating that poor status of both amplifies the risk of mortality.

For cardiovascular mortality and cardiovascular events, the researchers observed similar trends – hazard ratios of 1.42 and 1.28, respectively – though neither achieved statistical significance.

In related news, preliminary observations(2) have shown a correlation between low vitamin K and more severe COVID-19, as have low levels of vitamin D. A randomized, double-blind, placebo-controlled trial is underway in the Netherlands with the objective of determining whether vitamin K2 status affects degradation of elastic fibers in the lung (Clinical Trials.gov Identifier NCT04770740). Vitamin K-dependent matrix GLA protein protects elastin from both calcification and breakdown.

Since vitamin K is important for regulating lung health and blood clotting, the researchers postulate that supplemental vitamin K2 might help reduce COVID-related thrombosis and lung damage.

High GI Diet Linked to Higher Risk of CVD, Death

Foods with a high glycemic index (GI) such as white bread and rice, and sugary drinks raise blood glucose levels more rapidly than lower GI foods such as whole grains, beans, green vegetables and most fruit. Glycemic load not only measures how quickly a food makes glucose enter the bloodstream but how much glucose per serving it can deliver.

Studies have associated diets with a high glycemic index (GI) and/or a high glycemic load with increased risk of cardiovascular disease (CVD), as well as age-related macular degeneration and cataract. Most data showing a link between the GI and CVD come from high-income Western populations, with little data from other countries with low or middle incomes. To fill this gap, researchers analyzed data from nearly 138,000 participants from 20 culturally and economically diverse countries across 5 continents who were followed for a median 9.5 years(3). The 1º endpoint was a composite of a major cardiovascular event (nonfatal heart attack, death, stroke, heart failure) or death from any cause. It was found that:

• the highest GI diets vs. the lowest were associated with increased risk of death and CVD in those with and without preexisting CVD (hazard ratios 1.51 and 1.21 respectively), and was most pronounced in the overweight / obese

• the results for glycemic load were similar to those of the GI findings among those with pre-existing CVD, but the association was not significant among those without CVD at baseline

The evidence suggests a simple take home message: eat quality carbohydrates for better heart health.

References

1. van Ballegooijen AJ, et al. Combined low vitamin D and K status amplifies mortality risk: a prospective study. Eur J Nutr. 60:1645-54, 2021.
2. Kudelko M, et al. Potential beneficial effects of vitamin K in SARS-CoV-induced vascular disease? Immuno. 1:17-29, 2021.
3. Jenkins JA, et al. Gycemic index, glycemic load, and cardiovascular disease and mortality. NEJM. 384:1312-1322, 2021.