In the news: Magnesium & Arteries; Omega-3s & Breast Cancer Risk, Blood Pressure

Magnesium Linked to Healthier Arteries

Magnesium plays many roles in the body from helping to maintain healthy blood pressure, muscle and nerve function, to keeping heart rhythm steady and bones strong. A newly published study suggests that higher magnesium levels may reduce the risk of hypertension and calcification of the coronary arteries (1).

Researchers from Mexico’s National Institute of Cardiology conducted a population health study, measuring serum magnesium levels in more than 1,200 men and women aged 30-75 and free of symptomatic cardiovascular disease (CVD). An imaging procedure called computerized tomography was used to assess artery calcification.

After adjusting for other factors, the investigators found that low serum magnesium was independently associated with a higher prevalence not only of hypertension and type-2 diabetes, but also of coronary artery calcification – a predictor of CVD.

Participants with the highest average magnesium blood levels had a 48% lower risk of hypertension, 69% lower odds of having type-2 diabetes, and 42% lower odds of coronary artery calcification, compared to those with the lowest serum magnesium. Poor intake or low blood levels of this mineral have been linked to a higher risk of calcium in arteries in Korean and US population studies as well.

The 2015 Dietary Guidelines Advisory Committee has tagged magnesium as a nutrient commonly under-consumed. Good dietary sources include fruits, green leafy vegetables, whole grains, nuts and dairy.

Omega-3 May Lower Breast Cancer Risk

Being overweight or obese is a major breast cancer risk factor for post-menopausal women. Experts believe that inflammation is an important underlying cause, and normal weight women have less inflammation than heavier women.

Since omega-3 fatty acids have anti-inflammatory actions, researchers from Penn State, Emory and Colorado State Universities teamed up to examine the impact of omega-3s on breast density in women of different weights (2). Breast density is a validated biomarker for breast cancer risk – the higher the density the more likely cancer will develop. (High breast density means there’s more breast and connective tissue compared to fat in the breast).

Over 260 healthy post-menopausal women with high breast density received either the anti-estrogen drug Raloxifene, omega-3 (EPA and DHA), omega-3 and the drug combined or no treatment during this 2-year long study. Half the participants were normal weight, 30% overweight, and 20% were obese.

Increasing blood levels of omega-3 (DHA only) were associated with decreased breast density, and only in those bordering on obesity or obese. These promising results need to be confirmed in larger trials, perhaps testing EPA/DHA and DHA alone.

Lower Doses of Omega-3s for Hypertension?

Even modest amounts of omega-3s may lower blood pressure in clinically meaningful amounts for those with systolic hypertension, according to results of a study from the UK (3). The majority of trials looking at these fats and hypertension have used 3,000 mg of omega-3s or more, but recent studies have explored lower amounts in the 500 mg to 1,000 mg range.

In this analysis of a randomized controlled trial of over 300 participants, either 700 mg or 1,800 mg of supplemental omega-3 was given for 8 weeks. The results showed that both doses reduced systolic pressure by about 5 mmHg, but only in those with elevated systolic blood pressure at the trial’s start.

This level of blood pressure reduction would translate to about a 20% decrease in CVD risk in middle age, according to the authors, and is an amount achievable by consuming 2-3 weekly portions of oily fish.

References

1. Posadas-Sanchez R, et al. Serum magnesium is inversely associated with coronary artery calcification in the Genetics of Atherosclerotic Disease (GEA) study. Nutr J, 15:22, 2016.
2. Sandhu N, et al. Influence of obesity on breast density reduction by omega-3 fatty acids: Evidence from a randomized clinical trial. Cancer Prev Res, Dec 29, 2015 [Epub ahead of print].
3. Minihane AM, et al. Consumption of fish oil providing amounts of EPA and DHA that can be obtained from the diet reduces blood pressure in adults with systolic hypertension: A retrospective analysis. J Nutr, 146:516-23, 2016.