Study in middle-aged, multi-ethnic men links higher DHA levels to less artery calcification
Last week, the Centers for Disease Control and Prevention delivered some bad news on heart disease.
The CDC reported that heart disease death rates among middle-aged American men and women rose by 4% from 2011 to 2017.
Buildup of calcium in your coronary arteries is a key risk factor and predictor for heart disease — and for related adverse events like heart attacks or stroke.
Just by itself, having a relatively large amount of coronary artery calcium (CAC) can prompt a diagnosis of coronary atherosclerosis — commonly called “hardening of the arteries”.
Accumulation of coronary artery calcium is caused in part by chronic arterial inflammation, generated when oxidized cholesterol and lipids (fats) adhere to artery walls — which in turn prompts more inflammation.
Your CAC score — which is determined by a CT scan — helps assess the risk for heart attacks, strokes, and other adverse outcomes. CAC scores range from zero to 400 or more (see “What do CAC scores mean, and should I get tested?”, below).
Accordingly, cardiologists use the CAC scores of people who have no symptoms of heart disease to help them and their patients decide on preventive therapies such as statins and aspirin.
Fishy omega-3s linked to reduced artery calcification
Unfortunately, misleading media stories — including reports from generally respected outlets like The New York Times and PBS TV's Frontline — have conveyed serious distortions of the overall evidence.
And those misleading media reports failed to convey the highly positive overall results of most of the lab and clinical evidence about omega-3s and heart health.
Contradicting those misimpressions, recent clinical trials of prescription omega-3 drugs — which are not materially different from high potency omega-3 fish oil supplements — yielded very positive results: see Omega-3s Score 2nd Big Heart Win and Omega-3s’ Heart Value Vindicated in Long, Large Clinical Trial.
Almost certainly, some of the heart-risk-reduction benefit of omega-3 DHA and EPA flows from the fact that the body uses them to end chronic, counterproductive inflammation, which is a key risk factor for cardiovascular disease.
However, the results of several epidemiological studies also link higher fish intakes and/or higher blood levels of omega-3 DHA and/or EPA to reduced amounts of calcium in people’s arteries (Heine-Bröring RC et al. 2010; Sekikawa A et al. 2013; Alfaddagh A et al. 2019; Sekikawa A et al. 2019).
Importantly, researchers from UCLA reported finding the mechanism by which dietary omega-3s can reduce arterial calcification (Abedin M et al. 2006).
And the earlier epidemiological findings are echoed in two recent epidemiological studies: an international study involving multi-ethnic men in Japan and the US, and one involving only Japanese men.
Study #1: Omega-3 DHA linked to less arterial calcium in multi-ethnic men
This study was conducted by researchers at the University of Pittsburgh, Philadelphia’s Temple University, and two universities in Japan (Mahajan H et al. 2019).
The scientists recruited 998 forty-something men: 300 white Americans, 101 African-Americans, 287 Japanese-Americans, and 310 Japanese in Japan.
All the men underwent CT scans to determine their CAC or “Agatston” score, and blood tests to determine their omega-3 levels. About 57% of the men had some degree of arterial calcification.
Encouragingly, the results showed a 35% reduction in the participants CAC scores for every 2% increase in DHA levels.
The researchers speculated that this benefit may flow from the anti-inflammatory effects of omega-3 DHA.
As the authors wrote, “Evidence generated from this study adds to the evidence on the anti-atherosclerotic property of … [seafood source omega-3s] … especially DHA in healthy middle-aged men.”
They added, in what seems like an understatement, “Our study findings have public health significance.”
Unlike some other studies, the authors found no link between blood levels of EPA and degrees of artery calcification as reflected by CAC scores.
Study #2: Omega-3 DHA linked to less arterial calcium in Japanese men
This study comes from the same international team but involved only middle-aged Japanese men living in Japan (Sekikawa A et al. 2019).
The participants were 1,074 men aged 40-79. The researchers measured the volunteers’ artery calcification (CAC) scores, blood levels of omega-3 DHA and EPA, and other known risk factors.
And the results linked higher blood levels of DHA — but not EPA — to lower CAC scores and consequently levels of coronary atherosclerosis.
This suggestion from the study’s authors makes good sense: “Future trials are warranted comparing the effect of high-dose [supplemental] DHA and EPA on atherosclerosis and cardiovascular outcomes.”
What do CAC scores mean, and should I get tested?
Your CAC score usually predicts the amount of plaque in your coronary artery.
The result of a CAC test is expressed as a number that reflects the total area of arterial calcium deposits and the density of the arterial calcium:
- A CAC score of zero means you have no plaque in your coronary arteries, and a correspondingly low risk for suffering a heart attack.
- Scores ranging from 11-100 indicate some plaque and mild heart disease, with a moderate chance for a heart attack.
- Scores ranging from 101-400 indicate a moderate amount of plaque and a moderate to high risk of a heart attack.
- Scores over 400 indicate a 90% chance that plaque is blocking one of your arteries and that your chance of a heart attack is high.
According to guidelines issued by the American College of Cardiology and the American Heart Association, a heart CAC scan is not usually recommended for people in these categories, because it won’t add much useful information:
- People without a family history of heart attacks at an early age.
- People with symptoms or a diagnosis of coronary artery disease.
- People already determined to be at high risk for coronary artery disease.
- Men under age 40 and women under age 50, because it's unlikely calcium can be detected at younger ages.
Interestingly, very high levels of physical activity have been linked to higher levels of arterial calcification — and sometimes with a higher risk for coronary artery disease (DeFina LF et al. 2017; Laddu DR et al. 2019).
However, vigorous exercise is generally linked to better heart and overall health, so those apparent links shouldn’t be over-emphasized or taken out of context.
- Abedin M, Lim J, Tang TB, Park D, Demer LL, Tintut Y. N-3 fatty acids inhibit vascular calcification via the p38-mitogen-activated protein kinase and peroxisome proliferator-activated receptor-gamma pathways. Circ Res. 2006 Mar 31;98(6):727-9. Epub 2006 Mar 2.
- Alfaddagh A, Elajami TK, Saleh M, Mohebali D, Bistrian BR, Welty FK. An omega-3 fatty acid plasma index ≥4% prevents progression of coronary artery plaque in patients with coronary artery disease on statin treatment. Atherosclerosis. 2019 Jun;285:153-162. doi: 10.1016/j.atherosclerosis.2019.04.213. Epub 2019 Apr 13.
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