By now it's quite clear that fish and fish oil curb the risk of stroke and cardiovascular disease and their undesirable outcomes ... but deep-fried fish appears to raise heart and stroke risks.
More recently, evidence that fish and fish oil also curb the risk of heart failure has been growing ... see “Fish Oil Trial Finds More Heart-Failure Benefits.”
Heart failure is a burgeoning affliction that affects about five million Americans, as detailed in the sidebar, “Heart failure: A growing plague”, below.
There's even evidence that fish curbs heart failure risk in men and women alike … findings from, among other sources, the large Swedish studies we reported in “Female Heart Failure Cut by Fish” and “Fatty Fish May Cut Men's Heart-Failure Risk”.
Preliminary evidence from two clinical trials supports the presumption that the omega-3s in fish explainits heart-failure benefits: see “Fish Oil May Help Congestive Heart Failure” and “Heart Failure Findings Favor Omega-3s over Statin Drug”.
Now, we have supporting evidence that fish deters heart failure from the even larger Women's Health Initiative … one of the most far-reaching investigations of women's health in America (Belin RJ et al. 2011).
Cardiovascular disease (CVD) is a key underlying cause of heart attacks and heart failure.
And most studies link fishy diets and omega-3 fish oil supplements alike to reduced risk of CVD … probably because omega-3s lower triglycerides and raise HDL (good) cholesterol while moderating inflammation, oxidative stress, and blood pressure.
Huge study finds fatty fish lowers heart risks; fried fish raises them
The Women's Health Initiative (WHI) focuses on heart disease, cancer, and fractures in postmenopausal women … a 15-year project that includes epidemiological studies and controlled clinical trials.
The epidemiological or “observational” part of WHI – called the Women's Health Initiative Observational Study (WHI-OS) – compares participants' diets and lifestyles to their health outcomes over a 10-year period.
Fried fish clearly raise heart risks: Fryer oils' omega-6 fats are suspected
The new findings in women echo those of prior epidemiological studies, which uniformly link non-fried fatty fish to reduced risk of CVD, while linking fried fish to increased risk. (See “Deep-Frying Blocks the Heart Benefits of Fish”.)
Research strongly suggests that this increased risk from breaded, deep-fried fish flows from the vegetable frying oils used.
Standard frying oils – e.g., soy, cottonseed, and safflower – are dominated by generally pro-inflammatory omega-6 fats, in which the American diet is extremely overloaded.
For more on the effects of this gross imbalance in omega-6/omega-3 intake – now a well-documented risk factor for heart disease – see “Heart Group's Omega-6 Advice Takes a Huge Hit”.
The latest WHI-OS data analysis covered 84,493 postmenopausal women aged 50 to 79; average age 63 (Belin RJ et al. 2011).
Its findings echo those of prior population studies, which consistently linked fatty, non-fried fish to reduced heart disease risk, but tied fried fish of any kind to higher heart risk (see our sidebar, "Fried fish clearly raise heart risks").
Compared with women who rarely ate fish, women who reported eating five or more servings of baked or broiled fatty fish per week were 30 percent less likely to develop heart failure within the decade.
In contrast, eating fried fish just once a week appeared to raise the risk of developing heart failure by 50 percent.
Most of the reduction in heart-failure risk with frequent consumption of broiled or baked fish was due to eating fatty fish such as salmon, sardines, mackerel, and other species high in fat … therefore also high in omega-3 fatty acids.
Smaller risk reduction was associated with eating non-fried tuna or white fish (e.g., pollock, sole, snapper, or cod).
However, as with most diet surveys, the one used in this study probably did not ask women to differentiate between relatively lean “light” canned tuna (i.e., skipjack, tongol) and relatively fatty “white” canned tuna (albacore).
Study called scientifically solid and supportive of fatty, non-fried fish
Women with a history of heart attack were excluded from the study, and the researchers adjusted the results to account for the influence of known heart failure risk factors.
Heart failure: A growing plague
Heart failure is a chronic, progressive condition in which the heart muscle is unable to pump enough blood to meet the body's needs for blood and oxygen, causing fatigue, shortness of breath … and risk of premature death.
People who have heart failure usually also have (or had) one or more other heart conditions that weaken the heart muscle … such as cardiovascular or coronary artery disease, heart attack, high blood pressure, abnormal heart valves, and heart muscle disease or inflammation.
An estimated 4.8 million Americans have heart failure – with roughly equal numbers of men and women – and almost 1.4 million cases are under 60 years of age.
Heart failure is present in more than five percent of persons age 60 to 69, and 10 percent of persons age 70 and older.
Heart failure is the first-listed diagnosis in 875,000 hospitalizations, and the most common diagnosis in hospital patients age 65 years and older.
The women were surveyed for diet information, including their fish consumption and usual preparation form (baked, broiled, or fried).
Based on their replies to the diet survey, women were divided into five categories of broiled or baked fish consumption – from less than once a month (the so-called “reference” group) to five or more times a week – and three categories of fried fish consumption: from less than once a month to one or more times a week.
According to Dr. Rachel Johnson at the University of Vermont – a member of the AHA's nutrition committee – the study had a “strong design”, since it was a large, lengthy, and relied on a “rich database.” (Busko M 2011)
But it's important to note that, as with most population studies, the researchers had to try to account for the influences of other risk factors – so-called “confounders” – which can skew the results.
For example, the women who ate the fattiest, broiled or baked fish tended to be younger and more physically fit and to follow a healthier diet.
And the women who ate the most fried fish of any kind were more likely to smoke and to have a higher body-mass index (BMI), higher systolic BP, diabetes, atrial fibrillation, and coronary heart disease (clogged, inflamed major heart vessels).
Still, as Dr. Johnson said, “The take-home message is that if you are not already regularly eating fish, try to add it to your diet, and have it in a preparation method retaining the beneficial aspects of fish.” (Busko M 2011)
She also noted that the AHA recommends at least two servings of fish a week, and added, “There is certainly no harm in eating more than two servings a week, particularly if you have risk factors.” (Busko M 2011).
The authors noted that they found no significant associations between heart-failure risk and estimated intakes of omega-3 EPA+DHA (from fish), omega-3 ALA (from plant foods), or trans fats.
Therefore, they cautioned – apparently ignorant of the clinical evidence contradicting this concern – that omega-3 fish oil might not deliver heart-failure benefits to the same degree whole fatty does.
We'd agree, however, that other constituents in fatty fish – such as vitamin D – may reduce heart failure risk, and that people eating a diet high in fish likely eat less meat and poultry, which are generally less heart-healthful.
Belin RJ, Greenland P, Martin L, et al. Fish intake and the risk of incident heart failure: The Women's Health Initiative. Circ Heart Fail. 2011; DOI:10.1161/CIRCHEARTFAILURE.110.960450.
Busko M. Baked/broiled fish reduces HF, fried fish ups risk. May 25, 2011. Accessed at http://www.theheart.org/article/1231133.do
Marchioli R, Levantesi G, Silletta MG, Barlera S, Bernardinangeli M, Carbonieri E, Cosmi F, Franzosi MG, Latini R, Lucci D, Maggioni AP, Moretti L, Nicolosi GL, Porcu M, Rossi MG, Tognoni G, Tavazzi L; GISSI-HF Investigators. Effect of n-3 polyunsaturated fatty acids and rosuvastatin in patients with heart failure: results of the GISSI-HF trial. Expert Rev Cardiovasc Ther. 2009 Jul;7(7):735-48.
Gissi-HF Investigators, Tavazzi L, Maggioni AP, Marchioli R, Barlera S, Franzosi MG, Latini R, Lucci D, Nicolosi GL, Porcu M, Tognoni G. Effect of n-3 polyunsaturated fatty acids in patients with chronic heart failure (the GISSI-HF trial): a randomised, double-blind, placebo-controlled trial. Lancet. 2008 Oct 4;372(9645):1223-30. Epub 2008 Aug 29.