May 06, 2009

Mediterranean diet and coronary heart disease

From the paper:
As shown in Table 4, sufficient support from RCTs to satisfy the criterion for experimental evidence is observed only for marine or total ω-3 fatty acid intake and a Mediterranean dietary pattern. Little or weak evidence from RCTs is found for consumption of fruits, vegetables, fish, fiber, polyunsaturated fatty acids, and total fat and supplemental intake of beta carotene, vitamin E, ascorbic acid, and folate. Other factors have not been evaluated singly in clinical trials (Table 4). The evidence from RCTs agrees with the Bradford Hill results from cohort studies for intake of ascorbic acid and vitamin E supplements, polyunsaturated fatty acids, and total fats and a Mediterranean dietary pattern, but disagree for fish consumption, which shows moderate evidence of a causal link with CHD in cohort studies but virtually no effect in RCTs.
Covered elsewhere:
Eating a Mediterranean diet rich in vegetables and nuts does help protect the heart, a new review concludes.

"We took this on because there is a lot of confusion out in the public about what we should eat and what we should avoid eating in terms of preventing a heart attack," study co-author Dr. Sonia Anand of McMaster University in Hamilton, Ont., told CBC News on Tuesday.

"So the good thing is, we can say try and eat more like someone who would live in Greece or Italy, the Mediterranean diet, and try and avoid a Western-type of diet, which is your eggs and bacon breakfast or your hot dogs for lunch."

Arch Intern Med. 2009;169(7):659-669.

A Systematic Review of the Evidence Supporting a Causal Link Between Dietary Factors and Coronary Heart Disease

Andrew Mente, PhD; Lawrence de Koning, MSc; Harry S. Shannon, PhD; Sonia S. Anand, MD, PhD, FRCPC


Background Although a wealth of literature links dietary factors and coronary heart disease (CHD), the strength of the evidence supporting valid associations has not been evaluated systematically in a single investigation.

Methods We conducted a systematic search of MEDLINE for prospective cohort studies or randomized trials investigating dietary exposures in relation to CHD. We used the Bradford Hill guidelines to derive a causation score based on 4 criteria (strength, consistency, temporality, and coherence) for each dietary exposure in cohort studies and examined for consistency with the findings of randomized trials.

Results Strong evidence supports valid associations (4 criteria satisfied) of protective factors, including intake of vegetables, nuts, and "Mediterranean" and high-quality dietary patterns with CHD, and associations of harmful factors, including intake of trans–fatty acids and foods with a high glycemic index or load. Among studies of higher methodologic quality, there was also strong evidence for monounsaturated fatty acids and "prudent" and "western" dietary patterns. Moderate evidence (3 criteria) of associations exists for intake of fish, marine {omega}-3 fatty acids, folate, whole grains, dietary vitamins E and C, beta carotene, alcohol, fruit, and fiber. Insufficient evidence (≤2 criteria) of association is present for intake of supplementary vitamin E and ascorbic acid (vitamin C); saturated and polyunsaturated fatty acids; total fat; {alpha}-linolenic acid; meat; eggs; and milk. Among the dietary exposures with strong evidence of causation from cohort studies, only a Mediterranean dietary pattern is related to CHD in randomized trials.

Conclusions The evidence supports a valid association of a limited number of dietary factors and dietary patterns with CHD. Future evaluation of dietary patterns, including their nutrient and food components, in cohort studies and randomized trials is recommended.



Anonymous said...

Wow. I have done my share of reading articles on nutrition (WebMD is a good source), but I found the jargon in that paper almost incomprehensible.

I don't think that anyone would disagree that nuts -- which contain healthy monounsaturated fats -- and fish are healthy, and that hamburgers, french fries and other fried foods aren't (Americans destroy the nutrients in their foods when they fry them). Olive oil is also popular in the Mediterranean, and it's good for the heart, thus preventing coronary diseases. This isn't a scientific breakthrough.

Also, Mediterraneans are less prone to alcoholism than Northern Europeans, which gives them all of the benefits of a moderate intake of certain alcoholic drinks without the negative side-effects.

You can allow Spanish or Italian kids to drink wine and get drunk with little lifelong consequence -- but the Upper Paleolithic Irish will be hooked on the stuff to the day they die.

Anonymous said...

I tried looking for counterarguments to my little post from vegans, but it appears their main concern with eating fish stems from their sense of ethics.

Here are interesting quotes from them:

"Scientific studies confirm that fish have a complex nervous system and can feel physical pain."

"Research shows that pigs are much smarter than dogs and that their intellectual abilities exceed those of the average three-year-old human child. Mother pigs sing to their young while nursing, and pigs have more than 20 vocalizations to communicate everything from hunger to courtship intentions."

Crimson Guard said...

Its a good article but has some typical bias towards eggs. Eggs are very healthy and have been eaten by Mediterranean peoples since the dawn of time and even essential to the Roman diet. So I would'nt exclude it the way they do here.