Four diets forged in clinical trials offer real benefits for the entire cardiovascular system.
Do the basics of healthy eating - more fruits, vegetables, good fats, whole grains, and healthful protein packages, and less of the not-so-good stuff - work for the heart? Indeed they do.
A host of studies has shown that each of these elements, by itself, can lower cholesterol, blood pressure and blood sugar; improve the flexibility of arteries; or protect against heart attack, stroke, and other forms of cardiovascular disease. Put various pieces together and the protective effect is even more powerful.
There are scores of 'healthy heart' diet books in the marketplace. Very few of those diets, though, have been tested to see how well - or even if - they work.
If you are a do-it-yourself-er, don't hesitate to wade right in and fiddle with your diet. After all, this isn't rocket science, and only you know what foods you like, which ones you can't stomach, and what kinds of dietary changes you can realistically make.
But what if you'd rather have someone else cook up a diet to help you counter or prevent heart disease? There are scores of "healthy heart" diet books in the marketplace. Very few of those diets, though, have been tested to see how well - or even if - they work.
Four diets forged in rigorous clinical trials are the real McCoy. These are the DASH diet, a higher-protein diet, the cholesterol-lowering portfolio diet, and a Mediterranean-type diet.
These four are much better for the heart than the average American diet. Yet each has its own subtle effects that, in some cases, could detract from the benefits, and none except the Mediterranean-type diet has been studied long enough to know exactly how it affects heart disease or survival.
You can assume that the improvements that all four yield in cholesterol levels and blood pressure will translate into protection against heart attack or stroke. But when it comes to nutrition, making assumptions can be tricky.
Four for the heart
Here is a sketch of this quartet of carefully tested diets and how they stack up against heart disease.
These four diets are alike in many ways. They are heavy on food from plants (fruits,vegetables, beans, nuts, and seeds) and light on saturated fat, sodium, and sweets.
A dose of DASH. The Dietary Approaches to Stop Hypertension trial tested a diet that emphasised fruits, vegetables, and low-fat dairy foods and limited red meat, saturated fats, and sweets.
Compared with an average American diet, the DASH diet lowered systolic blood pressure (the upper number of a blood pressure reading) by 5.5 points and diastolic pressure (the lower number) by 3 points.
A low-sodium DASH diet worked even better. The DASH diet lowers levels of harmful LDL (bad) cholesterol and triglycerides, the main fat-carrying particles in the bloodstream. On the downside, it also reduces protective HDL ("good") cholesterol.
Help from protein. One of the diets tested in the Optimal Macronutrient Intake Trial to Prevent Heart Disease (OmniHeart, for short) replaced some carbohydrates of the DASH diet with additional good protein. This strategy lowered LDL and triglycerides and dropped blood pressure a bit more than the original DASH diet. But it, too, harmed HDL.
Improve your portfolio. Researchers at the University of Toronto created what they called a "dietary portfolio of cholesterol-lowering foods." It went after cholesterol by adding specific foods known to lower cholesterol: margarine enriched with plant sterols; oats, barley, psyllium, okra, and eggplant, all rich in soluble fibre; soy protein; and whole almonds. It substantially lowered LDL, triglycerides, and blood pressure, and did not harm HDL.
Mediterranean-type diet. The basics include fruits, vegetables, grains, beans, and nuts supplemented with some cheese or yogurt, fish, poultry, and eggs. It's beneficial across the board for cholesterol, blood pressure, and other cardiovascular risk factors.
In one long-term study, heart attack survivors who followed a Mediterranean-type diet suffered far fewer heart attacks, strokes, or other cardiovascular problems than survivors following a standard low-fat diet.
Bringing it home
These four diets are alike in many ways. They are heavy on food from plants (fruits, vegetables, beans, nuts, and seeds) and light on saturated fat, sodium, and sweets.
They aren't vegetarian, although the portfolio diet comes pretty close. Instead, they are "flexitarian" - they emphasise healthy plant foods, but also include poultry, seafood, dairy foods, and sometimes even steak.
The DASH and Mediterranean-type diets have been translated into popular books with meal plans and recipes. The OmniHeart and Portfolio approaches haven't.
From reports in medical journals, we've put together some daily meal plans that can give you ideas for setting up your own version.
Notice that the standard low-fat diet - less than 20% of calories from fat - isn't on the list. It was designed as a way to get people to eat less saturated fat, which is a good thing. But it also enticed dieters to see all fat as a villain.
That isn't so good, since unsaturated fats are actually good for the heart.
What's more, cutting back on fat often meant that people ate more refined starches and sugar, a dietary move that does the heart no favours. In clinical trials, the DASH, OmniHeart, and Mediterranean-type diets both soundly trumped a low-fat approach.
That's not to say the low-fat approach is bad. It works for some people. Dr. Dean Ornish uses it as one part of an effective program that also includes exercise and stress management.
The trick is adding healthy, slowly digested carbohydrates and sticking with the diet. Low-fat diets are generally harder to follow for long periods than a Mediterranean-type diet, which is more varied.
The most encouraging finding from trials comparing weight-loss diets is that long-term weight loss can be accomplished by a variety of ways - there's no one-size-fits-all strategy. The same will probably hold true for heart healthy diets. What's important is to find a plan you can stick with for a long lifetime.
Source: Harvard Health Publications. Copyright © 2008 President and Fellows of Harvard College. All rights reserved.
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