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Harvard Health Publications -- Harvard Medical School HEALTHbeat
June 21, 2006

Dear HEALTHbeat subscriber,

Fat. It seems to be on our minds all the time, whether we’re worrying about how much extra we carry around or what’s in the foods we eat. This issue of HEALTHbeat focuses on the second kind. If you’re thinking about slathering margarine on this summer’s corn on the cob, you’ll definitely want to read our main article. And you’ll learn about good sources of healthy omega-3 fats in this issue’s Question and Answer.

Wishing you good health,

Nancy Ferrari
Managing Editor
Harvard Health Publications

In This Issue
1 Butter vs. Margarine: Which is the winner?
2 Notable from Harvard Medical School:
* Harvard Health Letter
* The Healthy Heart:
   Preventing, detecting, and
   treating coronary artery
3 The Harvard Heart Letter answers:
Is flaxseed a good source of omega-3 fats?

From Harvard Medical School
Healthy Eating: A guide to the new nutrition

Your diet is your first defense in preventing a host of diseases. This updated and expanded report from Harvard Medical School explains how a healthy diet will help you prevent heart disease, hypertension, diabetes, gastrointestinal disorders, and even some forms of cancer and blindness. Understand the new nutrition guidelines and put your family on the path to healthy and delicious eating.

Invite someone to sign up for HEALTHbeat and you both will receive a FREE gift.
Click here to start.

1\ Butter vs. Margarine

If you enjoy butter on your baked potato, toast, or pasta, you’ve probably felt a pang of guilt when putting that golden pat on your plate. Or worse, you may feel conflicted and confused as to whether you should stick with butter or switch to margarine or another spread.

Although a staple of the American diet, butter came under a great deal of scrutiny when its high levels of saturated fat were associated with increased heart disease risk. Many people accepted the demise of butter in stride, ruing the loss of its savory flavor but agreeing that its effect on the heart might be too high a price to pay. They dutifully switched to margarine, as researchers and nutritionists suggested. Then the hazards of margarine came to light. Its high levels of trans fats packed a double whammy for heart disease by raising levels of LDL (bad cholesterol) and lowering levels of HDL (good cholesterol). Many people felt betrayed or duped.

The truth is, there never was any good evidence that using margarine instead of butter cut the chances of having a heart attack or developing heart disease. Making the switch was a well-intentioned guess, given that margarine had less saturated fat than butter, but it overlooked the dangers of trans fats.

Today the butter-versus-margarine issue is really a false one. From the standpoint of heart disease, butter is on the list of foods to use sparingly mostly because it is high in saturated fat, which aggressively increases levels of LDL. Margarines, though, aren’t so easy to classify. The older stick margarines that are still widely sold are high in trans fats, and are worse for you than butter. Some of the newer margarines that are low in saturated fat, high in unsaturated fat, and free of trans fats are fine as long as you don’t use too much (they are still rich in calories).

You can quickly compare the health value of spreads (including butter and margarine) simply by looking at the nutrition labels on these products. The FDA now requires nutrition labels to include information about both saturated fats and trans fats. Your goal is to limit intake of saturated fats and to avoid trans fats altogether.

Healthier alternatives to butter or margarine include olive oil and other vegetable oil–based spreads, which contain beneficial mono- and polyunsaturated fats. Next time you tear into a warm loaf of bread or roll, consider dipping it in olive oil rather than coating it in butter. If you're trying to lower your cholesterol, stanol-based spreads (for example, Benecol and Take Control) are even better, since regular use can help lower LDL cholesterol levels.

To learn more about choosing the healthiest foods, order our special health report, Healthy Eating: A guide to the new nutrition at

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2\ Notable from Harvard Medical School
** The Harvard Health Letter

Each month, the Harvard Health Letter covers a wide range of health issues from diabetes to cardiac health, Alzheimer’s disease, depression, preventive medicine, and much more. Take charge of your health with the Harvard Health Letter.

** The Healthy Heart: Preventing and treating coronary artery disease

Heart disease kills one in five people in the United States. But thanks to advances in prevention, diagnosis, and treatment, more people are avoiding or surviving heart disease.  It’s easy to become confused about what puts you at risk and how you can protect yourself. In The Healthy Heart, find out what you can do to lower your risk for heart disease. If you suffer from any heart-related conditions, The Healthy Heart explains how you can best benefit from new treatments and procedures.

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3\ Q&A: Is flaxseed a good source of omega-3 fats?

Q: Are the omega-3 fats in flaxseed oil as good for the heart as those in fish or fish oil? Do they have the same side effects? The American Heart Association warns about getting more than 3 grams of omega-3 fats a day without a doctor’s supervision, but one teaspoon of my concentrated flaxseed oil — the recommended dose — contains 6.2 grams. Should I be worried?

A: There are three main types of omega-3 fats. Their names are a mouthful (eicosapentaenoic acid, docosahexaenoic acid, and alpha-linolenic acid) so I’ll use their abbreviations: EPA, DHA, and ALA.

EPA and DHA are sometimes called the marine omega-3s, since we get them mostly from seafood. People who get plenty of EPA and DHA seem to have more protection against heart attack, stroke, and sudden death than people who get little of these essential fats.

ALA comes from plants. The best sources are ground flaxseeds and flaxseed oil (whole flaxseed passes through the digestive tract untouched, which means you miss out on the benefits of flaxseed oil). Other ways to get ALA include eating walnuts, tofu and other forms of soy, and omega-3 enriched eggs, as well as using vegetable oils such as canola, walnut, and soybean oils. Only a fraction of ALA, somewhere around 10%–15%, is converted to the more powerful omega-3s; the rest is burned for energy. A tablespoon of flaxseed oil delivers 120 calories — if you don’t cut back 120 calories somewhere else in your diet, or exercise more, that’s enough to add more than 10 pounds a year!

There is some controversy over whether ALA offers the same protection against heart attack, stroke, and sudden death as EPA and DHA. Some studies show a benefit, others don’t.

For people without heart disease, the American Heart Association recommends getting omega-3s from food — at least two servings a week of fatty fish such as salmon, sardines, trout, and herring, as well as daily servings of vegetable oils and foods rich in alpha-linolenic acid. Those with heart disease should try to get one gram total of EPA plus DHA per day, preferably from fatty fish, though fish-oil supplements are fine, too. Higher doses (two to four grams a day) may help lower high triglycerides.

The AHA warns against taking more than three grams of EPA and DHA a day without talking with a doctor. These substances make it harder for blood to clot, and so could cause excessive bleeding. The risk of bleeding increases if you are also taking aspirin, warfarin (Coumadin), an antiplatelet drug such as clopidogrel (Plavix), nonsteroidal anti-inflammatory drugs such as ibuprofen or naproxen, or herbal supplements such as garlic or ginseng.

If you don’t like fish, and fish oil capsules don’t agree with you, then ALA is a good backup. As an “adequate intake,” the Institute of Medicine recommends 1.6 grams/day for men and 1.1 grams for women. If ALA does, indeed, protect against heart disease, more is probably needed. The amount in your flaxseed oil supplement, 6.2 grams, gives you just over half a gram of the more potent omega-3s, EPA plus DHA, and so is within the heart association’s safety limits.

This Question and Answer first appeared in the November 2005 issue of the Harvard Heart Letter (

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Harvard Medical School publishes authoritative special health reports on a wide range of topics. Each report delivers practical information on diagnosis, treatment, and prevention of major health concerns in clear, easy-to-understand language. For more information on a specific topic, click the appropriate link below:

Alzheimer’s, Arthritis, Bladder, Cholesterol, Depression, Diabetes, Digestion, Energy, Exercise, Eye Disease, Headache, Heart Disease, High Blood Pressure, Memory, Menopause, Prostate, Sexuality, Sleep, Stroke, Vitamins

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Harvard Medical School offers special reports on over 50 health topics. Visit our Web site at to find reports of interest to you and your family.

Copyright 2006 by the President and Fellows of Harvard College.
To view our archive of past HEALTHbeat e-newsletters click here.
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