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Harvard Health Publications -- Harvard Medical School HEALTHbeat
September 27, 2006

Dear HEALTHbeat subscriber,

Equality between the sexes notwithstanding, when it comes to healthy eating, there are some crucial differences between men and women. This issue of HEALTHbeat explains what women and men need to know to in order to optimize their diets based on gender. Also, Dr. Walter C. Willett of the Harvard Heart Letter’s Editorial Board discusses whether coconut is good or bad for the heart.

Wishing you good health,


Nancy Ferrari
Managing Editor
Harvard Health Publications
HEALTHbeat@hms.harvard.edu

In This Issue
1 Nutrition for the sexes
[READ]
2 Notable from Harvard Medical School:
* The Healthy Heart:
   Preventing, detecting, and
   treating coronary artery
   disease
* The Sensitive Gut
[READ]
3 A Harvard Medical School doctor answers:
Is coconut good or bad for the heart?
[READ]

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

With new diets getting the spotlight every few months, it’s hard to decide what you should eat to stay healthy and lose weight or maintain a healthy weight. Healthy Eating: A guide to the new nutrition describes how new research has provided a new concept of good fats and bad fats, and a greater understanding of the components of foods and how they influence health.

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1\ Optimal nutrition: It’s different for men and women

You are what you eat. It’s true for both men and women. And it’s also true that a healthy, balanced diet is best for both genders. But there are differences in the nutritional needs of men and women; the fine print of nutrition is one more way that the sexes are opposite.

Calories

A person’s caloric requirement depends on body size and exercise level. Sedentary people of both genders will keep their weight stable by taking in about 13 calories per pound of body weight each day. Moderate physical activity boosts this requirement to 16 calories a pound, and vigorous exercisers need about 18 calories a pound. On average, a moderately active 125-pound woman needs 2,000 calories a day; a 175-pound guy with a similar exercise pattern needs 2,800 calories. For both women and men, losing weight means burning more calories than you take in.

Protein

Despite all the hype about high-protein diets, our protein requirements are really quite modest — only about a third of a gram per pound of body weight. Protein should provide about 15% of a healthy person’s daily calories. As a rule of thumb, people of both sexes and any size will do fine with about 60 grams of protein a day. About 8 ounces of chicken or 6 ounces of canned tuna, for example, will more than fit the bill. Excess dietary protein increases calcium loss in the urine, perhaps raising the risk for osteoporosis (more a worry for women) and kidney stones (a particular worry for men).

Carbohydrates

Carbohydrates should provide 45%–65% of daily calories for men and women. Most of those calories should come from the complex carbohydrates in high-fiber and unrefined foods, such as bran cereal and other whole-grain products, brown rice, beans and other legumes, and many fruits and vegetables. These carbohydrates are digested and absorbed slowly, so they raise the blood sugar gradually and don’t trigger a large release of insulin. People who eat lots of these foods have higher HDL (“good”) cholesterol levels and a lower risk of obesity, diabetes, and heart disease. Some studies have shown that fiber may help reduce the risk of colon cancer. Men need more fiber than women: 38 vs. 25 grams a day before the age of 50 and 30 vs. 21 grams a day thereafter.

Fat

Both men and women should keep their total fat consumption below 30%–35% of daily calories. Since fat is the most calorie-dense food (9 calories per gram), levels as low as 20%–25% are appropriate when weight is an issue.

To achieve these goals, cut down on saturated fat from animal products and certain vegetable products — palm oil, palm kernel oil, cocoa butter, and coconut. And it’s just as important to reduce your consumption of trans fatty acids, the partially hydrogenated vegetable oils found in stick margarine, fried foods, and many commercially baked goods and snack foods.

Make up the difference by including more unsaturated fats in your diet. Monounsaturated fats are healthy for both men and women; olive oil is a good source. The two omega-3 fatty acids found in fish are highly desirable for both sexes. But the vegetable omega-3 found in canola oil and flaxseed oil, alpha-linolenic acid (ALA), is a different matter.

Like the marine omega-3s, ALA is good for the heart. But ALA may not be so good for the prostate. Two Harvard studies have shown that men who consumed the most ALA were 3.4 times more likely to be diagnosed with prostate cancer than those who had the lowest dietary intake. It’s still an open question, but there is no question that ALA represents a dietary difference between the sexes.

Alcohol

There are gender differences here, too, but this time women face the dilemma.

In both men and women, low doses of alcohol appear to reduce the risk of heart attacks and certain strokes. For both, larger amounts increase the risk of many ills, including liver disease, high blood pressure, behavioral problems, and premature death. But women face an extra risk: Even low doses of alcohol can raise their risk of breast cancer. So women who choose to drink might be wise to limit themselves to one glass a day.

Calcium

Calcium is important for women; a high-calcium diet may help lower their risk of osteoporosis. Although it’s less common, men can get osteoporosis, too; but there is much less evidence that dietary calcium is protective for men.

Calcium may even be harmful for men, at least in large amounts. The worry is prostate cancer: A high consumption of calcium from food or supplements has been linked to an increased risk of advanced prostate cancer. The risk was greatest in men who got more than 2,000 mg a day.

What’s a man to do? The solution is moderation. Aiming for about 800 mg a day (two-thirds of the RDA) is a safe bet.

Iron

There’s not much doubt about this one: Women need more iron than men, because they lose iron with each menstrual period. After menopause, of course, the gap closes. The RDA of iron for premenopausal women is 18 mg a day, for men 8 mg. Men should avoid excess iron.

For more information on nutrition, order our special health report Healthy Eating: A guide to the new nutrition at www.health.harvard.edu/HE.

 
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2\ Notable from Harvard Medical School
** The Healthy Heart

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. In The Healthy Heart, find out what you can do to lower your risk for heart disease or get the most out of new treatments and procedures for existing heart-related conditions.

 
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** The Sensitive Gut

One in four people has frequent gastrointestinal problems that can severely disrupt a normal lifestyle. In The Sensitive Gut, a Harvard doctor will teach you how to help prevent and treat common and not-so-common digestive problems, ranging from heartburn and gastroesophageal reflux disease to gas and irritable bowel syndrome.

 
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3\ Q&A: Is coconut good or bad for the heart?

Q: I have heard that coconut is bad for the heart and that it is good for the heart. Which is right?

A: Viewed in isolation, coconut and coconut oil can’t be considered heart-healthy foods. A 2-ounce piece of fresh coconut contains more than 13 grams of saturated fat — nearly two-thirds of the recommended daily limit for the average person. Ounce for ounce, coconut oil delivers more saturated fat than butter, lard, or margarine. Studies in humans, monkeys, and rabbits show that coconut oil substantially elevates LDL (bad) cholesterol.

Viewed in context, though, coconut may not be so bad. Some food companies are testing coconut oil as a replacement for the once-ubiquitous partially hydrogenated vegetable oils, which contain hefty amounts of dangerous trans fats. Both coconut oil and trans fats increase LDL. But while trans fats reduce protective HDL, coconut oil has a powerful HDL-boosting effect.

Don’t take this as a ringing endorsement of coconut oil — I would much rather see food makers get rid of trans fats in our food supply by using unsaturated fats than by substituting coconut or palm oil. But when a hard fat is needed, coconut oil is an acceptable alternative, at least until better ones come along.

As you may know, books such as The Healing Miracles of Coconut Oil and Coconut Cures claim that coconut can prevent heart disease, dissolve kidney stones, control diabetes, protect against cancer, enhance the immune system, and maybe even prevent AIDS. There is no good evidence to back up these claims.

Do you need to avoid coconut? No. Fresh coconut is delicious, shredded coconut livens up pastries and granola, and who can resist a spicy coconut curry, or a piña colada at a beach party? But to take the best care of your heart and blood vessels, think of these as treats rather than as everyday choices.

— Walter C. Willett, M.D., Dr.P.H.
Harvard School of Public Health,
Harvard Heart Letter Editorial Board

This question and answer first appeared in the September 2006 Harvard Heart Letter, available at www.health.harvard.edu/heart.

 
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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 http://www.health.harvard.edu 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.
Harvard Health Publications
Harvard Medical School

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