all Department of Nutrition stories

Study shows benefits of eating fish greatly outweigh risks

70652986 — Mon, 26 Mar 2007 05:46:48 -0400

Many studies have shown the nutritional benefits of eating fish (finfish or shellfish). Fish is high in protein and omega-3 fatty acids. But concerns have been raised in recent years about chemicals found in fish from environmental pollution, including mercury, PCBs and dioxins. That has led to confusion among the public - do the risks of eating fish outweigh the benefits?

Researchers from the Harvard School of Public Health (HSPH) tackled that question by undertaking the single most comprehensive analysis to date of fish and health. In the first review to combine the evidence for major health effects of omega-3 fatty acids, major health risks of mercury, and major health risks of PCBs and dioxins in both adults and infants/ young children, the results show that the benefits of eating a modest amount of fish per week - about 3 ounces of farmed salmon or 6 ounces of mackerel - reduced the risk of death from coronary heart disease (CHD) by 36 percent.

Notably, by combining results of randomized clinical trials, the investigators also demonstrated that intake of fish or fish oil reduces total mortality - deaths from any causes - by 17 percent.

Included with the paper, which appears in the Oct. 18, 2006, issue of The Journal of the American Medical Association (http:// jama.ama-assn.org/), is the first comprehensive summary of levels of omega-3 fatty acids, mercury, PCBs and dioxins in various species of fish and other foods, including chicken, beef, pork, butter and eggs.

The research was supported by the National Institutes of Health.

High intake of vitamin D linked to reduced risk of multiple sclerosis

70652986 — Mon, 26 Mar 2007 05:33:44 -0400

More than 185,000 women from the Brigham and Women's-based Nurses' Health Study and Nurses' Health Study II, who were free of multiple sclerosis (MS), were selected for a research study. The participants filled out dietary questionnaires every four years between 1980 and 1999 that assessed their vitamin D intake along with other dietary information.

Coffee cuts diabetes risk

70652986 — Mon, 26 Mar 2007 05:33:49 -0400

More than 125,000 study participants who were free of diabetes, cancer, and cardiovascular disease at the start of a study were selected from the on-going Health Professionals Follow-up Study and the Brigham and Women's Hospital-based Nurses Health Study. Some 41,934 men were tracked from 1986 to 1998 and 84,276 women from1980 to 1998 via food frequency questionnaires every two to four years to assess their intake of both regular and decaffeinated coffee. During the span of the study, 1,333 new cases of type 2 diabetes were diagnosed in men and 4,085 among the women participants.

Low-carb more effective than low-fat

70652986 — Mon, 26 Mar 2007 05:32:39 -0400

A study put three groups of dieters on different regimens. They included a low-fat group, a low-carbohydrate group that ate the same number of calories, and a third group on a similar low-carbohydrate plan that included 300 extra calories a day. The low-carbohydrate dieters lost more weight than low-fat dieters despite eating 25,000 extra calories over a 12-week study period. The findings generated national attention after Penelope Greene, a visiting scholar in the Harvard School of Public Health's Nutrition Department, presented her research Oct. 13, 2003, at the annual meeting of the North American Association for the Study of Obesity, in Fort Lauderdale, Fla. Greene conducted the study with Walter Willett, Nutrition Department chair and Fredrick Stare Professor of Epidemiology and Nutrition. Participants in all three groups lost weight, Greene said, with the low-fat group losing an average of 17 pounds and the low-carbohydrate group that ate the same number of calories losing 23 pounds. The biggest surprise, however, was that the low-carbohydrate dieters eating extra calories lost more than those on the low-fat diet. Participants in that low-carbohydrate group lost an average of 20 pounds.

Anti-inflammatory drugs may reduce Parkinson's disease risk

70652986 — Mon, 26 Mar 2007 05:31:26 -0400

In the first study to investigate the potential benefit in humans of the use of non-steroidal anti-inflammatory drugs (NSAIDs) in reducing the risk of Parkinson's disease, Harvard School of Public Health researchers found that regular users of these drugs had a lower risk for Parkinson's disease than non-users. More than 44,000 men and nearly 99,000 women were followed for 14 years and 18 years, respectively. Use of aspirin and non-aspirin NSAIDs (such as Motrin, Advil, ibuprofen, Indocin, Naprosyn) was assessed via biennial questionnaires. A total of 236 men and 179 women developed Parkinson's disease during the course of the study. The risk of developing Parkinson's disease was 45 percent lower among men and women who regularly used non-aspirin NSAIDs than among non-users. Regular use of non-aspirin NSAIDs was reported by 6.1 percent of the men at the beginning of the study and 3.7 percent of the women. The findings appeared in the August 2003 issue of The Archives of Neurology.

Generous portions of TV make women fat

70652986 — Mon, 26 Mar 2007 05:29:10 -0400

The first study to compare the effects of inactivity on obesity and diabetes concludes that being a couch potato significantly raises the risk of both diseases. "Our data provide strong evidence that sedentary behaviors, especially prolonged TV watching, are directly related to the risk of obesity and type 2 diabetes," reports Frank Hu, leader of a team from the Harvard School of Public Health and the Harvard Medical School that did the research. "In contrast, even light to moderate activity, such as walking and housework, substantially lowers the risk." Previous studies have shown that children who watch too much TV gain too much weight. A different Harvard investigation, called the Health Professionals Follow-up Study, found a positive link between heavy TV viewing and type 2 diabetes.

Study finds frequent consumption of alcohol linked to lower risk of heart attack in men

70652986 — Mon, 26 Mar 2007 05:27:29 -0400

Men who drank moderate amounts of alcoholic beverages three or more times a week had a risk of myocardial infarction 30 to 35 percent lower than nondrinkers. The observational study, which tracked the drinking habits of nearly 40,000 men over a 12-year period, provides an important clue as to how alcohol helps guard against coronary heart disease, and for the first time, strongly suggests that routine consumption of alcoholic beverages is key. "Even relatively modest amounts of alcohol may be protective if consumed frequently,” said the study's first author, Kenneth Mukamal, of Beth Israel Deaconess Medical Center's Division of General Medicine and Primary Care and assistant professor of medicine at Harvard Medical School. “Our results document that a pattern of regular consumption at least three to four days per week is associated with the lowest risk of heart attacks.” The findings appeared in the Jan. 9, 2003, issue of The New England Journal of Medicine. This research was funded by grants from the National Institutes of Health.

Men can reduce stroke risk by eating fish

70652986 — Mon, 26 Mar 2007 05:27:27 -0400

Researchers tracked the diet and health outcomes of more than 43,000 male participants for 12 years. Using detailed food frequency questionnaires, participants were asked how often they ate fish, ranging from never or less than once per month to six or more times per week. The men in the study were also asked about four different fish items: canned tuna fish, dark meat fish such as mackerel, salmon sardines, bluefish and swordfish; other fish and shrimp, lobster, or scallops served as a main dish. The researchers assessed the effect of long-chain omega-3 polyunsaturated fatty acid, a constituent of fish believed to have healthful effects, on the risk of ischemic stroke (blood flow to a certain area of the brain is interrupted). They found that men who ate even a small amount of fish, one to three times per month from any of the fish categories, reduced their risk of ischemic stroke by 40 percent. There was no evidence of further risk reduction of stroke by consuming fish more often. The findings appeared in the Dec. 25, 2002, issue of the Journal of the American Medical Association.

Nuts lower diabetes risk

70652986 — Mon, 26 Mar 2007 05:27:16 -0400

Women in a study who reported eating nuts at least five times per week reduced their risk of type 2 diabetes by almost 30 percent compared to those who rarely or never ate nuts. The researchers also found that women in the study who frequently ate peanut butter reduced their risk for type 2 diabetes almost 20 percent. "We were not really surprised by our findings," said Rui Jiang, co-author of the study, and a researcher from the Departments of Nutrition and Epidemiology at the Harvard School of Public Health. "Nuts contain lots of fat, but most fats in nuts are mono- and polyunsaturated fats, which are good for insulin sensitivity and serum cholesterol. Nuts are also rich in antioxidant vitamins, minerals, plant protein and dietary fiber. To avoid increase in caloric intake, people should not simply add nuts on the top of the diet. Instead, people should substitute nuts for less healthy foods such as refined carbohydrates like white bread and red meats." The findings appeared in the Nov. 27, 2002, issue of the Journal of the American Medical Association. The study was supported in part by grants from the National Institutes for Health.

Key gene discovered for obesity and diabetes

70652986 — Mon, 26 Mar 2007 05:26:14 -0400

Obesity is closely associated with insulin resistance and is one of the leading risk factors for type 2 diabetes. Both affect more than 50 percent of the U.S. population. Little has been known about the molecular mechanisms linking these two metabolic diseases. Both are associated with a wide range of inflammatory molecular activity in fatty tissue. This activity puts into motion the JNK genes that interfere with insulin sensitivity. Type 2 diabetes usually occurs after age 40. People with this type of diabetes do not produce adequate amounts of insulin for the needs of the body and/or cannot use insulin effectively. To test the role of JNK in decreasing insulin sensitivity in a variety of obesity models, a research team bred mice lacking either form of the gene JNK1 or JNK2 and mice possessing the JNK genes. Weight gain rose the sharpest over an eight-week span for the mice on a high-fat diet but particularly for those with the JNK genes. In studying total body fat composition, JNK-deficient mice had significantly decreased total body fat accumulation in comparison. The research findings appeared in the Nov. 21, 2002 issue of the journal Nature.

New alternative to USDA dietary guidelines nearly twice as effective in reducing risk for major chronic disease

70652986 — Mon, 26 Mar 2007 05:27:14 -0400

Researchers at the Harvard School of Public Health rigorously assessed the diets of more than 100,000 men and women and found that the reduction in risk was nearly twice as great for those whose diet met the new guidelines when compared to those whose eating patterns reflected the current USDA dietary guidelines. The findings appeared in the December 2002 issue of the American Journal of Clinical Nutrition. "The current federal guidelines as displayed in the government food guide pyramid emphasizes large amounts of carbohydrates, doesn't make a distinction between types of fat or protein and lumps red meat, chicken, nuts and legumes together," said researcher Walter Willett, chair of the Department of Nutrition at the Harvard School of Public Health. "We developed a food guide pyramid based on the best available science and examined how people who followed it did over the next 10 to 15 years and we found that those who followed our guidelines had substantially reduced risks for major disease. These benefits, achieved by healthy dietary choices, are in addition to those from weight control and regular physical activity, which are also very important."

HIV-1 positive mothers taking vitamin A increase risk of transmitting HIV to newborns

70652986 — Mon, 26 Mar 2007 05:23:32 -0400

In many regions of Africa, between 15 and 30 percent of women attending prenatal care clinics are HIV-1 positive. And 20 to 45 percent of children born to HIV-1 positive mothers become infected through breastfeeding or during intrauterine or labor and delivery periods. Mother-to-child transmission of HIV-1 has been attributed in part to poor maternal micronutrient levels. Multivitamin supplementation has been viewed as a low-cost alternative in areas where drugs are not available. However, researchers from the Harvard School of Public Health and the Muhimbili University College of Health Services in Dar es Salaam, Tanzania, found that women taking vitamin A increased the risk of transmission of HIV-1 to their newborn child compared to mothers who did not take vitamin A. The study results appeared in the Sept. 27, 2002, issue of the journal AIDS. "Our findings give little encouragement for the use of vitamin A supplements in HIV-1 positive pregnant women," said Wafaie Fawzi, lead author of the study and associate professor of nutrition and epidemiology. The study was supported in part by the National Institute of Child Health and Human Development and the Fogarty International Center at the National Institutes of Health.

Medical student engineers protein to dissolve blood clots

70652986 — Mon, 26 Mar 2007 05:23:22 -0400

Heart attacks and strokes are caused by blood clots called thrombi that block blood flow in the arteries of the heart and of the brain. Body tissues become deprived of needed oxygen and nutrients, eventually dying. Cardiovascular disease is the number one killer of Americans each year -- and has been since 1900 with the exception of one year, according to a recent report by the American Heart Association. Harvard Medical School student Ryan Turner has spent the last year doggedly researching plasmin, a naturally occurring enzyme in the body with the primary responsibility of dissolving blood clots. Specifically, plasmin attacks fibrin, a substance that makes up clots. A protein inhibitor called alpha 2-antiplasmin in blood stops the clot-busting effects of plasmin.

Study links Western dietary pattern with greater risk for type 2 diabetes in men

70652986 — Mon, 26 Mar 2007 05:19:00 -0400

About 16 million Americans have type 2 diabetes, which can cause blindness, kidney failure, and heart disease. Now researchers from the Harvard School of Public Health have linked a diet high in consumption of red meat, processed meat, high-fat dairy products and refined grains, combined with obesity and inactivity, with a high risk for type 2 diabetes in men. Frank Hu, co-author and an assistant professor in the Department of Nutrition at the Harvard School of Public Health said, “The implications of the study are straightforward.

Nutrition book author Willett rebuilds USDA food pyramid

70652986 — Mon, 26 Mar 2007 05:15:23 -0400

For more than 20 years researchers at Harvard and elsewhere have been looking at the long-term health effects of eating certain types of foods. These researchers now have a good idea what's good for you and what's not, and in what quantities. However, that information is not reflected in the "food pyramid" produced by the U.S. Department of Agriculture. The food pyramid is the government's official pronouncement about what Americans should eat to stay healthy. But according to Walter Willett, chair of the Department of Nutrition at the Harvard School of Public Health, the government's pyramid is built on "shaky scientific ground." In a new book, Eat, Drink, and Be Healthy, Willett offers his own food pyramid, based on two decades of nutrition research. "The food pyramid is tremendously flawed," Willett says. "It says all fats are bad; all complex carbohydrates are good; all protein sources offer the same nutrition; and dairy should be eaten in high amounts. None of this is accurate."