All Posts tagged carbohydrates

A reversal on carbs

A growing number of top nutritional scientists blame excessive carbohydrates — not fat — for America's ills. They say cutting carbohydrates is the key to reversing obesity, heart disease, Type 2 diabetes and hypertension. “Fat is not the problem,” says Dr. Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health. “If Americans could eliminate sugary beverages, potatoes, white bread, pasta, white rice and sugary snacks, we would wipe out almost all the problems we have with weight and diabetes and other metabolic diseases.”

It's a confusing message. For years we've been fed the line that eating fat would make us fat and lead to chronic illnesses. “Dietary fat used to be public enemy No. 1,” says Dr. Edward Saltzman, associate professor of nutrition and medicine at Tufts University. “Now a growing and convincing body of science is pointing the finger at carbs, especially those containing refined flour and sugar.”

Americans, on average, eat 250 to 300 grams of carbs a day, accounting for about 55% of their caloric intake. The most conservative recommendations say they should eat half that amount. Consumption of carbohydrates has increased over the years with the help of a 30-year-old, government-mandated message to cut fat.

And the nation's levels of obesity, Type 2 diabetes and heart disease have risen. “The country's big low-fat message backfired,” says Dr. Frank Hu, professor of nutrition and epidemiology at the Harvard School of Public Health. “The overemphasis on reducing fat caused the consumption of carbohydrates and sugar in our diets to soar. That shift may be linked to the biggest health problems in America today.”

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Food Pyramid to be revised

This month the federal Department of Agriculture and Health and Human Services will release the 2010 dietary guidelines. These guidelines directly impact the eating habits of one in every four Americans whose meals are subsidized by federal programs. The precise timing of the release this month is unknown, according to John Webster, a spokesman for the USDA.

The major question here is whether or not the new guidelines will impact the obesity epidemic that is increasing ever so quickly in our country. Decisions about what to eat are generally made at the supermarket, not while reading federal guidelines. “What we need to do is put more effort into figuring out how to engage people who don’t use nutrition as a major deciding point when buying food,” says Alice H. Lichtenstein, a professor at the Friedman School of Nutrition Science and Policy at Tufts University. “We really need to learn more about consumer behavior.’’ Some experts wonder if more nutrition information helps or confuses shoppers.

It is arguable that the guidance needs to be much clearer, more like the wildly popular “Eat This, Not That!,’’ a magazine column, which was then reworked into a book and an iPhone app, that made its mark by telling readers which fast food was nutritionally better than others. Dr. David L. Katz, director of Yale University’s Prevention Research Center and an associate professor at the university’s School of Medicine, is an advocate for more specific guidance. For example, 45 to 65 percent of daily calories should come from foods that contain carbohydrates. But “lollipops and lentils are both carbs,’’ Katz says. And while the current federal recommendations do stress eating carbohydrates from whole grains, fruits, and vegetables, he adds, “We need to do a better job of specifically defining highly recommended foods.’’

While no one is talking about the final 2010 recommendations before their release, a June advisory report, open for public comment, gives some clues. Cohen of UMass Amherst expects the final guidelines to place even greater emphasis on physical activity and continue to recommend that people include more fruits, vegetables, nuts, seeds, foods with Omega-3 fatty acids, and a suggestion to eat three servings of low-calorie dairy products a day (some argue that calcium supplements should be used in place of the third serving).

 

 

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Omega 3s could improve metabolic syndrome outcomes

Positive effects

The new study looked into the effects of four different diet combinations on blood lipid metabolism, in 117 patients with metabolic syndrome.

In accordance with previous suggestions, the researchers found that a low-fat, high-complex carbohydrate diet had “several detrimental effects”, including significantly increasing total triglyceride levels, and triglyceride rich lipoprotein cholesterol levels.

In contrast, intake of the same diet supplemented with omega-3 was found to have no effects on blood lipid levels, with researchers observing that a diet rich in monounsaturated fats, or a low-fat diet rich in complex carbohydrates and omega-3 fatty acids, resulted in lower circulating blood lipid levels than a diet rich in high saturated fats or a diet low in fats and high in complex carbohydrates.

The data from the study suggest a place for higher omega-3 intake in people with metabolic syndrome, and supports previous research that suggests monounsaturated fatty acids can have a positive effect on blood lipid levels.

“The long-term effect of the low-fat, high-complex carbohydrate diet, pre vs. post intervention phases, showed several beneficial effects of long chain omega-3 PUFA supplementation,” stated the researchers.

“Our data suggest that long-term intake of an isocaloric, low-fat, high-carbohydrate diet supplemented with long chain omega-3 … have beneficial effects on postprandial lipoprotein response in patients with metabolic syndrome,”

Source: The Journal of Nutrition
“A Low-Fat, High-Complex Carbohydrate Diet Supplemented with Long-Chain (n-3) Fatty Acids Alters the Postprandial Lipoprotein Profile in Patients with Metabolic Syndrome”
Authors: Y. Jimenez-Gomez, C. Marin, P. Perez-Martinez, et al

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