Study suggests pasta can be part of a healthy diet without packing on the pounds

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Carbohydrates get a lot of bad press and blame for the obesity epidemic, but a new study suggests that this negative attention may not be deserved for pasta.
Unlike most 'refined' carbohydrates, which are rapidly absorbed into the bloodstream, pasta has a low glycemic index, meaning it causes smaller increases in blood sugar levels than those caused by eating foods with a high glycemic index.

04 april 2018--Researchers at St. Michael's Hospital undertook a systematic review and meta-analysis of all of the available evidence from randomized controlled trials, the gold standard of research design. They identified 30 randomized control trials involving almost 2,500 people who ate pasta instead of other carbohydrates as part of a healthy low-glycemic index diet. Their results were published today in the journal BMJ Open.
"The study found that pasta didn't contribute to weight gain or increase in body fat," said lead author Dr. John Sievenpiper, a clinician scientist with the hospital's Clinical Nutrition and Risk Modification Centre. "In fact analysis actually showed a small weight loss. So contrary to concerns, perhaps pasta can be part of a healthy diet such as a low GI diet."
The people involved in the clinical trials on average ate 3.3 servings of pasta a week instead of other carbohydrates. One serving equals about one-half cup of cooked pasta. They lost about one-half kilogram over a median follow-up of 12 weeks.
The study authors stressed that these results are generalizable to pasta consumed along with other low-glycemic index foods as part of a low-glycemic index diet. They caution more work is needed to determine if the lack of weight gain will extend to pasta as part of other healthy diets.
"In weighing the evidence, we can now say with some confidence that pasta does not have an adverse effect on body weight outcomes when it is consumed as part of a healthy dietary pattern," said Dr. Sievenpiper.
This work received funding from the Canadian Institutes of Health Research through the Canada-wide Human Nutrition Trialists' Network; the Diet, Digestive Tract and Disease Centre, funded through the Canadian Foundation for Innovation, and the Ministry of Research and Innovation's Ontario Research Fund, among other non-industry sponsors.
Some of the authors have received prior research grants, in-kind donations of pasta for a randomized controlled trial, and travel support from the pasta maker Barilla.


Provided by St. Michael's Hospital

Healthy eaters, ignore glycemic index: Clinical trial shows no beneficial effects on heart disease, diabetes risk

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22 dec 2014--Good news for people who are already following a diet rich in fruits, vegetables and whole grains, and low in sweets: New research suggests these heart-healthy eaters don't need to worry about choosing low glycemic index foods to lower the risk of diabetes and heart disease. Though the study was not designed to test the effects of low glycemic index foods on weight control, its lead researchers looked at studies that did focus on weight and found no clear proof of a benefit.

The glycemic index is a measure of how quickly foods containing carbohydrates, such as fruits, cereals and baked goods, raise glucose levels in the bloodstream. Conventional wisdom says that high glycemic index foods like bananas and pasta are "bad" for heart health and may increase diabetes risk. But in a clinical trial reported Dec. 17 in the Journal of the American Medical Association, researchers at the Johns Hopkins University School of Medicine and Harvard Medical School found little evidence to support these claims.

Study volunteers followed carefully planned diets high or low in carbohydrates and with high or low glycemic index scores. Tests tracked the volunteers' blood pressure, cholesterol levels and sensitivity to insulin at the beginning and end of each diet. The results showed little difference between high and low glycemic index foods, says study co-director Lawrence J. Appel, M.D., M.P.H., a professor of medicine and director of the Welch Center for Prevention, Epidemiology and Clinical Research at Johns Hopkins Medicine.

"We were really surprised," Appel says. "We did not detect any clear benefit of the low glycemic index diets on the major risk factors for heart disease, and we found no evidence of benefit for diabetes prevention."

The authors looked closely at other studies focusing on the use of low glycemic index foods in weight control. "The evidence has been inconsistent that low glycemic foods help people lose more weight or keep it off," Appel says. "In looking at the causes of obesity and ways to combat it, a narrow focus on the glycemic index seems to be unwarranted."

Several popular diets recommend choosing carbohydrates that score low on the glycemic index, but that's not always easy. Only laboratory tests can determine a food's glycemic index, and the results can be unexpected: Apples score low, but cantaloupe scores high.

Appel and study co-director Frank M. Sacks, M.D., a professor of medicine at Harvard Medical School, wanted to find out whether foods' glycemic index matters to heart health and diabetes prevention. They recruited 163 volunteers from Baltimore and Boston—all of whom were overweight and had above normal blood pressure—and randomly assigned them to follow one of four diets. Each diet contained the same number of calories, but those calories came from foods that were either high or low in carbohydrates, and also either high or low on the glycemic index. The volunteers ate the day's main meal at a research center and took home their next two meals.

After five weeks on their assigned diets, the volunteers switched to a different one. Researchers tested the volunteers' blood pressure; sensitivity to insulin; and levels of "good" high-density lipoprotein (HDL) cholesterol, "bad" low-density lipoprotein (LDL) cholesterol and triglycerides—fat molecules, or lipids, that play a role in heart health. The low glycemic index diets did not lower blood pressure or LDL cholesterol, and they did not improve insulin resistance.

Women made up 51 percent of the study's volunteers, and African-Americans made up 52 percent, so the results have broad relevance, says Appel, who offers simple advice for anyone overwhelmed by conflicting messages about diet and health.

"Get back to the basics that most people already know," he says. "Don't drink sugar-sweetened drinks. Try to eat fruits, vegetables and whole grains. Try to avoid sweets, salt, and foods high in saturated and trans fats. People who follow these principles will reap the benefits."

Appel and Sacks led three earlier clinical trials that tested ways to reduce the risk of cardiovascular disease and diabetes, providing volunteers with carefully designed diets and measuring the effects on key health indicators. Their work established the health benefits of the DASH (Dietary Approaches to Stop Hypertension) and OmniHeart Mediterranean-style diets.

More information: Paper: DOI: 10.1001/jama.2014.16658
Editorial: DOI: 10.1001/jama.2014.15338

Provided by Johns Hopkins University School of Medicine