The Year in Diet and Nutrition

NEW YORK -- The ban on trans fats in this city was the highest profile event during the year in diet and nutrition, as Americans continued to struggle against ever-expanding waistlines and foods deemed unhealthy.

NEW YORK, Dec. 22 -- The ban on trans fats in this city was the highest profile event during the year in diet and nutrition, as Americans continued to struggle against ever-expanding waistlines and foods deemed unhealthy.

The following summary reviews some of the highlights of the year in diet and nutrition. For fuller accounts, links to the individual articles published during the year in MedPage Today have been provided.

Big Apple Action

Earlier in the year, a review article found trans fatty acids to be a major villain in cardiovascular disease in the United States. The investigators reported that reducing trans fat intake could avert 10% to 19% of coronary heart disease events. Also, the FDA instituted new food labeling requirements for disclosing trans-fat content in January.

In December, New York City Health Commissioner Thomas Frieden declared a ban on most trans-fat containing frying oils for restaurants that is to go into effect July 1, 2007 and a full-scale elimination of trans fats for all restaurant foods by July 2008.

Diet Benefits Debunked

While the major rallying cry for weight loss has likewise been cardiovascular risk, researchers found this year that some of the most popular diets may, in the end, neither help nor harm the heart.

Low-carbohydrate diets appear to raise total and low-density lipoprotein cholesterol levels compared with low-fat diets, according to a Cochrane-style meta-analysis of five controlled clinical trials.

Furthermore, diets that emphasize foregoing carbs in favor of protein -- like the South Beach and Zone diets -- did not significantly affect the risk of coronary heart disease in the Nurses' Health Study. Although it was reassuring that such diets may not harm the heart, as had been presumed, the study found that vegetable, rather than animal, protein and fat may be best for reducing coronary heart disease.

Slimming Down Kids

A major theme in diet and nutrition this year was the necessity of combining diet and exercise to achieve clinically meaningful weight loss for adults and children alike.

A calorie-restricted diet and exercise appeared equally effective in preventing diabetes in another study. Insulin sensitivity index and glucose tolerance improvements were not significantly different between groups.

However, another research team found that while diet alone may be enough for a successful assault on the waistline, exercise is necessary to shrink subcutaneous abdominal fat cells that affect type 2 diabetes. In the study, diet, diet with moderate exercise, and diet with intense exercise all resulted in comparable loss of weight and waist. But, biopsies of subcutaneous abdominal fat cells revealed that these cells shrank significantly more for the two diet and exercise groups compared to the diet-only group (18% and 17% versus 0.8, P

Dieting women may also want to be cautious about diet soda. Bone density and therefore risk of fracture may be increased by carbonated cola, according to the Framingham Osteoporosis Study. It found a significant effect among older women but not men for regular, non-caffeinated and diet colas though not other carbonated drinks.

Diet and Wits

Other dietary aspects appear to be important for older adults as well for both body and mind.

Vegetables, in particular, appear to help keep the aging mind sharp. Just two servings of vegetables a day -- out of the four to 13 recommended by the FDA's dietary guidelines -- averted the equivalent of five years of mental aging in people older than 65 though fruit intake had no impact on cognitive decline.

Markers of poor nutrition, such as low serum vitamin B6, vitamin B12 and selenium levels, predicted loss of ability to perform activities of daily living among older women in the Women's Health and Aging Study.

Folic Acid a No-Brainer

However, using folic acid and other B vitamin supplements failed to improve cognition in older people at increased risk for dementia due to elevated levels of homocysteine, an amino linked to risk of heart disease, dementia, and poor cognitive performance.

This was a downer year for B vitamins on the cardiovascular front as well. Among more than 5,000 women in the Women's Antioxidant Cardiovascular Study, supplementing folic acid and vitamins B6 and B12 had no effect on the rates of heart attack, stroke, coronary revascularization, or cardiovascular-related death. A meta-analysis of 12 randomized controlled trials also found no benefit to secondary prevention with folic acid for mortality or any other cardiovascular outcomes.

It's time to stop focusing attention on B vitamins, suggested Lydia A. Bazzano, M.D., Ph.D., of Tulane University in New Orleans.

"It is important to focus on strategies of proven benefit in the secondary prevention of cardiovascular disease," she and colleagues wrote in the meta-analysis, "including smoking cessation, lipid reduction, treatment of hypertension and diabetes, maintenance of a healthy weight, and physical activity."