Eating Whole Grains While Restricting Calories Reduces Cardiovascular Disease Risk Factors

by | Aug 5, 2008 | 2008, Cardiovascular Health, Obesity, Whole Grains

Written by Susan Sweeny Johnson, PhD, Biochem. Of the 25 obese adults with metabolic syndrome but no diabetes, those in the whole grain group significantly reduced their C-reactive protein by 38% and lost more abdominal fat then those in the refined grain group.

Whole-grain foods are currently highly recommended for prevention of cardiovascular disease (CVD) because they contain many heart healthy compounds, including dietary fiber, trace minerals, phytoestrogens, and antioxidants (1).The American Heart Association now recommends that at least half of a person’s dietary grain intake come from whole grains (2). Similar recommendations are made in the 2005 dietary guidelines for Americans (3) and by the American Diabetes Association (4). Observational studies suggest that higher intake of whole grains reduces death from cardiovascular disease (CVD) (5) and incidences of metabolic syndrome (6). Metabolic syndrome is characterized by abdominal obesity, elevated blood glucose, elevated blood triglycerides, low HDL, and high blood pressure and it increases the risk of developing CVD and type-2 diabetes.

This new study was designed to compare weight loss and CVD risk factors in people with metabolic syndrome who were on a restricted calorie diet with and without using whole grain products. Twenty-five obese men and women who had metabolic syndrome but had not developed diabetes or CVD were randomly divided into two groups. Participants in both groups were put on a weight loss diet restricting daily calories by 500 per day for 12 weeks to lose a target of >1 lb. per week. They were encouraged to exercise moderately three or more times a week for 30 minutes or more. Each participant met with a dietician every other week to educate, encourage and assess compliance, and also to measure weight loss, abdominal circumference and blood pressure. Blood samples taken at the beginning of the study, and after 12 weeks were assessed for various CVD risk factors. Whole body scans were done at baseline and after 12 weeks to determine the percentage of abdominal fat.

All participants lost significant weight during the 12 weeks; the refined grain group lost 4.9% of their initial weight and the whole grain group lost 3.6%.  Although weight loss was similar in both groups, levels of blood C-reactive protein, a risk factor for CVD, was significantly reduced in the whole grain group (38%) but remained unchanged in the refined grain group. Also, percentage of abdominal fat was reduced significantly more in the whole grains group. Other CVD risk factors improved to a similar extent in both groups.

These results are supported by a study in which a two-year Mediterranean diet high in whole grains, fruit, vegetables, nuts, and olive oil was compared to a healthy diet comprised of 50–60% carbohydrate, 15–20% protein, and less than 30% fat in 180 men and women with metabolic syndrome. In that study, CRP decreased in the Mediterranean diet group independent of weight loss, whereas there was no change in CRP concentrations in men and women who adhered to the other healthy diet7.

It should be noted that the whole grains group took in more fiber and magnesium than the refined grains group as a result of the whole grains in their diet. Other studies examining the effect of dietary fiber on CRP yielded conflicting results (8-10).

The diets were based on the 2005 dietary guidelines for Americans (3): 5 servings of fruit and vegetables, 3 servings of low-fat dairy products, and 2 servings of lean meat, fish, or poultry per day. The target macronutrient composition for all participants was 55% of energy as carbohydrate, 30% of energy as fat (with an emphasis on unsaturated fats), and 15% of energy as protein. The whole grain group ate an average of 5 servings of whole grain per day.

In 2004, the Centers for Disease Control and Prevention (CDC) estimated that as many as 64 million Americans, or 27% of the United States population, have metabolic syndrome (11). Cardiovascular disease costs the US more than $300 billion. The average medical costs for diabetics is $10,000 per year, but for non-diabetics it is $2600. Average 3-ear medical costs for people with an at-risk (Body Mass Index) BMI were fifty percent higher than those of lean people (12).

Source: Katcher, Heather I., Richard S. Legro, Allen R. Kunselman, Peter J. Gillies, Laurence M. Demers, Deborah M. Bagshaw, and Penny M. Kris-Etherton. “The effects of a whole grain–enriched hypocaloric diet on cardiovascular disease risk factors in men and women with metabolic syndrome.” The American journal of clinical nutrition 87, no. 1 (2008): 79-90.

© 2008 American Society for Nutrition

Posted August 5, 2008.

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  12. See The American Association of Preferred Provider Organizations website.