Scientific Update

By Reed Mangels, PhD, RD, FADA

Vegan Diet Offers Health Benefits

Dean Ornish, MD, is known for his research using a very lowfat, near-vegan diet and other lifestyle mo difications to reverse heart disease. He is currently investigating whether similar dietary and lifestyle changes can also be used by men with early-stage prostate canc er. In 2006, VRG reported about his research (available online at ), which found his study diet to be nutrit ionally adequate.

Ornish and co-investigators have recently taken this research a step farther. They have examined whether a very lowfat, near-vegan diet offers health advantages. They studied 85 men around age 65 with early-stage prostate cancer. Study participants were divided into two groups. One group, called the Intervention Group, was asked to eat a very lowfat (10 percent of calories from fat) vegan diet supplemented with soy protein, to get moderate exercise, and to participate in a stress management program. The other group, the Control Group, received their usual level of care from their physicians. The groups' dietary intakes were compared. Although the Intervention Group was told to eat a vegan diet, study records show that they had some minor infractions and that they received supplementary fish oil; therefore, their diet can most accurately be described as a near-vegan diet. Over the year of the study, the Intervention Group nearly doubled their fiber intake and reduced their fat intake by 60 percent and their saturated fat intake by 75 percent. They also markedly increased their intake of most vitamins and minerals, including several like folate and calcium that play a role in reduced risk of heart disease, cancer, high blood pressure, and other chronic diseases. Similar changes were not seen in the Control Group, who continued eating their usual diet. These results suggest that a very lowfat vegan (or near-vegan) diet can be useful in reducing intake of unhealthy dietary components like saturated fat and cholesterol and in increasing intake of components that can reduce the risk of a number of chronic diseases, including cancer, heart disease, and diabetes.

Dewell A, Weidner G, Sumner MD, et al. 2008. A very-low-fat vegan diet increases intake of protective dietary factors and decreases intake of pathogenic dietary factors. J Am Diet Assoc 108:347-56.

More Evidence That Protein From Dairy Products May Increase the Risk of Prostate Cancer

Prostate cancer is a common cancer. Approximatel y one man out of six will be diagnosed with prostate cancer in his lifetime. While most men don't die from prostate cancer, it is the third most common cause of cancer deaths in men. Active research is focusing on ways to reduce the incidence of prostate cancer. One key question is whether diet plays a role in the development of prost ate cancer. A recent study adds to the accumulated evidence that it does. This study involved more than 142,000 men from 19 European countries. The men were asked about their diets and their health histories and were studied for a number of years. No association was found between meat, fish, or egg consumption or between total protein intake and prostate cancer in this large study. However, protein from dairy foods was significantly associated with an increased risk of prostate cancer. Total dietary calcium intake and calcium intake from dairy products were also associated with an increased risk, although there was no association between non-dairy sources of calci um and risk of prostate cancer. These results suggest that it is not calcium per se that is increasing the risk of prostate cancer but some other component of dairy foo ds. These results add to the evidence from other studies suggesting that dairy products are associated with increased risk of prostate cancer.

Allen NE, Key TJ, Appleby PN, et al. 2008. Animal foods, protein, calcium and prostate cancer risk: the European Prospective Investigation into Cancer and Nutrition. Br J Cancer 90:1574-81.

Avoiding Gout

Have you ever seen a painting of a nobleman with his bandaged foot propped up on a footstool? Chances are that he was suff ering from gout, a common, painful form of arthritis. Gout is still a problem today and most commonly occurs among men over age 40. Close to 3 million American men have gout. Where genetics can certainly play a role in determining one's risk for gout, other more controllable factors are also important.

A recent study examined close to 29,000 healthy, physically active male runners to see which factors affected their risk of having gout. One factor that was identified was meat consumption; even among this relatively healthy group, men eating the most meat had the highest risk of developing gout. Other factors that increased risk of gout included higher alcohol intake, lower fruit intake, being overweight or obese, and being less physically active. It looks like reducing risk of gout is another reason for becoming vegetarian.

Williams PT. 2008. Effects of diet, physical activity and performance, and body weight on incident gout in ostensibly healthy, vigorously active men. Am J Clin Nutr 87:1480-87.

Association Found Between Cured Meat and Increased Risk of COPD

COPD is the abbreviation for chronic obstructive pulmonary disease, a co ndition that makes it hard to breathe. Both chronic bronchitis and emphysema are types of COPD, the fourth-leading cause of death in the United States. Smokers are espe cially likely to develop COPD. A recent study looked at whether dietary factors also play a role.

Cured meats like bacon, hot dogs, and deli meats contain nitrites, which are added as preservatives. Nitrites, which are also present in tobacco smoke, can damage lung tissue. Frequent consumption of cured meats containing nitrites could potentially cause damage to the lungs. (Of course, if you're choosing vegetarian products such as veggie bacon, dogs, and deli slices, you don't have to worry about nitrites since these foods don't contain them.)

Epidemiologists looked at more than 71,000 registered nurses and found that those who consumed cured meats most frequently were most likely to have COPD. Those at lowest risk for COPD were women who never smoked and who rarely or never ate cured meat; those at highest risk were current smokers who ate four or more servings of cured meat a week. You might guess that smokers were more likely to eat cured meats. They were, but the increased risk of COPD in women who ate cured meat was seen even when adjustments were made for smoking. Similar results were seen in an earlier study of male health professionals done by the same researchers. This study provides one more reason to choose a vegetarian diet (and to stop or never start smoking).

Jiang R, Camargo Jr CA, Varraso R, et al. 2008. Consumption of cured meats and prospective risk of chronic obstructive pulmonary disease in women. Am J Clin Nutr 87:1002-1008.

Is There a Connection Between Poor Diet and Higher Stress Levels?

Stress and anxiety are often seen as a part of today's rapid pace. In some cases, mild stress can lead to improved performance. However, enduring constant stress and anxiety can be debilitating and increase risk for chronic diseases like heart disease.

Do dietary factors play a role in stress? That's the question researchers from Greece asked when they studied close to 1,000 men and women. Subjects of this small study were asked questions about their diet and their current level of anxiety; nervousness and worry was assessed. Among women, those who described themselves as less anxious ate less red meat and fewer sweets than women who described themselves as more anxious. The less anxious women were more likely to eat a vegetarian or near-vegetarian diet. Less anxious men also tended to eat a healthier diet. The researchers speculate that during times of stress, people are more likely to choose convenient and familiar foods like meat, potatoes, and soft drinks. One question that is raised by this study is whether a more vegetarian-like diet contributed to reduced feelings of anxiety and stress rather than simply being the result of less anxiety and stress.

Yannakoulia M, Panagiotakos DB, Pitsavos C, et al. Eating habits in relations to anxiety symptoms among apparently healthy adults: A pattern analysis from the ATTICA Study. Appetite 2008 Apr 8. [Epub ahead of print].