Scientific Update

Bone Density of Vegetarians

Bone density is important because the denser our bones are, the lower the chance that we will have osteoporosis later in life. If you have denser bones early in life, you will likely still have denser bones when you are 70 or 80 years old than will someone who had less dense bones in early adulthood.

Do young vegetarian women have bone densities which are different from non-vegetarian women? This was the question which Canadian researchers decided to study. Study subjects were 15 lacto-ovo vegetarians, 8 vegans, and 22 non-vegetarian women aged 20 to 40 years. All subjects had followed their chosen diet for at least 2 years.

Vegetarians, whether lacto-ovo or vegan, were leaner than were non-vegetarians. Bone density tended to be lower among vegetarians, but this was not statistically significant. Bone density was related in part to body weight, with vegetarians tending to have lower bone density and lower body weight. Vegan women did not have lower bone density than lacto-ovo vegetarians, despite the fact that vegans have lower calcium intakes than all other groups. Bone density was measured in some study subjects one year later. While bone density increased in non-vegetarians, it did not change in vegetarians.

These results suggest that women with low body weight, whether vegetarian or not, should be especially aware of dietary sources of nutrients associated with bone health, such as calcium and vitamin D, as well as other factors affecting bone density, such as weight-bearing exercise.

Polyunsaturated Fats Do Not Appear to Increase Risk of Cancer in Humans

Increased use of polyunsaturated fat to replace saturated fat is commonly recommended in order to reduce blood cholesterol levels and to reduce the risk of heart disease. Polyunsaturated fats, often derived from plants, are usually liquid at room temperature. Saturated fats, often derived from animal-based products, are usually solid at room temperature. There is concern that increasing polyunsaturated fat may increase risk of cancer.

Dutch researchers looked at many published studies and combined data from these studies to see if increasing polyunsaturated fats increases cancer risk. They concluded that it is unlikely that high intakes of polyunsaturated fats markedly increase the risk of cancer of the breast, colon, rectum, or prostate in humans.

Improving Hospital Diets

Are hospitals meeting the needs of their patients? It's questionable. A 1996 report found that only 19 percent of the university-affiliated hospitals studied met recommendations for dietary cholesterol, more than half had meals which were above recommendations for sodium, and over a third served meals which averaged more than 30 percent of calories from fat. Study authors commented on barriers to improvement of hospital diets in a recent issue of The Journal of the American Dietetic Association. Barriers included a focus on disease treatment rather than prevention, lack of nutrition training among physicians, concern that healthful foods do not taste good, and concerns that healthful diets cost more. Among the authors' recommendations are that foodservice staff be trained in purchasing, preparing, and serving meals lower in fat and higher in fruits, vegetables, and grains; hospital directors establish dietary improvements as a priority; national and state guidelines be expanded to include prevention of risk factors for chronic disease; and dietary directors work with chefs to improve the quality of food served to patients.