Bronchitis

A diet high in antioxidants may protect against the free-radical-damaging effect of environmental toxins or cigarette smoke. Studies comparing different populations have shown that increasing fruit and vegetable consumption may reduce the risk of developing chronic bronchitis.

Cataracts

People with low blood levels of antioxidants and those who eat few antioxidant-rich fruits and vegetables have been reported to be at high risk for cataracts.

Crohn’s disease

A high-animal-protein and high-fat diet (from foods other than fish) has been linked to Crohn’s disease in preliminary research. As with many other health conditions, it may be beneficial to eat less meat and dairy fat and more fruits and vegetables.

Diabetes

A high-fiber diet has been shown to work better in controlling diabetes than the diet recommended by the American Diabetes Association (ADA), and may control blood sugar levels as well as. The high-fiber diet also reduced the need for oral diabetes drugs. In this study, the increase in dietary fiber was accomplished exclusively through the consumption of foods naturally high in fiber—such as leafy green vegetables—to a level beyond that recommended by the ADA.

Diverticular disease

Dietary factors influence the frequency and severity of diverticular disease recurrences. A diet high in fiber has been shown to be protective against diverticular disease. One study of food intake revealed a 50 percent increase in incidence of diverticular disease in persons eating a diet high in meat and low in vegetables relative to those eating a high-vegetable and low-meat diet. In addition to helping prevent the disease, a high-fiber diet may also be useful as a treatment for diverticular disease.

Heart attack

A large study of male healthcare professionals found that those men eating mostly a “prudent” diet (high in fruits, vegetables, legumes, whole grains, fish, and poultry) had a 30 percent lower risk of heart attacks compared to men who ate the fewest foods in the “prudent” category. In contrast, men who ate the highest percentage of their foods from the “typical American diet” category (high in red meat, processed meat, refined grains, sweets, and desserts) had a 64 percent increased risk of heart attack, compared to men who ate the fewest foods in that category. A parallel study of female healthcare professionals showed a 15 percent reduction in cardiovascular risk for those on a prudent diet compared to the effect of those eating a low fruit and vegetable diet.

Making positive dietary changes immediately following a heart attack is likely to decrease the chance of a second heart attack. In one study, individuals began eating more vegetables and fruits, and substituted fish, nuts, and legumes for meat and eggs 24 to 48 hours after a heart attack. Six weeks later, the diet group had significantly fewer fatal and nonfatal heart attacks than a similar group who did not make these dietary changes. This trend continued for an additional six weeks.

Hypertension

Vegetarians have lower blood pressure than do people who eat meat. This occurs partly because fruits and vegetables contain potassium—a known blood pressure-lowering mineral. In the Dietary Approaches to Stop Hypertension (DASH) trial, increasing intake of fruits and vegetables (and therefore fiber) and reducing cholesterol and dairy fat led to large reductions in blood pressure in just eight weeks. Even though it did not employ a vegetarian diet itself, the outcome of the DASH trial supports the usefulness of vegetarian diets because diets employed by DASH researchers were related to what many vegetarians eat.

Pap smear

High blood levels of folate (the food form of folic acid) have been linked to protection against the development of abnormal Pap smears, but these folate levels may only be a marker for eating more fruit and vegetables.