Scientific Update

Carotenoids Help Reduce the Risk of Lung Cancer

More men and women die of lung cancer than of any other cancer in the United States. Smoking is known to be a very important risk factor for developing lung cancer. Other factors in our diets are also being examined to see if dietary changes could reduce our risk.

In a study of more than 100,000 men and women, those who ate more foods containing the carotenoids alpha-carotene and lycopene had the lowest risk. Alpha-carotene is found in bright orange vegetables like carrots and pumpkin, while lycopene is found in tomatoes and products made from tomatoes. In subjects who never smoked, a 63% reduction in the incidence of lung cancer was seen in those with the highest intakes of alpha-carotene. Smokers had a reduction in risk of developing lung cancer when they had high intakes of lycopene.

These results may make some people look for a pill containing lycopene or alpha-carotene. Don’t do it. The study showed that eating a diet high in a variety of carotenoids (not just lycopene or alpha-carotene) reduced risk of lung cancer. There is also a strong possibility that other substances found in plants may reduce the risk of cancers, including lung cancer. These important substances would not be found in a pill that only has alpha-carotene or lycopene. Also, no matter how healthy your diet is, there is still a greater risk of developing lung cancer if you smoke.

Lower Fat Diet Does Not Appear to Interfere with Brain Development in Children

Dietary Guidelines for children over the age of 2 encourage caregivers to gradually adopt a diet that has no more than 30% of calories from fat by the time the children reach 5 years. This recommendation was developed in order to reduce the risk of heart disease and obesity later in life. Many vegetarian children between 2-5 eat a diet that has no more than 30% of calories from fat; so this is of interest to many vegetarian families.

We have previously reported on studies showing that children on diets that are lower in fat than typical American diets grow normally. A recent study examined the neurological development (speech and language skills, motor skills, and visual function) of children who had received a low-saturated fat, low-cholesterol diet since infancy. Parents of around 1,000 Finnish infants were either instructed to limit their child’s fat intake to 30-35% of calories (with approximately 10% of calories from saturated fat, 10% from monounsaturated fat, and 10% from polyunsaturated fat) and to limit cholesterol to less than 200 milligrams per day, while other parents were given routine health information (no limitation of fat, saturated fat, nor cholesterol). When the children were 5 years old, they were tested for neurological development. There was no significant neurological difference found between the two groups of children. However, the children who were on the lower-fat, lower-cholesterol diet had lower blood cholesterol levels.

The question of the appropriate level of fat for children has not been conclusively resolved. It does appear, from this study, that a diet with 30% of calories from fat leads to a reduction in blood cholesterol levels without interfering with neurological development. Rask-Nissila L, Jokinen E, Terho P, et al. 2000. Neurological development of 5-year-old children receiving a low-saturated fat, low-cholesterol diet since infancy: A randomized controlled trial. JAMA 248:993-1000. Health Benefits of a Plant-Centered Diet (Women) Cardiovascular disease, a name for a number of conditions including high blood pressure and stroke, is a serious problem in the United States. It is the leading cause of death in the US and is responsible for 1 in every 2.4 deaths. Almost 60 million Americans have some form of cardiovascular disease, including high blood pressure and heart disease. The annual cost of heart disease and stroke in the US in 2000 was estimated at $326.6 billion.

Many factors that increase a person’s risk of developing cardiovascular disease are heavily affected by diet. Diet impacts high cholesterol, high blood pressure, obesity, and diabetes, all of which increase the risk for cardiovascular disease. While the American Heart Association and other groups have recommended including five or more servings of fruits and vegetables daily as one means of reducing risk, there has been little research in this area.

A new study of more than 39,000 women provides important information about the role of fruits and vegetables in the prevention of cardiovascular disease. In 1993, the women reported about how often they ate a serving of 44 different fruits and vegetables. The participants were studied for the next 5 years to see which women developed cardiovascular disease. Those who ate the highest number of servings of fruits and vegetables had the lowest risk of developing cardiovascular disease, lower by about 20-30%. More servings of fruits and vegetables also seemed to reduce the risk of having a heart attack.

The average woman in this study ate about 6 servings of fruits and vegetables daily, and there was a reduction in risk seen when 10 or more servings of fruits and vegetables were eaten. The average American has less than 2 servings of fruits and vegetables daily. An editorial accompanying the published results of this study calls for a plant-centered diet to be more strongly encouraged than it is now. It’s not enough to take a pill or use a specially formulated food to get single nutrients that appear to prevent disease; we need to eat more whole foods, including fruits and vegetables. Vegetarians have been aware of the benefits of fruits and vegetables for many years. We hope that others will follow our lead. Liu S, Manson JE, Lee I-M, et al. 2000. Fruit and vegetable intake and risk of cardiovascular disease: The Women’s Health Study. Am J Clin Nutr 72:922-928. Jacobs DR, Jr, Murtaugh MA. 2000. It’s more than an apple a day: An appropriately processed plant-centered dietary pattern may be good for your health. Am J Clin Nutr 72:899-900. Health Benefits of a Plant-Centered Diet (Men) A study of almost 45,000 men suggests that a plant-based diet can help reduce the risk of heart disease in men. The participants were questioned about their eating habits in 1986 and were studied for the next 8 years to see which men developed heart disease. Two major patterns were seen in the men’s reported eating habits. One group ate more fruits, vegetables, legumes, whole grains, fish, and poultry, while the other group ate more red meat, processed meat, refined grains, sweets, French fries, and high-fat dairy products. Over the 8 years, 730 men had nonfatal heart attacks and 359 men died from heart disease. Men in the group eating more fruits and vegetables had a markedly lower risk of developing heart disease or of dying from a heart attack than did the men eating the fatty, more typical American diet.

The authors state, “This study provided strong evidence that a diet high in vegetables, fruits, legumes, whole grains, fish, and poultry, and low in red meat, processed meat, high-fat dairy products, and refined grains may reduce the risk of coronary heart disease.” Of course, vegetarians will wonder whether a diet high in fruits, vegetables, whole grains, and legumes, without meat, fish, or poultry, might be more beneficial. This study did not examine that question. It did point out a benefit of a diet containing many plant foods. The authors noted that other studies suggest that a more plant-based pattern of eating is also associated with a lower risk of developing colon cancer and a lower total mortality. Hu FB, Rimm EB, Stampfer MJ, et al. 2000. Prospective study of major dietary patterns and risk of coronary heart disease in men. Am J Clin Nutr 72:912-921. Vegetarian Diet as “Alternative” Therapy for AIDS Patients (contributed by Patrice Green, MD) In developing countries with little access to antiviral therapy, there is evidence that counseling and adhering to a vegetarian diet can delay the progression of AIDS.

A vegetarian diet was just one component of “alternative” therapies that included massage, yoga, acupuncture, and cessation of smoking. In one study in India, 85% of patients still had CD4 counts above 500 for as long as eight years since first infected.

In a study closer to home, HIV-infected individuals in San Francisco confirmed that acupuncture, herbs, and a vegetarian diet improved their quality of life without side effects.

In many countries, the adoption of a healthy lifestyle, including a vegetaran diet, is viewed as an alternative for patients who cannot afford costly antiviral therapy. In this country, where drug therapy is generally available, so-called “alternative” therapies have been shown to enhance the lives of people with HIV/AIDS.