What science really says about diet and nutrition

For the past 35 years, Walter Willett, M.D., Chairman of Nutrition at Harvard University’s School of Public Health, has been sorting through theories and beliefs about diet and nutrition to find out what is true and what is not. His most surprising finding was that, contrary to mainstream advice, fat is good for you.

Speaking to the students at the Institute for Integrative Nutrition this year, Dr. Willett discussed other findings he uncovered in the last 10 to 20 years that contradict some widely accepted nutrition theories.

Fruits and vegetables do not decrease overall cancer risk…

According to Dr. Willett, based on studies looking at over 100,000 people, there is no support for any relationship between fruit and vegetable consumption and overall rates of cancer. The studies have concluded that there is no difference in general cancer rates between those who consume 8 or more servings of fruits and vegetables per day and those who consume less than 1 ½ servings per day.

…but just 3 to 5 servings of fruits and vegetables will decrease cardiovascular disease risk.

There is a strong correlation between fruits and vegetables and a decreased rate of cardiovascular disease. The studies show that eating between 3 to 5 servings per day decreases the risk of heart disease and stroke by about 30%. However, eating more servings than 5 per day does not give you any additional benefit. Dr. Willett considers this good news since, despite efforts to encourage the general population to eat more fruits and vegetables, there really hasn’t been much of an increase in daily consumption for the past 25 years.

Alcohol reduces cardiovascular risk…

Much attention has been given to studies concluding that daily moderate consumption of alcohol of any type (including beer, white or red wine, or whiskey) over the age of 50 will reduce cardiovascular risk. What is not commonly known is that the beneficial effects of alcohol are only realized if there are sufficient levels of folic acid in the diet. Folic acid is a synthetic form of folate which is a B vitamin found naturally in fruits and vegetables. 

…but alcohol increases risk of breast cancer.

Even one drink every other day increases breast cancer risk by about 17% according to Dr. Willett, which puts women over 50 in a bind because alcohol could reduce heart disease but increase cancer risk. The good news here again is that the increased breast cancer risk is only evident in women with low folic acid levels. Dr. Willett’s advice to women over 50 is to take folic acid if you drink alcohol.

Folic acid is an important nutrient for breast and heart health

Although there are many things in fruits and vegetables that can explain their beneficial effect on heart health including antioxidants, fiber, minerals and vitamins, Dr. Willett says that the science points to folic acid as a prime operator. This is borne out by the alcohol studies showing increased heart benefits and decreased breast cancer risk with adequate levels of folic acid.

How do you get folic acid into your diet? Dr. Willett recommends fruits and vegetables rich in folate (leafy greens, fruits, dried beans and peas) as well as taking a folic acid supplement in the amount of the recommended daily allowance (400 micrograms).