By Krista Kleczewski and Claire Karlsson
Evidence is growing about the many ways in which eating nuts, seeds, and legumes can improve your health. These foods have been linked to healthier hearts and a lower risk of diabetes, but now studies show they may also cut your risk of getting cancer! Here’s what we know and don’t know.
Several studies show a great benefit from eating nuts, seeds, and legumes. In 2015, a Dutch study of 120,000 men and women between the ages of 55-69 found that those who ate about half a handful of nuts or peanuts each day were less likely to die from respiratory disease, neurodegenerative diseases, diabetes, cardiovascular diseases, or cancer than those who consumed no nuts or seeds.1 The same benefit was not seen for peanut butter, however, which suggests that the salt, vegetable oils, and trans fatty acids in peanut butter may counterbalance the benefits of the peanuts. A 5-year study conducted in Spain of 7,000 men and women aged 55 to 80 years old found that eating at least three servings of nuts per week reduced the risk of cardiovascular and cancer death.2 Another study similarly found eating nuts – especially walnuts — reduces the risk of developing cancers, diabetes and heart disease when eaten in conjunction with the Mediterranean Diet, which also emphasizes fruits, vegetables, whole grains, and legumes.3 Walnuts were highlighted by the study as reducing inflammation associated with certain cancers and other conditions like diabetes and heart disease. More evidence is needed, however, to determine the specific impact of walnuts on cancer risk.
Eating large amounts of peanuts, walnuts, or almonds can reduce the risk of developing breast cancer, according to a 2015 study of 97 breast cancer patients. 4 The researchers compared the lifetime consumption of nuts and seeds among the breast cancer patients with the consumption of those without breast cancer, finding that women who ate large quantities were half to one-third as likely to develop breast cancer. No difference was found between people who ate a small amount of nuts and seeds and those who ate none at all, suggesting that a person needs to consume a substantial amount of nuts and seeds over their lifetime to reduce their chances of developing breast cancer.
Girls who regularly eat peanuts and nuts may be less likely to develop breast cancer as adults. In a study published in 2013, girls between the ages of 9-15 who regularly ate peanut butter or any kind of nuts had almost a 40% lower chance of developing benign breast conditions as adults.5 Although not dangerous, benign breast conditions increase a woman’s chances of eventually getting breast cancer.
Many people think of peanuts as nuts, but they are actually a type of legume. Researchers found that eating legumes, which include beans, lentils, soybeans, and corn, may all reduce the risk of benign breast conditions (and therefore, breast cancer).
Can eating nuts, legumes and seeds reduce colorectal cancer risk?
To find out whether snacking on foods with peanuts lowers your chances of getting colorectal cancer (also called colon cancer), researchers studied more than 23,000 adults in Taiwan, ages 30 and older.6 The researchers found that women who ate meals with peanut products at least twice each week were less likely to develop colorectal cancer. More research is needed to see if this benefit is actually from the peanuts.
In one of the largest studies of diet and cancer, which was conducted in 10 European countries, researchers discovered that eating nuts and seeds reduced women’s chances of developing colon cancer, but did not lower the risk for men.7 Women who ate a modest daily amount of nuts and seeds (about 16 peanuts or a small handful of nuts or seeds) every day were less likely to develop colon cancer, and women who ate the largest quantities of these foods were the least likely to develop colon cancer. Again, more research is needed to understand these findings.
Eating nuts also seems to lower the risk of developing diabetes,8 which may then lower the risk of developing pancreatic cancer. In addition, a large study of women found that frequently eating nuts was associated with less chance of developing pancreatic cancer,9 one of the most deadly cancers.
What about ovarian cancer?
A 2010 study examined the possible link between ovarian cancer and foods high in phytoestrogens and/or fiber, including nuts, beans, and soy. They found that these foods seemed to help prevent “borderline ovarian cancer”—slow-growing tumors that are less dangerous and more likely to affect younger women. However, these foods did not seem to protect against the more aggressive types of ovarian cancer.10
The Bottom Line
There is growing evidence that nuts, legumes, and seeds reduce the risk for several types of cancer, as well as having other health benefits. Nuts are high in calories, so don’t overdo it. It seems safe to assume that adding these foods to your diet, in small quantities several times a week, is a good idea, especially if you use them to replace less healthy snacks.
This gives new meaning to the name “health nut”!