Why You Should Eat Nuts and How Many You Need
Quick, what are your favorite nuts? If you said peanuts, you may be surprised to know that peanuts actually are not nuts (they are legumes). However, there are many other bona fide nuts from which to choose, and new research, as well as previous studies, explain why you should eat nuts and how many you need.
Experts are nuts about nuts
Just for clarification, the term “nuts” is defined as a simple, dry fruit that has one or (rarely) two seeds with a case wall that is hard at maturity. True nuts are acorns, hazel, pecans, and sweet chestnuts, while almonds, cashews, pine nuts, pistachios, and walnuts are actually seeds or drupes, which are fruit with an outer coating around a hard shell that contains a seed. Thus the broad use of the word “nut” generally includes seeds and drupes as well.
That said, the newest findings about nut consumption come from analyses of the PREDIMED nutrition intervention trials. In one analysis, experts looked at the impact of nut consumption (e.g., almonds, hazelnuts, peanuts, pine nuts, pistachios, and walnuts) on overall mortality and cancer mortality among 7,216 individuals ages 55 to 90 who were at risk for cardiovascular disease.
The investigators evaluated the impact of following a Mediterranean diet with additional nuts and virgin olive oil and compared that group with those who consumed a low-fat diet. Here’s what they discovered:
- Individuals who ate more than 3 servings of nuts per week had a 55 percent reduced risk of dying from cardiovascular disease and a 40 percent reduced risk of dying from cancer when compared with people who did not eat nuts. One serving is equal to 28 grams or about 1 ounce
- Individuals who followed the Mediterranean diet improved their risk of dying by 39 percent, and those who consumed walnuts in particular reduced their rate by 45 percent
But there’s more, and it comes from another new study published in PLoS One. In this analysis, the investigators evaluated data from 7,210 PREDIMED participants and looked at the association between eating nuts and the prevalence of obesity, metabolic syndrome, type 2 diabetes, high blood pressure, and high lipid levels (cholesterol, triglycerides).
This analysis revealed the following information:
Participants who ate more than 3 servings of nuts per week had a 22 percent lower prevalence of type 2 diabetes than those who ate less than 1 serving per
- Those who ate more than 3 servings of nuts per week had a 45 percent lower prevalence of obesity than those who ate less than 1 serving per week
- Individuals who consumed more than 3 servings of nuts weekly had a 35 percent lower prevalence of metabolic syndrome than those who ate less than 1 serving per week
The authors did not see any significant association between eating nuts and an impact on high blood pressure, lipid levels, or elevated fasting glucose. It should be noted, however, that some previous research has shown nut consumption does have a positive impact on these factors.
What is special about nuts?
Generally, nuts are a rich source of healthy fats, antioxidants, and phytonutrients that have been shown to be beneficial on insulin sensitivity and inflammation. Walnuts in particular have been found to be an excellent source of heart-friendly nutrients.
For example, a study presented at the American Chemical Society’s National Convention in March 2011 noted that a serving of walnuts has nearly twice as much antioxidants as the same amount of almonds, pecans, pistachios, and other nuts.
What else do nuts offer?
- Fiber, a substance that helps reduce cholesterol, fills you up (so you will hopefully eat less), and has a role in preventing diabetes
- Vitamin E, which helps reduce the development of plaque in blood vessels and also is a potent antioxidant
- Plant sterols, also shown to reduce cholesterol
- L-arginine, an amino acid that can promote the health of artery walls, making them more flexible and thus less likely to support blood clots
The benefits of the healthy fats should be noted as well, especially monounsaturated fats and polyunsaturated fats, which help lower bad cholesterol; and omega-3 fatty acids, shown to reduce inflammation, which is a key element in cardiovascular disease and diabetes.
Thus there is a body of evidence supporting the consumption of nuts to reduce the risk of dying and reduce the risk of serious health problems such as type 2 diabetes and associated conditions such as metabolic syndrome and obesity. As for how many nuts you should eat, the authors of the latest study noted that “Several dietary guidelines recommend replacing one of five servings of fruits and vegetables a day by a serving of nuts,” while three servings of nuts per week have also been shown to be beneficial.
Guasch-Ferré M et al. Frequency of nut consumption and mortality risk in the PREDIMED nutrition intervention trial. BMC Medicine 2013; 11:164
Ibarrola-Jurado N et al. Cross-sectional assessment of nut consumption and obesity, metabolic syndrome and other cardiometabolic risk factors: the PREDIMED study. PLoS One 2013; 8(2): e57367
Rohrmann S and Faeh D. Should we go nuts? BMC Medicine 2013; 11:165