A handful of nuts a day cuts the risk of a wide range of diseases

Credit: Lawrencekhoo / Wikipedia.

A large analysis of current research shows that people who eat at least 20g of nuts a day have a lower risk of heart disease, cancer and other diseases.

11 DEC 2016--The analysis of all current studies on nut consumption and disease risk has revealed that 20g a day - equivalent to a handful - can cut people's risk of coronary heart diseaseby nearly 30 percent, their risk of cancer by 15 percent, and their risk of premature death by 22 percent.
An average of at least 20g of nut consumption was also associated with a reduced risk of dying from respiratory disease by about a half, and diabetes by nearly 40 percent, although the researchers note that there is less data about these diseases in relation to nut consumption.
The study, led by researchers from Imperial College London and the Norwegian University of Science and Technology, is published in the journal BMC Medicine.
The research team analysed 29 published studies from around the world that involved up to 819,000 participants, including more than 12,000 cases of coronary heart disease, 9,000 cases of stroke, 18,000 cases of cardiovascular disease and cancer, and more than 85,000 deaths.
While there was some variation between the populations that were studied, such as between men and women, people living in different regions, or people with different risk factors, the researchers found that nut consumption was associated with a reduction in disease risk across most of them.
Study co-author Dagfinn Aune from the School of Public Health at Imperial said: "In nutritional studies, so far much of the research has been on the big killers such as heart diseases, stroke and cancer, but now we're starting to see data for other diseases.
"We found a consistent reduction in risk across many different diseases, which is a strong indication that there is a real underlying relationship between nut consumption and different health outcomes. It's quite a substantial effect for such a small amount of food."
The study included all kinds of tree nuts, such as hazel nuts and walnuts, and also peanuts - which are actually legumes. The results were in general similar whether total nut intake, tree nuts or peanuts were analysed.
What makes nuts so potentially beneficial, said Aune, is their nutritional value: "Nuts and peanuts are high in fibre, magnesium, and polyunsaturated fats - nutrients that are beneficial for cutting cardiovascular disease risk and which can reduce cholesterol levels.
"Some nuts, particularly walnuts and pecan nuts are also high in antioxidants, which can fight oxidative stress and possibly reduce cancer risk. Even though nuts are quite high in fat, they are also high in fibre and protein, and there is some evidence that suggests nuts might actually reduce your risk of obesity over time."
The study also found that if people consumed on average more than 20g of nuts per day, there was little evidence of further improvement in health outcomes.
The team are now analysing large published datasets for the effects of other recommended food groups, including fruits and vegetables, on a wider range of diseases.

More information: Dagfinn Aune et al, Nut consumption and risk of cardiovascular disease, total cancer, all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis of prospective studies, BMC Medicine (2016). DOI: 10.1186/s12916-016-0730-3


Provided by Imperial College London

Large study links nut consumption to reduced death rate

Credit: Lawrencekhoo / Wikipedia.

In the largest study of its kind, people who ate a daily handful of nuts were 20 percent less likely to die from any cause over a 30-year period than were those who didn't consume nuts, say scientists from Dana-Farber Cancer Institute, Brigham and Women's Hospital, and the Harvard School of Public Health.

24 nov 2013--Their report, published in the New England Journal of Medicine, contains further good news. The regular nut-eaters were found to be more slender than those who didn't eat nuts, a finding that should alleviate the widespread worry that eating a lot of nuts will lead to overweight.

The report also looked at the protective effect on specific causes of death.

"The most obvious benefit was a reduction of 29 percent in deaths from heart disease – the major killer of people in America," said Charles S. Fuchs, MD, MPH, director of the Gastrointestinal Cancer Center at Dana-Farber, who is the senior author of the report. "But we also saw a significant reduction – 11 percent – in the risk of dying from cancer," added Fuchs, who is also affiliated with the Channing Division of Network Medicine at Brigham and Women's.

Whether any specific type or types of nuts were crucial to the protective effect couldn't be determined. However, the reduction in mortality was similar both for peanuts and for "tree nuts" – walnuts, hazelnuts, almonds, Brazil nuts, cashews, macadamias, pecans, cashews, pistachios and pine nuts.

Several previous studies have found an association between increasing nut consumption and a lower risk of diseases such as heart disease, type 2 diabetes, colon cancer, gallstones, and diverticulitis. Higher nut consumption also has been linked to reductions in cholesterol levels, oxidative stress, inflammation, adiposity, and insulin resistance. Some small studies have linked increased nuts in the 

diet to lower total mortality in specific populations. But no previous research studies had looked in such detail at various levels of nut consumption and their effects on overall mortality in a large population that was followed for over 30 years.

For the new research, the scientists were able to tap databases from two well-known ongoing observational studies that collect data on diet and other lifestyle factors and various health outcomes. The Nurses' Health Study provided data on 76,464 women between 1980 and 2010, and the Health Professionals' Follow-up Study yielded data on 42,498 men from 1986 to 2010. Participants in the studies filled out detailed food questionnaires every two to four years. With each food questionnaire, participants were asked to estimate how often they consumed nuts in a serving size of one ounce. A typical small packet of peanuts from a vending machine contains one ounce.

Sophisticated data analysis methods were used to rule out other factors that might have accounted for the mortality benefits. For example, the researchers found that individuals who ate more nuts were leaner, less likely to smoke, and more likely to exercise, use multivitamin supplements, consume more fruits and vegetables, and drink more alcohol. However, analysis was able to isolate the association between nuts and mortality independently of these other factors.

"In all these analyses, the more nuts people ate, the less likely they were to die over the 30-year follow-up period," explained Ying Bao, MD, ScD, of Brigham and Women's Hospital, first author of the report. Those who ate nuts less than once a week had a seven percent reduction in mortality; once a week, 11 percent reduction; two to four times per week, 13 percent reduction; five to six times per week, 15 percent reduction, and seven or more times a week, a 20 percent reduction in death rate.

The authors do note that this large study cannot definitively prove cause and effect; nonetheless, the findings are strongly consistent with "a wealth of existing observational and clinical trial data to support health benefits of nut consumption on many chronic diseases." In fact, based on previous studies, the US Food and Drug Administration concluded in 2003 that eating 1.5 ounces per day of most nuts "may reduce the risk of heart disease."

Provided by Dana-Farber Cancer Institute