Scientists from Imperial College London, Harvard University, and other institutions sifted through the available evidence looking at the connection between various causes of death and people's daily intake of nuts. Reviewing 29 different studies that collectively involved around 800,000 participants, they found higher nut consumption consistently was linked to lower rates of death, particularly from heart and respiratory disease as well as cancer.
All told, the risk of death was 19 percent lower among people with high nut intake relative to those with low nut intake. Worldwide, they estimated that at least 4.4 million deaths in 2013 were linked to eating less than 20 grams a day of nuts. For comparison's sake, a handful of nuts is generally around 28 grams or 1 ounce.
Nutrition science can often be a tricky thing to navigate, since it's often very hard to show a clear cause-and-effect chain between eating a single food and a person's health and clearly there may be other factors coming into play that explain the link between high nut consumption and health. The authors did not look at the reasons behind the correlation between nut intake and health, but the general consensus has long stood behind nuts as a good guy snack, even if they are bit high in calories. As they point out, nuts are a fine source of fiber, magnesium and the healthier polyunsaturated fats, to say nothing of other nutrients and antioxidants suspected of reducing cancer risk.
Research has continuously shown a link between eating nuts and avoiding cardiovascular disease, but there's been less work done on its potential benefits elsewhere, which inspired the team to look deeper. According to them, their review is the largest of its kind to date, though there was limited evidence available on which specific types of nut or legume, be it peanut or tree nut, is best and not a lot of data available from some parts of the world, like Africa and the Middle East.
"The main take home message is that you can obtain quite substantial health benefits in terms of reduced risk of coronary heart disease, cardiovascular disease overall, total cancer, and all-cause mortality simply by eating a handful of nuts every day (unless you have a nut allergy of course)," study author and Imperial College London epidemiologist Dagfinn Aune told Vocativ in an email.
Not all the news was good, however. Unlike earlier research, they found no definitive buffer effect on stroke prevention. And though eating nuts to our heart's content isn't generally a problem in the States, the authors noted, people living in less developed nations do have to worry more about their stocks being contaminated by aflatoxin, a nasty, cancer-causing chemical that species of fungi produce in the warmer areas of the world. So any global public health efforts to promote nut consumption should make sure to also safeguard against the toxin, the authors said.
Ultimately, it seems apparent that you can do a lot worse for your health than downing a handful of nuts often (President Obama apparently endorses this habit). According to the CDC, around 40 percent of Americans eat nuts on any given day, but even then, the majority of these folks still eat less than 1.5 oz. worth of them, the amount recommended by the FDA.