Peanuts and tree nuts are tiny packages of big nutrition. They contain protein, unsaturated fats, fiber, antioxidants, and are good sources of a variety vitamins and minerals. A large new study finds that eating a few nuts a day can add years to your life.

The Netherlands Cohort Study study began in 1986 and has followed over 120,000 people — men and women aged 55 to 69 — for 29 years. People in the study who ate about a half a handful of nuts a day had a lower risk of dying from several major causes of death than people who didn’t eat nuts.

Each kind of nut has its own unique combination of nutrients, so it's best to eat a wide variety.

Researchers asked those in the study how often they ate peanuts, tree nuts, and peanut butter, as well as how much they ate, and compared the results with overall cause-specific mortality.

Nuts and peanuts have been found to lower the risk of death from cardiovascular disease; however, this study reported an even broader set of benefits: a high reduction in mortality from respiratory diseases, diabetes, and neurodegenerative diseases, as well as cardiovascular disease and cancer. Equal effects were seen in both men and women.

Keep in mind that each kind of nut has its own unique combination of nutrients, so it's best to eat a wide variety. A handful about three times a week is all it takes to reap their nutritional benefits.

And more is not better. Eating lots of nuts did not provide any further benefits. Nuts range in caloric value from 160 calories for 49 pistachios to 190 calories for six Brazil nuts. The average is 13 calories per nut taking into consideration all types. Eating too many can lead to weight gain and the risk of chronic weight-related diseases.

Unfortunately, peanut butter does not seem to provide the same positive health effects as whole nuts do. Its nutritional composition is not the same as that of peanuts. Conventional peanut butters can contain trans fats, sugar, salt and other ingredients. The health effects of these ingredients may offset any protective effect of peanuts in this form.

The study was published in the International Journal of Epidemiology.