“Nuts are a good source of unsaturated fat and contain little saturated fat,” said study author Dr Noushin Mohammadifard of Isfahan Cardiovascular Research Institute, Iran. “They also have protein, minerals, vitamins, fibre, phytosterols, and polyphenols which benefit heart health. European and US studies have related nuts with cardiovascular protection but there is limited evidence from the Eastern Mediterranean Region.”
This study examined the association between nut consumption and the risk of cardiovascular disease and death in the Iranian population. A total of 5,432 adults aged 35 and older with no history of cardiovascular disease were randomly selected from urban and rural areas of the Isfahan, Arak and Najafabad counties. Intake of nuts including walnuts, almonds, pistachios, hazelnuts, and seeds was assessed in 2001 with a validated food frequency questionnaire.
Participants or family members were interviewed every two years until 2013 for the occurrence of cardiovascular events and death. The specific outcomes investigated were coronary heart disease, stroke, total cardiovascular disease, death from any cause, and death from cardiovascular disease.
During a median 12-year follow-up, there were 751 cardiovascular events (594 coronary heart disease and 157 stroke), 179 cardiovascular deaths, and 458 all-cause deaths.
Eating nuts two or more times per week was associated with a 17% lower risk of cardiovascular mortality compared to consuming nuts once every two weeks. The connection was robust even after adjusting for factors that could influence the relationship such as age, sex, education, smoking, and physical activity. Nut intake was inversely associated with the other outcomes but lost significance after adjustment.
ESC guidelines list 30 grams of unsalted nuts per day as one of the characteristics of a healthy diet, while noting that the energy density of nuts is high.
“Raw fresh nuts are the healthiest,” added Dr Mohammadifard. “Nuts should be fresh because unsaturated fats can become oxidised in stale nuts, making them harmful. You can tell if nuts are rancid by their paint-like smell and bitter or sour taste.”