A large study in BMC Medicine has shown that eating nuts protects against cardiovascular disease and cancer, even if you have a healthy diet. Marta Guasch-Ferre and her colleagues studied 7,216 individuals over 4.8 years, and those who consumed more than 3 servings of nuts a week (one serving = 28g, which is about a handful) had a 39% lower mortality risk.
What is so special about nuts?
Tree nuts have been an important part of our diet since the Stone Age, but their consumption has recently declined in most industrialised countries.
The most popular edible ones include walnuts, hazelnuts, pistachios, pine nuts, brazil nuts, macadamia and almonds. Peanuts are in fact legumes, but as they have a nutritional profile similar to tree nuts, they are considered as such. Chest nuts on the other hand, are different, and even though botanically they are nuts, they are not consider as such here.
Nuts contain a large amount of vegetable protein, fibre and unsaturated fatty acids. They are cholesterol-free and rich in phytosterols. The latter interfere with our cholesterol absorption and can therefore help us to keep our cholesterol levels down.
Nuts are rich in vitamins (such as folic acid, vitamin B6 and E), and many other bioactive substances such as phenols. Their outer soft shell or skin contains most of the antioxidants, and when this pellicle is removed, more than halve of the antioxidants are lost. Blanching also destroys them. It is therefore better to have your nuts raw and unprocessed.
They have an excellent combination of minerals: a small amount of sodium, and plenty of calcium, magnesium and potassium. This will protect you against arterial hypertension and insulin resistance, and therefore against cardiovascular disease. Obviously, if you eat your nuts salted, you will lose these benefits.
Marta Guasch-Ferre and her colleagues have also shown that walnuts help to protect you against cancer. They are richer in polyphenols than other nuts, and as you usually eat them raw and with their skin on, you will also get more antioxidants from them.
Adverse effects of nuts
As they are rich in fat, people tend to avoid them to keep slim. However, studies have demonstrated that regular consumption does not lead to weight gain, and some researchers have even shown that nut-eaters are leaner than the general population. This is probably due to the fact that nuts make you feel full for longer, and as a consequence you will eat less other energy-dense food.
The big problem is that they can trigger a life-threatening allergic reaction. Once the diagnosis of nut allergy is made, the patients and their families should avoid all nut products, which can be challenging as they are often hidden in processed food. If somebody you live with suffers from this condition, you should know exactly how to recognise and treat an allergic reaction.
Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider
M Guasch-Ferre, M Bullo, M A Martinez-Gonzalez et al. Frequency of nut consumption and mortality risk in the PREDIMED nutrition intervention trial. BMC Medicine 2013; 11:164 doi: doi:10.1186/1741-7015-11-164.
E Ros. Health benefits of nut consumption. Nutrients 2010; 2(7): 652-682