Nuts – Their Nutritional Benefits

A squirrel on a tree boll eating some nuts.
Squirrel enjoying nuts. Photo by artemisphotos. Courtesy of FreeDigitalPhotos.net

Nuts are the seeds of new plants and must provide all the fat, protein and energy that a newly germinating plant must receive to continue its growth. No wonder we find them so nutritious ! We find them a great snack as attested to the world over where we eat tonnes of them. Not only are they delicious and valuable as ingredients in all sorts of foods from savoury to dessert, but also good for us. According to nutritional research we should be munching a few every week just for maintaining great health.

There are many types of nuts and the benefits of consuming them are in part due to their lipid profile. Nuts abound – walnuts, almonds, pistachios, peanuts, brazils etc. all have a strong cultural and nutritional value. They are rich in the monounsaturated and polyunsaturated fatty acids, tocols (tocopherols and other related substances) and phytosterols (Griel and Kris-Etherton, 2006). In fact, nuts contains lots of omega-6 fatty acids which are associated with inflammation but not all news is bad. They are also rich in proteins and fiber which all help.

Nuts In Healthy Eating 

Eating nuts has been an integral part of the Mediterranean Diet and this is consistent with lower levels of cardiovascular disease. We are regularly reminded that we should cut out the saturated fatty acids and we have seen numerous studies demonstrating that consumption of nuts should be in moderation. 

The nuts eaten most often  with the lowest calories are almonds at 160 per ounce (23 nuts; 6 grams protein, 14 grams fat); cashews (16 to 18 nuts; 5 grams protein, 13 grams fat); and pistachios (49 nuts; 6 grams protein, 13 grams fat). Sweet chestnuts actually have the lowest calorie and fat content  of all and they are lower in protein.

There is no evidence that eating nuts leads to increasing body weight (Fraser et al., 1992; Hu et al., 1998; Ellsworth et al., 2001; Albert et al., 2002; Sabaté, 2003; Griel et al., 2004).

Nuts coated in oil or packaged generally have much higher calorie values and are probably not regarded as healthy as raw nuts.

Generally the European Society of Cardiology guidelines state 30g of unsalted nuts per day is listed as one of the characteristics of a healthy diet, and the energy density of nuts is high. 

Various Health Benefits

Several clinical and epidemiological studies show that regular consumption of nuts produces a favourable blood lipid profile (Griel and Kris-Etherton, 2006; Ternus et al., 2009), lowers the risk of cardiovascular disease (Kelly and Sabaté, 2006; Kris-Etherton et al., 2008) as already mentioned, influences type 2 diabetes (Jiang et al., 2002; Jenkins et al., 2008), and even sends certain types of cancer cell lines into reverse (González and Salas-Salvadó, 2006; Davis et al., 2008). 

Nuts are often consumed as part of a weight loss programme because of the range of vitamins and minerals they contain. They are also contributors to improved sexual function and improving the quality of orgasm in men in particular. 

Nut Consumption And Heart Health

A study presented in 2019 at the European Society of Cardiology’s annual conference suggested we should be eating an afternoon snack of nuts rather than  munching a bag of crisps. It would appear a portion of nuts at least twice a week is associated with a 17 per cent lower risk of heart attack, stroke or some other cardiovascular related issue. The study was conducted in Iran and assessed the cardiovascular disease risks in 5,432 adults of 35 years and older. They did not have a previous history of heart disease and came from a mix of urban and rural backgrounds. The amount of nuts of all sorts was measured starting in 2001 using a food frequency questionnaire. The measures were made every 2 years until 2013. At each point the subjects were interviewed on the occurrence of any cardiovascular issues or if death had occurred.

A median 12 year follow up concluded that there were 751 cardiovascular events. The researchers found 594 were from coronary heart disease and 157 were strokes. There were also 179 cardiovascular deaths and 458 all-cause deaths. Eating nuts twice a week or more was associated with a 17% lower risk of cardiovascular mortality in comparison to eating nuts once every two weeks.

Dr Noushin Mohammadifard, study author from Isfahan Cardiovascular Research Institute in Iran claimed

“Nuts are a good source of unsaturated fat and contain little saturated fat. They also have protein, minerals, vitamins, fibre, phytosterols and polyphenols which benefit heart health.” 

Long-Term Nut Consumption Can Improve Cognition In Older Adults

A study at the University of South Australia in 2019 has found that long-term consumption of nuts in high enough amounts could be enough to improve cognitive health in older people.

The study was conducted in 4,822 Chinese adults who were 55 years and over. The researchers discovered that eating more than 10 grams of nuts every day was positively associated with better mental abilities, better reasoning, improved memory and reasoning.

The UniSA study analysed nine waves of China Health Nutrition Survey collected over 22 years. In all the studies, 17 per cent of the participants were regular consumers of nuts but mostly peanuts. Dr Li, lead researcher stated that peanuts have specific anti-inflammatory and antioxidant effects which alleviate and reduce cognitive decline.

The key finding that eating 10 g which equates to two teaspoons of nuts per day was significant came about because it appeared to improve their cognitive function by up to 60 per cent. This was compared to the group who were not eating as many nuts. The nut eaters were ‘effectively warding off what would normally be experienced as a natural two-year cognition decline’. 

The study has considerable implications for the Chinese population generally because by 2015, 330 million Chinese will be over the age of 65 with 90.4 million over the age of 80. Generally the population in China is aging faster than any other in the world. Continuing in good health and maintaining a strong mental outlook are key aspects in the support of such a huge population. It is feasible that this research could be extended to other populations where similar studies with specific nuts have been conducted into overall cognitive health. These studies show similar results where different cognitive benefits have been reported.

Eating 60 Grams Of Nuts Daily Can Improve Male Sexual Function.

A study was reported in the journal Nutrients which was authored by  Albert Salas-Huetos and URV’s Human Nutrition Unit, and CIBERobn Network led by URV professor Jordi Salas-Salvado in 2019 (Salas-Huetos et al., 2019a). In this study, 83 mean who followed a typical western diet which was high in animal fats and low in fruit and vegetables were split into two groups. The control group continued to follow their normal diet over a period of 14 weeks.  The other group added 60g of walnuts, hazelnuts and almonds to their diet every day. After the study, participants completed a questionnaire known as the IIEF-15 which asked various questions about their sexual function. 

The study showed that adding nuts to the generally unhealthy diet improved quality of orgasm and sexual desire. Whilst such studies need careful examination, there is a need to increase the statistical validity of the trial by increasing the numbers involved. One of the reasons is to identify why the addition of nuts improves sexual desire for example. It may be related to erectile dysfunction and reducing the impact of this condition as an example.

One study reported in the American Journal of Clinical Nutrition buy the same authors also attributed improvements to sperm quality to consumption of certain types of nuts. That study did not look at sexual function though (Salas-Huetos et al., 2018). 

References

Albert, C.M., Gaziano, J.M., Willett, W.C., Manson, J.E. (2002) Nut consumption and decreased risk of sudden cardiac death in the Physicians’ Health Study. Arch Intern Med. 162 pp. 1382–7.

Davis, P.A., Jenab, M., Heuvel, J.P.V., Furlong, T., Taylor, S. (2008). Tree nut and peanut consumption in relation to chronic and metabolic diseases including allergy. J Nutr 138(9):  pp. 1757–62.

Ellsworth, J.L., Kushi, L.H., Folsom, A.R. (2001) Frequent nut intake and risk of death from coronary heart disease and all causes in postmenopausal women: the Iowa Women’s Health Study. Nutr Metab Cardiovasc Dis. 11 pp. 372–7.

Fraser, G.E., Sabate, J., Beeson, W.L., Strahan, T.M. (1992) A possible protective effect of nut consumption on risk of coronary heart disease. The Adventist Health Study. Arch Intern Med. 152 pp. 1416–24.

Hu, F.B., Stampfer, M.J., Manson, J.E., Rimm, E.B., Colditz, G.A., Rosner, B.A., Spitzer, F.E., Hennekens, C.H., Willett, W.C. (1998) Frequent nut consumption and risk of coronary heart disease in women: prospective cohort study. BMJ. 317 pp. 1341–5.

González, C.A., Salas-Salvadó,  J. (2006). The potential of nuts in the prevention of cancer. Br J Nutr 96(2)  pp. 87–94.

Griel AE, Eissenstat B, Juturu V, Hsieh G, Kris-Etherton PM. (2004)  Improved diet quality with peanut consumption. J Am. Coll. Nutr.  23 pp. 660–8.

Griel, A.E., Kris-Etherton, P.M. (2006) Tree nuts and the lipid profile: a review of clinical studies. Br. J. Nutr. 96(2) pp. 68–78.

Jenkins, D.J.A., Hu, F.B., Tapsell, L.C., Josse, A.R., Kendall, C.W.C. (2008). Possible benefit of nuts in type 2 diabetes. J. Nutr 138(9):  pp. 1752–6.

Jiang, R., Manson, J.E., Stampfer, M.J., Liu, S., Willett, W.C., Hu, F.B. (2002). Nut and peanut butter consumption and risk of type 2 diabetes in women. J Am. Med. Assoc.  288(20) pp. 2554–60.

Kelly, Jr. J.H., Sabaté,  J. (2006). Nuts and coronary heart disease: an epidemiological perspective. Br. J. Nutr.  96(2)  pp. 61–7.

Kris-Etherton, P.M., Hu, F.B., Ros, E., Sabaté, J. (2008). The role of tree nuts and peanuts in the prevention of coronary heart disease: multiple potential mechanisms. J Nutr. 138(9):  pp. 1746–51.

Sabaté, J., (2003) Nut consumption and body weight. Am. J. Clin. Nutr. 78 Suppl 3:S647–50.

Sabaté, J., Ros, E., & Salas-Salvadó, J. (2006). Nuts: nutrition and health outcomes. Br. J. Nutri., 96(S2), S1-S2.
Salas-Huetos, A., Moraleda, R., Giardina, S., Anton, E., Blanco, J., Salas-Salvadó, J., & Bulló, M. (2018). Effect of nut consumption on semen quality and functionality in healthy men consuming a Western-style diet: a randomized controlled trial. The American journal of Clinical Nutrition108(5), pp. 953-962 (Article). 
Salas-Huetos, A.; Muralidharan, J.; Galiè, S.; Salas-Salvadó, J.; Bulló, M. (2019) Effect of Nut Consumption on Erectile and Sexual Function in Healthy Males: A Secondary Outcome Analysis of the FERTINUTS Randomized Controlled Trial. Nutrients  11, 1372 (Article).

Ternus, M.E., Lapsley, K., Geiger, C.J. (2009) Health benefits of tree nuts. In: Tree nuts: composition, phytochemicals, and health effects. Alasalvar C, Shahidi F, editors.  Boca Raton, Fla.: CRC Press. pp 37–64.

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