If you have ever seen a walnut, you can be forgiven for thinking they are good for the brain. They look like a mini brain, so it would make good mother-nature sense that walnuts would be great for the brain. Unfortunately, we don’t have the high quality, human based research delving into this. The best we could do is animal studies, nutrient analyses, and educated guesses. With this in mind, researchers are going as deep as stating that the compounds within walnuts are thought to reduce the oxidant and inflammatory load on the brain cells and improve brain cell signalling. We can thank this nut’s unique composition for their health benefits – the make-up of the fatty acids in walnuts is high in alpha-linoleic acid and rich in polyunsaturated fats. Unseen in other common nuts.
Let’s have a look at what we do know about walnuts, scientifically.
In 2005 a couple of researchers sat down and combed through all the high-quality human research available, looking at how walnuts affected cholesterol. By comparing all seven papers they found that in over half of the studies, there was a significant decrease in total cholesterol and LDL cholesterol, compared to the control group. 40-84g of walnuts daily showed an up to 12% decrease in total cholesterol, and an up to 16% decrease in LDL cholesterol. Further to this, they also found a statistically significant improvement in the good to bad cholesterol ratio (HDL:LDL) and the total cholesterol to good cholesterol ratio (HDL:TC). All within 6 weeks!
A few years later, in 2009, another team of researchers completed a similar study, locating 13 papers, and coming to the same conclusion; walnuts are good at lowering cholesterol.
I think it’s fair to say that everyone knows that walnuts have good fats in them – that’s generally what makes them so popular. But have you considered walnuts for bacterial health? A 2018 study examined how eating walnuts can alter your gastrointestinal microbiota (your gut bugs). After only 3 weeks of eating 42g of walnuts daily, it was found that function and composition of the gastrointestinal microbiota significantly improved, while microbially derived proinflammatory secondary bile acids (bad guys) decreased. A further study in 2018 showed that 43g of walnuts over 8 weeks significantly improved gut microbiome by enhancing probiotic and butyric acid-producing species (good guys) in healthy humans. These results suggest that walnuts may have a wider health improving reach than originally anticipated.
Unfortunately, a lot of people are still confused about fats when going on a weight loss journey. Don’t be concerned about walnuts and weight gains. A study in 2017 has found that those on a weight loss diet, and those on the same weight loss diet but with walnuts included, lost a very similar amount of weight. Whilst this study didn’t show an increased weight loss with walnuts (it would have been nice), it did show that weight loss was still as achievable with or without walnuts. As an added bonus, this study found that those who ate the walnuts benefited from a reduced systolic blood pressure. This, coupled with the cholesterol improving benefits mentioned earlier, make walnuts a great addition to the diet for anyone concerned about cardiovascular disease or heart health.
Still not convinced to grab some walnuts with the next grocery shop?
How about ageing – if you worried about ageing, eat walnuts. 30-60g of walnuts daily for 2 years has been found to delay telomere shortening, and thus reduce the time it takes for our chromosomes to become damaged and unusable. Telomeres shorten with each round of cell division, limiting the production of human cells to a finite number (keeping us mere humans mortal). Once a telomere gets too short, that cell can no longer reproduce, causing our tissues to degenerate and eventually die. This 2018 study has found that walnuts delayed this process in cognitively healthy individuals aged over 63years old.
Adding to this ageing potential, a 2012 study has highlighted the superiority of walnuts over fatty fish. Both walnuts and fatty fish contain high amounts good fats, however walnuts were found to produce a significantly higher level of antioxidant potential. This study found that walnuts have such a large antioxidant capacity that daily inclusion of walnuts have the potential to maintain a myriad of benefits via antioxidant protection.
And finally, but not so scientifically, sleep. Walnuts are rumoured to contain melatonin. Melatonin is the lovely sleep hormone that reduces with age, and what many menopausal women miss. While a handful of walnuts won’t knock you out, it may help improve your sleep, especially if eaten at night.
Walnuts are a specialty that shouldn’t be over-looked. In addition to all the great research done on the benefits of walnuts, we also know the following:
- Walnuts are high in B1, B6 and folate
- Walnuts are high in manganese, magnesium, phosphorous, zinc, copper and iron
- Walnuts are a great source of fibre, and a decent source of protein
- Walnuts are exceptionally rich in antioxidants
- Plus all the good fats. Can’t forget about the good fats and the extreme benefits they provide.
 Poulose, S. M., et al. (2014). “Role of walnuts in maintaining brain health with age.” J Nutr 144(4 Suppl): 561s-566s.
 Mukuddem-Petersen, J., et al. (2005). “A systematic review of the effects of nuts on blood lipid profiles in humans.” J Nutr 135(9): 2082-2089.
 Banel, D. K. and F. B. Hu (2009). “Effects of walnut consumption on blood lipids and other cardiovascular risk factors: a meta-analysis and systematic review.” Am J Clin Nutr 90(1): 56-63.
 Holscher, H. D., et al. (2018). “Walnut Consumption Alters the Gastrointestinal Microbiota, Microbially Derived Secondary Bile Acids, and Health Markers in Healthy Adults: A Randomized Controlled Trial.” J Nutr 148(6): 861-867.
 Bamberger, C., et al. (2018). “A Walnut-Enriched Diet Affects Gut Microbiome in Healthy Caucasian Subjects: A Randomized, Controlled Trial.” Nutrients 10(2).
 Rock, C. L., et al. (2017). “Walnut consumption in a weight reduction intervention: effects on body weight, biological measures, blood pressure and satiety.” Nutr J 16(1): 76.
 Freitas-Simoes, T. M., et al. (2018). “Walnut Consumption for Two Years and Leukocyte Telomere Attrition in Mediterranean Elders: Results of a Randomized Controlled Trial.” Nutrients 10(12).
 Hudthagosol, C., et al. (2012). “Antioxidant activity comparison of walnuts and fatty fish.” J Med Assoc Thai 95 Suppl 6: S179-188.