Evidence mounts: new health study bolsters case for daily nut consumption

The taste and texture of nuts have long made them a popular addition to snacks, meals and a host of manufactured food and beverage products. What is increasingly clear is that nuts not only taste great, they’re also great for you.

A woman holding a macadamia nut in one hand and a small container of macadamia nuts in the other

Thanks to the plethora of scientific studies conducted over the years, we now have a robust understanding of the nutrients that nuts contain, and the key role these play in human health. In fact, the case for enjoying a daily handful of your favourite nuts has never been stronger.

Here we take a closer look at findings from a recent study, and dive deeper into some of the health benefits specific to macadamias.

New research review confirms nuts’ heart health benefits

A major new research review has found that eating a daily handful of nuts is linked with improved blood lipid profiles. Examining 19 previously published scientific papers, the review1 showed a strong relationship between nut consumption and significant reductions in:

  • Total cholesterol
  • ‘Bad’ cholesterol (low-density lipoprotein or LDL)
  • Triglycerides

Nut dose was noted as a major factor in these cholesterol lowering effects. The research review also noted preliminary evidence that adding nuts to a person’s regular diet reduces blood levels of apolipoprotein B, a protein that helps carry fat and cholesterol in the body, while improving ‘good’ cholesterol function. Adding nuts may also be linked with a reduced number of harmful small and dense, bad cholesterol particles.

Why do blood lipid profiles matter?

If someone has unhealthy levels of any kind of lipid in their blood, be that elevated total cholesterol, bad cholesterol or triglycerides, or decreased good cholesterol, they have what’s known as ‘dyslipidemia.’ This condition is a well-known risk factor for cardiovascular disease and a leading cause of death worldwide.

According to the authors of the review, there are multiple mechanisms at play when it comes to how nut consumption improves blood lipid profiles. The favourable fatty acid profile of nuts as well as their unique and complex synergy of nutrients and bioactive compounds appear to play a role. However further research is needed to understand these mechanisms better.

Evidence continues to mount

This latest study adds to the findings of another major evidence review published last year2. This ‘umbrella review’ of 145 systematic reviews and meta-analyses concluded that consuming a handful of nuts per day, compared to eating no nuts, was associated with a range of compelling health benefits, including:

  • 21% reduced risk for cardiovascular disease
  • 25% reduced risk for coronary heart disease
  • 22% reduce risk of death from cardiovascular disease
  • 11% reduced risk of dying from cancer
  • 22% reduced risk of dying from all causes
  • Reduced risk of mortality from respiratory diseases, infectious diseases, and diabetes

Macadamias: good for body, mind and mood

When it comes to the specific benefits of macadamias, there’s a lot to unpack. They’re a deliciously indulgent ingredient ideal for people seeking dairy-free, sugar-free, and gluten-free dishes and products. But that’s just the start.

Heart health

In addition to the heart health benefits of nuts outlined earlier, macadamias are a rich source of phytosterols (or ‘plant sterols’). These are natural substances, found in many plant foods, that are similar in structure to cholesterol. Plant sterols can reduce cholesterol levels by being absorbed in place of some of the ‘bad’ (LDL) cholesterol, which results in reductions in blood cholesterol levels3.  They also contain the amino acid arginine, which acts as a precursor to the chemical messenger nitric oxide that causes blood vessels to dilate and remain elastic. This can reduce blood pressure, among other benefits4.

The #1 nut source of mono-unsaturated fats

Fat helps with absorption of fat-soluble nutrients such as vitamin E and also helps to keep us feeling satiated5. However, there are several types of fat and not all of them are equally beneficial.

Good monounsaturated and polyunsaturated fats are beneficial for heart health and reduce the risk of heart disease, and nuts are an excellent source of these important nutrients. For consumers or brands eager to leverage the health benefits of these good fats, macadamias are a great choice as they have the highest monounsaturated fat content of all tree nuts. 80% of the total fat content in macadamias is the heart-healthy monounsaturated type6, 7.

Gut health

There are different types of dietary fibre that benefit the body in different ways and macadamias have a combination of these essential fibre types. One handful of macadamias contains 2g of dietary fibre, which is comparable to a slice of wholemeal bread8.

Nuts like macadamias, also contain prebiotic fibre9, a fermentable food for the gut’s natural microflora. When this prebiotic fibre is fermented by gut bacteria, short chain fatty acid gases are produced that are beneficial to the lining of the gut. This activity plays a role in the production of the mood stabilising hormone serotonin10 as well as influencing hormones that affect weight management, appetite, blood sugar levels and the immune system.11

Brain health

Macadamias contain copper, magnesium and manganese that aid in the maintenance of healthy neurotransmitters in the brain. Healthy neurotransmitters are a key component of good brain and mental health. Macadamias also contain a monounsaturated fatty acid called palmitoleic acid, which is an important component of the myelin sheath. This fatty layer insulates and protects nerve cells to allow electrical impulses to transmit efficiently around the whole body, including in the brain12.

Having a healthy heart is linked to brain health13 and so the monounsaturated fats, vitamin E, antioxidants and other compounds in macadamias that support heart health will help support brain function too. Blood vessel health is essential for good brain health because the brain needs a good blood supply. Macadamias contain oleic acid (omega 9), a monounsaturated fat which may play a role in reducing inflammation.

Skin health

Macadamias contain useful amounts of the antioxidant manganese. This is essential for the skin’s collagen production, which helps it to stay plump and wrinkle free. Macadamias are also high in palmitoleic acid, which humans produce naturally but less as we age, that is believed to help replenish the skin’s youthful appearance14.

Macadamias are also a source of protein, calcium, potassium, dietary fibre and a number of antioxidants – all of which we need to support our health and maintain glowing skin, strong nails and shiny hair14.

Cosmetic-grade macadamia oil is a 100% natural, lightweight skin moisturiser for all skin types.

Looking for more information?

If you have any questions about the health benefits of macadamias contact Australian Macadamias Market Development Manager Jacqui Price. If you’re looking for an Australian macadamia supplier, head to our supplier directory.


References

1 Guasch-Ferré, M., et al. Effects of nut consumption on blood lipids and lipoproteins: A comprehensive literature update. Nutrients, 2023. 15:596.
2 Balakrishna, R., et al. Consumption of nuts and seeds and health outcomes including cardiovascular, diabetes and metabolic disease, cancer, and mortality: An umbrella review. Advances in Nutrition, 2022. nmac077, https://doi.org/10.1093/advances/nmac077
3 Rocha, M., et al., A review on the role of phytosterols: new insights into cardiovascular risk. Curr Pharm Des, 2011. 17(36): p. 4061-75.
4 Boger, R.H., The pharmacodynamics of L-arginine. Altern Ther Health Med, 2014. 20(3): p. 48-54.
5 https://wisdom-site-nutsforlife-com-au.s3.amazonaws.com/uploads/2019/07/NFL516-NFL-Ready-Reckoner-2018-LR.pdf
6 Perfilyev A, Dahlman I , Gillberg L et al, Am J Clin Nutr. Impact of polyunsaturated and saturated fat overfeeding on the DNA-methylation pattern in human adipose tissue: a randomized controlled trial. 2017 Apr;105(4):991-1000.
7 Del Gobbo LC, Falk MC, Feldman R et al. Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: systematic review, meta-analysis, and dose-response of 61 controlled intervention trials. Epub 2015 Nov 11.
8 https://www.betterhealth.vic.gov.au/health/healthyliving/fibre-in-food
9 https://www.monash.edu/medicine/ccs/gastroenterology/prebiotic/faq#4
10 Banskota S, Ghia J-E, Khan WI. Serotonin in the gut: Blessing or a curse. Biochimie. 2019;161:56-64. doi:10.1016/j.biochi.2018.06.008
11 Martin CR, Osadchiy V, Kalani A, Mayer EA. The Brain-Gut-Microbiome Axis. Cell Mol Gastroenterol Hepatol. 2018;6(2):133–148. Published 2018 Apr 12. doi:https://plu.mx/a/?doi=10.1016/j.jcmgh.2018.04.003
12 Kim E, Ko HJ, Jeon SJ, et al. The memory-enhancing effect of erucic acid on scopolamine-induced cognitive impairment in mice. Pharmacol Biochem Behav. 2016;142:85-90. doi:10.1016/j.pbb.2016.01.006
13 Grodstein F. Cardiovascular risk factors and cognitive function. Alzheimers Dement. 2007;3(2 Suppl):S16-22. doi:10.1016/j.jalz.2007.01.001
14. https://www.nutsforlife.com.au/resource/macadamias/

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