Learning & Healthy Living

Macadamia Academia

The much-maligned Dr. Robert Atkins said it first: Macadamia nuts are a dieter’s best friend. Maybe not for those who prefer low-fat diets but for individuals who fare best on reduced-carbohydrate approaches macadamias are a delicious way to stay on plan. The past several years haveseen a plethora of research supporting a beneficial role for nuts in a healthy diet. With their fatty acid profiles dietary fiber and micronutrient content nuts certainly live up to their positive reputation.

Just about all nuts and seeds have something going for them. Walnuts flax and chia seeds provide omega-3 fats; pumpkin seeds are loaded with minerals; almonds are frequently touted for their fiber and monounsaturated fat content. Macadamia nuts tend to get less attention than other nuts and seeds in health and nutrition headlines. This isn’t because they don’t hold their own nutritionally speaking. Perhaps it’s simply due to their cost. Compared to other nuts and seeds macadamias are pricey! This is because macadamia nut trees yield approximately one third as many nuts as other nut trees so they’re more expensive to grow. Moreover because macadamia shells have multiple hard layers the processing required to remove them is more involved than for other nuts.  

In North America macadamia nuts typically bring to mind images of Hawaiian leis and pristine beaches. Hawaii does produce a significant amount of macadamias but the nuts are actually native to Australia which produces over 40% of the world’s supply. In fact another name for macadamias is “Queensland nut” reflecting their Australian origins. (Other macadamia producing countries include South Africa Costa Rica Brazil and Kenya.)

Regarding nutrient content macadamias are rich in thiamin manganese and copper. Where they really shine however is in their fatty acid profile. Monounsaturated fat accounts for approximately 80% of the total fat in macadamias. About 74% of this is 18-carbon oleic acid the same one that predominates in olive oil. The rest is mostly 16-carbon palmitoleic acid an omega-7 fat that may be beneficial for reducing insulin resistance and hepatic triglyceride accumulation. As for their polyunsaturated fat content macadamias have about six times as much omega-6 as omega-3. This may sound like a strong imbalance but considering there’s less than one gram of polyunsaturated fat in an ounce of macadamias the total amount of omega-6 in them is miniscule.

The fatty acid profile of macadamias has led researchers to conduct experiments to determine whether macadamia oil would be beneficial for cardiovascular disease risk. Animal studies show that the oil does in fact have a positive impact on markers for heart health. Macadamia oil reduces inflammation and fat cell hypertrophy in mice fed a high-fat diet designed to induce obesity. Hypercholesterolemic men who consumed 40-90g of macadamia nuts daily for four weeks showed significant reductions in plasma markers of inflammation and oxidative stress. Women also experience cardiovascular disease risk improvement after consuming a diet rich in macadamia nuts. Researchers do specify however that the effects are not solely due to the presence of macadamia nuts in the diet but rather the substitution of these monounsaturated-rich nuts for an isocaloric amount of saturated fat. Therefore it’s likely not a wise idea for someone consuming a “standard American diet” to just add macadamia nuts to their regular meals. Rather they might consider going a little lower on dairy products and other foods high in saturated fat and replacing them with macadamia nuts or oil. 

A study that examined the effects of macadamia nut consumption on lipid profiles showed that the macadamia-rich diet resulted in small but notable improvements in total and LDL cholesterol levels. However the macadamia-rich diet had 37% of total calories coming from fat—the same amount as in the study’s baseline “typical American” diet. Presumably the carbohydrate content of both diets was close to—or possibly exceeded—40%. It would be interesting to see the results of a study looking at macadamia nut or oil consumption in the context of a low-­carbohydrate higher fat diet. The metabolic changes and alterations in fuel partitioning that occur on such an approach might lead to an even greater positive impact from macadamias’ monounsaturated fat. Certainly for low-carb dieters macadamias are a delicious albeit expensive way to snack and still stay on plan. And like other nuts and seeds macadamias are a great source of healthy fats for vegetarians and vegans.

And don’t be fooled: white chocolate and macadamia cookies aren’t the only way to indulge in these nuts. There’s no shortage of savory applications such as macadamia oil mayonnaise and macadamia nut crusted mahi mahi.