Macadamia nuts and its oil contain high levels of monounsaturated fats (MUFAs), namely oleic and palmitoleic acid, as well as phenolic compounds which may provide a beneficial outcome with regards to human biomarkers. A unique relationship exists between the healthful compounds found within macadamia nuts and their capability of interacting with numerous bioenzymatic pathways. This pilot study was conducted with 60 participants to ascertain the effects of consuming macadamia nut oil (MNO) over an 8-week period on various human health markers of interest, mainly relating to changes in hepatic health markers, inflammation, as well as lipid and glycemic profiles. The effects of MNO on the aforementioned human health markers were compared with that of both coconut and olive oil. Participants followed either a low carbohydrate high fat (LCHF) diet (carbohydrates <130 g/d or <26% total energy) or a standard diet (carbohydrates >130g/d or >45% total energy). Participants were randomly assigned one of the three natural oil supplements for the duration of the intervention.
In the LCHF macadamia nut group (LMN), improvements to HDL-C and triglyceride concentrations were observed. Overall, total cholesterol in the LMN increased by 7.36%. Furthermore, GGT, amylase and lipase concentrations bettered. MNO consumption positively affected average fasting glucose concentrations.
The standard diet group (SMN) recorded more improvements than that of the LMN group. CRP levels improved significantly within the group and a positive effect on all hepatic health markers was detected. There was improvement to both LDL-C and triglyceride concentrations. The SMN group followed the same pattern as that of the LMN where fasting glucose levels improved, whilst HbA1c levels negatively increased. Fewer health markers showed improvement in both dietary groups for coconut and olive oil when compared with the MNO groups.
However, improvements to the overall lipid profile of the LCHF coconut oil (LCO) group was observed. Only HDL-C concentrations improved within the standard coconut oil (SCO) group. Markers of inflammation within the LCO group showed improvements, with a significant result for ESR. ESR is a good indicator of inflammation within the body. Average amylase and lipase readings for the SCO group positively decreased. Of the three oil groups, olive oil showed the least improvements to health markers after the intervention. The LCHF olive oil (LOO) group followed the same amylase and lipase pattern as the SCO group, showing a small decline. The olive oils groups were the only ones to show an improvement in HbA1c levels, however, both did not show fasting glucose level improvements. Lastly, both olive oil groups presented a reduction in triglyceride levels.
Macadamia nuts and their unique properties have the potential to lower inflammation and oxidative stress, which may assist in mitigating the risk for chronic diseases. The results of the pilot indicate that including macadamia nut oil into a daily diet may have cardioprotective effects and aid in the prevention of future diseases of lifestyle. From the results obtained in this pilot study, macadamia nut oil demonstrated promising beneficial effects for human health when compared to oils, such as coconut and olive oil. Further research on long-term macadamia nut or macadamia nut oil consumption and its positive effects on certain health markers should be explored in depth.