he acai berry is a fruit found in palm trees (Euterpe oleraceae) native to the Amazon basin and surrounding areas in South America. The fruit of the tree holds economic value to the indigenous populations of these areas where it is used as a food and medicine. Clinical trials have shown positive effects from administration of the fruit to overweight subjects. For example, in one study1 subjects with body mass indexes between 25 and 30 kg/m2 were administered 100 grams acai fruit pulp twice per day for one month while their cardiovascular risk factors were monitored. Compared to their baseline values, the subjects had reductions in fasting glucose and fasting insulin concentrations with consumption of the acai berry pulp. There was also an amelioration of the postprandial glucose and insulin response to a meal and subjects had reductions in total cholesterol and low density lipoprotein (LDL).
Therefore consumption of the acai berry may cause favourable effects on some of the cardiovascular risk factors associated with metabolic syndrome. The favourable shift in lipoprotein ratios may be caused by the modulation of glucose and insulin levels seen upon consumption of the berry. This is because elevated plasma glucose and insulin concentrations are characteristic of the insulin resistance seen in the metabolic syndrome which is a primary driver of the associated hepatic dysfunction. This dysfunction is the likely cause of the modified lipoprotein ratios seen in the metabolic syndrome that gives rise to an increased risk of cardiovascular disease. Berries are known to contain a cocktail of sugars which are able to produce favourable effects on digestion rates of glucose due to inhibition of enzymes and transporter involved in intestinal metabolism of glucose. The sugar content of the berries may therefore be a contributory factor in their health benefits.
In addition, research has shown that the acai berry is a rich source of polyphenols, which may have beneficial effects on oxidative stress in humans, particularly the superoxide and peroxyl radical2. Analysis of berry extracts have shown them to contain flavonoids of the anthocyanin and proanthocyanidin subgroups as well as a range of other minor flavonoid constituents3. The stilbene resveratrol, also found in grapes and red wine, was also detected in the fruit berry extracts. Because flavonoids are bioavailable and are able to regulate oxidative stress in humans, they may be beneficial to obese individuals with metabolic syndrome, a condition characterised by systemic oxidative stress. The polyphenols in the berry fruit may also inhibit absorption of glucose in the same way as other sugars present in the berry fruit. Some polyphenols have been shown to share common transporters with sugars and this may therefore also favourably affect blood glucose concentrations.
Another interesting component of the berry fruit is the fatty acid profile. Analysis of the berry has revealed it to contain a plethora of fatty acids including the polyunsaturated fatty acids linoleic acid (LA, C18:2 (n-6)) and α-linolenic acid (ALA, C18:3 (n-3)), the monounsaturated fatty acid oleic acid and the saturated fatty acid palmitic acid2. The cholesterol modulating effect of the berry could relate to the presence of the sterols β-sitosterol, campesterol and sigmasterol that have been detected in acai berry extract3. Studies show that plant sterols are able to favourably modulate plasma cholesterol concentrations in mammals including humans. The mechanism for this is thought to relate to the ability of the sterols to inhibit cholesterol absorption from the gut. Short chain fatty acids present in the berry extract may modulate lipoproteins because they inhibit hepatic cholesterol synthesis.
1Udani, J. K., Singh, B. B., Singh, V. J. and Barrett, M. L. 2011. Effects of acai (Euterpe oleracea Mart.) berry preparations on metabolic parameters in a healthy overweight population: a pilot study. Nutrition Journal. 10: 45
2Schauss, A. G., Wu, X., Prior, R. L., Ou, B., Huang, D., Owens, J., Agarwel, A., Jensen, G. S., Hart, A. N. and Shanbrom, E. 2006. Antioxidant capacity and other bioactivities of freeze-dried Amazonian palm berry, Euterpe oleraceae Mart. (Acai). Journal of Agriculture and Food Chemistry. 54: 8604-8610
3Schauss, A. G., Wu, X., Prior, R. L., Ou, B., Patel, D., Huang, D. and Kababick, J. P. 2006. Phytochemical and nutrient composition of the freeze-dried Amazonian palm berry, Euterpe oleraceae Mart. (Acai). Journal of Agriculture and Food Chemistry. 54: 8598-8603