I’ll admit that I enjoy the occasional açaí bowl – and not just to look trendy. I find them very tasty and refreshing, and with such a vibrant colour I assumed they must contain some compounds that have health benefits. However, I am always dubious of so-called ‘superfoods’. The scientist in me had to dig deeper into this açaí phenomenon that has swept over all the cafés in my local area. I wanted to know if it was actually worth spending $12.50 on a small bowl of blended purple mush with some chopped fruit and coconut on top. So I went to the scientific literature and had a look at the actual studies that have been conducted on açaí.
What is açaí?
Firstly, what exactly is açaí? Açaí, or Euterpe oleracea Martius to be precise, is a slender, multi-stemmed palm plant that can reach over 30 meters. It is widely distributed in northern South America and is particularly abundant and important in the flood plains of the Brazilian Amazonian state of Pará (1). Each palm tree produces 3 to 4 bunches of berry-like fruit, each bunch having from 3 to 6kg of fruit. These round-shaped fruit start as green clusters but ripen to a dark, purple-coloured fruit that ranges from 1 – 1.5cm in diameter. The seed makes up most of the fruit, which is covered by thin fibrous fibers. There is a small edible layer under these fibres. Only 17% of the fruit is edible. Açaí berries are not eaten fresh. A juice can be made by crushing the edible pulp. This is known as açaí pulp. It is very perishable and must be frozen for export.
OK, now that we are clear on what açaí is let me tell you what I found in the scientific literature. There has been 186 studies published on açaí. One of the first studies was in 2004 published in the Journal of Agricultural and Food Chemistry. This study analysed the anthocyanin and polyphenolic compounds in açaí and the contribution these compounds have to its antioxidant capacity. It was shown that açaí pulp had a high antioxidant content compared to other anthocyanin-rich fruits such as blueberries, strawberries, raspberries and blackberries. In fact, açaí pulp had 10 times the antioxidant content of blueberries and double the antioxidant content of raspberries (2). Why is this beneficial for your health? Briefly, the production of reactive oxygen species or free radicals have been implicated in contributing to a number of chronic diseases, such as Alzheimer’s disease, cardiovascular disease and diabetes. The brain is particularly sensitive to reactive oxygen species. Dietary antioxidants, such as polyphenols, may help prevent these diseases.
A complete nutrient analysis of freeze-dried açaí found that it contains saturated and unsaturated fatty acids (32.5%), amino acids (7.6%) and sterols. Plant sterols are compounds that have been shown to lower LDL-cholesterol. Açaí is actually quite high in calories due to the presence of the fatty acids and is a complete meal containing fats, proteins and a small amount of carbohydrates (3).
Açaí is also a good source of potassium, magnesium, calcium, phosphorus, sodium and vitamins E and B1 (3). In addition, freeze-dried açaí was shown to have the highest reported antioxidant activity against the peroxyl radical (a reactive oxygen species) out of any food (4).
Another set of compounds, known as lignans, have been identified in açaí (5). The lignans from açaí contribute to the antioxidant activity of this fruit. The lignans from açaí were shown to kill human cancer cells – but remember this was done in the laboratory and not in actual human subjects (6).
Human studies involving açaí consumption
Studies conducted in animals have shown potential positive health benefits from the consumption of açaí including improvements in cholesterol levels of hypercholesteremic rats (7) and rabbits (8), protection against the characteristics of metabolic syndrome in mice (9) and a reduction of colon cancer in rats (10). Cell-based assays have found that açaí can protect human red blood cells and white blood cells from oxidative damage (11), reduce oxidative damage and inflammation in brain cells (12) and has an anti-inflammatory effect on mouse immune cells (13, 14). However, there have been very few clinical trials involving human subjects consuming açaí.
A study from 2008 found that the levels of serum antioxidants increased in human subjects 1 hour and 2 hours after they drank a juice blend containing mostly açaí when compared to subjects drinking a placebo (11). A study from the same year showed that anthocyanin concentrations in plasma increased after human subjects consumed açaí pulp or juice (15) (remember anthocyanins are one of the major antioxidants in açaí). Anthocyanins levels peaked at two hours and were higher after consuming açaí pulp compared to juice. This tells us that the antioxidants found in açaí enter the human circulation following consumption.
Another study looked at the effects of consuming açaí pulp (100 grams) as a smoothie twice per day for one month in overweight subjects who were at risk for developing metabolic syndrome. Consumption of açaí reduced total cholesterol levels, LDL-cholesterol levels and fasting glucose and insulin levels, however, consumption of açaí had no effect on body weight, blood pressure or levels of C-reactive protein, which is a marker of inflammation (16).
An analysis of cardiovascular parameters in healthy human volunteers following açaí consumption found no impact on blood pressure, heart rate or electrocardiogram endpoints. However, they did find that açaí decreased the standing systolic blood pressure compared to a placebo (17).
I came across a study that was of interest to me as an endurance athlete. This study looked at the effects of supplementation with açaí juice on the blood antioxidant defence capacity in junior hurdlers. Why did these sports scientists investigate this? Well, it is accepted that strenuous exercise is associated with increased production of free radicals and reactive oxygen and nitrogen species (ROS/RNS). Antioxidant supplementation in athletes may prevent exercise-induced tissue injury and assist recovery. These ROS/RNS are also important in muscle adaptation to exercise. So too much ROS/RNS can cause damage but at the same time they are required to signal to our muscles causing adaptation.
In the study I mentioned above elite junior hurdlers drank 100ml of an açaí juice blend daily for 6 weeks. The açaí juice had no effect on performance as assessed by 300m running times, however, it did cause increases in the antioxidant capacity of the plasma of the hurdlers. It also improved the lipid profile by reducing total cholesterol, LDL cholesterol and triglycerides. These young hurdlers were within normal ranges at the start of the study anyway, but these values improved over the 6 weeks. Supplementation with the açaí juice also lowered the levels of the enzymes creatine kinase and lactate dehydrogenase post-exercise. These enzymes are markers of muscle damage. This means that supplementation with açaí may help recovery after training.
Traditionally in the Amazon river basin açaí is used for its antidiarrheal activity. This has not been substantiated in any scientific studies.
To summarize, the human studies conducted on açaí consumption show us that the antioxidants from açaí do enter the blood stream and could potentially have a beneficial impact. These studies also show that açaí may have a cholesterol lowering effect but does not seem to impact cardiovascular outcomes, such as blood pressure or heart rate. Also, açaí may be useful for recovery after exercise and training.
Are there any negative effects from consuming açaí?
Açaí pulp is rich in the essential minerals calcium, iron, magnesium and zinc, while the levels of copper and manganese are exceptionally high. In some parts of Brazil, up to 300mls of açaí pulp can be consumed per day. This means that the daily intake of manganese could be six times the recommended amount. This could be a problem, especially for children, vegetarians/vegans and people with anemia, as iron absorption is impaired by manganese (18).
Açaí certainly is abundant in antioxidants and these compounds are bioavailable in humans. There is also evidence that the juice and pulp from this fruit can lower LDL-cholesterol levels. It is also very nutritious being rich in potassium, magnesium, calcium, phosphorus, sodium and vitamins E and B1, as well as containing unsaturated fatty acids and proteins.
OK, I feel better about spending $12.50 on an açaí bowl, and I like the findings about exercise recovery. Am I going to go out and buy açaí powder/frozen pulp? Maybe – but I would probably save it for directly after training for maximum benefits due to the cost. But remember, other vegetables and berries also contain antioxidants and various vitamins and minerals. And the benefits of regular exercise with bursts of high-intensity are key to optimal health. So don’t feel bad if you are not willing to fork out $50 for açaí powder. You can still be a healthy person in my opinion.
- Muñiz-Miret N, Vamos R, Hiraoka M, Montagnini F, & Mendelsohn RO (1996) The economic value of managing the açaí palm (Euterpe oleracea Mart.) in the floodplains of the Amazon estuary, Pará, Brazil. Forest Ecology and Management 87(1-3):163-173.
- Del Pozo-Insfran D, Brenes CH, & Talcott ST (2004) Phytochemical composition and pigment stability of Acai (Euterpe oleracea Mart.). Journal of agricultural and food chemistry 52(6):1539-1545.
- Schauss AG, et al. (2006) Phytochemical and nutrient composition of the freeze-dried amazonian palm berry, Euterpe oleraceae mart. (acai). Journal of agricultural and food chemistry 54(22):8598-8603.
- Schauss AG, et al. (2006) Antioxidant capacity and other bioactivities of the freeze-dried Amazonian palm berry, Euterpe oleraceae mart. (acai). Journal of agricultural and food chemistry 54(22):8604-8610.
- Chin YW, Chai HB, Keller WJ, & Kinghorn AD (2008) Lignans and other constituents of the fruits of Euterpe oleracea (Acai) with antioxidant and cytoprotective activities. Journal of agricultural and food chemistry 56(17):7759-7764.
- Hu J, et al. (2014) Antioxidant neolignan and phenolic glucosides from the fruit of Euterpe oleracea. Fitoterapia 99:178-183.
- de Souza MO, et al. (2012) The hypocholesterolemic activity of acai (Euterpe oleracea Mart.) is mediated by the enhanced expression of the ATP-binding cassette, subfamily G transporters 5 and 8 and low-density lipoprotein receptor genes in the rat. Nutrition research 32(12):976-984.
- Feio CA, et al. (2012) Euterpe oleracea (acai) modifies sterol metabolism and attenuates experimentally-induced atherosclerosis. Journal of atherosclerosis and thrombosis 19(3):237-245.
- de Oliveira PR, et al. (2010) Effects of an extract obtained from fruits of Euterpe oleracea Mart. in the components of metabolic syndrome induced in C57BL/6J mice fed a high-fat diet. Journal of cardiovascular pharmacology 56(6):619-626.
- Fragoso MF, Romualdo GR, Ribeiro DA, & Barbisan LF (2013) Acai (Euterpe oleracea Mart.) feeding attenuates dimethylhydrazine-induced rat colon carcinogenesis. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association 58:68-76.
- Jensen GS, et al. (2008) In vitro and in vivo antioxidant and anti-inflammatory capacities of an antioxidant-rich fruit and berry juice blend. Results of a pilot and randomized, double-blinded, placebo-controlled, crossover study. Journal of agricultural and food chemistry 56(18):8326-8333.
- Poulose SM, et al. (2012) Anthocyanin-rich acai (Euterpe oleracea Mart.) fruit pulp fractions attenuate inflammatory stress signaling in mouse brain BV-2 microglial cells. Journal of agricultural and food chemistry 60(4):1084-1093.
- Xie C, et al. (2012) The acai flavonoid velutin is a potent anti-inflammatory agent: blockade of LPS-mediated TNF-alpha and IL-6 production through inhibiting NF-kappaB activation and MAPK pathway. The Journal of nutritional biochemistry 23(9):1184-1191.
- Matheus ME, et al. (2006) Inhibitory effects of Euterpe oleracea Mart. on nitric oxide production and iNOS expression. Journal of ethnopharmacology 107(2):291-296.
- Mertens-Talcott SU, et al. (2008) Pharmacokinetics of anthocyanins and antioxidant effects after the consumption of anthocyanin-rich acai juice and pulp (Euterpe oleracea Mart.) in human healthy volunteers. Journal of agricultural and food chemistry 56(17):7796-7802.
- Udani JK, Singh BB, Singh VJ, & Barrett ML (2011) Effects of Acai (Euterpe oleracea Mart.) berry preparation on metabolic parameters in a healthy overweight population: a pilot study. Nutrition journal 10:45.
- Gale AM, Kaur R, & Baker WL (2014) Hemodynamic and electrocardiographic effects of acai berry in healthy volunteers: a randomized controlled trial. International journal of cardiology 174(2):421-423.
- da Silva Santos V, de Almeida Teixeira GH, & Barbosa F, Jr. (2014) Acai (Euterpe oleracea Mart.): a tropical fruit with high levels of essential minerals-especially manganese-and its contribution as a source of natural mineral supplementation. Journal of toxicology and environmental health. Part A 77(1-3):80-89.