| Health / Plants and plant products |
Açaí
The açaí palm tree, (Euterpe oleracea), native to tropical Central and South America, produces a deep purple fruit. The açaí fruit has long been an important food source for indigenous peoples of the Amazon region.
Açaí palm with fruit. Photo: CostaPPPR/Wikipedia
In a study of three traditional Caboclo populations in the Brazilian Amazon, açaí palm was described as the most important plant species because the fruit makes up a major component of their diet, up to 42% of the total food intake by weight.
The fruit, commonly known as açaí or açaí berry, is a small, round, black-purple drupe about 25 mm (1 in) in circumference, similar in appearance to a grape, but smaller and with less pulp and produced in branched panicles of 500 to 900 fruits.
The exocarp of the ripe fruits is a deep purple color, or green, depending on the kind of açaí and its maturity. The mesocarp is pulpy and thin, with a consistent thickness of 1 mm (0.04 in) or less.
It surrounds the voluminous and hard endocarp, which contains a single large seed about 7–10 mm (0.3–0.4 in) in diameter. The seed makes up about 60–80% of the fruit.
The palm bears fruit year round but the berry cannot be harvested during the rainy season.
Açaí products have become popular in the United States, where they have been promoted for weight-loss and anti-aging purposes.
In 2003, American celebrity doctor Nicholas Perricone included açaí berries among "superfoods", but such extravagant marketing claims regarding açaí as miracle cures for everything from obesity to attention-deficit disorder were challenged in subsequent studies.
Açaí fruit pulp has been used experimentally as an oral contrast agent for magnetic resonance imaging (MRI) of the digestive tract.
How Much Do We Know?
Anthocyanins define the blue pigmentation of açaí and the antioxidant capacity of the plant's natural defense mechanisms and in laboratory experiments in vitro. Anthocyanins in açaí accounted for only about 10% of the overall antioxidant capacity in vitro.
The Linus Pauling Institute and European Food Safety Authority state that "the relative contribution of dietary flavonoids to (...) antioxidant function in vivo is likely to be very small or negligible".
Unlike in controlled test tube conditions, anthocyanins have been shown to be poorly conserved (less than 5%) in vivo, and most of what is absorbed exists as chemically modified metabolites destined for rapid excretion.
A powdered preparation of freeze-dried açaí fruit pulp and skin was shown to contain cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside as major anthocyanins (3.19 mg/g).
The powdered preparation was also reported to contain twelve flavonoid-like compounds, including homoorientin, orientin, taxifolin deoxyhexose, isovitexin, scoparin, as well as proanthocyanidins (12.89 mg/g), and low levels of resveratrol (1.1 μg/g).
Its anthocyanins have also been characterized for stability as a natural food coloring agent.
Nutritional content
A powdered preparation of freeze-dried açaí fruit pulp and skin was reported to contain (per 100 g of dry powder) 534 calories, 52 g carbohydrates, 8 g protein, and 33 g total fat.
The carbohydrate portion included 44 g of dietary fiber with low sugar levels, and the fat portion consisted of oleic acid (56% of total fats), palmitic acid (24%), and linoleic acid (13%).
The powder was also shown to contain (per 100 g) negligible vitamin C, 260 mg calcium, 4 mg iron, and 1002 IU vitamin A.
Açaí oil
Açaí oil is suitable for cooking or as a salad dressing, but is mainly used in cosmetics as shampoos, soaps or skin moisturizers.
The oil compartments in açaí fruit contain polyphenols such as procyanidin oligomers and vanillic acid, syringic acid, p-hydroxybenzoic acid, protocatechuic acid, and ferulic acid, which were shown to degrade substantially during storage or exposure to heat.
Although these compounds are under study for potential health effects, there remains no substantial evidence that açaí polyphenols have any effect in humans. Açaí oil is green in color, has a bland aroma, and is high in oleic and palmitic fatty acids.
Very little research has been done in people on the health effects of açaí products.
What Have We Learned?
There's no definitive scientific evidence based on studies in people to support the use of açaí for any health-related purpose.
No independent studies have been published in peer-reviewed journals that substantiate claims that açaí alone promotes rapid weight loss. When investigating the safety profile of an açaí-fortified juice in rats, researchers found no differences in body weight changes between animals given the juice and animals not given the juice.
A preliminary study suggested that eating açaí fruit pulp might reduce blood sugar and cholesterol levels in people who are overweight.
Laboratory studies have focused on açaí's potential antioxidant properties, and a juice blend with açaí as the main ingredient has been shown to have an antioxidant effect in people. (Antioxidants are substances that may protect cells against certain types of damage.)
What Do We Know About Safety?
Açaí pulp appears to be safe when consumed in the amounts commonly used in foods; however, drinking unprocessed açaí juice has been linked to an illness called American trypanosomiasis (also known as Chagas disease).
Consuming açaí might affect MRI test results. If you use açaí products and are scheduled for an MRI, check with your health care provider.
Little is known about whether it’s safe to use açaí during pregnancy or while breastfeeding. (National Institutes of Health/Wikipedia)
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