By 2030, it is estimated that more than 1 billion people on earth will be overweight.
So, understanding the mechanisms involved in obesity and the conditions it promotes is vitally important.
Over recent years, it has become clear that gut bacteria form part of this mechanism; they play a role in metabolism and therefore influence obesity-related diseases.
Because consuming fruit improves the diversity of bacteria in the gut, benefits overall health, and reduces weight gain, it has become of particular interest to obesity researchers.
Specifically, fruits that are high in polyphenols are considered to be most beneficial. For instance, some researchers have discovered that fruit extracts rich in these chemicals can reduce weight gain and improve insulin resistance.
What is camu camu?
Researchers from Université Laval's Faculty of Medicine in Canada recently decided to investigate the potential benefits of an Amazonian fruit called camu camu (Myrciaria dubia).
Native to Peru and Brazil, the camu camu is a reddish-purple fruit that is similar to a cherry. Though indigenous people have long harvested the fruit, it has only recently started being cultivated and sold to a wider market. Camu camu is particularly popular in Japan.
Although the acidic camu camu won't win any prizes for its flavor, which has been likened to a mix of sour cherry and lime, it is particularly rich in potentially healthful phytochemicals.
In particular, it has high levels of antioxidants, including ellagic acid (which might protect against some chronic diseases), ellagitannins (which are thought to safeguard vascular health), and proanthocyanidins (a chemical with a range of posited health benefits).
Camu camu's nutrient load
Camu camu also boasts an impressive vitamin C cargo of around 3,000 milligrams per 100 grams; that's 20–30 times more than kiwis, giving it one of the highest vitamin C contents of any fruit.
The fruit's impressive nutritional haul was what intrigued study co-author Prof. André Marette; he wanted to know whether camu camu could positively affect metabolic disease and obesity.
To investigate, he and his team fed mice a high-fat, high-sugar diet for 8 weeks. They gave half of the mice extract of camu camu each day. The findings were recently published in the journal Gut.
By the end of the study, the mice that consumed camu camu extract had gained 50 percent less weight than those who did not consume the extract.
When the team looked at the mice's insulin resistance, there were noteworthy changes there, too. Both glucose tolerance and insulin sensitivity improved; meanwhile, levels of endotoxins and inflammation decreased. Specific changes in the animals' microbiome were also measured.
"All these changes were accompanied by a reshaping of the intestinal microbiota, including a blooming of Akkermansia muciniphila and a significant reduction in Lactobacillus bacteria."
Prof. André Marette
Transplanting the microbiome
In the next phase of their experiments, they transplanted the gut bacteria from the camu camu-fed mice into germ-free mice, which are animals bred to have no gut bacteria. These rodents also saw the beneficial metabolic changes seen in the camu camu-fed mice, although only temporarily.
Prof. Marette takes this as evidence that the camu camu "exerts its positive metabolic effects, at least in part, through the modulation of the gut microbiota."
The next, natural step is to take this research to humans; and because the fruit is already widely marketed, safety concerns are minimal.
Of course, no single fruit is going to cure obesity or metabolic disease; both are complex and multifaceted. However, because of the prevalence of obesity, if a fruit compound could help — even in a relatively minor way — it might have a significant impact for the population at large.
It is tempting to jump the gun, but proof of camu camu's ability to alter metabolism in humans will be needed first and foremost.