Lemon compound helps reduce weight gain – 02/05/2023 – Equilibrium

A study conducted at the Food Research Center reveals that limonene, a substance abundant in citrus fruits, is capable of reducing weight gain. The local researchers – a Fapesp Research, Innovation and Dissemination Center headquartered at USP (University of São Paulo) – also identified new molecules that act in the body associated with the compound. The results were reported in the journal Metabolites.

Limonene belongs to the class of monoterpenes, bioactive organic compounds with several beneficial effects already described by science: antimicrobial, antitumor, healing, antioxidant and analgesic, for example. However, further studies are still needed so that its mechanisms of action are better understood.

The effect on weight control was observed in mice, in a study coordinated by Jarlei Fiamoncini, a professor at the Department of Food and Experimental Nutrition at the Faculty of Pharmaceutical Sciences.

For six weeks, two groups of animals received a diet high in fat daily, enough for them to become obese. In the ration, the researchers added different doses of limonene. One group received low doses of the compound, which corresponded to 0.1% of the daily ration, while another ate high doses, equivalent to 0.8% of the daily ration. For comparison purposes, a third group was fed the same fatty diet, but without the compound, while a fourth received an isocaloric diet, that is, moderate in fat and carbohydrate.

At the end of this period, the animals fed an isocaloric diet did not gain weight, while those that received only a fatty diet gained about 7 g. Mice that received fatty chow with high doses of limonene gained approximately 25% less weight (compared to those fed only fatty chow), while those that received low doses, 30% less.

It was also found that the lower dose promoted less accumulation of fat in different structures of adipose tissue (the body’s fat reservoir, located mainly in deeper layers of the skin).

According to the first author of the study, José Fernando Rinaldi Alvarenga, a researcher collaborating with the research center responsible for the study and receiving a scholarship from Fapesp, one of the hypotheses that explain these results is the action of limonene on the intestinal microbiota of the animals.

“When consumed, limonene, in addition to being absorbed by the organism, could be acting in the modulation of the microbiota. However, in high concentrations, it may have eliminated the beneficial bacteria of the intestinal microbiota, thus reducing the benefits related to the reduction of weight gain” , he says.

Another hypothesis is that limonene, when absorbed, was biotransformed by the body into other molecules. In this process, it was observed that the compound gained new structures in relation to the original molecule.

“It could be that these molecules biotransformed by the organism are bioactive and, therefore, would be responsible for the effects. Not always the compound we ingest is the compound that produces the effects in the organism”, evaluates Alvarenga.

new molecules

By analyzing the urine of these animals, performed by mass spectrometry, it was possible to identify new molecules, some of which had never been described in the scientific literature.

“We found some metabolites already identified and other molecules that we did not yet know about. In the future, we will be able to study these new molecules to assess the potential benefits. This is important because, in addition to possibly identifying these benefits, it may be that other already known effects, such as glycemic control and the modulation of the microbiota, are in part also propitiated by the monoterpenes”, says the researcher.

The authors emphasize the importance of further work, not only in relation to limonene. According to a review article published by the group last year, the levels of monoterpenes found in foods, in general, vary greatly from study to study. The same goes for the possible effects of these compounds. The most robust evidence is that monoterpenes, in addition to being antimicrobial, may have beneficial effects on metabolic syndromes, such as obesity and diabetes, and on reducing cell inflammation.

Furthermore, it is still unknown whether the ingestion of these compounds, through a supplement, for example, would be effective and safe for humans. “For the time being, priority should be given to the consumption of herbs, spices and fruits, foods in which monoterpenes are found. In the case of limonene, fruits such as lemons and oranges”, highlights Alvarenga.

With information from FoRC, a Research, Innovation and Dissemination Center of FAPESP.