- Cocoa, apple, grapeseed, red wine and a few other food sources contain high levels of flavanols (FL), also known as flavan-3-ols, which have been linked to certain health benefits. health.
- Previous studies suggest that FL-rich foods have significant potential in managing cardiovascular health, improving cholesterol levels, and increasing glucose tolerance.
- Now, using mouse models, scientists have investigated the relationship between dietary FL intake and fat metabolism.
- The study results reveal new clues that could one day become beneficial treatments for cardiovascular and obesity-related diseases.
Flavanols (FL), also known as flavan-3-ols, are among the most widely consumed flavonoids in the American diet.
These compounds are found in various foods, beverages, whole and processed foods, and herbal supplements.
However, the exact mechanism of action by which LFs trigger their protective functions has long eluded scientists.
Recently, researchers in Japan set out to increase the body of scientific knowledge about FLs.
Using mouse models, they investigated the ability of ingested FL to brown white adipose tissue.
Adipose tissue, or body fat, is an essential organ for maintaining energy homeostasis in the body, and it is made up of white adipose tissue and brown adipose tissue. While white adipose tissue acts as an energy store, brown adipose tissue is important for maintaining body temperature.
Scientists call the phenomenon of conversion of white adipose tissue to brown adipose tissue fat browning. Here, white fatty tissues that store energy turn into brown fatty tissues that break down blood sugar and fat molecules.
This is an important therapeutic event because the accumulation of excess white adipose tissue is linked to obesity and the development of cardiovascular disease. Additionally, the conversion process also generates heat, which helps maintain body temperature.
The results of their research appear in the journal nutrients.
Medical News Today contacted the study’s lead author, Naomi Osakabe, a professor at the Graduate School of Engineering and Science, Shibaura Institute of Technology, Japan, to understand the motivation behind the study.
“It is known that the ingestion of foods rich in flavan 3-ols (cocoa, apples, etc.) reduces the onset of obesity and its complications and also prevents heart disease. However, flavan 3-ols are poorly absorbed from the gastrointestinal tract, therefore, it is unknown why they induce such health-promoting actions.
“In our previous results,” she added, “we found that hemodynamic alteration after ingestion of flavan 3-ols [was] induced by sympathetic activation. Therefore, we hypothesized that flavan 3-ols might promote beige fat and conducted this experiment to prove it.
To test their hypothesis, the researchers conducted two sets of independent experiments.
In the first experiment, the scientists randomly divided the animals into two treatment groups. One group received a single dose of cocoa-derived FL diet, while the other group, not fed a high FL diet, served as a control.
For both groups, the research team collected 24-hour urine samples. This was done to measure the effects of pre- and post-oral administration of a control and high-FL diet – respectively – on catecholamine (CA) levels.
For the second experiment, the researchers also divided the animals into two treatment groups. One group was repeatedly fed the cocoa-derived FL diet for 14 days, while the other group, not fed the high FL diet, served as controls.
At the end of the treatment period, the researchers sampled white and brown fatty tissue from both treatment groups. They did this to study the long-term effects of sympathetic nervous system (SNS) activity on the structure and function of these tissues.
The researchers write that parts of their previous study inspired this new study. Previously, they observed that a single oral dose of a FL-rich diet induced a stress response in animals. This, in turn, led to SNS activation and a significant increase in catecholamine levels.
Catecholamines (CA), such as dopamine, adrenaline and noradrenaline, are released by the SNS during stressful events and help manage the body’s response – fight or flight – to these events.
In this study, the researchers concluded that an increase in CA levels can be used to assess SNS activity.
Therefore, when another
In the first experiment, researchers found that over 24 hours, the amount of CA excreted by the control group was almost similar before and after ingesting the control diet.
However, they noticed that a single dose of a FL-rich diet in the test group resulted in a significant increase in CA levels over 24 hours.
For the second experiment, the team noticed an increase in the expression of protein markers of browning in the brown adipose tissues of FL-fed animals. Moreover, they also observed that in response to the activation of the SNS, beige adipose tissues developed in the white adipose tissues.
These findings led the research team to conclude that oral administration of FL activated the SNS and was associated with fat browning.
Surprisingly, they also found that “the effect of 3-ols flavans [FLs] has been shown not only in subcutaneous fat but also in visceral fat.
This finding is important because excess visceral fat increases the risk of developing obesity. Therefore, LFs may open new avenues of investigation and new potential treatments for cardiovascular and obesity-related diseases.
However, there is still a long way between animal studies and human treatments.
In 2018, Dr. Gunter Kuhnle, Ph.D., Professor in the Department of Food Science and Nutrition, University of Reading, UK, wrote an article in the journal Molecular aspects of medicine on the FLs.
The article reviews the known unknowns regarding the health benefits of FLs.
In the article, Dr. Kuhnle explains that although FLs have health benefits, the data used to gather the results are mostly short-term, self-reported studies.
He concluded by saying that the observed health benefits of LFs “require large-scale confirmation and greater rigor.”
Incidentally, one can’t help but notice that part of that mandate is almost similar to what researchers at Japan’s Shibaura Institute of Technology hope to do in their future research.
The team revealed that further studies are still needed to fully understand the mechanism of action of LFs.
Furthermore, Professor Osakabe’s latest comments on the study also suggested playing the long game. She said, “[…] in this study, we found [that] flavan-3-ols increase white adipose browning via sympathetic nerve hyperactivity. This [finding] brought us closer to elucidating the mechanism of the risk-reducing effect of flavan-3-ols on cardiovascular disease, which had been unknown for many years.
Although Professor Osakabe and his team may not have gotten “clean cut” answers, their study brings scientific knowledge about LF one step closer to a meaningful conclusion.