BCAAs: Possible Link to Gestational and Type 2 Diabetes

With Deirdre Tobias, PhD, and Caroline Apovian, MD

Women who develop diabetes during pregnancy, called gestational diabetes (GD), are known to be at higher risk for developing type 2 diabetes later in life. Now, researchers have some possible new clues as to why and how that risk might be identified and maybe even reduced,according to study findings published in the journal Clinical Chemistry.

This well-regarded team of researchers focused on what is known as branched chain amino acids (BCAAs), which come from both animal and vegetable sources of protein in the diet.2 A high blood level of these amino acids ''has been associated with a high risk of diabetes down the road," says Deirdre Tobias, ScD., assistant professor at Harvard Medical School and an epidemiologist at Brigham & Women's Hospital in Boston, Massachusetts, who led the study.

"We looked particularly in this high-risk group [of women with GD] and we found this association is even stronger," she says.

Nutritional supplements of BCAAs while popular following exercise may raise the risk for type 2 diabetes.

Possible New Clue for Increased Risk for Type 2 Diabetes  

Dr. Tobias and her team looked at 347 women with a history of gestational diabetes who had given blood samples as participants in the renowned Nurses' Health Study II,3 one of the largest, longest running trials examining women’s health over time. They then examined the data from 172 women who had developed type 2 diabetes in comparison to 175 women in the study who did not have diabetes.

The researchers estimated the dietary intake for three common BCAAs based on diet surveys completed by the participants.1 Then, the BCAA levels in the blood were analyzed, taking into account other factors that drive up the risk for type 2 diabetes, such as obesity, family history, and high LDL-cholesterol.

A high dietary intake of BCAAs appeared to linked only with type 2 diabetes only when blood levels for the BCAAs were also high, but not when they were low. The researchers also found that high blood circulating levels of these branched chains amino acids were associated with a greater risk for type 2 diabetes regardless of the participants’ dietary intake.1

This lead the researchers to conclude that an increased risk for type 2 diabetes risk among women with a history of GD may have to do with impaired metabolism or a problem in breaking down or absorbing the branch chain amino acids.1

Why the Interest in BCAAs?

Sufficient circulating BCAAs plays a role in fat metabolism and glucose regulation as well as energy use muscle; yet, there is controversy about whether taking a dietary supplement containing branch chain amino acids will boost muscle recovery and provide other metabolic benefits.4,5

Even so, the popularity of protein-rich supplements with BCCAs remains strong among many dedicated exercise enthusiasts. Hence, the value of examining the impact of BCAAs in disease prevention, including that of women with gestational diabetes and those at risk for type 2 diabetes.

BCAAs­ are found naturally in protein-based foods, such as dairy (whey and milk proteins), meat, poultry, fish, soy, eggs, beans (ie, chickpeas, lentils, lima beans), almonds, and corn.2 When it comes to nutritional supplements, it is important to keep in mind that these products are not regulated by the Food and Drug Administration so there is no certainty that what is promised on the package label is what you’ll get.6 So don’t be lulled into thinking you are fine taking a protein powder; buyer beware.

BCAAs Could Be Another Risk Factors for T2D

This Harvard-led study,1 along with earlier study findings, indicates that ''along with blood sugar, insulin levels, and blood inflammatory markers, higher fasting concentrations of BCAAs are associated with an increased risk of type 2 diabetes," in women who have had gestational diabetes, says Caroline Apovian, MD, FACP, FACN, professor of medicine and pediatrics at Boston University School of Medicine.

She tells EndocrineWeb that the authors speculated that high levels of BCAAs in the blood appear to increase toxic metabolites that interfere with beta cell mitochondrial functioning, which may be behind the increased risk for T2D.

"In essence, it is most likely that increased blood levels of BCAAs act as a marker of insulin dysfunction, but is not the cause. Simply said, protein [from the diet] may not cause type 2 diabetes." That is often the assumption, she says, that having high BCAA levels in the blood ''means you must be eating meat and that is [what explains] the diabetes risk," says Dr. Apovian, as well as raising the risk for heart disease.7

BCAAs May Hint at Heart Disease Risk in Diabetes

In another recent study,7 Dr. Tobias and her colleagues evaluated blood samples from more than 27,000 women from the Women's Health Study and found that higher blood levels predicted the future risk of heart disease in the same way and extent as risk factors such as high LDL or ''bad" cholesterol. 

This link [between higher circulating BCAAs and heart disease] was stronger, according to the researchers, in women who were diagnosed with diabetes before having a heart attack or other cardiovascular events.7

"Clearly this further goes to emphasize the link between type 2 diabetes and heart disease in women," Dr. Tobias tells EndocrineWeb. "The biology is becoming slightly clearer between the two" since the risk of developing heart disease is known to be higher in people who have diabetes.

What Does This Mean for Women with Gestational Diabetes?

A lot is still unknown, the researchers say, and while they have uncovered another possible link to example why some women with gestational diabetes may be more likely to develop T2D, the data from this study isn't enough to suggest a direct cause.1

It's not clear, for instance, what leads to the higher BCAA levels in the blood or what can be done clinically to reduce them, says Dr. Tobias. The problem with BCAA metabolism, she speculates, may represent ''a shared pathway" helping to explain the links between type 2 diabetes and heart disease.

Yet, the findings do point to the value of addressing lifestyle behaviors, says Dr. Tobias. "We do know a lot about ways to prevent type 2 diabetes and cardiovascular disease, and it starts with lifestyle: maintaining or achieving a healthy body weight and adhering to an overall, high fiber dietary pattern," she says. And getting some physical activity nearly every day.

As to why some people may have higher levels of circulating blood levels of BCAAs than others, Dr. Tobias says, ''obesity is strongly associated with the higher levels of branched chain amino acids." So for now, getting to and staying at a healthy weight may be the best way to reduce the risk of developing heart disease and type 2 diabetes, especially when you have a history of gestational diabetes.

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