~ Higher PFAS concentrations tied to weight regain, slower metabolism

by Kristen Monaco, Staff Writer, MedPage Today
February 13, 2018

Long-term weight maintenance may be compromised by exposure to compounds used in many consumer products to make them nonstick or waterproof and that are thought to be endocrine-disrupting chemicals, researchers reported.

In a subanalysis of the POUNDS Lost trial, higher concentrations of plasma perfluoroalkyl substances (PFASs) were tied to a larger weight regain following initial weight loss, according to research by Gang Liu, PhD, of Harvard T.H. Chan School of Public Health in Boston, and colleagues.

As described in the study in PLOS Medicine, people in the highest tertile for PFAS concentration had on average approximately 3.75 to 4.85 pounds more weight regain during the 6-24 months after initial weight loss versus those in the lowest tertile of exposure.

Interestingly, this association with weight regain — seen across five types of PFAS — was most notable among women, as follows:

• Perfluorooctanesulfonic acid (PFOS): Regain of 8.82 pounds [highest tertile] versus 4.63 [lowest tertile] (P-trend=0.01)
• Perfluorooctanoic acid (PFOA): 9.48 pounds versus 4.85 (P-trend=0.007)
• Perfluorohexanesulfonic acid (PFHxS): 10.80 pounds versus 5.95 (P-trend=0.009)
• Perfluorononanoic acid (PFNA): 10.36 pounds versus 5.51 (P-trend=0.006)
• Perfluorodecanoic acid (PFDA): 9.26 pounds versus. 5.51 (P-trend=0.03)

“Perfluoroalkyl substances, especially perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), have been identified as plausible endocrine disruptors with the potential to perturb weight regulation,” wrote the authors.

“PFASs are extensively used in many industrial and consumer products, including food packaging, paper and textile coatings, and non-stick cookware,” the team noted, citing a previous study that reported that the drinking water supplies for at least six million American might possibly exceed the health advisory limit for PFOS and PFOA exposure set by the U.S. Environmental Protection Agency.

The 2-year POUNDS Lost trial included a total of 811 individuals who were overweight or obese at baseline. Through an intervention of four energy-reduced diets, the trial found that the majority of weight loss occurred within the first 6 months of diet change — with an average weight loss of 14.12 pounds — followed by a smaller weight regain, averaging around 5.95 pounds.

Plasma concentrations were collected at baseline to assess the levels of PFASs, the researchers explained. However, these measurements were not repeated throughout the trial. “Given the long elimination half-lives (3±8 years) of these chemicals and a strong stability over time observed in our pilot study, concentrations in the blood likely reflect relatively long-term PFAS exposures.”

At baseline, women had significantly lower concentrations of PFOS, PFOA, and PFHxS compared with men, the study showed. However, these baseline PFAS concentrations were not related to the extent of initial weight loss within the first 6 months of dietary intervention.

Other metabolic parameters, including resting metabolic rate, also showed a significant relationship with PFAS concentrations. Specifically, those with higher concentrations at baseline showed a larger drop in resting metabolic rate during weight loss, followed by a lesser increase in resting metabolic rate during the weight-regain period.

“Although the production of PFOS and PFOA in the U.S. has largely been phased out, the production of other PFASs, such as PFNA, may continue or even increase, especially in developing countries,” Liu et al said. “Given the persistence of these PFASs in the environment and the human body, their potential adverse effects remain a public health concern.”