Excess visceral fat, the fat stored deep within the abdomen around organs, has now been linked to faster biological aging of the heart and blood vessels, according to new findings from researchers at the Medical Research Council (MRC) Laboratory of Medical Sciences in London, U.K. Published in the European Heart Journal, the new analysis of data from the UK Biobank shows that visceral adipose tissue negatively affects both cardiometabolic health and the acceleration of physiological aging of the cardiovascular system.
“We have known about the apple and pear distinction in body fat, but it hasn’t been clear how it leads to poor health outcomes,” said Declan O’Regan, PhD, lead investigator of the study and a professor of cardiovascular AI at Imperial College London. “Our research shows that ‘bad’ fat, hidden deep around the organs, accelerates aging of the heart. But some types of fat could protect against aging—specifically fat around the hips and thighs in women.”
For this research, the MRC investigators used the whole-body and cardiovascular MRI imaging from 21,241 participants in the UK Biobank. The researchers applied an artificial intelligence model to estimate the biological age of the cardiovascular system of each person, their “heart age,” based on a variety of factors including vascular stiffness, cardiac motion, and tissue fibrosis. This “age-delta” was then compared to chronological age and correlated with fat distribution in the body.
The findings showed that the overall volume of visceral adipose tissue was one of the strongest predictors of increased cardiovascular age-delta in both men and women. The analysis also found other factors that influence heart aging, including liver fat fraction and muscle fat infiltration. Subcutaneous abdominal fat in men was shown to affect heart aging more modestly than these other factors.
The new study continues to add to the body of research that has linked obesity to inflammation and accelerated cardiovascular aging. Visceral fat has been associated with a range of deleterious effects including inflammation, insulin resistance, and dyslipidemia. Now, this new analysis further links these conditions caused by visceral adipose tissue to heart age, while also implicating its effects on brain aging.
The study found sex-specific differences in fat distribution and its relationship to cardiovascular aging. While men typically accumulate more visceral fat and were more prone to early heart aging when carrying abdominal fat, women with a higher fat distribution in the hips and thighs, the so-called “pear-shaped” body, showed this provided a protective effect on cardiovascular aging. “Genetically predicted gynoid fat showed an association with decreased age-delta,” the researchers wrote, adding that “this suggests that hormonal factors that regulate fat distribution could also directly influence aging.”
In particular, the researchers data showed that higher levels of the hormone estradiol in premenopausal women were associated with slower heart aging, indicating that there may be a pathway for hormonal protection against vascular decline. This finding could provide clinicians with the option of hormone replacement therapies for women as a preventative measure against cardiovascular decline.
The team noted that body mass index (BMI) continues to be used as a risk assessment tool for heart disease, but “BMI wasn’t a good way of predicting heart age which underscores the importance of knowing where fat is stored in the body and not just total body weight,” O’Regan said.
The researchers noted that their findings present future preventative and therapeutic interventions to preserve cardiovascular health. “Our observation that visceral fat promotes aging of the heart and circulation in humans provides support for the potential role of emerging treatments that target adipose tissue function to extend health-span,” the researchers wrote. Current medication such as GLP-1 receptor agonists, which are currently used to treat diabetes and obesity, have been shown to reduce visceral and liver fat and modulate age-related inflammation and fibrosis.
While the study’s strengths include its large cohort and use of advanced imaging and machine learning to estimate heart aging, the MRC team noted that the cross-sectional design of their study doesn’t take into account changes over time, and instead provides a snapshot of a moment in time. Further, the UK Biobank cohort has an under-representation of older adults, socioeconomically disadvantaged people, and people of non-European ancestries.
To address these shortcomings, “future work will seek to generalize these findings through approaches that can be used on more widely available phenotypic data, in particular to study the effects of ancestral diversity,” the researchers wrote. The collection of longitudinal data in the UK Biobank cohort has been planned to better understand how visceral fat influences the trajectory of aging and the resultant health outcomes over time.
