Obesity due to environmental influences is more harmful to cardiovascular health than genetic obesity

Obesity’s impact on cardiovascular disease: genes or the environment?
Obesity is a complex disease that can lead to a variety of adverse health effects, including cardiovascular disease (CVD). Interestingly, the health impacts of obesity can vary depending on whether obesity is primarily due to genetic factors or environmental influences. Thus, this study examined obesity’s impact on cardiovascular disease and whether it varies between individuals having a genetically predicted low, medium, or high body mass index (BMI).

Three NEAR population studies: the Swedish Adoption/Twin Study of Aging (SATSA), Screening Across the Lifespan Twin Study (SALT), and Aging in Women and Men: A Longitudinal Study of Gender Differences in Health Behavior and Health among Elderly (GENDER) were used to explore this. These studies include data from Swedish twins born before 1959. They looked at the twins’ BMI, a common measure of obesity, at two life stages: midlife (ages 40-64) and late-life (age 65 and onwards). They also had access to the twins’ health records up to 2016, allowing them to track CVD onset. To differentiate between genetically and environmentally influenced obesity, they used a polygenic score for BMI (PGSBMI), which is a measure of genetic predisposition to high BMI.   

Obesity due to environmental influences is more harmful to cardiovascular health than genetically predicted obesity
The study found that midlife obesity was associated with a higher risk of CVD across all polygenic score categories for BMI (PGSBMI). However, the risk was higher for those with a genetically predicted lower BMI. This suggests that obesity due to environmental factors (despite a low genetic predisposition) may be more harmful than obesity due to genetic predisposition. The results were similar when obesity was measured in late-life, although the statistical power was lower due to less data.

In conclusion, the study found that obesity is associated with CVD regardless of genetic predisposition. However, obesity that occurs despite a low genetic predisposition (i.e., likely due to environmental factors) may be more detrimental to cardiovascular health than obesity that aligns with a high genetic predisposition. This highlights the complex interplay between our genes, environment, and cardiovascular health.

Elsa Ojalehto, first author of the study. Photo: Gunilla Sonnebring

Publication
Ojalehto E, Zhan Y, Jylhävä J, Reynolds CA, Dahl Aslan AK, Karlsson IK. Genetically and environmentally predicted obesity in relation to cardiovascular disease: a nationwide cohort study. EClinicalMedicine. 2023; 58:101943. doi: 10.1016/j.eclinm.