Non-industrial societies with low energy balance levels are expected to be less vulnerable than industrial societies to diseases associated with obesity including knee osteoarthritis. However, as non-industrial societies undergo rapid lifestyle changes that promote positive energy balance, individuals whose metabolisms are adapted to energetic scarcity are encountering greater energy abundance, increasing their propensity to accumulate abdominal adipose tissue and thus potentially their sensitivity to obesity-related diseases.
Objectives Here, we propose that knee osteoarthritis is one such disease for which susceptibility is amplified by this energy balance transition.
Methods Support for our hypothesis comes from comparisons of knee radiographs, knee pain and anthropometry among men aged ≥40 years in two populations: Tarahumara subsistence farmers in Mexico undergoing the energy balance transition and urban Americans from Framingham, Massachusetts.
Results We show that despite having markedly lower obesity levels than the Americans, the Tarahumara appear predisposed to accrue greater abdominal adiposity (ie, larger abdomens) for a given body weight, and are more vulnerable to radiographic and symptomatic knee osteoarthritis at lower levels of body mass index. Also, proportionate increases in abdomen size in the two groups are associated with greater increases in radiographic knee osteoarthritis risk among the Tarahumara than the Americans, implying that the abdominal adipose tissue of the Tarahumara is a more potent stimulus for knee degeneration.
Conclusions Heightened vulnerability to knee osteoarthritis among non-industrial societies experiencing rapid lifestyle changes is a concern that warrants further investigation since such groups represent a large but understudied fraction of the global population.
- knee osteoarthritis
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Handling editor Josef S Smolen
Correction notice This article has been corrected since it published Online First. The author details have been updated.
Contributors IJW, DTF, SW and DEL designed research. IJW, DTF, JD, MC, PA, GNE, JJS, ALB and DEL performed research. IJW and SW analysed data. IJW, DTF, SW and DEL wrote the paper.
Funding Supported by the Hintze Family Charitable Foundation, the American School of Prehistoric Research (Harvard University) and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (National Institutes of Health).
Competing interests None declared.
Patient and public involvement statement During fieldwork in Mexico, local Tarahumara community leaders were consulted regarding the study design and conduct, but study participants were not involved in the work.
Patient consent for publication Not required.
Ethics approval Approved by the institutional review boards of Boston University Medical Center, Harvard University and Massachusetts General Hospital.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data from the Tarahumara are available on reasonable request to IJW or DEL. Data from the Framingham individuals may be obtained from a third party (www.framinghamheartstudy.org).
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