Making Sense of the Highly Variable Effects of Alcohol on Bone

Alcohol consumption is often reported to influence bone health in a dose-dependent manner where moderate alcohol intake is deemed beneficial and heavy drinking detrimental. However, this relationship may not be valid for individual alcohol consumers, as small quantities of alcohol can have detrimental skeletal effects and not all studies report clinically relevant bone loss with long-duration alcohol abuse. These discrepant findings suggest that factors beyond quantity of alcohol consumed contribute to the observed skeletal response. We propose that the interplay between intrinsic (e.g., age, sex, skeletal site) and extrinsic (e.g., age of onset of drinking, duration of drinking, comorbidities) factors influence the precise impact of alcohol consumption on bone health. In this review, we summarize literature reporting the effects of alcohol on the human skeleton. Based on the finding that alcohol alters the circulating levels of dozens of peptides shown to influence bone metabolism, we arrive at the conclusion that no single unifying mechanism adequately explains the diversity of reports or successfully predicts individuals most likely to be impacted favorably or unfavorably by alcohol consumption. We propose that a more holistic approach - in which drinking pattern and intrinsic factors are accounted for - is required to better understand and respond to the end organ effects of alcohol on the skeleton.