Are Dairies Really Source for the New DMOAD?

April 16, 2014

An observational study finds that regularly drinking low-fat milk slows joint narrowing in arthritic knees. Needs confirmation, but the prospective remedy is harmless and promising.

Lu B, Druban JB, Duryea J, et al., Milk Consumption and Progression of Medial Tibiofemoral Knee Osteoarthritis: Data from the Osteoarthritis Initiative. Arthritis Care & Research (2014) DOI: 10.1002/acr.22297. Published online April 7, 2014

Sahni S and McLean RR. Got OA? Maybe Milk Can Help. Arthritis Care & Research (2014) DOI: 10.1002/acr.22334. Published online April 7, 2014 

Patients with knee osteoarthritis (OA) may be asking about a recent news-making study that concluded drinking more milk may slow progression, at least for women.

Note that it comes from a longstanding and reputable source, the multicenter, longitudinal Osteoarthritis Initiative sponsored by the National Institutes of Health. Conducted among 2,148 men and women with knee OA ages 45 to 79, its conclusions are based on data from dietary questionnaires and four years’ worth of annual knee X-rays (that’s 3,064 eligable knees).

Those women who drank at least 8 ounces a day of fat-free or low-fat milk had less joint space width (JSW) narrowing in their arthritic knees than those who drank no milk at all. There was no significant association with milk consumption among men.

Eating yogurt or calcium supplements didn’t help women with knee OA, and there was a suggestion that eating cheese might even increase JSW narrowing.

Here's the actual size of the difference between the women:

•    No milk:  JSW=0.26mm
•    3-6 8-ounce glasses/week:  JSW=0.29mm
•    >7 glasses/week:  JSW=0.38mm

Benefits persisted over the 48-month followup period, even after adjusting for OA severity, body mass index (BMI), smoking, physical activity, and other dietary factors. The vast majority of participants drank low- or non-fat milk, and the heavier drinkers were most likely to be Caucasian and nonsmokers.

As with all observational studies, this one can only offer an association and says nothing about causation or mechanism. On the positive side, while questionnaire-based data is always suspect, it's difficult to imagine any ulterior motive for confabulating about consumption of milk.

An editorial noted that this is the first study to make this connection and, if confirmed, it may provide a simple solution for a painful problem in an aging population.