If you’re a woman, drinking fat-free or low-fat milk may delay the progression of osteoarthritis (OA) of the knee.
In a study of over 2,100 people with knee OA, researchers at Brigham & Women’s Hospital in Boston found that regular milk consumption slowed a decrease in the joint space of women. Space in knee joints typically grows smaller as knee OA progresses, due to cartilage loss and changes in bone composition and shape.
The study – the largest to investigate the impact of dairy consumption on knee OA — is being published in the journal Arthritis Care & Research.
“Our findings indicate that women who frequently drink milk may reduce the progression of OA,” said lead author Bing Lu, MD, of the Division of Rheumatology, Immunology and Allergy, Brigham & Women’s Hospital and Harvard Medical School.
Milk contains many essential nutrients, including calcium, phosphorus, protein and vitamin D. Several clinical trials have shown that vitamin D and calcium supplements can reduce bone loss and lower the risk of bone fractures.
“Our results indicated that milk consumption may reduce knee OA progression partially through elevated dietary calcium intake. Nevertheless, the biologic mechanism for an effect of milk consumption on the radiographic progression of OA remains unclear,” said Bing.
Also unclear is why the beneficial effect of drinking milk did not appear in men. As the study progressed over the course of 48 months, the intake of milk for both men and women gradually increased from no milk to more than seven 8 ounce glasses per week. Women who were “milk drinkers” experienced 4-year decreases in joint space that were 0.09 to 0.12 mm less than non-milk drinkers. No such changes were reported in men.
“If dietary calcium is a possible mediation factor to link between milk consumption and knee OA progression, women may be more sensitive for the effect of calcium intake through milk than men. However the gender differences in the relationship of milk consumption with OA progression are not completely understood,” said Bing.
Nearly 27 million Americans suffer from OA, a common degenerative joint disease that causes pain and swelling of joints in the hand, hips, or knee. OA of the knee is more prevalent and severe in women.
“Should health professionals start telling their patients to drink more milk to prevent knee OA progression? The limited evidence does not warrant this advice,” said Shivani Sahni and Robert McLean of the Harvard-affiliated Hebrew Senior Life Institute for Aging Research in an editorial also published in Arthritis Care & Research.
“However, the findings by Bing and colleagues suggest that dairy foods have potential as a novel non-pharmacologic tool to help OA patients. Furthermore, these results could have a major impact on public health nutrition.”
The 2010 Dietary Guidelines for Americans recommends that adults consume 3 cups per day of fat-free or low-fat milk and milk products. However, the mean dairy consumption by adults is about half the recommended level and declines further with age.