Drinking Milk Reduced Knee Arthritis in Women, Not Men

Progression of osteoarthritis of the knee less in women who drank more milk

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Milk has long been associated with the prevention of weak bones (osteoporosis). New research now suggests that the more milk a woman drinks, the less of a problem she may have with progression of her osteoarthritis.

Osteoarthritis is a chronic condition in which the material that cushions the joints (cartilage) breaks down. It’s usually caused by wear and tear.

New research suggests that low-fat or fat-free milk may help women lessen this problem, but its beneficial effects did not work as well in men.

"Ask your doctor if drinking milk may help with your arthritis."

Researchers, led by Bing Lu, M.D., Dr. P.H. at Brigham and Women’s Hospital in Boston, enrolled people of both sexes in their study beginning in 2004. Participants were 45 to 79 years of age and had to have arthritis in at least one knee.

Data was collected on 2,148 participants (3,064 knees) who were followed for an eight-year period. At the start of the study, participants were asked about their intake of a variety of foods — including cheese, yogurt, combined milk products and milk.

The study participants were grouped into those that did not drink any fat-free or low-fat milk weekly, those that drank less than three glasses a week, those that drank four to six glasses in a week, and those that drank seven or more glasses a week.

At four different points in the study (12 months, 24 months, 36 months and 48 months), knee measurements taken by X-ray were used to assess progress of the osteoarthritis. The measurement used is called joint space width (JSW), and it indicates the thickness of the cartilage. The higher the JSW, the more cartilage there was to cushion the knee.

The more milk women consumed, the higher their JSW, or the slower the progression of their arthritis.

This was not true for men. In men, only those that drank seven or more glasses of milk per week had a reduction in the progression of the arthritis in their knee(s).

There was no slowing of osteoarthritis in relation to how many milk products or yogurt was consumed in either sex. However, the more cheese consumed, the faster a person’s osteoarthritis progressed. The authors of the study suggested this may be due to the high saturated fat content of cheese.

As to why the milk works at lessening the speed of osteoarthritis in women, the study authors wrote that it may be an increased dietary calcium that is at work, but “the biologic mechanism for an effect of milk consumption on the radiographic progression of OA remains unclear.”

According to Carolyn Dean, MD, ND, a Medical Advisory Board Member of the non-profit Nutritional Magnesium Association, "The findings that fat-free and low-fat milk may delay the progression of knee osteoarthritis, yet cheese increased progression and yogurt had no effect, doesn’t seem to make sense.

“However, almost all the milk in the U.S. is fortified with Vitamin D, which is necessary for proper absorption/direction of calcium into bones and joints. Cheese and yogurt contain little to no Vitamin D. The fact that is even more obscured is that when the body ingests Vitamin D, magnesium is drawn into the blood stream from storage sites in bone and muscle to metabolize Vitamin D to its active form.

“An influx of magnesium will also serve to support bones and joints because this mineral is vital to proper bone and joint function; it acts as an anti-inflammatory; and it prevents brittle bones and joints that can occur with excess calcium supplementation.”

The study authors speculated that the reason men did not experience a similar benefit to women may be that women are more sensitive to the effect of calcium intake through milk than men.

This study was published in Arthritis Care and Research.

The authors declared no conflicts of interest.

Review Date: 
April 6, 2014
Last Updated:
April 7, 2014