The aching, tenderness, and throbbing pain of the knees can lead to unsettling moments in the most inopportune times for knee arthritis sufferers. The physically debilitating condition attacks the joints, and carrying on daily activities such as walking or standing for long periods of time becomes burdensome. While we all know drinking milk is good for your bone health, a recent study published in the American College of Rheumatology (ACR) journal, Arthritis Care & Research, found consuming seven glasses of fat-free or low-fat milk per week can keep knee arthritis at bay in women.

"Milk consumption plays an important role in bone health," said Dr. Bing Lu, lead author of the study from Brigham & Women's Hospital in Boston, in the press release. "Our study is the largest study to investigate the impact of dairy intake in the progression of knee OA,” he said. To achieve greater muscle strength, improvement in physical functioning, and preservation of cartilage, adults between the ages of 19 to 70 must have 600 to 800 International Units (IU) of vitamin D a day, according to the National Institutes of Health. Skim milk or one percent low-fat milk is one of the best foods to consume to meet the daily requirement.

Although the consumption of milk has long been recognized for its important role in bone health, its role in the progression of knee osteoarthritis (OA) has been unclear. Lu and colleagues sought to examine the possible association of milk consumption with radiographic progress of knee OA in a large cohort from the Osteoarthritis Initiative. A total of 2,148 participants (888 men and 1,260 women) were recruited for the study.

At the start, dietary data was collected and joint space width was measured by X-ray to evaluate OA progression. The participants were followed up at 12, 24, 36, and 48 months throughout the duration of the study. Milk consumption was assessed with a Block Brief Food Frequency Questionnaire completed at baseline. The researchers used quantitative joint space width (JSW) between the medial femur and the tibia of the knee based on plain radiographs to examine the progression of OA in the participants, according to Medical Xpress.

The findings revealed as the intake of milk increased, the JSW in women decreased even after adjusting for baseline disease severity, body mass index, and dietary factors. As milk intake increased from none to less than three, four to six, and more than seven (eight ounce) glasses per week, the JSW in women also decreased by 0.38mm, 0.29mm,0.29mm and 0.26mm, respectively. In men, the researchers did not find an association between milk consumption and JSW.

"Our findings indicate that women who frequently drink milk may reduce the progression of osteoarthritis. Further study of milk intake and delay in osteoarthritis progression are needed," Lu said. Even though the study found an association between milk intake and knee health, it could not prove a cause-and-effect. Despite the need for further research, women with OA should consider choosing low-fat and fat-free milk to reduce the progression of the disease since its vitamin D content can promote good bone health.

In regard to men, the team of researchers speculate women are more sensitive to the effect of calcium intake through milk than men, and therefore, this is why they were able to reap its benefits compared to their counterparts. Marlo Mittler, nutritionist at Cohen Children's Medical Center of New York, in New Hyde Park, N.Y., told HealthDay, she believes estrogen’s role in bone health could help explain why milk intake seems to help ward off arthritis in the knees of women but not men. “Calcium may also affect bone health in women in a different way than it does for men,” she added.

Researchers also observed cheese and yogurt intake, but the two foods did not show a positive effect for delaying OA symptoms in the knee. Higher amounts of cheese speed the progression of OA in women, while consuming higher amounts of yogurt had no effect on knee OA in women or men. Mittler suggests the high fat content of cheese may explain the speedy progression of knee OA.

This study provides the first evidence that increasing fat-free or low-fat milk consumption may delay the progression of OA among women who are burdened by knee OA. The condition affects more than 26 million Americans and is known to be the most common cause of disability in the U.S., according to the Centers for Disease Control and Prevention. Risk factors for OA include older age, obesity, and joint injuries.

Source: Driban JB, Duryea J, Eaton CB, Lapane KL, Lu B, McAlindon T. Milk Consumption and Progression of Medial Tibiofemoral Knee Osteoarthritis: Data from the Osteoarthritis Initiative. Arthritis Care and Research. 2014.