April 8, 2014
News Review From Harvard Medical School -- Milk May Help Protect Women with Arthritis
Women who drink more milk may be able to fend off severe osteoarthritis longer, a new study suggests. The study included 1,260 women and almost 900 men with knee arthritis. They answered questions about what they ate. Researchers also X-rayed people's knees at the start of the study and then each year for 4 years. Osteoarthritis grew worse more slowly in women who drank more low-fat or fat-free milk. But it got worse faster in women who ate more cheese. Eating yogurt had no effect. None of these links were seen in men. The study does not show that drinking milk actually prevented arthritis from getting worse. Researchers said more studies are needed. Experts interviewed by HealthDay News noted that milk contains calcium, vitamin D and other nutrients that have a role in bone health. They noted that estrogen also affects bone health. This may explain the difference in results by gender. The fat content of cheese may lead to weight gain, they said. Excess weight increases the risk of osteoarthritis. The journal Arthritis Care & Research published the study. HealthDay wrote about it April 7.
By Robert H. Shmerling, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
The news that drinking milk might help arthritis certainly got my attention. I'm an arthritis doctor. My patients often ask if there's anything they can eat or drink (or avoid) to improve joint health.
For the most common type of arthritis -- osteoarthritis -- there is a link to obesity. So choosing a diet that helps you maintain an ideal body weight can reduce the risk of osteoarthritis. But there is little convincing evidence that specific foods matter.
A new study could change that.
Researchers enrolled more than 2,000 people with knee osteoarthritis. Each person answered a survey about 60 foods. They also had knee X-rays each year for 4 years. The study found that:
- Over time, the knee joint gradually narrowed in most study subjects. This indicates that the arthritis was growing worse.
- For women in the study, the more milk consumed, the slower the arthritis got worse. Compared with women who drank the least milk, those who drank seven or more servings a week had about one-third less narrowing of the joints.
- Women who ate seven or more servings of cheese each week had worse arthritis than those who ate no cheese.
- For men, there was no link between milk or cheese consumption and the course of knee osteoarthritis over time.
It's important to note that this study did not find that drinking milk prevented osteoarthritis. Everyone already had the disease. The study found that drinking more milk seemed to slow the rate at which women's osteoarthritis grew worse.
Despite the findings of this new research, I'm skeptical that simply increasing milk consumption will slow the progression of osteoarthritis. Here's why:
- There is no obvious reason that drinking milk should affect osteoarthritis differently in men and women. This raises the possibility that the findings for women occurred by chance.
- Several factors are thought to contribute to the development of osteoarthritis. They include body weight, genetics and trauma. Therefore, it would be surprising if consuming more of a single food would slow it down.
- A study of this type cannot account for every factor that might contribute to worsening arthritis. It's possible that something other than drinking milk could explain the findings of this study.
- This study relied on the recall of study subjects about how much milk they drank. Such memories can be unreliable.
- X-ray results may not be the most reliable way to assess how quickly knee osteoarthritis gets worse. MRI may be better.
One study rarely changes doctors' advice. We need confirmation of these findings in larger studies.
What Changes Can I Make Now?
For osteoarthritis, the most important change you can make now is to lose excess weight. Obesity is a well-recognized and important factor that increases the risk of osteoarthritis.
You also can take these other measures to reduce your risk of osteoarthritis:
- Protect your joints. Preventing joint injuries can reduce the risk of osteoarthritis. So train well and wear appropriate gear during exercise or work activities that put stress on your joints.
- Stay active. Keeping your joints moving can prevent stiffness, maintain motion and, perhaps, lessen the risk of osteoarthritis.
- Avoid osteoporosis. This disease causes thin bones that break easily. Fractures caused by osteoporosis may lead to osteoarthritis. Exercise and adequate intake of vitamin D and calcium are the first steps. Your doctor also may recommend other medicines, such as alendronate (Fosamax, Binosto and generics) or risedronate (Actonel, Atelvia and generics).
- Get appropriate treatment for any conditions that might contribute to joint damage. Examples include hemochromatosis (a condition marked by excess iron in the body), gout and rheumatoid arthritis.
- See your doctor if you have joint pain that is major or won't go away. For many types of arthritis, early diagnosis and treatment may prevent disability.
Drinking milk may be helpful. But we'll need more research to be sure about that.
What Can I Expect Looking to the Future?
If other researchers confirm the findings of this latest research, new questions will emerge. For example:
- Why is milk good for women with osteoarthritis? Why does cheese seem to worsen it? The answers could provide a new understanding about its cause and how it gets worse.
- Why doesn't milk help men with osteoarthritis?
- Are the benefits of drinking milk limited to knee osteoarthritis, or is it also helpful for other joints?
- Can drinking milk help other types of arthritis? (Prior studies show that a diet high in dairy products can reduce the risk of gout. But there's little information about whether a high-diary diet can help previously diagnosed gout.)
You can expect future research to address these and other questions regarding the relationship between diet and arthritis.