Can Diets Fight Chronic Pain? The Science Isn't There

 

Claims that strawberries and other foods rich in antioxidants can reduce inflammation and pain aren't backed up by much research

RENEE MONTAGNE, host: It's MORNING EDITION from NPR News. Good morning. I'm Renee Montagne.

STEVE INSKEEP, host: And I'm Steve Inskeep. Today in Your Health, a look at the potential benefits of certain foods and the risks of tattoo ink. First, we're going to hear about diets and supplements that claim they can cure everyday aches and pains by reducing inflammation（炎症;发炎）.

Reporter Gretchen Cuda-Kroen sorts out fact from fiction surrounding anti-inflammation diets.

GRETCHEN CUDA-KROEN: Inflammation is a buzz word in the diet world these days. Alternative medicine guru（大师）Andrew Weil recommends an anti-inflammation diet, and diets like The Zone and the Mediterranean diet are also built on the principles of the anti-inflammation theory.

Lisa Cimperman is a dietitian at University Hospitals in Cleveland.

Ms. LISA CIMPERMAN (Dietitian, University Hospitals): When you talk about a diet that emphasizes antioxidants（抗氧化剂） or a diet that emphasizes foods that are said to have an anti-inflammatory effect, the diets are going to look very, very similar. And that's because they are.

CUDA-KROEN: The idea is that eliminating foods that promote inflammation - like omega-6 fatty acids found in vegetable and corn oils, processed foods and animal fats and increasing foods rich in antioxidants, phytochemicals（抗氧化植化物） and molecules known to reduce inflammation - can improve some health problems and the pain associated with them.

But Cimperman says it's probably too early to say that these diets really have such healing effects.

Ms. CIMPERMAN: We are not at the point yet where we can say that diet directly modifies the inflammatory process. We’re just not there yet.

CUDA-KROEN: The problem is the majority of studies linking diet and disease are either too small, or they look at what people ate over years before they ever got the disease. Cimperman says these studies are good for generating ideas, but they don't show cause and effect. And diets that say they do are making claims that are largely overblown.

Ms. CIMPERMAN: What they are doing is taking, you know, maybe some smaller study or a study that wasn't as rigorous as we'd like to see, and they're using that as a jumping point for making these claims.

CUDA-KROEN: What's still needed is a study that takes two groups of similar people - some eating normally and others eating an anti-inflammatory diet - and compares the changes in their health over time. That's not an easy thing to do.

And what's even more difficult to achieve: the entire time, neither the doctors nor the patients can know which diet they're on. It's the way most pharmaceutical（a.制药的） drugs are evaluated.

But what about the people who say they do get better because of a diet? Eric Matteson, a rheumatologist（风湿病专家）at the Mayo Clinic, says some people do have sensitivities to certain foods, like wheat gluten（小麦蛋白） or milk proteins, that can cause pain and joint swelling（关节痛或关节肿）, and can benefit from eliminating those foods. But those cases are very rare.

Instead, he argues that the biggest impact of any diet on arthritis（n.关节炎） pain has nothing to do with the effects of antioxidants on cells, but with calories.

Dr. ERIC MATTESON (Rheumatologist, Mayo Clinic): The most important thing to consider is the effect of having too much of anything in your diet. And by that I mean that a big contributor to worsening of arthritis is body weight.

CUDA-KROEN: Matteson says some rigorous studies have shown that omega-3 fatty acids and herbs（n.药草，(调味用的)香草，草本植物） like turmeric（姜黄） work the same way in the body as ibuprofen（治疗关节炎的止痛退烧药） to reduce inflammation and pain, something roughly equivalent to a typical 200 to 400 milligram dose of the pain killer.

Dr. MATTESON: It does vary a little bit from study to study what that effect actually is, but the effects are very modest.

CUDA-KROEN: But even if these diets don't deliver miracle cures, they still are healthy diets. Dietitian Lisa Cimperman says she'd recommend them to anyone. A healthy diet, weight loss and modest exercise is likely to make everyone feel better, including those with chronic pain.

But Cimperman and Matteson both warn that a diet is meant to enhance, not replace medical treatments that have been scientifically proven to work.

For NPR News, I'm Gretchen Cuda-Kroen in Cleveland.