Following a healthy diet may help you control ankylosing spondylitis (AS) symptoms — but not necessarily because there’s a special diet that people with AS need to follow.
"The best spondylitis diet is the same diet that is good for maintaining a healthy weight and keeping your whole body in good shape,” says Ruth Kadanoff, MD, a rheumatologist who is affiliated with the Edward Hines Jr. Veterans Affairs Hospital in Hines, Illinois.
That means choosing foods that help fight inflammation, keep your bones strong, and keep your heart healthy.
You can take your diet a step further to customize it based on your body’s response to foods you eat. The Spondylitis Association of America recommends that you keep a food diary to track which foods seem to make you feel better or worse.
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Healthy Weight May Improve AS Symptoms
"One thing that will help ankylosing spondylitis or any arthritis symptoms is to maintain a healthy weight,” Dr. Kadanoff says. “Carrying too much weight will put extra strain on inflamed joints in your back, hips, and knees."
A number of studies have found that carrying excess body weight can lead to greater inflammation, more severe symptoms, and a higher risk for structural damage in people with AS.
A study published online in June 2016 in the journal RMD Open found that in a group of 168 people with ankylosing spondylitis, there was a direct correlation between body mass index (BMI) and levels of C-reactive protein (a blood marker of inflammation) in women. This relationship was generally weak, though, and wasn’t seen in men. In this study, there was no observed relationship between body weight and overall disease activity in ankylosing spondylitis.
But in another study of 105 people with AS, published in September 2020 in the International Journal of Rheumatic Diseases, obesity was linked to higher C-reactive protein levels, greater disease activity, worse physical mobility, and greater structural damage as seen on imaging scans. Central obesity (around the waist) was linked to higher AS severity in particular.
A third study, published in December 2020 in the Journal of Clinical Rheumatology, found that in 270 people with AS, a higher BMI was one factor that predicted more severe spinal damage, along with an earlier age of AS onset, longer smoking duration, longer delay in AS diagnosis, and greater hip involvement in AS. A high BMI and hip involvement together dramatically increased the risk for severe spinal damage; it was 5.07 times as high as in participants with a low BMI and without hip involvement.
Eating Right for AS: Do’s and Don’ts
Most of the dietary recommendations for people with AS aren’t very different from those you may have seen for general health. Here are some foods and ingredients to eat — or avoid — when you have AS, according to the Spondylitis Association of America:
Do eat lots of fruits and vegetables. Focus on consuming a wide range of produce, especially colorful fruits and vegetables, as they are typically high in antioxidants. Antioxidants may help with AS symptoms because they protect cells from substances called free radicals, which may contribute to inflammation.
Do drink plenty of fluids. Drinking 8 to 10 glasses of water every day is important for everyone, including people with AS.
Do eat plenty of omega-3 fatty acids. These healthy fats — which are found in fatty fish like salmon, herring, trout, and anchovies, as well as in flaxseed, canola oil, and walnuts — may help reduce inflammation.
Do consider supplements. "Any arthritis that limits movement can lead to osteoporosis," Kadanoff says — a dangerous condition in which the bones become thinner and more porous, potentially leading to fractures. Because of this risk, she says, "A person with ankylosing spondylitis should consider supplementing their diet with calcium and vitamin D." Certain supplements may also be recommended to compensate for drug side effects. Talk to your doctor about what supplements are right for you.
Don’t eat many high-fat, high-cholesterol foods. These foods should be limited in any healthy diet. Saturated fat, found in animal products like red meat, poultry, and dairy, may promote inflammation and raise your heart disease risk.
Don’t eat many processed foods. Highly processed foods are typically low in fiber and high in sodium, and they often contain inflammation-promoting refined grains and sugars as well. Eating low-nutrient-density processed foods also limits the amount of healthy foods you’re likely to eat, potentially contributing to not getting the nutrients you need for optimal bone and muscle health.
Don’t consume alcohol in excess. While calcium and vitamin D may help promote stronger bones, too much alcohol can weaken your bones. In general, more than two drinks per day is considered risky for bone health. Talk to your doctor about any risks associated with combining alcohol with any medications you’re taking, since certain combinations may lead to serious side effects in your gastrointestinal tract, liver, or kidneys.
Additional reporting by Chris Iliades, MD.