The idea that the foods you eat — or avoid — may slow the progression of ankylosing spondylitis or help to control its symptoms is an appealing one, but so far, no diet or particular food choices have been shown to reliably have these effects. Indeed, very little research has been conducted on the relationship between diet and ankylosing spondylitis, noted an article published in March 2018 in the European Journal of Rheumatology. (1)

Still, there are good reasons to pay attention to what you eat when you have ankylosing spondylitis. Following a healthy diet can have numerous benefits, including:

• Helping you maintain a healthy weight
• Promoting strong bones
• Giving you the energy you need to stay active
• Helping to prevent some forms of anemia

Before you make any major changes to your diet, however, and especially before you start taking any new supplement or probiotic, speak to your doctor about the dietary change or product you would like to try.

Excess body weight puts more stress on your joints, particularly your knees, causing pain and potentially damaging the cartilage, leading to osteoarthritis.

Being overweight can also make you less mobile, so that daily activities — and any other physical activities — are more difficult.

Being underweight is not necessarily healthy, either. People who are underweight may be prone to fatigue and anemia (if they’re underweight due to malnutrition), and often have lowered resistance to infection.

Consuming enough calories — but not too many — can help you stay healthier with ankylosing spondylitis.

RELATED: Eat to Beat Knee Osteoarthritis

As many as one-half of people with ankylosing spondylitis also have osteoporosis, according to the American College of Rheumatology.

Osteoporosis is particularly common in those whose spines have fused.

Following a diet that provides adequate calcium and vitamin D can help to keep your bones healthy and prevent osteoporosis if you don’t already have it.

Calcium is found in dairy products such as milk and yogurt, as well as in a variety of nondairy foods, including:

• Collard greens
• Broccoli
• Kale
• Edamame (green soybeans)
• Bok choy
• Figs
• Sardines with bones
• Canned salmon
• White beans
• Okra
• Tofu made with calcium
• Almonds

Vitamin D is naturally present in only a few foods, including fish, shellfish, and egg yolks, but your body can manufacture it when you expose your skin to sunlight.

In the northern parts of the United States, Europe, Asia, and Canada, however, the sun isn’t strong enough in the winter to promote vitamin D formation.

People who live in those areas often need to take supplements to get enough vitamin D.

Vitamin K, found mainly in green, leafy vegetables, is also important to bone health.

According to The Nutrition Source from the Harvard T.H. Chan School of Public Health, the vitamin K in foods such as broccoli, Brussels sprouts, dark green lettuce, collard greens, and kale is absorbed better when eaten along with some fat.

RELATED: What to Eat and What to Avoid for Osteoporosis Prevention

Nonsteroidal anti-inflammatory drugs (NSAIDs) help a lot of people with ankylosing spondylitis control their pain levels and other symptoms.

However, NSAIDs can irritate the lining of the small intestine and the stomach, causing bleeding, ulcers, or stomach upset.

You may be able to help protect your stomach by consuming yogurt or kefir on a regular basis.

Yogurt and kefir contains probiotics, the so-called “good” bacteria that offer protection from “bad” bacteria in the digestive tract.

While the ability of probiotics to counteract the side effects of NSAIDs is as yet unproven, a limited amount of research suggests they may have some beneficial effect.

The Problem With Alcohol and AS Treatment

Alcohol can interfere with your ankylosing spondylitis treatment and your ability to absorb nutrients from your food.

Alcohol is known to:

• Intensify the effects of some drugs
• Interact with certain drugs, making them ineffective
• Damage the lining of the stomach and small intestine, impairing the absorption of essential nutrients
• Interfere with the absorption and storage of some vitamins

Before you drink, ask your doctor or pharmacist whether alcohol interacts with any of the drugs you take.

Smoking does matter, for all of the usual reasons and then some.

Smoking worsens ankylosing spondylitis and can speed up the rate of spinal fusion.

In addition, ankylosing spondylitis can cause breathing problems by limiting the movement of the chest and reducing the amount of air the lungs can hold.

Smoking compounds those problems and also raises the risk of respiratory infections.

If you smoke, make every effort to quit smoking.

Fish oil is high in omega-3 fatty acids (eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA), and it’s well-documented that fish oil supplementation decreases inflammation in the body. (2) Because the human body cannot make omega-3 fatty acids, many people add fatty fish (such as salmon, sardines, and tuna) to their diets or take over-the-counter (OTC) fish oil supplements to increase their omega-3 intake.

Fish oil has been shown in numerous studies to bring about significant improvements in health, function, or quality of life in some types of inflammatory arthritis, such as systemic lupus erythematosus and rheumatoid arthritis, per a review published in September 2017 in the Journal of Clinical Rheumatology. (3) But although one small study suggested possible benefits of omega-3 supplementation in people with ankylosing spondylitis, in general, there are a dearth of studies looking at the effects of fish oil in people with AS, so it’s not possible to say what a safe and effective dose is. (4)

Eating one or two servings of fatty fish per week, however, is safe for most adults, and contributes to an overall healthy diet. If you’d like to increase your omega-3 intake but prefer not to eat fish, the Mayo Clinic recommends eating walnuts, pecans, ground flaxseed, and soy instead. Vegetables oils, chia seeds, pumpkin seeds, and leafy green vegetables are also sources of omega-3 fats.

Many health organizations recommend minimizing saturated fat intake to lower your risk of heart disease and possibly other chronic diseases, such as type 2 diabetes.

A small study published in February 2019 in the journal Advances in Rheumatology suggested that following this advice may have additional benefits for people with ankylosing spondylitis. (5) The researchers found that the calorie and fat intake of study participants with ankylosing spondylitis was significantly higher than in the healthy controls and further found that a high saturated fat intake was correlated with more functional limitations in people with AS.

The American Heart Association identifies the following foods as having a high saturated fat content:

• Butter
• Cheese
• Dairy products (whole or reduced fat)
• Fatty beef
• Lamb
• Lard and cream
• Pork
• Poultry with skin

When you cut back on foods high in saturated fat, replace them with foods that are sources of good fats, such as vegetables, nuts, seeds, and fish.