It's important to get enough of certain nutrients that help reduce your risk of thin, weak, and porous bones (osteoporosis), a common complication of ankylosing spondylitis. And a healthy diet can help you manage your weight, which may affect your symptoms.

If you have ankylosing spondylitis, be sure to:

Get enough calcium. Calcium is essential for strong bones. Men and women between the ages of 18 and 50 need 1,000 milligrams of calcium a day. Women who are 50 and up and men older than 70 need 1,200 milligrams a day. Good sources include low-fat dairy products, dark green leafy vegetables, canned salmon, tofu, and other soy products.

Don't skip vitamin D. It improves your body's ability to absorb calcium and improves bone health in other ways. It's possible to get enough vitamin D from sunlight. But sunlight may not be a good source if you have limited sun exposure — for example, you live in a high latitude, or you regularly use sunscreen or avoid the sun.

Scientists don't yet know the best daily dose of vitamin D. A good starting point for adults is 600 to 800 international units (IU) a day, through food or supplements. Up to 4,000 IU of vitamin D a day is safe for most people.

Limit alcohol. Drinking more than one or two alcoholic drinks a day speeds bone loss and reduces your body's ability to absorb calcium. Drinking alcohol with meals slows calcium's absorption, as well. Mixing alcohol with certain medications also can cause serious side effects to your liver and kidneys.

Hold the caffeine. Caffeine can slightly increase calcium loss during urination. But much of its potentially harmful effect stems from substituting caffeinated beverages for milk and other healthy drinks. Moderate caffeine use — about two to three cups of coffee a day — won't be harmful as long as your diet contains enough calcium.

Maintain a healthy weight. Being overweight puts added stress on your bones and joints. Being underweight increases the chance of bone loss and fractures. So, maintaining healthy body weight is good for your bones, as well as for your health in general. Keep in mind that certain ankylosing spondylitis medications and complications may contribute to weight loss or gain. Talk to your doctor if you're struggling to maintain a healthy weight.

The general guidelines for a healthy diet also apply — eat lots of vegetables and fruits, seek out whole grains and lean proteins, and limit fat and processed foods. When choosing what you eat, remember that a healthy diet will help you manage your weight and protect your bones.