NUTRITION HOTLINE: The Importance of Minerals

Q: I have anorexia and recently found out that my iron is low. The supplement I have been taking is making me constipated. Do I really need it?

A: Yes! Low iron stores (measured by a ferritin blood level) can have a profound effect on the body: hair loss, decreased bone density, pica (craving non-food substances like dirt or paper), fatigue, muscle weakness, abnormal limb movements during sleep, decreased immune function, and problems with concentration. Foods high in iron include seafood, red meats, poultry, legumes, blackstrap molasses, enriched grains and dark green leafy vegetables. Low iron stores are replenished most quickly when you combine an iron supplement with vitamin C. Ferrous fumarate, found in such products as Twin Lab Iron Caps®, is non-constipating for most people. Ask your physician or dietitian about the right amount of iron and vitamin C for you to take.

Other mineral deficiencies common to anorexia include calcium, magnesium and zinc:

• Calcium is necessary for healthy bones and teeth, and for many important metabolic functions. Low blood calcium levels can cause muscle cramping, irregular heartbeats, and seizures. Research has shown that calcium supplementation may help to lessen, but cannot restore, anorexia-related bone loss (only complete weight restoration has been shown to increase bone density). The foods highest in calcium are dairy products, including milk, cheese, and yogurt. Other good sources include fortified orange juice, salmon, sardines, and tofu. The recommended amount of calcium per day (from food and supplements) for people with anorexia is 1500 mg per day. For people with bulimia (and normal bone density) the recommended amount for teens is 1300 mg per day, and for adults (up to age 51) 1000 mg/day. After age 51 the recommended amount increases to 1200 mg per day.

• Magnesium, found primarily in dark green, leafy vegetables, is necessary for the synthesis of fatty acids and proteins, metabolic reactions, neuromuscular transmission, healthy immune function, muscle relaxation, the regulation of blood glucose and pressure, and healthy bones. Magnesium deficiency can cause muscle cramps, irregular heartbeats, nausea, fatigue, mitral valve prolapse, atherosclerosis, and possibly contribute to asthma. It is best if calcium and magnesium are consumed in a 2:1 ratio. The minimum amount of magnesium needed in the diet is 300-400 mg per day. (Note: Most multivitamin and mineral supplements do not contain that much magnesium, so ask your dietitian or doctor about the need for a separate magnesium supplement.)

• Zinc is necessary for a host of reasons: bone formation, appropriate immune response, wound healing, healthy skin, regular menstruation, normal brain function (including mood, and cell growth and division), taste acuity and appetite, and the metabolism of carbohydrates, proteins, and fats. One study found that patients with anorexia who were given zinc supplements were more successful at regaining weight and enhancing their recoveries than those given a placebo. Good food sources of zinc include meat, fish, poultry, legumes, nuts, wheat germ, soy products, and whole grains. Ask your doctor or dietitian about taking a zinc supplement. And be aware that zinc supplementation can increase the body’s requirement for copper, so taking a multivitamin with copper is a good idea.

Before adding these or any supplements to your diet, ask your physician or dietitian what amounts are appropriate specifically for you, and how long you’ll need to take them.