We tend to think of hair loss as a guy thing, but the truth is that roughly half of all women over age 40 experience excessive hair loss. And one study estimates that hair loss occurs in 75 percent of women over age 65. The most common type of hair loss (officially called androgenetic alopecia) is hereditary, and either your mom or dad can pass it along to you.

In other cases, certain health conditions can lead to thinning hair, including stress, thyroid disease, anemia, and medications for heart disease, high blood pressure, depression, arthritis, and gout, as well as hormonal changes (post-pregnancy or starting or stopping birth control pills, for example).

If you're concerned about higher-than-usual hair loss, it's a good idea to see a doctor to rule out these conditions first. If you get a clean bill of health, try these helpers to encourage regrowth and prevent more thinning.

Protein. Eat a couple of 3- to 4-oz servings of fish, chicken, or other lean sources of protein every day. Protein is needed by every cell in your body, including the cells that make your hair. Without adequate protein, the cells in your body don't work efficiently and can't make new hair to replace old hair that's been shed.

Iron. To guard against iron-deficiency anemia, which can cause hair loss, make sure that you eat a well-balanced diet that includes a daily serving or two of iron-rich foods. Good sources of iron include lean red meat, steamed clams, cream of wheat, dried fruit, soybeans, tofu, and broccoli. You can also turn to iron supplements paired with vitamin C, which aids iron absorption.

Vitamin B6. Experts aren't sure why it works, but 100 mg a day of vitamin B6 seems to decrease hair shedding in some people. Just don't take any more than that without consulting a doctor.

Omega-3s. Consuming too few of these essential fatty acids can lead to brittle hair (and nails too). A fish oil supplement will ensure you get enough, but it's also a good idea to eat omega-3-rich fish, such as salmon or mackerel, at least twice a week or to sprinkle flaxseed (another good source) into cereal and salad.

Evening primrose oil. This supplements gamma-linolenic acid, a type of omega-6 fatty acid essential for healthy hair. It's difficult to come by in the diet but can be found in capsules or soft gels of these oils. Take 500 mg of either twice a day and expect to wait up to eight weeks for results.

Relaxation! Extreme levels of stress can cause follicles to go dormant or be attacked by white blood cells; hair loss can result weeks later. Try yoga, meditation, whatever works for you to ease the stress—and avoid stressing further over your hair loss.