The Insulin Connection
One hormone may cause cancer, heart attacks, and many more ills.
Ovary Disease
According to the American Association of Clinical Endocrinologists, polycystic ovary syndrome affects 1 in 10 women and is the leading cause of infertility in the United States. High levels of insulin trigger excess production of other hormones by the ovaries, disrupting regular egg growth and menstrual cycles and preventing pregnancy. Some of these overproduced hormones, or androgens, can also cause male-pattern hair growth on the face and some other unpleasant appearance changes. Basically, says Mark Perloe, an Atlanta endocrinologist and polycystic ovary syndrome specialist, "insulin is driving the ovary crazy."
Doctors now treat this ovary syndrome with insulin-sensitizing medications like those taken by Chapman, and also recommend weight loss, which lowers insulin levels. Treatment is important even beyond fertility problems, because untreated women with the polycystic syndrome have more than seven times the risk of heart disease and three times the risk of diabetes of women without it.
Alzheimer's
Cells in the brain's memory and learning centers have a lot of insulin receptors. A quick spike in insulin improves memory and performance; take insulin away, and brain function begins to decline. But paradoxically, more insulin in the blood--insulin resistance--means less in the brain. One leading theory: Insulin's corrosive effects on blood vessel linings gums up tiny portals in the vessels that supply the brain, making it harder for the hormone to bring in sugar. Ultimately, this starves brain cells, suggests researcher Suzanne Craft of Veterans Administration Puget Sound Health Care System. That could set the stage for some cases of Alzheimer's, Parkinson's, and Huntington's diseases. Insulin also seems to clear away some beta-amyloid, a substance long implicated in Alzheimer's damage, so less of it could cause problems.
There are, of course, many theories about Alzheimer's, and this is far from the final word. But whatever the reason for the disease, there is preliminary evidence that getting insulin to the brains of Alzheimer's patients improves symptoms. In Craft's recent study, a small group of Alzheimer's patients, including Marincin, inhaled insulin. (Inhalation provides more of the hormone to the brain.) Compared with a group that only inhaled saline solution, these patients better recalled stories and lists. It's not known, however, how long these improvements last. Craft is now testing the insulin sensitizer Avandia in people with Alzheimer's to see if it might slow down the disease.
The tests of all these drugs may sound good, but they are far from the only treatment--or the best--for insulin resistance. There's a lot of hope to be found around the dinner table. Most people with resistance can actually undo it by losing as little as 5 to 20 pounds. The best eating plans, say experts, offer lots of soluble fiber, the kind found in berries and beans and whole oats, which seems to indirectly diminish resistance, as well as lean proteins like fish. Saturated fats may cause insulin to spike, so look for foods with healthy fats like nuts and avocados. But enjoy them in moderation.
Weight loss is important because all the risks for all the diseases associated with insulin resistance are multiplied by obesity. That spare tire many of us carry around the middle packs the liver in fat, and the liver responds by tossing high levels of free fatty acids into the blood. These fats seem to block insulin from docking with its receptors on cells, increasing the risk of starting the resistance syndrome.
Regular exercise also helps muscles better use insulin, so in addition to her medication, Kristin Chapman works out four times a week. She also gets her heart checked every year, and has started getting regular mammograms early, at age 35. If insulin does indeed turn on many diseases, she plans on doing her best not to throw the switch.
advertisement
