You may crave foods like chocolate because they actually make you feel better by manipulating pleasure-producing chemicals in the brain.
So suggests Dr. Adam Drewnoski, at the University of Michigan. Drewnoski gave test subjects foods like ice cream and candy for their cravings. But when he injected a drug that blocks certain pleasure-producing brain chemicals, the cravings stopped. "People liked the foods less," he says. His speculation: pleasurable sensations, somehow induced by the food, led to the cravings.
Not surprisingly, the most "addictive" foods are milkshakes, cookies and chocolate candy. "Most of the action comes from Snickers bars and M&M;'s," says Drewnoski. These foods are high in both sugar and fat. And studies show that animals lose fat and sugar cravings when injected with the same drug used in Drewnoski's human tests.
Further, he finds that people who practice "yo-yo dieting," seem to develop cravings for high-fat, high-sugar foods. Exactly how such addictive foods affect brain chemistry is unclear.
"Some people think if salt doesn't raise their blood pressure, they can eat all the salt they want," says Dr. Louis Tobian, professor of medicine at the University of Minnesota and an expert in high blood pressure.
But his new studies suggest that's not true. Salt can be extremely dangerous, even when it doesn't boost blood pressure. "Salt may still damage arteries," he says, "causing death."
Tobian fed rats either a high-salt or low-salt diet. Their blood pressure did not rise because they are bred to be resistant to salt. Still, within 15 weeks, 100% of the high-salt animals were dead compared with only 12% of the low-salt animals. The brains of the dead rats on high-salt diets revealed injured arteries and dead tissue, caused by a series of fatal mini-strokes.
This means, says Tobian, that everyone with mild high blood pressure should cut back on salt, even if salt does not raise blood pressure.
High levels of a strange type of cholesterol called Lp(a) may double the risk of heart attack, even with low levels of total cholesterol. It's been estimated that high Lp(a) helps trigger a quarter of all heart attacks in men younger than 60.
A tendency to Lp(a) is inherited, and neither drugs nor low-fat diets help much in lowering it.
But recently, Dr. Jorn Dyerberg, a leading scientist in Denmark, found that fish oil lowered Lp(a) by 15% in a group of otherwise healthy men. The men took fish oil (4 grams daily--equivalent to seven ounces of mackerel) for nine months. But Dyerberg and others find no impact of fish oil in reducing normal levels of Lp(a).