"What if Bad Fat is Actually Good for You?"

"For decades, Americans have been told that saturated fat clogs arteries and causes heart disease. But there's just one problem: No one's ever proved it." Check out this article from Men's Health. It's long but highly informative. Some excerpts:

Suppose you were forced to live on a diet of red meat and whole milk. A diet that, all told, was at least 60 percent fat -- about half of it saturated. If your first thoughts are of statins and stents, you may want to consider the curious case of the Masai, a nomadic tribe in Kenya and Tanzania.

In the 1960s, a Vanderbilt University scientist named George Mann, M.D., found that Masai men consumed this very diet (supplemented with blood from the cattle they herded). Yet these nomads, who were also very lean, had some of the lowest levels of cholesterol ever measured and were virtually free of heart disease. . . .

Although more than a dozen types of saturated fat exist, humans predominantly consume three: stearic acid, palmitic acid, and lauric acid. This trio comprises almost 95 percent of the saturated fat in a hunk of prime rib, a slice of bacon, or a piece of chicken skin, and nearly 70 percent of that in butter and whole milk.

Today, it's well established that stearic acid has no effect on cholesterol levels. In fact, stearic acid -- which is found in high amounts in cocoa as well as animal fat --is converted to a monounsaturated fat called oleic acid in your liver. This is the same heart-healthy fat found in olive oil. As a result, scientists generally regard this saturated fatty acid as either benign or potentially beneficial to your health.

Palmitic and lauric acid, however, are known to raise total cholesterol. But here's what's rarely reported: Research shows that although both of these saturated fatty acids increase LDL ("bad") cholesterol, they raise HDL ("good") cholesterol just as much, if not more. And this lowers your risk of heart disease. That's because it's commonly believed that LDL cholesterol lays down plaque on your artery walls, while HDL removes it. So increasing both actually reduces the proportion of bad cholesterol in your blood to the good kind. This may explain why numerous studies have reported that this HDL/LDL ratio is a better predictor of future heart disease than LDL alone. . . .

We've spent billions of our tax dollars trying to prove the diet-heart hypothesis. Yet study after study has failed to provide definitive evidence that saturated-fat intake leads to heart disease. The most recent example is the Women's Health Initiative, the government's largest and most expensive ($725 million) diet study yet. The results, published last year, show that a diet low in total fat and saturated fat had no impact in reducing heart-disease and stroke rates in some 20,000 women who had adhered to the regimen for an average of 8 years. . . .

Now here's the saturated-fat connection: Dr. Krauss found that when people replace the carbohydrates in their diet with fat--saturated or unsaturated -- the number of small, dense LDL particles [the bad ones] decreases. This leads to the highly counterintuitive notion that replacing your breakfast cereal with eggs and bacon could actually reduce your risk of heart disease. . . .

Perhaps the apparent bias against saturated fat is most evident in studies on low-carbohydrate diets. Many versions of this approach are controversial because they place no limitations on saturated-fat intake. As a result, supporters of the diet-heart hypothesis have argued that low-carb diets will increase the risk of heart disease. But published research doesn't show this to be the case. When people on low-carb diets have been compared head-to-head with those on low-fat diets, the low-carb dieters typically scored significantly better on markers of heart disease, including small, dense LDL cholesterol, HDL/LDL ratio, and triglycerides, which are a measure of the amount of fat circulating in your blood.

For example, in a new 12-week study, University of Connecticut scientists placed overweight men and women on either a low-carb or low-fat diet. Those who followed the low-carb diet consumed 36 grams of saturated fat per day (22 percent of total calories), which represented more than three times the amount in the low-fat diet. Yet despite this considerably greater intake of saturated fat, the low-carb dieters reduced both their number of small, dense LDL cholesterol and their HDL/LDL ratio to a greater degree than those who ate a low-fat diet. In addition, triglycerides decreased by 51 percent in the low-carb group--compared with 19 percent in the low-fat group. . . .