Trans fat alternative may have its own problems

By Amy Norton

NEW YORK (Reuters Health) - Cholesterol-raising trans fats may be disappearing from supermarket shelves and restaurants, but one type of fat taking their place may be no healthier, new research suggests.

Artificial trans fats are formed when food manufacturers add hydrogen to vegetable oil to make it solidify, in a process called hydrogenation. Partially hydrogenated oil boosts the stability of a food's flavor, as well as its shelf life, and the oils have long been a key ingredient in baked and fried foods.

Research has shown that trans fats in these oils may be even worse for heart health than the saturated fat found in foods like meat and butter. Not only do trans fats raise "bad" LDL cholesterol, as saturated fat does, but they also lower heart-healthy HDL cholesterol.

With trans fats so out of favor -- New York City recently banned them from restaurants, and other cities may follow suit -- the search for alternatives is on.

However, one of those replacement fats -- so-called interesterified fats -- may carry their own health threats, according to a study published in the journal Nutrition & Metabolism.

The interesterified oils may not only lower HDL levels but also cause a significant rise in blood sugar, researchers found.

The findings are concerning, study co-author Dr. K. C. Hayes told Reuters Health, in part because the study volunteers used the interesterified fats for only four weeks. "Blood glucose went up quite precipitously," said Hayes, a professor of biology at Brandeis University in Waltham, Massachusetts.

The problem, he and his colleagues found, seems to be that interesterified fats change the body's levels of insulin, which regulates blood sugar.