Morning Rounds: Why is the FDA banning trans fats?

(CBS News) CBS News chief medical correspondent Dr. Jon LaPook and CBS News contributor Dr. Holly Phillips joined "CBS This Morning: Saturday" to discuss the major medical stories of the week.

Trans fats are the ingredients that make many processed foods taste better and last longer, but this week the Food and Drug Administration said trans fats are no longer recognized as safe and intends to ban them. Trans fats are created by taking liquid vegetable oil and turning it into fat.

FDA Commissioner Dr. Margaret Hamburg told CBS News' Chip Reid that reducing the levels of trans fats in the American diet could save thousands of people from preventable death.

"Trans fats increase your risk for heart disease. It turns out that they elevate the so-called bad cholesterol, LDL," she said. "This action will save lives. The CDC estimates that if we can reduce the levels of trans fat currently in the American diet we can probably save about 7,000 people from a preventable death and prevent about 20,000 heartattacks."

Trans fats have been used in food for decades, but the FDA is now just recognizing the risk and taking action to remove them. However, LaPook told the "CBS This Morning: Saturday" co-hosts that there has been a movement to remove trans fats from our food supply by other groups.

"There has been about a 75 percent drop in the consumption of it in recent years, but it's still not down to zero, and even a little bit can cause heart disease," said LaPook. "It can be anywhere, you know. It's not like a pack of cigarettes, where you see it and you know what you're doing. It's kind of invisible, and we're not quite sure what products have it, so the FDA is finally just saying, 'You know what? We're going to take it out."

Banning trans fats got started a few years ago in places like New York, where restaurants have had to eliminate its use. LaPook said that the ban is indeed "working."

"People were so frightened at the beginning that it was going to crash the number of people that were coming into these restaurants, and it hasn't done that at all," said LaPook. "In fact, in other countries like Denmark, Iceland, Switzerland that have entirely gotten rid of it for years, there's been absolutely no problem."

Also, a new study in the journal Pediatrics says the age at which some girls begin puberty is dropping. Researchers followed more than 1,000 girls for seven years. They discovered that the onset of breast development is directly related to a girl's body mass index. The heavier the girl, the earlier puberty is likely to start, and BMI was a better indication than race or ethnicity.

Phillips told the "CBS This Morning: Saturday" co-hosts that the study did break data down "a bit" by ethnicity, but for all groups "puberty started surprisingly early." According to the study, the median age of breast development for Caucasian and Asian children was around 9.7 years old. For Hispanic children it was 9.3 years old, and for African-American girls it was 8.8 years old.

"Those are really, really early ages, but the biggest predictor, again, was obesity and your body mass index," she said. "That's because fat cells really trigger hormonal cascades. They trigger the release of hormones that wouldn't be there otherwise, and that causes puberty to happen much earlier."

Phillips said that girls this age do not cope well hitting puberty so early and it is "very challenging" for them.

"Some of the studies have shown that they have lower self-esteem, they perform more poorly in school, even greater rates of depression," she said. "I feel like childhood is such a fleeting time ... one of the things we have to focus on is making sure our children are healthy, that they are not obese, so that their bodies develop at the same time as their minds."

For Dr. Jon LaPook and Dr. Holly Phillips' full roundup on this week's medical stories, watch the video in the player above.

Check out more from Morning Rounds with Dr. LaPook