Nina Teicholz is an independent journalist who has written for Gourmet magazine, The New Yorker, The Economist, The New York Times and The Washington Post on a variety of topics. Her book, The Big Fat Surprise, was published May 13, 2014, and revisits the decades-old idea that saturated fats are bad for your health.

The following are some thoughts she shared withProgressive Dairyman on her new book and the science behind it.

In The Big Fat Surprise and your recent article in The Wall Street Journal, you write that the low-fat diet was recommended by the health establishment before it was proven. Where did that idea come from?

The idea that saturated fat causes heart disease goes back to the 1950s, with Ancel Keys. His solution to the rising tide of heart disease in the country was that it was saturated fat that caused heart disease.

He was this very outsized, charismatic and persuasive man who was able to get that idea implanted in the American Heart Association, so that the very first anti-saturated-fat guidelines were published in 1961. But at that time, there was almost no evidence for them, just mainly the seven-country study by Ancel Keys himself.

In your article and in your book, you say that Keys' assertions haven't held up when subjected to scrutiny, especially recently. What's changed?

The bottom line is that evidence behind the idea that saturated fat causes heart disease was never strong, and has since been undermined by two major, independent groups of scientists conducting meta-analyses. That's where you look at all the data on saturated fats, and they concluded that it could not be said to cause heart disease.

Those two meta-analyses, one by Siri-Tarino et al. published in twoparts in The American Journal of Clinical Nutrition and the other by Chowdhury et al. published in Annals of Internal Medicine, have received some criticism for alleged errors in the way the analyses were conducted, specifically for not accounting for trans fats in the Sydney Diet Heart Study.

The effect of trans fats would be minimal, since trans only marginally raises LDL-C and therefore has a relatively small impact on CHD risk compared to what has been assumed to be the case for saturated fats.

Moreover, the larger point is that meta-analyses usually amplify biases in science, especially when applied to observational data. In this case, the bias has for decades been in favor of finding deleterious effects of saturated fats. Therefore the absence of such a finding, against the prevailing bias, is especially meaningful.

I don't find these objections persuasive, and they do not undermine my book's conclusions. My book sets out a far broader range of scientific and historical evidence for the case that saturated fats have been unfairly condemned.

What are the benefits of saturated fats?

If saturated fats don't cause heart disease, then there's no reason to avoid full-fat milk, full-fat cheese. And there are reasons for eating those foods, because you need the fat in order to absorb the fat-soluble vitamins in the food. Vitamin A, vitamin D – we currently have a crisis in vitamin D in this country. One of the best sources is milk, but you need the fat in the milk to absorb the vitamin D.

The USDA and the Department of Health and Human Services are scheduled to release an update to their dietary guidelines next fall. How might these findings change the guidelines?

The current Dietary Guidelines Advisory Committee is talking about reducing even more the limits on saturated fat intake. Current level of 7 percent is already extremely low and undocumented in human history.

It's pretty clear that their guidelines on sodium don't reflect the current science. There's a recent institute of medicine study showing that moderate levels of sodium are better than really low levels of sodium, rethinking the whole story on fat and animal foods. I think that the committee needs to start from zero, start from scratch, and build a new pyramid based on the best and most-current science, which is their mandate: to review the "best and most current science" for health, which they're currently not doing.

The 496-page book is available on Amazon.com, Barnes and Noble and other retailers. A two-chapter free preview is available on Amazon.com.