Hidden truths about hidden fats — a special note for women on the latest scare

This past week, women were threatened that eating fats hidden in processed foods — even as little as a single donut or serving of chips — could harm their chances of having a baby. The study behind this news story showed nothing to support such a claim. But it appears already well on its way to becoming conventional wisdom. The news reported:

Food fats threaten women’s fertility

Scientists warn that hidden fats can increase the risk of fertility problems by 70 per cent or more. Fats hidden in thousands of foods can harm a woman’s chance of having a baby, scientists said yesterday....Eating as little as one doughnut or a portion of chips a day can have a damaging effect.

The scientists behind the study advised women who want to have a baby to avoid the fats, known as trans fats...Nutrition campaigners said the research provided ‘considerable new weight and urgency’ for trans fats to be banned.

This last sentence may be the actual point of the story, but if you are wanting to become a new mother, you just want the facts, not the political-driven scares.

The study behind this news story was published in the American Journal of Clinical Nutrition and was conducted in Boston at Harvard School of Public Health and Brigham and Women’s Hospital. If you’re a regular reader of this blog, you know that this group is famous for its data dredges and this was another one, with all of the concurrent weaknesses. They culled through a database of food-frequency questionnaires looking for correlations between types of dietary fats and pregnancies among a subgroup of women in the Nurses Health Study who said they had been trying to get pregnant for longer than a year.

There were 438 women who had problems conceiving due to ovarian causes. That is your Trojan number. The data from them were compared to that of married women with planned pregnancies.

So, what did the authors find? That the more total fat the women ate, the less likely they were to have problems conceiving. Those eating lower fat were more likely to have problems getting pregnant. Each quintele of higher fat intake was associated with an improved ability to conceive. (Saturated fats had a 31% reduced risk of infertility for the highest compared to the lowest consumptions.) Boy, you didn’t hear that in the news!

Not only that, but the type of fat made no statistical difference. Saturated, monounsaturated, total polyunsaturated, omega-3 and omega-6 fatty acids were not associated with ovulatory infertility. Nor was dietary cholesterol.

The only newsworthy correlation they could create was an untenable relative risk that wasn’t outside what could have mathematically popped up by random chance or statistic error. They claimed that “an increase of 2% in the intake of energy from trans-unsaturated fats, if substituted for carbohydrates was associated with a 73% higher risk of ovulatory infertility.” Not only is this an uncredible relative risk that does not equate with clinical relevance to begin with, but it is important to look closely at the wording they carefully chose to use. Otherwise, it’s very easy to come away with the wrong conclusions, as news reports did.

This relative risk associated with transfats, while actually inconsequential to begin with, is not referring to fertility or a woman’s chance of having a baby, as the news reported. It is referring to “ovulatory infertility,” an unusual term these researchers have popularized. There are many reasons for infertility and female factors account for only 32% of them, as Dr. Jairo E Garcia, M.D., associate professor and director of the Fertility Center and In Vitro Fertilization at the Department of Gynecology and Obstetrics of Johns Hopkins University School of Medicine reports. Remember, men are part of the equation!

And within those female causes there are all sorts of things, including the fallopian tubes (damage, blockage), endometrial (such as endometriosis), peritoneal, cervical, uterine (such as fibroids), pelvis (such as adhesions), ovaries (such as cysts, ovulation disorders and hormones), thyroid problems, medications, and other medical conditions such as amenorrhea (pituitary tumors, excessive exercise or excessive dieting). So, they are claiming a relative risk not of overall infertility, not just female causes, but only for ovarian factors within those. This week’s study is probably beginning to sound much less worrisome. But there’s more.

The phrasing of an increase of “2% in the intake of energy from transfats” sounds like the merest morsel of transfats increases your risk by 73% because 2% doesn’t sound like much at all. Neither the researchers nor the mainstream media made any attempt to clarify this misconception. I’ll leave the reason for that for you to surmise.

As all nutrition scientists and health professionals know, according to the FDA, the amount of transfats Americans eat is about 2.6% of total calories. So increasing that by an additional 2% would be nearly doubling the amount of pure transfats we would have to consume. But that is not ever likely to happen, anymore than eliminating them, and these researchers know that most of all.

Why? Because it was Harvard researchers, including Dr. Walter C. Willett in this study, who documented and reported in the New England Journal of Medicine last year that the average amount of transfats eaten by Americans has not changed since the 1960s.

Yes, contrary to all of the panic we hear about transfats, we are eating the same amounts we have for nearly half a century. While transfats in margarines dropped with softer versions, they increased in baked goods and other foods.

Meanwhile, the actual health of Americans has greatly improved and we’ve gained more than seven years in life expectancy. Heart disease; most cancers, including colon cancer; and premature deaths have been dropping for more than 50 years. Overall mortality from heart disease alone has dropped by half since 1960, according to the latest U.S. 2006 National Center for Health Statistics, National Vital Statistics Reports. And, according to Dr. Garcia, the fecundability (the chance of getting pregnant each month) remains fairly constant among the population and is about 0.22/month.

That’s why the FDA, after years reviewing all available evidence on transfats, said in its July 2003, 260-page ruling (Docket No. 94P-0036), that any fears of a public health concern from the small amounts of transfats in our diets were not supported by the evidence. These fatty acids, in reality, haven't been shown to be better or worse than any other dietary fat. The FDA expert panel specifically stated that transfats needn’t be eliminated from the diet and they refused to establish a daily recommended intake due to lack of evidence.

Transfats make up a tiny part of the fats in our diet (we eat 5 times more saturated fats) and they have never been shown to actually harm health in human studies. At high levels (beyond real-life consumptions in many such studies), the most they have been shown to do is temporarily increase blood “cholesterol” levels. But such changes in blood chemistry haven’t been shown to increase heart attacks, cholesterol in women most of all. [Remember to be cautious of false surrogate endpoints.]

“None of the eight human population studies comes close to linking transfats with heart disease,” said Steve Milloy, now adjunct scholar with Competitive Enterprise Institute and publisher of Junkscience.com. His critical examination of the scientific evidence was an good look at what the studies actually found, the researchers, and how the public was been misled.

Professor David Klurfeld, chairman of the Department of Nutrition and Food Science at Wayne State University, editor-in-chief of the Journal of the American College of Nutrition wrote a special series of articles in Nutrition News Focus examining the evidence on transfats. He concluded that any association between transfats and health problems is weak. For example, he noted that the Nurses Health Study, conducted by Harvard researchers, has failed to find a link between transfats or any other dietary fats and heart disease in more than 20 years.

In this week’s study, the Harvard researchers said infertility might be another reason to avoid transfats but that it wasn’t clear how transfats might affect ovulation and fertility. Just two months ago, the Harvard researchers reported another dietary correlation from the Nurses Health Study: higher iron intakes were associated with improved fertility.

With their new finding that higher dietary fats and saturated fats are also associated with improved fertility, those burgers don’t seem so “bad” for you.

© 2007 Sandy Szwarc