Source: alex9500/123RF

Saturated Fat Strikes Again

Lock your doors—saturated fat is on the prowl again . . . and this time it’s not waiting around until you're middle-aged to clog your arteries and give you diabetes. It’s coming for your ’ brains. Yes, according to the press release headline announcing this new study in the peer-reviewed journal Brain, Behavior and Immunity, is the new fatty on the block:

“ADOLESCENTS WHO CONSUME A DIET HIGH IN SATURATED FATS MAY DEVELOP POOR STRESS COPING SKILLS, SIGNS OF POST-TRAUMATIC STRESS DISORDER AS ADULTS.”

This new headline about PTSD has already been picked up and published by a number of online news outlets.

We’ve been told for decades that saturated fat is public health enemy number one. It's been easy for us to buy this argument because it sounds so simple, obvious and logical: eating fat should make us fat. Since we know that is associated with all kinds of other serious health conditions, it has been tempting for researchers and the general public to blame saturated fat for all of the diseases we fear most. It's easy to simply swallow headlines about fat, especially when they confirm our long-held beliefs. Yet there are good reasons to question these beliefs, not the least of which is that it makes no sense that an ancient macronutrient found in all whole foods from steak to coconuts would be responsible for any modern human health epidemic.

Why shouldn’t you trust this fat-phobic headline?

1. It’s a rat study. If you are a rat, raise your little paw and you may be excused. If not, sit tight and read on. Sadly, none of the media headlines about this study mention that this research was not conducted in human teens.

2. The experimental design reveals a glaring error that renders the entire study worthless—and it's the same error I find in most anti-fat studies, such as this study claiming that high-fat diets cause depression.

What's so terribly wrong with this study?

Source: studiostoks/GraphicRiver (modified)

The answer lies in the chow, my friends.

It’s ALWAYS about the chow.

The researchers set out to compare the effects of a "Western high-fat diet" to a standard "control" diet. Unfortunately, the study's authors don't disclose the ingredients in either chow, stating only that both chows are “based on” a formula manufactured by Bio-Serv, catalog #AIN93G. We (should not have to) go to Bio-Serv’s website to find the ingredient list for the base formula, which turns out to be:

Corn Starch, Casein, Maltodextrin, Sucrose, Soybean Oil, Cellulose, Mineral Mix, Vitamin Mix, L-Cystine, Choline Bitartrate, tBHQ.

Poor rats—talk about a highly-processed junky diet. No rat in the wild has access to any of these manufactured ingredients. The truth is that BOTH diets used in this study can be described as “Western” if we define Western diets as being composed of ultra-processed proteins, fats and carbohydrates.

The authors buried their description of the nutrient content of each diet in a table in the appendix (see below). Yes, the "Western high-fat" chow reported to raise levels in teenage rats was clearly much higher in saturated fat than the control diet. . . but can you find any other significant differences between these two diets?

Supplemental Table 1. Detailed Diet Composition

Source: Vega-Torres JD et al. Exposure to an obesogenic diet during adolescence leads to abnormal maturation of neural and behavioral substrates underpinning fear and anxiety. Brain, Behavior, and Immunity. 2018;70:96-117.

Yes, the “high-fat” diet is about 12 times higher in saturated fat. But, as you can see, it also has four times the monounsaturated fat, half the protein, 67% more calories, and more than 17 times the sugar!!

Any (human) high school science student who designed a saturated fat study like this would get an F in biology.

Nowhere in their paper do the authors mention or explain any differences between the two diets other than the fat content. Why didn’t the scientists mention these other MAJOR differences in the two diets?

In my opinion, the two most likely possibilities for this glaring omission are:

They didn’t bother to look at the chow ingredients. If this is the case, it is not only lazy—it is scientific malpractice. The single most important thing about any diet study is the composition of the diet. If you don’t know what you’re testing, you should find another job.

They are (consciously or unconsciously) biased against saturated fat and either don’t want readers to know what else was in the chow or can't fathom that any other ingredient matters. Do we have any evidence that these scientists may have an anti-fat agenda? In this case, we absolutely do.

This study was conducted at Loma Linda University, a private Seventh-Day Adventist institution in southern California. The diet famously promoted by the Seventh-Day Adventist faith, per their official website is:

“A well-balanced vegetarian diet that avoids the consumption of meat coupled with intake of legumes, whole grains, nuts, fruits and vegetables, along with a source of vitamin B12, will promote vigorous health.”

It is not my intention to cast aspersions on those choosing a vegetarian diet. It is simply my goal to expose bad science and set the record straight about saturated fat. If you aren’t convinced of the innocence of saturated fat, I highly recommend familiarizing yourself with the work of two brilliant, pioneering women in the world who always do their homework:

Dr. Zoe Harcombe, a UK-based scientist with a Ph.D. in nutrition and a leading expert on saturated fat. I highly recommend reading her brief, exceedingly logical summary of what saturated fat is and why you don’t need to fear eating it.

Nina Teicholz, a U.S.-based investigative journalist who wrote The Big Fat Surprise, a thoroughly-researched book exposing the history, and science of the anti-saturated fat movement.

You’ll notice I’m not delving into the details of what the Loma Linda researchers claim to have discovered about the effects of diet on rat brain chemistry and behavior. That is because it is not worth anyone’s time to do this given a) how sloppily the study was conducted and b) that it is a rat study.

Even if this were a well-designed rat study, we are not rats. The ideal rat diet is arguably different than the ideal human diet, as we are different species. Even if saturated fat damages adolescent rat brains (and this study cannot tell us this), this would not necessarily mean that saturated fat damages adolescent human brains.

Source: Suzi Smith, used with permission

A plea for a better process

Sloppiness in science, peer review, and journalism not only wastes everyone’s time; it endangers public health and erodes public trust in science. When scientific journal peer review boards and journalists give studies like this a pass, they contribute to the divisive, mistrusting culture of our time. Journal editors and journalists: please do your homework before publishing or printing nutrition information. It took me about 30 minutes to find this study, skim the methods section and look up the ingredients in the chow used in this blatantly biased study. Headlines matter. You have an important responsibility to the scientific community and to the public. Most people don't have access to scientific journal articles (this particular study is not open-access) and even when articles are available to the general public, most people don’t have the time or specialized scientific background required to analyze the research themselves. The public relies on you to more accurately represent the truth about nutrition science.

Here’s the real headline for you:

HIGH-SUGAR, HIGH-FAT, LOW-PROTEIN, HIGH-CALORIE, ULTRA-PROCESSED CHOW NEGATIVELY AFFECTS ADOLESCENT RAT BRAINS.

Now I ask you: is that a headline worth printing?