The dangerous reason why eating French fries and potato chips feels so good

Do you ever wonder why it’s so hard to just eat one French fry or potato chip? Well, a new study suggests it may have something to do with the processed soybean oil used to make these highly addicting foods. In fact, in a recent lab study, researchers found that soybean oil caused changes to the brain and even increased production of a “feel good” hormone.

I’ll tell you all about that important, eye-opening study in a moment. But first, let’s back up to discuss the long and complicated history of soy…

Soybean farming began in China

Thousands of years ago, the Chinese civilization was among the first to practice intensive, organized agriculture. And they learned early on how to cultivate grains like rice, which provided a source of much-needed calories to its large, growing population.

The problem is, rice contains very little protein. So, that’s where soybeans came in…

As the Chinese learned, soy is a viable source of protein (when prepared correctly)—providing much-needed nutrients for your muscles and organs—especially the brain. So, they came to consider soybeans (which are legumes) as one of the five sacred, traditional “grains” (or plants) of agriculture.

Plus, soybeans, like all legumes, have “nitrogen-fixing” bacteria on their root nodules. These nodules capture nitrogen from the atmosphere and put it back into the depleted soil. So, in essence, soybeans act like natural fertilizers for the soil.

In fact, Dr. Solomon Katz, my professor of anthropology in graduate school at Penn, did research to show that the ancient Chinese probably first began planting soybeans for the purpose to replenish the soil, which had been exhausted by growing grains.

But there are a few important things to remember about eating soy…

The toxins in raw soybeans impair digestion

Raw, “unprocessed” soybeans contain a toxin (called antitrypsin factor) that interferes with digestion. In fact, we now know that regularly eating foods with antitrypsin factor can lead to serious malabsorption and nutritional deficiencies. Which is why I recommend you only eat edamame, or raw soybeans, sparingly.

Of course, long ago, the Chinese developed traditional processing methods to remove the toxins and make protein-rich soy safe to eat.

For example, when making tofu, they learned to dissolve soybeans in sea water. The calcium and magnesium in sea salt causes the soy protein to gather and form into a block. Then, they press the block to remove the fluid containing the antitryptic toxins.

Similarly, they learned to ferment soy to make products like soy sauce. This process uses natural probiotic bacteria to break down the chemical toxins.

Unfortunately, modern agriculture and modern food manufacturers have all-but-abandoned the lessons learned by the Chinese about how to safely and traditionally “process” soy. And they’ve turned it into a highly profitable, unhealthy processed food commodity…

Modern, processed soy products pose serious health hazards

There are three major problems with modern, processed soy products…

First, almost all of them use genetically modified (GM) soybeans—which have been treated to withstand herbicides like glyphosate (Roundup®). And now, some experts even believe the increasing rates of food intolerance and allergies actually stem from exposure to glyphosate. (For more details, refer to the October 2017 issue of my Insiders’ Cures newsletter [“Revealed: Poison in your pasta”].)

Second, there are concerns that the plant hormones in modern, processed soy may mimic the effects of estrogen hormones in humans. And estrogen exposure has been linked to breast and other cancers, as well as disruptions in the normal reproductive cycle.

Third, we’re now learning that modern, processed soy—as found in processed soy milk, fake meats, veggie burgers, and protein bars—interferes with many normal hormonal and metabolic processes. Which brings me back to the new lab study I mentioned at the beginning of this Dispatch

Soybean oil disrupts hypothalamus function in the brain

For this study, researchers at the University of California in Riverside divided mice into three groups—giving them each a different diet. The first diet was high in coconut oil. The second was high in soybean oil. And the third was high in a modified soybean oil that was low in linoleic acid.

Linoleic acid is an omega-6 fatty acid. And some researchers have theorized that it’s what causes hormonal and metabolic problems associated with soy.  But it turns out, the lower linoleic acid didn’t make any difference at all…

In fact, both groups of mice that ate soybean oil experienced disruption in the hypothalamus. In mice and in humans, this part of the brain regulates all of the hormones in the body. And it influences everything from body weight and physical growth to reproduction and stress responses. It’s also the center for important mind-body connections, like the brain-endocrine-immune system pathways.

Both groups of mice that ate soybean oil also experienced a disruption in the expression of approximately 100 different genes. These genes are associated, at the cellular level, with inflammation, insulin regulation, and neurochemical and neuroendocrine signaling.

Last, and perhaps most interestingly, both groups of mice that ate soybean oil experienced an increase in the expression of the gene that produces oxytocin— sometimes labeled the “love” hormone. This finding perhaps helps explain why foods like French fries and chips, which are made with soybean oil, are so addicting and hyperpalatable.

Indeed, soybean oil is primarily used in fried fast foods, packaged foods, and livestock feed. So, if you ask me, I would guess that manufacturers already knew soybean oil is addicting and hyperpalatable—and they used that knowledge to make their products more profitable!

But clearly, it is something we should avoid, due to its clear disruption to brain function.

Not to mention, in 2015, this same group of researchers found that soybean oil induces insulin resistance, fatty liver, obesity, and diabetes in lab mice. And in 2017, they found that soybean oil, modified to be low in linoleic acid, still induced insulin resistance and obesity, but to a lesser extent.

So—with all of these serious concerns, why even bother with soy? After all, there are plenty of safe ways to maintain your protein intake without resorting to it.

If you’d like to learn more about the dangers of eating modern, processed soy, check out the January 2017 issue of my Insiders’ Cures newsletter (“Is it time to say ‘soyo-nara’ to soy?”). If you’re not yet a subscriber, now is the perfect time to become one.

P.S. Tune back in tomorrow for my full report on olive oil—the only oil you should ever use in cooking.


“Dysregulation of Hypothalamic Gene Expression and the Oxytocinergic System by Soybean Oil Diets in Male Mice.” Endocrinology, February 2020; 161(2): bqz044.