Science Fact: Junk food has an evil reputation. No one (except perhaps its retailers) would claim that junk food is actually “healthy” to eat. Many folks would go farther, and castigate it as a devilish substance that will impurify all of our precious bodily fluids.
Junk food is overwhelmingly popular. Apparently a jolt of fats and carbohydrates addresses an inner hunger. We may surmise that humans evolved their craving for junk food eons ago, when they were living hand-to-mouth and had to grab every source of calories that came to hand.
Nevertheless, there is strong medical belief that a diet high in saturated fats, which characterizes a lot of junk food, is harmful to your health.
It’s a lot easier to do research on mice than on humans: they have short life spans, and they don’t complain when you put them in a cage and restrict their diets (although PETA may organize protests outside your lab). It’s well recognized that a “mouse model,” that is, using mice to simulate human beings, raises many questions of validity. We may learn things about a healthy or unhealthy life that are valid for mice but don’t apply to people at all. Nevertheless, studying mice gives us valuable information, and helps researchers decide which tests may be most valuable to try on humans.
With that introduction, let’s look at a fascinating new piece of research on junk food. A new article has been published whose lead author is Eugenia Morselli, who has joint appointments at University of Texas Southwestern Medical Center in Dallas and Pontificia Universidad Católica in Santiago, Chile. Her co-authors hail from UT Dallas, Cedar-Sinai Los Angeles, and the Technical University of Munich, Germany. A great example of collaboration across institutions and across nations. The full article is highly technical but there are news summaries at ABC Australia and more briefly in Science Magazine.
The study, led by Deborah Clegg at UT Dallas, focused on the hypothalamus. In humans, the hypothalamus is a small portion of the brain about the size of an almond, located under the center of the main brain mass. It links the endocrine system to the nervous system and helps to control many metabolic processes.
It is known that in mice, a high-fat diet causes inflammation in the hypothalamus, and inflammation in that part of the brain is correlated with cardiovascular problems. In other words, saturated fats inflame the hypothalamus, which disrupts the endocrine function, and that leads to heart disease.
The researchers pointed out that obesity is known to have quite different effects on the health of men and women. Obese men are very susceptible to diabetes and heart disease. However, obese women suffer far fewer adverse effects, at least while they are pre-menopausal. So the research team decided to see whether a junk food diet has different effects on male mice versus female mice.
Morselli and her colleagues chose equal numbers of male and female mice, matched for age and genetic background. Half of each gender were fed a standard diet; the other half were fed a diet with 42% fat and a lot of carbohydrates. In other words, junk food.
The high fat food was tasty – like cookie dough. It would be like eating a burger and a coke.
Dr. Clegg implies, though she does not say so, that she sampled the mouse chow herself!
The study team found startlingly different results for males and females. After only 16 weeks on the junk food diet the male mice showed brain inflammation, but the female mice showed none. The brain inflammation appeared to be due to palmitic acid, a saturated fat found in palm oil, dairy foods and meat and a common component of junk food. The researchers also found that the male mice were more likely than females to become glucose intolerant – a step towards diabetes – and to have impaired heart function.
These are fascinating research results, and they invite us to speculate on where they might lead.
Science Speculation: We can start by saying, if you are raising pet mice, you need to watch the diets of the boy mice much more carefully than the girl mice. But I suspect that not too many readers of this blog are maintaining a mouse colony.
More to the point, what if these results in mice prove also to be true for human beings, as has been the case with a lot of other medical research?
Then we would conclude the following:
– Men who eat a lot of junk food are significantly increasing their risk of getting heart disease and diabetes. And since many health conditions are impaired by inflammation, they may be subject to other ailments as well.
– Women who eat junk food are largely protected from heart disease, diabetes and other conditions that are worsened by brain inflammation. This protection is believed to derive from women’s estrogen, and therefore it may not continue after menopause.
Homer Simpson is one of the world’s most renowned lovers of junk food. So one might expect Dr. Hibbert to hand out this advice:
– To Homer and Bart, “Take it easy, boys.”
– To Marge, Lisa and Maggie, “Chow down, ladies!”
Do you notice any differences in junk food consumption among men versus women whom you know?
Image Credit: “Burger” from The Print Shop 2 Collection. Not for download or reuse.