The science is clear that regularly eating a diet high in saturated fats is damaging to your heart, but it may also be devastating to your brain. That’s the finding of new research that focused on the effects of consuming hefty portions of saturated fat on the connections between brain cells.
The study used mice to track the comparative effects of two diets that mirrored low- and high-saturated fat diets in humans. One group of mice ate a diet with only 10% of calories from saturated fat, while the other group’s diet contained 60% saturated fat. Their weight, insulin and blood glucose levels were measured at regular intervals for 12 weeks. The research team also measured the levels of proteins in the brains of the mice that correspond to their number of synapses (the connections between brain cells), and they measured their cytokine proteins, which indicated their level of cellular inflammation.
During the first eight weeks, the blood tests between the two groups of mice were roughly the same, although the high-fat group gained weight. But at the 12-week mark the high-fat diet group had significantly reduced levels of synaptic proteins (meaning the number of synaptic connections in their brains dropped) and increased levels of cytokine.
The conclusion is that the high-fat diet triggered chronic inflammation, which in turn triggered an autoimmune response in the mice's central nervous systems. Normally this response protects the brain from invaders like bacteria, but a high-saturated fat diet knocks the process off track, resulting in damage to synapses in the brain – specifically in the hippocampus. Since the hippocampus is a brain area central to memory and learning, the eventual outcome is impaired brain function. In short, the high-fat diet caused brain damage.
The good news, however, is that the damage appears to be reversible (at least in mice). When the high-fat diet group was placed on the low-fat diet, their brains returned to normal in about two months, even though they’d not lost all of the weight gained on the high-fat diet.
Quoting lead study author Dr. Alexis M. Stranahan, from the Department of Neuroscience and Regenerative Medicine at the Medical College of Georgia at Georgia Regents University, “On the one hand, that is very scary, but it's also reversible, meaning that if you go back on a low-fat diet that does not even completely wipe out the adiposity, you can completely reverse these cellular processes in the brain and maintain cognition."
Once again, as we’re seeing in study after study, the main culprit is chronic inflammation triggered by external factors – in this case a high-saturated fat diet. Inflammation at the cellular level (as opposed to the surface-level inflammation experienced after an injury) is a prime contributor to many disorders and diseases affecting the heart and the brain -- with diabetes, depression, stroke, Alzheimer's and Parkinson's all on the list. Finding ways of controlling and reducing chronic inflammation is becoming one of the most important health science challenges of this century.
The study was published in the journal Brain, Behavior and Immunity.
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