High-fat diets can harm your immune, gut and brain health

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A comprehensive study from UC Riverside, published in the journal Scientific Reports, offers a new perspective on the effects of high-fat diets, extending beyond traditional concerns of obesity and colon cancer.

This research uniquely investigates the influence of high-fat diets on gene expression in the intestines, immune system, brain function, and potentially COVID-19 risk.

The study involved feeding mice three different high-fat diets (with at least 40% of calories from fat) for 24 weeks. The diets included saturated fat from coconut oil, monounsaturated fat from modified soybean oil, and polyunsaturated fat from unmodified soybean oil.

The findings showed significant changes in gene expression related to fat metabolism and gut bacteria, even in diets derived from plant sources.

Frances Sladek, a UCR cell biology professor and senior author of the study, pointed out the unexpected scope of the diets’ impact.

“Word on the street is that plant-based diets are better for you, and in many cases, that’s true. However, a diet high in fat, even from a plant, is one case where it’s just not true,” Sladek said.

Key findings include:

  • All three high-fat diets led to changes in gene expression related to various health aspects.
  • There were major alterations in genes linked to fat metabolism and the composition of gut bacteria, such as an increase in pathogenic E. coli.
  • Changes in genes regulating susceptibility to infectious diseases were observed, impacting immune response and inflammation control.
  • The diets increased the expression of ACE2 and other host proteins used by COVID spike proteins to enter the body, suggesting a potential link to increased COVID-19 risk.
  • Signs of increased stem cells in the colon were seen, raising concerns about cancer risk.

In terms of impact on gene expression, the coconut oil diet showed the most changes, followed by unmodified soybean oil.

These effects were more pronounced in mice fed the soybean oil diet, echoing the team’s previous research on soybean oil’s negative health effects, including obesity, diabetes, and alterations in brain-related genes.

Poonamjot Deol, a UCR microbiologist and co-first author of the study, emphasized the study’s specificity to soybean oil and not to other soy products.

“There are some really good things about soybeans. But too much of that oil is just not good for you,” Deol said.

While the study was conducted on mice, and results may not directly translate to humans, the shared DNA between humans and mice makes these findings concerning.

With soybean oil being widely consumed in the United States and increasingly in other countries, this research prompts a reevaluation of dietary habits.

The study suggests that the long-term effects of high-fat diets, rather than occasional indulgences, are cause for concern.

Regular consumption of such diets could impact not just weight and metabolic health but also immune system functionality and brain health.

The researchers hope their work will encourage people to reconsider their long-term eating habits, understanding that exercise alone may not counteract the effects of a consistent high-fat diet.

This study adds to the growing body of research urging caution in dietary choices and highlights the multifaceted impact of diet on overall health.

If you care about gut health, please read studies about how junk food harms your gut health, and how probiotics can protect gut health.

For more information about health, please see recent studies about how fiber affects weight loss and your overall health, and results showing why a glass of red wine is good for your gut.

The research findings can be found in Scientific Reports.

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