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Inclusion of cholesterol in plant-based diets improves gut health of GIFT tilapia

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By Milthon Lujan

Nile tilapia. Source: Earlham Institute
Nile tilapia. Source: Earlham Institute

Plant-based proteins offer a more sustainable alternative to traditional fishmeal in tilapia feed. While raising tilapia on plant-based diets is more sustainable, it may come with a hidden cost: intestinal damage.

Tilapia are omnivores and can utilize plant-based proteins, but a primarily plant-based diet can alter the intestinal barrier, causing inflammation and harming overall health.

A new study published by researchers from the Yangtze River Fisheries Research Institute (China), Shanghai Ocean University, and the Institute of Microbiology (China) explores the effects of supplementing cholesterol in plant-based feeds on the intestinal barriers of GIFT tilapia (Oreochromis niloticus).

Plant-based feeds: Potential benefits and challenges

Sustainable aquaculture practices often use plant proteins instead of fishmeal in tilapia feed. While this is environmentally friendly, plant proteins can contain compounds that disrupt the intestinal barrier system. Additionally, plant-based diets may lack sufficient cholesterol, a molecule essential for cellular health and intestinal function.

The cholesterol conundrum

Plant proteins offer a more eco-friendly alternative to traditional fishmeal in aquaculture. However, these ingredients often lack essential nutrients like cholesterol, which is crucial for gut health and overall fish growth.

Various studies have reported that excessive intake of plant proteins can lead to inflammation and damage in the intestines of tilapia. This condition, known as food-induced enteritis (FIE), impairs nutrient absorption and overall fish health.

On the other hand, limited research suggests that the lack of cholesterol in plant-based feeds could contribute to FIE. Cholesterol plays a vital role in maintaining intestinal health by promoting healthy cell function and bile acid production. Bile acids help regulate harmful bacteria in the gut.

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Can cholesterol help?

The study found that adding cholesterol, particularly at levels of 0.6% and 1.2% of the diet, led to significant improvements in the gut health of tilapia. Here’s how:

  • Improved physical barrier: The intestinal muscle layer, a key part of the physical barrier, was significantly thicker in fish fed diets supplemented with cholesterol.
  • Improved chemical barrier: The activity of digestive enzymes (trypsin and lipase) increased, indicating better nutrient breakdown and absorption. Additionally, genes associated with tight junctions, which regulate the passage of molecules, were upregulated, suggesting a stronger barrier against harmful substances.
  • Improved immune barrier: Inflammation-related genes were downregulated in the groups that received cholesterol supplements, indicating reduced intestinal inflammation.
  • Balanced microbiome: The diversity and populations of beneficial bacteria within the gut microbiota significantly improved with cholesterol supplementation.

Optimal level for gut health

While cholesterol supplements at both 0.6% and 1.2% produced benefits, the 1.2% level appeared to be the most optimal dose. It resulted in the most significant improvements across the four components of the intestinal barrier.

Conclusion: The way forward

“Cholesterol supplementation in a concentration range of 0.6% to 1.2% in plant-based diets exhibits the potential to enhance intestinal tight junction function and improve gut microbiota composition, thereby significantly promoting tilapia gut health,” the scientists conclude.

Thus, the study focuses on understanding the role of cholesterol in tilapia health when fed plant-based diets. Future research is needed to:

  • Optimize cholesterol levels: Determine the ideal amount of cholesterol supplements needed for optimal intestinal health and growth in tilapia.
  • Explore broader application: Investigate the potential benefits of cholesterol supplementation in other fish species raised on plant-based feeds.
See also  Ocean Acidification and Human Health

By exploring innovative solutions like cholesterol supplementation, we can unlock the full potential of sustainable plant-based feeds in tilapia aquaculture, ensuring a healthy and thriving aquaculture industry.

The study was funded by the China Agriculture Research System and the Central Public Interest Scientific Institution Basal Research Fund.

Contact
Ming Jiang
Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences
Wuhan, China
Email: jiangming@yfi.ac.cn

Reference
Jiang, J., Lu, X., Dong, L., Peng, D., Zhang, J., Tian, J., Wen, H., & Jiang, M. (2024). Dietary cholesterol intervention could alleviate the intestinal injury of Oreochromis niloticus induced by plant-based diet via the intestinal barriers. Fish & Shellfish Immunology, 150, 109621. https://doi.org/10.1016/j.fsi.2024.109621