Vitamin E significantly improves immune function in sea cucumbers, new study finds

Krystal Kasal
contributing writer

Gaby Clark
scientific editor

Robert Egan
associate editor

Sea cucumbers (Apostichopus japonicus) have been slowly disappearing from ocean floors over the last few decades, mostly due to overfishing for food and medicinal purposes. Despite their name, sea cucumbers are aquatic animals that have been shown to have a positive impact on coral in the ocean, as they reduce detrimental sediment while feeding on nearby bacteria and microalgae. To combat their decreasing natural populations, sea cucumbers are now often cultivated and farmed in a controlled commercial setting.
However, sea cucumbers, like many other commercially farmed species, are vulnerable to disease in intensive aquaculture because they lack adaptive immunity. The use of antibiotics for disease control is problematic because it can lead to bacterial resistance and environmental issues from residual antibiotic leakage. Consequently, there is a need for alternative methods to keep sea cucumber stocks healthy.
Since vitamin E supplementation has been shown in prior studies to be beneficial for some aquatic creatures, a new study, in the journal Biology, has tested out the effect of vitamin E on farmed sea cucumbers to determine if supplementation of the vitamin might help reduce the need for antibiotics.
For the experiment, 180 healthy sea cucumbers were separated into groups and given either 0, 200, or 400 mg/kg of vitamin E along with their food for 21 days. The study also sought to determine the relationship between vitamin E and the Nodal gene, a gene tied to collagen synthesis that leads to healthier intestinal lining.
Around half of each of these three groups was also given a substance that knocks down Nodal gene expression through RNA interference. After the experiment, the sea cucumbers' growth, immune enzyme activities, intestinal histology, collagen content, and gene expression were analyzed.
Overall, the group given 200 mg/kg of vitamin E without Nodal gene knockdown showed significantly improved growth, immune enzyme activities and intestinal morphology, compared to the other groups. As expected, all groups with Nodal gene knockdown experienced reduced growth, intestinal damage and impaired collagen synthesis, but these results were especially pronounced in the group without vitamin E added to their diet.
"These detrimental effects were partially alleviated by the addition of 200 mg/kg vitamin E. Thus, the beneficial effects of vitamin E on intestinal function could be attributed to enhanced intestinal antioxidant capacity and collagen synthesis through a Nodal-dependent pathway," the study authors write.
The theory is that both the Nodal gene and vitamin E enhance immune function through beneficial changes in the gut of sea cucumbers. This is done by a combination of promoting collagen synthesis and improving the intestinal structure through the Nodal pathway.
The researchers also noted that the higher vitamin E doses of 400 mg/kg did not produce additional benefits, compared to the 200mg/kg dose, and actually showed signs of detrimental effects.
The researchers explain, "When administered at high levels, vitamin E was reported to promote the generation of reactive oxygen species through redox cycling mechanisms, which in turn induced oxidative stress, disrupted cellular membranes and organelles, and ultimately led to structural damage of the intestinal tissue. In this study, evident intestinal damage and a significant reduction in antioxidant capacity were observed in the group treated with 400 mg/kg vitamin E."
As overfishing and bacterial resistance to antibiotics become more of an issue, sustainable aquaculture is vital for maintaining a reliable food supply, as well as protecting the environment and wild sea cucumber populations. This and similar studies can provide alternative pathways to sustainability. The study authors say that these findings may apply to other aquaculture species and encourage others to build upon this work by exploring the effects of other nutritional immune stimulants.
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More information: Zitong Wang et al, Vitamin E Enhances Immune Function and the Intestinal Histological Structure by Regulating the Nodal-Mediated Signaling Pathway: A Case Study on the Sea Cucumber Apostichopus japonicus, Biology (2025).
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