Vitamin E deficiency disrupts the supply of nutrients to the brain that are crucial to neuronal health, making the case for why vitamin E is necessary for brain health, especially in utero.
The findings show that embryos produced by vitamin E-deficient zebrafish have malformed brains and nervous systems. Scientists often use zebrafish in studies because they develop quickly, going from a fertilized egg to a swimming fish in just five days.
They are also very similar to humans at molecular, genetic and cellular levels, making the findings especially relevant to humans.
"Why does an embryo need vitamin E? We've been chasing that for a long time," noted Maret Traber, professor in the OSU College of Public Health and Human Sciences, who led the research.
The research, published in Scientific Reports, set out to test whether vitamin E is necessary for nervous system development, scientists fed adult zebrafish either Vitamin E sufficient (E+) or deficient (E-) diets, which were spawned to obtain E+ and E− embryos, and then expressed and quantitated their genes using in situ hybridization and RT-PCR methods.
"What we know is the vitamin E-deficient embryos lived to 24 hours and then started dying off,” explained Traber. “At six hours there was no difference, by 12 hours you see the differences but they weren't killing the animals, and at 24 hours there were dramatic changes that were about to cause the tipping point of total catastrophe."
"This is totally amazing — the brain is absolutely physically distorted by not having enough vitamin E," said Traber.
In healthy organisms, neural crest cells detach from the neural tube and migrate to help build the nervous system and form cartilage and bones.
"Acting as stem cells, the crest cells are important for the brain and spinal cord and also go on to be the cells of about 10 different organ systems including the heart and liver," explained Traber. "By having those cells get into trouble with vitamin E deficiency, basically the entire embryo formation is dysregulated. It is no wonder we see embryo death with vitamin E deficiency."
Traber, who has been researching Vitamin E for three decades, pointed out, "With this newest study we actually started taking pictures so we could visualize: Where is the brain? Where is the brain forming? How does vitamin E fit into this picture?"
Without vitamin E, the zebrafish embryos showed neural tube and brain defects.
"They were kind of like folic acid-deficient neural tube defects, and now we have pictures to show the neural tube defects and brain defects and that vitamin E is right on the closing edges of the cells that are forming the brain," Traber said.
The study could have key ramifications for women of childbearing age.
"Plants make eight different forms of vitamin E, and you absorb them all, but the liver only puts alpha-tocopherol back into the bloodstream," said Traber. "All of the other forms are metabolized and excreted. I've been concerned about women and pregnancy because of reports that women with low vitamin E in their plasma have increased risk of miscarriage."
According to the National Institute of Health, most vitamin E is obtained from the oils of soybean, canola, corn and other vegetables. The best sources of the vitamin are nuts and seeds such as sunflower seeds, almonds and hazelnuts. Vegetables like avocados, spinach and broccoli also contain significant amounts of vitamin E.
Source: Scientific Reports
Sci Rep 10, 15028 (2020) doi.org/10.1038/s41598-020-71760-x
"Vitamin E is necessary for zebrafish nervous system development"
Authors: B. Head et al