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High-vitamin diets in pregnant rats can alter their offspring’s brain development and behaviour, University of Toronto researchers have found. 

The study raises questions about the effects of diets, fortification of foods with nutrients and the use of vitamin supplements on prenatal brain development in humans.

The study looked at the effects of a high-vitamin A, D, E, and K diet during pregnancy on body weight gain, food intake and food preference in offspring. The results showed little effect on the rats’ weight gain and food intake, but their brain development and food preference were affected. For example, offspring showed changes in the brain dopamine system, which controls reward-seeking behaviour, and they had a decreased preference for sweetness.

“While this data provides novel information on the fundamental role of fat soluble vitamins in development in the rat brain, development stages are not the same as in the human,” said Harvey Anderson, the principal investigator on the study and a professor in the departments of nutritional sciences and physiology.

“Nevertheless, it is clear we know little about the effect of vitamins when taken above requirements on brain development.”

The journal published the results March 19.

Most of the research in this area has focused on preventing deficiencies and the toxicity of very high intakes. At the same time, there is little science on the effect of intakes above requirements. Current diets may be high in vitamins because of mandatory fortification, non-mandatory additions to foods such as cereals and increased consumption of health foods and vitamin supplements.

Anderson, who also serves as executive director of the new U of T Centre for Child Nutrition, Health and Development, hopes that the work of researchers at the Centre will help clarify implications for human mothers and children.

Many women consume better quality diets during pregnancy. At the same time, they are also likely to use vitamin supplements, putting them at risk for excessive vitamin consumption. Anderson says the relationship between human mothers’ vitamin intake and its effects on their children’s development needs close study in future research.

“Some of the Centre’s ongoing research on brain fat metabolism and maternal diet will help build on the findings of this study,” said Anderson. “It will help us develop new evidence to support better guidelines and policy, and improve childhood and maternal nutrition and health.”

Vitaly Kazakov is a writer with the Faculty of Medicine at the University of Toronto.