High-dose vitamin diets reduce sugar cravings: Rat study

By Niamh Michail

- Last updated on GMT

High-vitamin diets shown to effect reward circuitry for foods like sugar...in rats at least
High-vitamin diets shown to effect reward circuitry for foods like sugar...in rats at least
Baby rats whose mothers are given high levels of vitamins A, D, E, and K while pregnant have a reduced preference for sugar, say Canadian scientists.

However there was no impact on food intake, body weight gain or fat preference.

The scientists from the University of Toronto explained that the decreased preference for sucrose was likely due to the development of higher hedonic regulatory pathways associated with food preference.

Excessive doses

While research has confirmed that maternal vitamin intake is important for foetal brain development, the researchers wanted to look at the effects of doses higher than recommended levels. 

Due to high levels of supplement use, the fact that women tend to eat better while pregnant and food fortification becoming increasingly commonplace in developed countries, pregnant women are likely to exceed the recommended daily intake for vitamins, they said.

“Intake of multivitamin supplements during pregnancy in developed countries is likely to result in intakes greater than the recommended quantities. In addition, the safety and effectiveness of vitamin A and D supplementation specifically have been questioned. Accordingly, studies are needed to support recommendations for safe intakes, particularly for these vitamins.”

The scientists have called for more research into how the findings can be applied to human subjects.

"While these data provide novel information on the fundamental role of fat-soluble vitamins in brain development, the rat brain developmental stages are not the same as in the human," ​said Dr Harvey Anderson, co-author of the study which was published in the Journal ofApplied Physiology, Nutrition, and Metabolism.

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

The study

Pregnant female rats were allocated to two different food groups, one with high fat-soluble vitamins and one with the recommended amount of vitamins as a control. The female rats were kept on the diet during lactation.

The researchers weighed the rat pups at birth, during weaning and throughout the post-weaning period of 14 weeks. Food intake was calculated on a daily basis.

Preference for sucrose was assessed two weeks after weaning using a two-bottle preference test – offspring were simultaneously presented with two bottles filled with either water or a 4% sucrose solution. Preference for sucrose was measured as a percentage of the total fluid intake.

To evaluate the impact on brain development the scientists selected one pup from each female at three different time periods – at birth, during weaning and after 14 weeks – and dissected the pups’ brains. They analysed the DNA and gene expression of the hippocampus and hypothalamus.

The researchers found that while the gestational diet had no influence on body weight, food intake or fat preference, the high vitamin intake led to a 4% decrease in sugar preference among pups.

The effect of high-vitamin diets on reward circuitry is consistent with our past studies on pregnant rats and their offspring that demonstrates the role that vitamin composition has on regulating feeding behaviour.It may affect the development of higher hedonic regulatory pathways associated with food preference.”​ 

"The diet may have other behavioural consequences not examined in the present study. Because dopamine projections ... to the hippocampus also mediate memory and learning, future studies are needed to assess the impact of such vitamins on neurodevelopment and associated behaviours in the offspring later in life," ​the study added.

Source: Journal ofApplied Physiology, Nutrition, and Metabolism

Published online ahead of print 19 March 2015, dx.doi.org/10.1139/apnm-2014-0480

“A gestational diet high in fat-soluble vitamins alters expression of genes in brain pathways and reduces sucrose preference, but not food intake, in Wistar male rat offspring”

Authors: D Sanchez-Hernandez et al

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