Adult rats’ sodium appetite linked to early polyunsaturated fat deficiency

The World Health Organization recommends a daily intake of five grams of salt a day – just under a teaspoon – but in most western countries, people are consuming around double that amount. This latest research suggests that deficiency of polyunsaturated fats, found in high amounts in fish, nuts and seeds, early in life could contribute to high sodium appetite in adulthood.

In two separate experiments, the Australian researchers fed female rats one of two diets prior to mating until weaning of offspring, differing only in their dietary fat source. In the first experiment, they were given safflower oil, contributing less than 0.1 percent alpha-linoleic acid (ALA, a short-chain polyunsaturated fat acid) or canola oil, contributing 1.2 percent ALA. Pups were then weaned at five weeks onto one of two crossover diets, either maintaining the level of ALA or changing to the other experimental condition.

In the second experiment, the ALA amounts were less than 0.1 percent and 0.8 percent respectively. However, pups were weaned onto a crossover diet earlier, at three weeks instead of five.

Referring to both experiments, the authors wrote: “Our findings indicate that inadequate dietary ω-3 PUFA ​[polyunsaturated fatty acids] during development results in an exaggerated sodium appetite later in life.”​

Sodium consumption​

When the pups reached 26 weeks of age, the researchers measured their intake of a sodium solution – provided alongside water and food – over a three-day period, prior to depriving them of the sodium solution for 24 hours. Then sodium intake was then measured for five days.

“In both experiments presented in this report the raising diet had an impact on sodium appetite response to sodium depletion,” ​the researchers wrote. “…The results suggest that the mechanisms involved in sodium appetite are influenced by the diet present in early development.”​

They speculated that consuming fewer polyunsaturated fatty acids early in life may affect the rennin-angiotensin system of hormones, a system involved in both the control of sodium appetite and blood pressure.

“Dietary ω-3 PUFA are known to influence expression of genes involved in ion channel formation, signal transduction, and synaptic plasticity,” ​they concluded. “Dietary ω-3 PUFA manipulation may induce these changes in brain gene expression resulting in altered sodium appetite.”​

Source: Appetite​

Published online ahead of print

“Sodium appetite in adult rats following ω-3 polyunsaturated fatty acid deficiency in early development”​

Authors: R.S. Weisinger, J.A. Armitageb, N. Chenc, D.P. Begga, M.L. Mathaic, A.P. Jayasooriyac, A.J. Sinclaird, and H.S. Weisinger