Rebalancing essential amino acids intake by self-selection in the rat

Area of Science:

• Nutritional Science
• Animal Behavior

Background:

• Dietary choices are crucial for meeting essential amino acid requirements.
• Rats typically avoid nutritionally imbalanced or inadequate diets.

Purpose of the Study:

• To determine if rats can self-select appropriate proportions of two essential amino acid-deficient diets.
• To investigate if rats can overcome aversion to inadequate diets when offered a choice.

Main Methods:

• Rats were presented with a choice between a protein-free diet and a diet lacking either threonine or isoleucine.
• Diet proportions were designed to achieve nutritional balance if consumed in specific ratios (1/3 and 2/3).
• Preliminary tests identified aversions to individual diets, except for a 60 g casein/kg diet.

Main Results:

• Rats successfully selected proportions that nearly met essential amino acid requirements, with a slight excess of isoleucine.
• Rats did not show aversion to the individually aversive diets when offered together.
• Rats gained body weight when allowed to consume both inadequate diets.

Conclusions:

• Rats possess a sophisticated ability to rebalance nutrient intake through dietary selection.
• The presence of multiple food options can override learned aversions to nutritionally inadequate diets.