The nutritive value of single foods

Area of Science:

• Nutritional Science
• Animal Nutrition Studies
• Food Science

Background:

• Previous research indicated commercial bread alone could not sustain weanling rats.
• Criticism suggested other single foods would yield similar deficient results.
• This study addresses skepticism regarding the nutritional completeness of various single food items.

Purpose of the Study:

• To evaluate the nutritional adequacy of single foods when fed to animals.
• To compare the efficacy of biological testing versus food composition tables.
• To investigate the potential for improving deficient food products through supplementation.

Main Methods:

• Weanling rats were fed single diets including improved bread, milk, eggs, meat, breakfast cereals, and macaroni.
• Animal survival, growth rates, and signs of deficiency were monitored over a 90-day test period.
• Nutritional value was assessed through direct biological response rather than solely relying on composition data.

Main Results:

• Rats fed the improved bread demonstrated significantly faster growth.
• Eggs were found to be a remarkably complete food source.
• Milk was excellent until iron deficiency manifested; "enriched" cereals and macaroni were highly deficient.
• Biological testing revealed substantial nutritional differences not apparent from composition tables, e.g., puffed rice vs. eggs.

Conclusions:

• Biological testing provides a more accurate assessment of food nutritional value than composition tables.
• Dietary enrichment and supplementation can significantly improve the nutritional profile of certain foods.
• The nutritional completeness of single foods varies greatly, necessitating careful evaluation.