Amino acids are necessary for the health of animal and human. They were traditionally classified as essential and non-essential based on nitrogen balance or growth. It is unfortunate that dietary requirements of non-essential amino acids (NEAA) still have not been recommended for animals and humans. NEAAs can be synthesized de novo in adequate amounts by the animal organism. Scientists assumed that all NEAAs were synthesized sufficiently in the body to meet the needs for maximal growth and health. Is their assumption according to the truth? There has been no compelling experimental evidence to support this assumption over the past century.

 

Researchers from Department of Animal Science, Texas A&M University and laboratory of animal nutrition and health and key laboratory of agro-ecology, Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA), and other cooperating organizations summarized the physiological functions of NEAAs, which can regulate the synthesis of nitric oxide, carbon monoxide, and hydrogen sulfide, and these molecules participate in gaseous signaling in cells through cGMP and cAMP production to enhance blood flow, nutrient transport, protein deposition. In general, NEAAs influence lactation, reproduction, nutrient metabolism, immune responses, anti-oxidative defense and other physiological functions. The research group also has a discussion on the requirement of NEAAs in diets.

The research team considered that the classic concept of ‘‘the ideal protein’’ should include both essential amino acids and NEAAs to improve food efficiency, growth, and health of mammals, including humans, birds, and fish. “NEAAs play important roles in regulating gene expression, cell signaling, anti-oxidative responses, neurotransmission, and immunity. NEAAs also regulate various cellular processes, including gene expression; nutrient metabolism; cell proliferation, differentiation, and migration; mitosis and cell survival; cell cycle progression; cell survival and apoptosis; and inflammatory responses. NEAAs are substrates for the synthesis of many nitrogenous substances with important functions. Some of these bioactive molecules include carnosine, creatine, glutathione, neurotransmitters, polyamines, taurine, and low-molecular-weight hormones. NEAAs can regulate the utilization of dietary protein by bacteria in the lumen of small intestine. Additionally, glutamate, glutamine and aspartate are major metabolic fuels for the small intestine to maintain its digestive function and protecting its mucosal integrity. NEAAs should be taken into consideration in “ideal protein” concept and formulating balanced diets to improve protein accretion, food efficiency, and health in animals and humans. ” said Yin yulong, a professor at ISA.

The research was supported by National Research Initiative Competitive Grants from the Animal Reproduction Program (2008-35203-19120) and Animal Growth and Nutrient Utilization Program (2008-35206-18764) of the USDA National Institute of Food and Agriculture, AHA (10GRNT4480020), Texas A&M Agri-Life Research (H-8200), the National Natural Science Foundation of China (no. u0731001, 30810103902, 30928018, 30972156, 31172217 and 31272450), China Postdoctoral Science Foundation (2012T50163), Chinese Universities Scientific Funds (No. 2012RC024), and the Thousand-People Talent program at China Agricultural University.

The study entitled “Dietary requirements of ‘‘nutritionally non-essential amino acids’’ by animals and humans” has been published in the April issue of Amino acids, details could be found at http://link.springer.com/article/10.1007%2Fs00726-012-1444-2