Glutamate and glutamine: Nonessential or essential amino acid

Abstract Text:

Rose defined an essential amino acid as one that the body cannot make in sufficient amounts to maintain growth or nitrogen balance.  Despite Rose’s finding that glutamate added to diets of traditionally essential amino acids improved the maximal rate of growth, glutamate and glutamine are not usually considered as essential.  In part this is due to the almost total metabolism of dietary glutamate and glutamine in the intestine, and the very high concentration, and turnover, of these two amino acids in the body.   In human medicine however, glutamine has been recognized as a conditionally essential amino acid during hypercatabolic states and while such conditions are not a concern in the domestic animal industry, the question arises “is glutamine conditionally essential at other times”?  We observed that plasma and skeletal muscle glutamine concentrations fall throughout lactation in both horses, pigs and mice, and that this was accompanied by a loss of skeletal muscle.  We proposed that this was due to the high demand for glutamine (and glutamate) both for milk production and as a fuel for the enlarged maternal intestine.  Furthermore, the provision of supplemental glutamine to both suckling and weaned piglets has demonstrated improvements in growth and health, most probably related to improved intestinal status and immune function.   The daily supplementation of suckling piglets is not feasible on an industrial scale and we established that supplementing lactating sows with either glutamine, or a mixture of glutamine and glutamate, increased the glutamine and glutamate content of the milk and also prevented some of the loss of lean body mass in the sow.  Furthermore, sows receiving the supplement had higher concentrations of lipids in both colostrum and mature milk, and similar increases were seen in milk somatic cell count.  Thus we propose that glutamate and glutamine should be considered essential both during lactation for the health of both the mother and the neonate.  

Keywords:  Glutamine, Glutamate, Lactation,