Proline supplementation stimulates immune system


If you’re suffering from flu, or youve just had a vaccination against a nasty bacteria or unpleasant virus, then supplementation with the amino acid proline [structural formula shown here] can give your immune system a boost. At least, that’s what you’d expect after reading the results of the animal study by scientists at the Chinese ministry of agriculture that’s about to be published in Amino Acids.

Proline is not an essential amino acid. It is found in gelatin, but your body also makes it by converting L-ornithine. Nevertheless, proline is an important amino acid. It plays a key role in the healing of wounds and the functioning of the immune system. The latter aspect caught the attention of the Chinese.

Vaccines often contain small quantities of aluminium hydroxide. This compound makes vaccines more effective, but also inhibits immune cells. There must be a better way doing things, the Chinese thought – so they went in search of an alternative. They hope they’ve found this in the form of proline.

The Chinese performed experiments with mice. The mice were injected with a vaccine against the bacteria Pasteurella multocida. A control group were given no vaccine [Control].

The first group of vaccinated mice were given two injections containing a vaccine only [V-O]; the second group were given a vaccine with aluminium hydroxide [V-H]. The third group were given food that had been enriched with the amino acid L-alanine for a month [V-A], and a vaccine without aluminium hydroxide. The fourth group was given food for a month that contained 0.4 percent L-proline, and a vaccine without aluminium hydroxide. The Chinese used amino acids produced by Ajinomoto.

At the end of the month the Chinese injected the lab animals with Pasteurella multocida. Two days later all mice in the Control group were dead.


The mice that had had a vaccine that contained aluminium hydroxide [V-H] all survived. Not all mice in the V-A and the V-O group survived. But the mice that had been given proline in their food, and had had vaccines without aluminium hydroxide, all survived too.

The researchers were not able to uncover exactly how proline helps the immune system to work better. They did see slightly higher levels of antibodies in the blood of the proline mice than in the blood of the animals in the V-A and V-O groups.


“To our knowledge, this is the first study to determine the adjuvant effect of proline in mammals”, the researchers write. “Our findings have important implications for preventive medicine in humans and animals.”

So doing a quick calculation: a mouse eats about 4 g food per day. If the diet consists of 0.4 percent L-proline, that works out at 16 mg proline. The mice weighed 20 g. Per kg bodyweight they therefore ate 800 mg proline. Converted to human proportions, that means 80 mg per kg bodyweight. So if you weigh 80 kg you would need about 6 g proline per day to stimulate your immune system.

Dietary L-proline supplementation confers immunostimulatory effects on inactivated Pasteurella multocida vaccine immunized mice.

Ren W, Zou L, Ruan Z, Li N, Wang Y, Peng Y, Liu G, Yin Y, Li T, Hou Y, Wu G.


Key Laboratory of Agroecology and Processing of Subtropical Region, Institute of Subtropical Agriculture, Research Center for Healthy Breeding of Livestock and Poultry, Hunan Engineering and Research Center for Animal and Poultry Science, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central China, The Chinese Academy of Science, Ministry of Agriculture, 410125, Changsha City, Hunan, People’s Republic of China.


This study was conducted to determine the immunostimulatory effect of L-proline on inactivated vaccine immunized mice. Ninety-five female KM mice were randomly divided into five groups: (1) mice received dietary supplementation with 0.4 % L-proline and immunized with inactivated vaccine (V-P group); (2) mice received dietary supplementation with 0.3 % L-alanine (isonitrogenous control) and immunized with inactivated vaccine (V-A group, negative control); (3) mice were immunized with inactivated vaccine with oil adjuvant (V-O group, positive control); (4) mice were immunized with inactivated vaccine with aluminum hydroxide adjuvant (V-H group, positive control); (5) mice immunized with phosphate-buffered saline (control group). All mice were dead in the control group between 36 and 48 h post infection. Mice in the V-P group showed 100 % protection after challenge with P. multocida serotype A (CQ2) at dose of 4.4 × 105 CFU (2LD50). Meanwhile, serum antibody titers in the V-P group were higher than those in the V-A group before infection and those in the V-A and V-O groups at 36 h post infection. Moreover, serum IL-1? levels in the V-P group were lower than those in V-O group. Furthermore, serum GSH-PX levels in the V-P group were higher than those in the V-A and V-O groups. Collectively, dietary proline supplementation confers beneficial immunostimulatory effects in inactivated P. multocida vaccine immunized mice.

PMID: 23584431 [PubMed – as supplied by publisher]