Nutri-information

OMEGA 3 AND DISEASE Of ALZHEIMER

Preceding studies had suggested that the docosahexaénoïque acid (DHA) could appear useful in the treatment of the disease of Alzheimer, but this new study is the first, according to the researchers, to show that it could delay or prevent the development of the disease late in the life.

In this study, researchers examined the effects of the DHA on mice produced to develop the cerebral plates associated with the disease with Alzheimer.

A group of animals received a food resembling a typically American food with ten times more fatty-acids omega-6 than of omega-3, as those which one finds in the sunflower or groundnut, corn oils. A high report/ratio omega-6 on omega-3 is associated with an increase in the risk of many diseases. 

Three other groups of animals were nourished with a healthier food bringing a 1:1 report/ratio of omega-6 on omega-3. One received a supplementation in DHA and two other groups, DHA more of the fatty-acids omega-6. The quantities of calorie and protein, carbohydrates were identical in all the modes.

 
After three months, all the mice having received a food rich in DHA had lower beta-starch protein levels and tau that those in the reference group. But at the end of nine months, only the mice receiving the food only enriched in DHA had lower levels of these two proteins.

The researchers concluded from it that these results suggested that the DHA better only acted that associated with the fatty-acids omega-6 and that studies on the man were now necessary to evaluate how the fatty-acids omega-3 could act against the disease of Alzheimer.

(Newspaper off Neuroscience, April 18,2007, vol. 27, News release, University off California, Irvine.)

LEUCINE AGAINST SARCOPENIE

The decline of the muscular mass with the age is often synonymous with loss of autonomy and fall of quality of life. Studies in the old rat suggest that meals rich in leucine could stimulate the synthesis of proteins and block their degradation.

The muscle being the principal protein reserve of the organization, the fall of the mass and the force muscular at the elderly (or sarcopénie) predisposes with the falls, with the risk of fractures that comprises. In the same way, the sarcopénie increases susceptibility to the infections, the stress, and represents finally a high cost. Because of the similarities existing in the man and the rodents with regard to deteriorations of the skeletal muscle with ageing, the rats were selected as model experimental for better including/understanding the physiopathological mechanisms in question.

Variations during the day…

During the day, there exist fluctuations of the muscular mass: the periods of fast (between the meals) correspond to a proteinic catabolism at the expense of the muscle, but, after the following meal, stocks are reconstituted with, again, a phase of proteinic anabolism. The muscular mass thus fluctuates during the day, while remaining constant from one day to the next, at least as long as the protein losses are compensated by an identical profit.

At the man, studies showed that, if the synthesis of body proteins depends on hormonal and nutritional factors, in fact especially the amino-acids play a key function in their storage, in phase postprandiale. In fact, when the content of proteins of a meal increases, passing from 0,36 to 2,77 g/kg/j, the synthesis of body proteins is more stimulated and the degradation of muscular proteins, more inhibited. At least, in the still young adult.

… And according to the age

The other work completed in young rats and old rats (which measured the speed of degradation of proteins of the muscle after a meal) showed that, with the advance in age, the food catch did not manage any more to inhibit both and before the degradation of muscular proteins. In the old animals, there exists, after the meals, a defect of regulation of the principal way of degradation of contractile muscular proteins. In the same way, the stimulation of the synthesis of proteins after a meal would be less. For lack of compensation of the proteinic losses by the food catch, the decline of the muscular mass would be then inexorable: about 0,5 to 2% per annum. Moreover, at the man, the reduction in this thin mass would be associated with an increase in the storage of the lipids, so noxious for the organization.

The role of leucine

However leucine seems to play a key function in the control of the proteinic mass. It would act by giving a signal able to control the protéosynthèse and the proteolysis. In the old rat, studies clearly showed that the only fact of adding leucine to the food was enough to restore at the same time the synthesis of proteins and to block their degradation. A mode rich in leucine could thus allow a real saving of muscular proteins and, therefore to fight against the sarcopénie of the elderly…

Dr. Nathalie Szapiro - Source: QUOTIMED- June 2007

According to a communication of Didier Attaix, Dominique Dardevet, Lydie Combaret and Laurent Mosoni, unit of human nutrition and research center in human nutrition of Auvergne, Inra Clermont-Ferrand.