The nature and significance of nutritional adaptation

Abstract

Possible adaptations to a low protein intake are: a decrease in the obligatory nitrogen loss, which would be too small to detect in short-term studies, but would be signi®cant over a longer term; an increase in the ef®ciency of protein utilization, which has been demonstrated in depleted subjects; and a decrease in lean body mass, mainly at the expense of muscle. However, we do not know the extent to which this last mechanism may really be an adaptation without signi®cant functional loss.In the case of energy there is controversy about the extent to which the gross ef®ciency of muscular work can be improved. One mechanism might be an alteration in the distribution of ®bre types, with a shift from fast to slow ®bres. A possible way of reducing the cost of both muscular work and basal metabolism would be a reduction in the mitochondrial proton leak. Both these mechanisms are at least partially under the control of the thyroid gland, which therefore may play an important role in economizing energy expenditure.

A concept of dietary dipeptides: a step to resolve the problem of amino acid availability in the early life of vertebrates

“…In fed animals, weight gains usually arise as a result of increased protein synthesis and decreased protein degradation in comparison with fasted animals (Waterlow, 1999). Several factors are pivotal in determining the effectiveness of these processes, such as concentrations and correct proportions, i.e.…”

The biology of the colonizing ape

“…Childhood growth can also exhibit more minor fluctuations in relation to ecological pressures such as climatic conditions (Weitz et al, 2004). Studies of exposure to chronic low energy intake have demonstrated adaptability in metabolism, ergonomics, mechanical efficiency, and muscle structure (Waterlow, 1999), illustrating the capacity to maintain function across a range of ecological conditions. Equally, the 20th century showed a major secular trend in growth in industrialized populations (Cole, 2003), especially during the first 2 years after birth, with girls in particular reaching puberty and ceasing growth at substantially earlier ages (Garn, 1987;Karlberg, 2002).…”

Nutrition et santé : lipides et protéines d’origine végétale - De nouvelles données pour juger de la qualité des protéines végétales chez l’homme - Implications et perspectives

“…Ce point reste controversé, certains auteurs arguant que les capacités d'adaptation métabolique de l'organisme à long terme lui permettent de diminuer de manière très importante le besoin en certains acides aminés [31,50], si bien que même les régimes exclusivement à base de céréales ne poseraient aucun problème nutritionnel, dans la mesure où l'apport énergétique est assuré [51]. Ces considérations restent cependant théoriques car il y peu de données expérimentales pour évaluer l'étendue des capacités d'adaptation [52,53]. Les conséquences de ces "adaptations" ou de ces "accommodations", sont également difficiles à évaluer [53].…”

“…Ces considérations restent cependant théoriques car il y peu de données expérimentales pour évaluer l'étendue des capacités d'adaptation [52,53]. Les conséquences de ces "adaptations" ou de ces "accommodations", sont également difficiles à évaluer [53]. D'un point de vue plus pragmatique, dans le cadre des populations des pays industrialisés, une certaine diversité des sources protéiques assure la bonne utilisation des différentes protéines alimentaires.…”