Dietary modulation of body composition and insulin sensitivity during catch-up growth in rats: effects of oils rich inn-6 orn-3 PUFA

Abstract

The present study investigates whether excessive fat accumulation and hyperinsulinaemia during catch-up growth on high-fat diets are altered by n-6 and n-3 PUFA derived from oils rich in either linoleic acid (LA), a-linolenic acid (ALA), arachidonic acid (AA) or DHA. It has been shown that, compared with food-restricted rats refed a high-fat (lard) diet low in PUFA, those refed isoenergetically on diets enriched in LA or ALA, independently of the n-6:n-3 ratio, show improved insulin sensitivity, lower fat mass and higher lean mass, the magnitude of which is related to the proportion of total PUFA precursors (LA þ ALA) consumed. These relationships are best fitted by quadratic regression models (r 2 . 0·8, P,0·001), with threshold values for an impact on body composition corresponding to PUFA precursors contributing 25-30 % of energy intake. Isoenergetic refeeding on high-fat diets enriched in AA or DHA also led to improved body composition, with increases in lean mass as predicted by the quadratic model for PUFA precursors, but decreases in fat mass, which are disproportionately greater than predicted values; insulin sensitivity, however, was not improved. These findings pertaining to the impact of dietary intake of PUFA precursors (LA and ALA) and their elongated -desaturated products (AA and DHA), on body composition and insulin sensitivity, provide important insights into the search for diets aimed at counteracting the pathophysiological consequences of catch-up growth. In particular, diets enriched in essential fatty acids (LA and/or ALA) markedly improve insulin sensitivity and composition of weight regained, independently of the n-6:n-3 fatty acid ratio.Key words: Obesity: Thermogenesis: Programming and insulin sensitivity: Weight regain It has long been known from studies of nutritional rehabilitation in malnourished humans and other mammals that the recovery of body fat occurs at a disproportionately faster rate than that of lean tissue deposition (1,2) , independently of the level of dietary energy or protein supplementation (1,3,4) . This phenomenon of preferential catch-up fat, with lean tissue recovery lagging, has been demonstrated not only during weight recovery in adults who have lost weight in response to poverty and famine-related malnutrition (1 -4) , anorexia nervosa (5) and disease-related cachexia (6 -8) , but also during nutritional rehabilitation of undernourished children (9 -12) and in young adolescents recovering from anorexia nervosa (13,14) . In more recent years, there has also been a resurgence of interest into this phenomenon of preferential catch-up fat in infants and younger children, primarily because its occurrence concomitant to hyperinsulinaemia during catch-up growth (15 -19) is viewed to be of central importance in the mechanisms by which catch-up growth predisposes to obesity, type 2 diabetes and CVD later in life (20 -22) . Consequently, approaches that redirect nutrient partitioning from preferential catch-up fat to enhanced lean tissue accretion are of pote...

Overfeeding Polyunsaturated and Saturated Fat Causes Distinct Effects on Liver and Visceral Fat Accumulation in Humans

“…A previous supplementation trial in postmenopausal women reported that a daily dose of 8 g PUFA (safflower oil) increased lean tissue and reduced trunk fat (48). In accordance, rats isocalorically fed with PUFAs (high in linoleic acid) gained more lean tissue and less fat compared with an SFA-rich diet, in line with similar studies (16,17,49,50). The mechanism behind these observations remains to be determined.…”

“…In the current study, n-6 PUFAs were investigated, but it is possible that n-3 PUFAs have similar effects on body fat accumulation (50)(51)(52). The amount of sunflower oil used in the current study (;40 g per day) corresponds to about three times the customary intake of linoleic acid in the Swedish population.…”

A Role for Adipose Tissue De Novo Lipogenesis in Glucose Homeostasis During Catch-up Growth

“…Fatty acid analysis of tissues and diet were determined on extracted lipids by automated gas liquid chromatography as previously detailed (20). …”

Polyunsaturated Fatty Acids Stimulate De novo Lipogenesis and Improve Glucose Homeostasis during Refeeding with High Fat Diet

“…In the light of previous findings showing that the phenomenon of catch-up fat and the degree of insulin resistance during refeeding on a high fat (lard) diet can be ameliorated using high fat diets rich in safflower/linseed oil (polyunsaturated fatty acids (PUFA) of omega-6 and omega-3 series) (Dulloo et al, 1995; Yepuri et al, 2011), we investigated here the extent to which these metabolic improvements could be related to the regulation of de novo lipogenesis by these dietary fatty acids. To this end, we investigated here the regulation of the pathway of de novo lipogenesis by the different fatty acids in liver, WAT, and brown adipose tissue (BAT) using a high fat diet, rich in safflower/linseed oil (PUFA diet) or a high fat diet rich in lard (SFA-MUFA diet), given to rats during refeeding after a period of caloric restriction.…”