Salvador Zamora

Relationship between fat cell size and number and fatty acid composition in adipose tissue from different fat depots in overweight/obese humans

Objective:To evaluate the body fat distribution and fat cell size and number in an overweight/obese population from both genders, and to determine the possible relationship between fat cell data from three different adipose tissue localizations (subcutaneous (SA), perivisceral and omental) and adipose tissue composition and dietary fatty acid.Design:The sample consisted of 84 overweight/obese patients (29 men and 55 women) who have undergone abdominal surgery. The adipocyte size and total fat cell number was studied. Fat cell data were related with anthropometric, adipose tissue and subjects habitual diet fatty acid composition.Measurements:Fat cell size was measured according to a Sjöström method from the three adipose depots. Total fat cell number was also calculated. The fatty acid composition of adipose tissue was examined by gas chromatography. The subjects diet was studied by a 7 days dietary record.Results:Our data showed a negative relationship between the adipocyte size and the n-6 and n-3 fatty acids content of the SA adipose tissue (r=−0.286, P=0,040; r=−0.300, P=0.030) respectively, and the n-6 in the omental depots (r=−0.407, P=0.049) in the total population. Positive associations with the total of saturated (r=0.357, P=0.045) and negative (r=−0.544, P=0.001) with the n-9 fatty acids were observed when the relationship between the adipocyte number and the fatty acid composition of the different anatomical fat regions was studied. Dietary fatty acids composition positively correlated with fat cell size for the myristic acid (14:0) in men in the visceral depot (r=0.822, P=0.023), and for the saturated fatty acids (SFAs) in women in the omental depot (r=0.486, P=0.035).Conclusion:In the present study, for the first time in humans we found that n-3 and n-6 fatty acids are related to a reduced adipocyte size according to the depot localization. In contrast, adipose tissue and dietary SFAs sinificantly correlated with an increase in fat cell size and number. No significant associations were found between n-9 acids content and adipocyte size. However, n-9 adipose tissue fatty acids content was inversely associated with fat cell number showing that this type of fatty acid could limit hyperplasia in obese populations. The differences observed in the three different regions, perivisceral, omental and SA fat, indicate that this population adipose tissue have depot-specific differences.

Dietary trans fatty acids in early life: a review

Trans fatty acids are unsaturated fatty acids with at least a double trans configuration, resulting in a more rigid molecule close to a saturated fatty acid. These appear in dairy fat because of ruminal activity, and in hydrogenated oils; margarines, shortenings and baked goods contain relatively high levels of trans fatty acids. These fatty acids can be incorporated into both fetal and adult tissues, although the transfer rate through the placenta continues to be a contradictory subject. In preterm infants and healthy term babies, trans isomers have been inversely correlated to infantile birth weight. However, in multigenerational studies using animals, there is no correlation between birth weight, growth, and dietary trans fatty acids. Maternal milk reflects precisely the daily dietary intake of trans fatty acids, from 2% to 5% of the total fatty acids in human milk. The level of linoleic acid in human milk is increased by a high trans diet, but long-chain polyunsaturated fatty acids remain mostly unaffected. Likewise, infant tissues incorporate trans fatty acids from maternal milk, raising the level of linoleic acid and relatively decreasing arachidonic and docosahexaenoic acids. This suggests an inhibitory effect of trans fatty acid on liver Delta-6 fatty-acid desaturase activity. As opposed to blood and liver, the brain appears to be protected from the trans fatty-acid accumulation in experimental animals, but no data have yet been reported for human newborns. Further investigations in humans are needed to definitively establish the potential physiological consequences of trans fatty-acid intake during the neonatal period.

Dietary fructooligosaccharides and potential benefits on health

Fructooligosaccharides (FOS) are oligosaccharides that occur naturally in plants such as onion, chicory, garlic, asparagus, banana, artichoke, among many others. They are composed of linear chains of fructose units, linked by β (2-1) bonds. The number of fructose units ranges from 2 to 60 and often terminate in a glucose unit. Dietary FOS are not hydrolyzed by small intestinal glycosidases and reach the cecum structurally unchanged. There, they are metabolized by the intestinal microflora to form short-chain carboxylic acids, L -lactate, CO2, hydrogen and other metabolites. FOS have a number of interesting properties, including a low sweetness intensity; they are also calorie free, non-cariogenic and are considered as soluble dietary fibre. Furthermore, FOS have important beneficial physiological effects such as low carcinogenicity, a prebiotic effect, improved mineral absorption and decreased levels of serum cholesterol, triacylglycerols and phospholipids. Currently FOS are increasingly included in food products and infant formulas due to their prebiotic effect stimulate the growth of nonpathogenic intestinal microflora. Their consumption increases fecal bolus and the frequency of depositions, while a dose of 4–15 g/day given to healthy subjects will reduce constipation, considered one of the growing problems of modern society, and newborns during the first months of life.

Effect of three feeding strategies (automatic, ad libitum demand-feeding and time-restricted demand-feeding) on feeding rhythms and growth in European sea bass (Dicentrarchus labrax L.)

Abstract We studied the effect of automatic-feeding (A), ad libitum demand-feeding (D) and time-restricted demand-feeding (RD) on the feeding rhythm and growth performance of European sea bass maintained under natural summer conditions. RD and A had access to feed during three meals a day of 1 h duration each (08:00–09:00, 16:00–17:00 and 00:00–01:00). Feeding demands in D showed daily rhythms that varied according to both water temperature and photoperiod. When submitted to system RD, their feeding patterns were strongly associated with periods of feed availability. Feeding strategies affected both biomass increase and feed efficiency ratio, the worst results being obtained in A. On the other hand, the feeding system had no effect on body composition nor on weight homogeneity of the different groups. These results showed that sea bass can adapt to different feeding strategies, although for maximum benefit to be gained from the diet, these strategies should reflect the feeding rhythms of the fish.

Annual Rhythms of Demand-Feeding Activity in Sea Bass: Evidence of a Seasonal Phase Inversion of the Diel Feeding Pattern

Seasonal changes in the phasing of diel feeding rhythms were investigated in sea bass held under natural conditions. Demand-feeding behavior was continuously monitored over a complete annual cycle in 10 groups of 15 fish maintained in an outdoors laboratory subjected to natural fluctuations of photoperiod (from 9.5h to 15h) and water temperature (from 13.2 degrees C to 27.4 degrees C). A double seasonal phase inversion was detected in all groups: fish that were diurnal in summer and in autumn changed to nocturnal in winter and returned to being diurnal in spring. Diurnal sea bass displayed a positive and stable phase relationship between the peak of the feeding phase and the daily acrophase of water temperature (phi l = 0.72h +/- 0.33h) and between the peak of the feeding phase and sunset (phi s = 2.94h +/- 0.53h), but both phi l and phi s became negative when sea bass shifted to nocturnalism in winter. The percentage of diurnal feeding behavior peaked in June (94.1%) and dropped in February (29.1%), following a cyclic dynamic modulated by both monthly photoperiod and water temperature. These results contribute to better understanding of the dual phasing behavior of sea bass, which exhibits diurnal or nocturnal behavior according to the time of the year so that flexibility in phasing may be advantageous for the fish to cope with seasonal changes in their environment.

Light-dark and food restriction cycles in sea bass: Effect of conflicting zeitgebers on demand-feeding rhythms

Sea bass, a fish species characterized by its dualistic feeding pattern, was investigated to study the synchronizing effect of light and food on the demand-feeding rhythm. Nocturnal and diurnal sea bass, both in groups and individually, were exposed to restricted-feeding (RF) and light-dark (LD) cycles of different periods. The phase relationship between both zeitgebers was also studied. The results show that food-demand rhythms synchronize to periodic food availability under constant light conditions (DD) and that there is a partial coupling between food-entrained and light-entrained activity under conflicting zeitgebers (LD 13:13 h and RF 4:20 h), suggesting the existence of a feeding entrainable oscillator (FEO) in addition to the master light entrainable oscillator (LEO). In some cases, food availability restricted to the light or dark phase contrary to that of the previous feeding phase changed a diurnal feeding pattern into nocturnal and viceversa, suggesting that food can be one of the switching factors that decides whether the circadian system of sea bass is nocturnal or diurnal. However, the fact that the feeding pattern of some fish was unrelated with the phase in which food was available suggests that other internal and/or external factors could be involved in the temporal flexibility of sea bass.

Demand feeding and locomotor circadian rhythms in the goldfish, Carassius auratus: Dual and independent phasing

In contrast to the common diurnal and nocturnal ways of life, some fish species have been shown to have a dual phasing behaviour. Therefore, the daily pattern of behaviour is not always rigidly confined to the light or dark phase and a diurnal fish may become nocturnal and vice versa. In the present study, the locomotor and feeding activities of single goldfish were simultaneously investigated to examine the existence of such dual behaviour. Nineteen goldfish weighing 97.2 g on average were placed individually in 35-1 glass tanks equipped with an infrared sensor and a newly developed self-feeding device. Fish were exposed to a light:dark (LD) 12:12 h cycle, constant darkness (DD), and 45:45 min LD pulses to study endogenous rhythmicity. Under LD 12:12, the daily pattern of behaviour differed between individual fish; some goldfish were diurnal and others were nocturnal. Furthermore, some of them displayed an extraordinary flexibility in phasing because they were light active but dark feeding, and vice versa. Generally, goldfish tended to be day active, although their feeding habits appeared equally distributed between light and dark phases. Under DD, goldfish showed free-running rhythms that averaged 25.3 +/- 1.8 h and 24.4 +/- 1.7 h for locomotor activity and feeding, respectively, but that were slightly shorter under LD pulses. These results indicate that the type of phasing of locomotor activity did not necessarily decide the feeding phase; much of this is explained by the fact that goldfish were self-fed. Flexibility in phasing and a certain degree of independence between locomotor and feeding activities could be seen as an adaptative response of the highly adaptable circadian system of fish.

Differences in dietary intake and activity level between normal-weight and Overweight or obese adolescents

BACKGROUND To investigate the prevalence of overweight and obesity in an adolescent group representative of a rural Mediterranean area and to determine possible associations with energy and nutrient intakes and levels of physical exercise. METHODS A representative sample of adolescents was drawn from the secondary school of Torre Pacheco (Murcia), a rural Mediterranean area located in the southeast of Spain. The population selected (331 adolescents aged 14-18 years), was divided into two groups: normal-weight subjects with a body mass index less than 23 kg/m2 and overweight or obese subjects with a body mass index of 23 kg/m2 or more. Weight, height, abdominal and hip perimeters, triceps skinfold, and upper arm circumference were measured. A prospective 7-consecutive-days food record and physical activity questionnaire were completed. RESULTS Overweight boys and girls had an apparently lower energy intake (P = 0.001 and P = 0.042, respectively), and carbohydrate intake (P = 0.000, P = 0.032) than their normal-weight counterparts, but they tended to underreport more often. Overweight boys derived a greater percentage of their energy from fat (P = 0.049) and less from carbohydrate (P = 0.016) than their normal-weight counterparts. Among girls, the percentage of energy derived from fat increased with body mass index (r = 0.210, P = 0.008), whereas fiber intake decreased (r = -0.145; P = 0.041). Overweight and obesity were negatively related to physical activity level only among boys (P = 0.033). CONCLUSION There is a high prevalence of overweight and obesity in the adolescent population studied (48.2% in boys and 30.7% in girls). The study shows an association between overweight and obesity and nutrient intake and activity level.

Placental transfer of fatty acids and fetal implications

Considerable amounts of long-chain polyunsaturated fatty acids (LC-PUFAs), particularly arachidonic acid and docosahexaenoic acid (DHA, 22:6n-3), are deposited in fetal tissues during pregnancy; and this process is facilitated by placental delivery. Nevertheless, the mechanisms involved in LC-PUFA placental transfer remain unclear. Stable isotope techniques have been used to study human placental fatty acid transfer in vivo. These studies have shown a significantly higher ratio of (13)C-DHA in cord to maternal plasma compared with other fatty acids, which reflects a higher placental DHA transfer. In addition, a selective DHA accumulation in placental tissue, relative to other fatty acids, has been reported. The materno-fetal transfer of fatty acids is a slow process that requires ≥12 h. A high incorporation of dietary (13)C-DHA into maternal plasma phospholipids appears to be important for placental uptake and transfer. DHA in cord blood lipids correlates with placental messenger RNA expression of fatty acid transport protein (FATP)-4, compatible with a role of FATP-4 in DHA transfer. Impaired materno-fetal LC-PUFA transport has been proposed in pregnancies complicated by abnormal placental function (eg, due to gestational diabetes mellitus or intrauterine growth restriction), which should be addressed in future studies. Given that placental DHA transfer is important for child outcomes, elucidation of its potential modulation by transport mechanisms, maternal diet, and disease appears to be important.

Feeding entrainment of locomotor activity rhythms in the goldfish is mediated by a feeding-entrainable circadian oscillator

Abstract Periodic food availability can act as a potent zeitgeber capable of synchronizing many biological rhythms in fishes, including locomotor activity rhythms. In the present paper we investigated entrainment of locomotor rhythms to scheduled feeding under different light and feeding regimes. In experiment 1, fish were exposed to a 12:12 h light/dark cycle and fed one single daily meal in the middle of the light phase. In experiment 2, we tested the effect of random versus scheduled feeding on the daily distribution of activity. During random feeding, meals were randomly scheduled with intervals ranging from 12 to 36 h, while scheduled feeding consisted of one single daily meal set in the middle of the light or dark phase. Finally, in experiment 3, we studied the synchronization of activity rhythms to feeding under constant darkness (DD) and after shifting the feeding cycle by either advancing or delaying the feeding cycle by 9 h. The results revealed that goldfish synchronized to feeding, overcame light entrainment and significantly changed their daily distribution of activity according to their feeding schedule. In addition, the daily activity pattern modulated by feeding differed between layers: a peak of activity being noticeable directly after feeding at the bottom, while an anticipatory behaviour was obvious at the surface of the tank. Under DD and no food, free-running rhythms averaging 25.5 ± 1.9 h (mean ± SD) were detected. In conclusion, some properties of feeding entrainment (e.g. anticipation of the feeding time, free-running rhythms following termination of periodic feeding, and the stability of ø after shifting the feeding cycle) suggested that goldfish have (a) separate but tightly coupled light- and food-entrainable oscillators, or (b) a single oscillator that is entrainable by both light and food (one synchronizer being eventually stronger than the other).