Functional foods and the immune system: a review.

In the last decade, preventive medicine has undergone a great advance, especially in developed countries. Research has demonstrated that nutrition plays a crucial role in the prevention of chronic diseases, as most of them can be related to diet. Functional food enters the concept of considering food not only necessary for living but also as a source of mental and physical well-being, contributing to the prevention and reduction of risk factors for several diseases or enhancing certain physiological functions. In reference to the immune system, many studies have pointed out that not only pre- and probiotics, but also single micronutrients incorporated into functional foods contribute to an enhancement of immunocompetence. In fact, one of the authorized claims consists of pointing out the immunomodulator properties of functional foods. In this article, the effect of some functional foods and ingredients such as probiotics, selenium and dietary antioxidants (vitamins A, E and C) on the immune function are reviewed. However, the optimum intake level and recommended amounts of functional foods have not yet been established. Thus, in order to remove the controversy surrounding functional food, further research studies are necessary, both in experimental animals and in humans. Finally: efforts should be directed towards the ultimate goal, that is, a 'functional diet'.

The implication of the binomial nutrition-immunity on sportswomen's health.

The diet of many athletes is inadequate due to overly restrictive habits and an obsession with losing weight in order to maintain a particular level of body weight. Many female athletes, particularly those who participate in sports that emphasize leanness (gymnastics, distance running, diving, figure skating and classical ballet), have suboptimal energy and nutrient intakes and are at risk of compromised nutritional status, including fatigue, dehydration, nutrient inadequacies, delayed growth and an impaired immunocompetence. It is very well known that active women and girls who are driven to excel in sports may develop the so-called female athlete triad in which malnutrition, amenorrhoea and osteoporosis appear as typical signs of medical complications, frequently linked to serious psychological alterations. This outcome is mainly related to that found in eating disorders-syndromes in which athletes have been defined to be at increased risk. As a consequence of all these alterations, the immune system may be affected in athletes, and subsequently they might be more prone to infections. As there is a lack of knowledge about how the immune system may be affected in basal conditions of athletes, the study of immunocompetence as an index of the nutritional status is reviewed. In summary, it is necessary to encourage all professionals surrounding athletes to be aware of the importance of taking care of their nutritional status in order not only to avoid physical and psychological complications but also to improve performance and, thus, to achieve sporting goals.

Chronobiological features of the immune system. Effect of calorie restriction.

The circadian organization of living organisms is fully established being a key component the activity of the neuro-endocrin-immune system that maintains the homeostasis. Secondary lymph organs, such as submaxillary lymph nodes and spleen, have been shown to exhibit a 24 h variation in blastogenic proliferative capacity and distribution of B and T subsets, with specific achrophases depending on the parameter studied or the lymphoid organ considered. However, less is known about the thymus. The immune system has been shown to change by calorie restriction, although no information is available about possible effects in 24 h variations. Similar questions can be posed for the neuro-endocrine system. As an example, some data are shown in this article about the effects of calorie restriction on the neuro-endocrin-immune system in growing male Wistar rats. Calorie restriction blunted the circadian secretory pattern of TSH observed in the control group that was characterized by the existence of two peaks at 17:00 or 01:00 h and that explained the low basal metabolic rate of these animals under this experimental condition. Concerning the immune system, the thymus gland exhibited 24 h variations in T, B and immature cells in both control and calorie-restricted male rats, thus confirming the circadian organization of the immune system. Moreover this circadian organization was changed by calorie restriction.

Decreased food efficiency ratio, growth retardation and changes in liver fatty acid composition in rats consuming thermally oxidized and polymerized sunflower oil used for frying.

Changes in food intake, body weight, liver weight, hepatosomatic index and hepatic fatty acid composition were studied in growing male Wistar rats fed a diet containing sunflower oil that had been used repeatedly for frying. During a period of 27 days, the animals were fed semi-synthetic diets containing either 15% used oil with 19.1% polar material (group 2) or 15% unused oils with 5.1% polar material (group 1). Although food intake was similar in both experimental groups, final body weight, body weight gain, food efficiency ratio and protein efficiency ratio were significantly lower in group 2. The increase of the hepatosomatic index in rats of group 2 seems related to a higher ingestion of potential toxic components (dimers and polymers of triglycerides and oxidized triglycerides) by this group. The livers of nine out of the 10 animals studied also showed moderate fibrotic degenerative areas with severe vacuolization, together with regenerative areas containing eosinophilic binuclear hepatocytes. In addition, livers of group 2 animals showed a 12% higher content of arachidonic acid. Data suggest that higher arachidonic acid levels would be needed for regeneration to palliate liver injury. These data suggest that frying sunflower oil is potentially toxic; assessment of risk is therefore necessary for frying fats with a high polar content.

Maternal body weight gain and fetus development of rats fed a moderately altered olive oil.

The present study examines whether the consumption of a moderately altered olive oil influenced body weight gain and food efficiency ratio of pregnant rats as well as placental and fetal development. Olive oil used for frying 15 times undergoes a relatively slight alteration involving a statistically significant increase in polar content (9.0+/-0.1 mg/100 mg oil vs 2.0+/-0.1 mg/100 mg oil; p < 0.001). The methyl ester content also increased (5.1+/-0.8 mg/100 mg oil vs 1.8+/-0.5 mg/100 mg oil; p < 0.02), while the linoleic acid and oleic acid contents decreased significantly (6.2+/-0.6% oil vs 7.2+/-0.2% oil and 75.8+/-0.6% vs 78.9+/-0.2%, respectively, both p < 0.05). Wistar rats were divided into four groups, two of which included pregnant rats (P1 and P2) and the other two, non-pregnant rats (NP1 and NP2). Groups NP1 and P1 received a diet containing 15% of fat as unused olive oil, while groups NP2 and P2 were fed a diet with a fat content of 15% as the olive oil used in 15 fryings. Pregnancy increased food intake, body weight, weight gain and food efficiency ratio (P1 vs NP1, and P2 vs NP1), while consumption of the used olive oil diet with respect to the unused oil diet did not alter food intake, body weight, weight gain and food efficiency ratio, placental weight, fetal weight and the number of fetuses in P2 rats with respect to P1 ones. These results suggest that in pregnant rats consumption of olive oil with a moderate level of alteration, as the only dietary fat source, exerts no detrimental effects on the mother weight gain or conceptus development.

Nutritional status of young female elite gymnasts.

The purpose of this study was to evaluate the nutritional status of a group of 10 young female elite gymnasts aged 13-17 years, who do a physical exercise of 48 h/wk. Assessment included dietary intake for 7 days, body mass index, ideal body weight, and skinfold thickness. In addition, the number of total leukocytes, total lymphocytes and lymphocyte subsets CD2, CD3, CD4, CD8, CD19 and CD56 were counted. The results were compared with a control group consisting of 50 volunteer students doing less than 12 h/wk of physical exercise, who were matched by sex, age, and sociocultural level. The total weekly calorie intake was lower in gymnasts than in controls; gymnasts showed a higher calorie intake from dietary protein together with a lower calorie intake from lipid and carbohydrate sources in comparison with controls. All the anthropometric parameters, except height which was not different in the two groups, were lower in gymnasts than in controls. The lymphocyte and leukocyte counts were also lower in gymnasts in relation to controls, except CD19 and CD56 subsets which were similar in both groups. It is suggested that gymnasts are at risk of malnutrition, which when compounded with intense physical exercise could lead to immunosuppression in these athletes.

[Effect of the diet on the nutritional status of ballerinas: immunologic markers]. / Influencia de la dieta en el estado nutricional de bailarinas: marcadores inmunológicos.

UNLABELLED: Athletes have special nutritional needs that will vary with sex, age, body composition and most importantly by the type, intensity, frequency and duration of the physical exercise. However the diet of certain groups of athletes such as ballet dancers is inadequate due to overly restrictive habits as a consequence of their obsession with losing or maintaining a low body weight that reflects an aesthetic preference for thinness. Physical exercise implies energy expenditure and thus, an increase in the energy intake is required to avoid possible situations of malnutrition. Both a negative energy balance and physical exertion have been shown to induce immunological changes which have been implicated as a possible explanation for increased susceptibility to illness and infections. OBJECTIVE: To find out the influence of a restricted energy intake on the immune system of 14 ballet dancers (20-25 h/w) in comparison with a control sedentary group (n = 23) by evaluating dietetic, anthropometric and some immunological parameters. RESULTS: Ballet dancers consumed a hypocaloric diet (mean: 1555 kcal), the energy intake being significantly lower than in the control group. None of both groups showed a similar calorie profile to the recommended intake for Spanish population, especially fat percentage was higher than it should. Regarding weight, ideal body weight and BMI values, no significant differences were shown between both groups. However, all the skinfolds thickness and the sum of skinfolds were significantly lower in ballet dancers than in controls. Leukocytes, lymphocytes and all lymphocyte subset counts were lower in ballet dancers in comparison with controls. CONCLUSIONS: In view of these results, ballet dancers may suffer from an impaired nutritional status, determined by a depletion of anthropometric and immunological parameters. The nutritional requirements for this population should be increased in order to compensate their high-energy expenditure, avoid a negative energy balance and lessen the nutritional damage.

Lipaemia and liver composition in pregnant rats consuming olive oil and olive oil used for frying.

The effect of the consumption of unused olive oil (polar content, 2%; oleic acid, 78.9 mg/100 mg oil, and linoleic acid 7 mg/100 mg oil) and olive oil used discontinuously for frying potatoes 15 times (polar content, 9%; oleic acid, 75.8 mg/100 mg oil and linoleic acid 6.2 mg/100 mg oil) was studied in pregnant rats with the aim of better understanding the relationship between the consumption of fat used in frying and lipid metabolism during periods of intense anabolism. Trials were performed in pregnant Wistar rats, divided into 2 groups and fed isocaloric diets in which the fat content (15% wt/wt) consisted of unused olive oil (P1) or oil previously used for frying (P2), and the results were compared with those of nonpregnant rats fed unused olive oil (NP1) and olive oil used for frying (NP2). Pregnancy increased (p < 0.01) food intake, body weight, weight gain, and food efficiency ratio (P2 vs NP2 and P1 vs NP1, respectively), but the treatment of oil included in the diets did not alter these parameters. Gestation significantly increased the serum triglyceride (TG) (p < 0.01) and total cholesterol (TC) (p < 0.05) concentrations and diminished that of phospholipids (PH) (p < 0.01). A significant effect of the type of oil consumed and a pregnancy x oil interaction on Tg and PH levels was observed. The weight of the liver and its fat content increased significantly (p < 0.05) as a result of pregnancy. Liver TC, TG, and PH increased (approximately 3 times the original values) during gestation, but no significant differences due to the intake of used or unused oil (P2 vs P1) were observed. The results indicate that the consumption of moderately altered olive oil, as the sole source of fat, does not alter the effect of pregnancy on the mothers' weight gain, lipaemia, and hepatic fat composition to any important degree.

Relationship between chemical and physical indexes and column and HPSE chromatography methods for evaluating frying oil.

Standard chemical and physical indexes, such as color index, acid value, and K270 were compared with the polar content and the specific thermoxidative and hydrolytic compounds originated during 75 potato fryings with sunflower oil. The color index, acid value, K270 and total polar content showed a significant increase (p < 0.05) after the first 30 fryings, followed by a tendency of the last three indexes to reach a near-steady state. Triglyceride polymers and triglyceride dimers showed a significant increase (p < 0.05) after 30 fryings, while the oxidized triglycerides were not increased significantly after 30 fryings. The amount of diglycerides and free fatty acids related to hydrolytic alteration did not change significantly throughout the frying operations. The significant correlations between acid value and total polar content, triglyceride dimers, triglycerides polymers and oxidized triglycerides, or between color index and polar content and triglyceride polymers or between K270 and triglyceride polymers indicate that these simple and standard methods can be applied and they are as useful as more specific methods of evaluation in the monitoring of frying operations, provided that initial values of all of these indexes are available.

Influencia del binomio nutrición-inmunidad en la salud del deportista / Influence of the binomium nutrition-immunity on the athlete’s health

La dieta de ciertos grupos de deportistas es restrictiva e inadecuada como consecuencia de la obsesión por mantener un bajo peso corporal con el fin de obtener un óptimo rendimiento deportivo. Así, en determinados colectivos de deportistas, en especial de mujeres deportistas, donde se enfatiza en exceso la delgadez (gimnasia, carreras de fondo, natación sincronizada, patinaje artístico, danza clásica), la ingesta energética no alcanza las recomendaciones, produciéndose en la mayoría de los casos déficits nutricionales. Como consecuencia de ello se produce fatiga, deshidratación (desequilibrio de electrolitos), bajo peso, amenorrea (en la mujer), retraso del crecimiento, disminución de la densidad ósea, sistema inmunitario comprometido e incluso trastornos del comportamiento alimentario. A esta situación, muchos autores la denominan triada del deportista y este término se refiere a tres factores que se encuentran íntimamente relacionados: desorden alimentario, amenorrea y osteoporosis. Como consecuencia de estas alteraciones, el sistema inmunitario de estas deportistas se encuentra afectado, produciéndose un aumento de la susceptibilidad a sufrir infecciones. De ahí la importancia de concienciar a los profesionales que trabajan en estas disciplinas deportivas de la importancia de una adecuada nutrición que consiga no solo una mejora del rendimiento sino que evite posibles complicaciones médicas en estos grupos de deportistas (AU)