Nutritional control of immunity: Balancing the metabolic requirements with an appropriate immune function

The immune system is a highly integrated network of cells sensitive to a number of environmental factors. Interestingly, recent years have seen a dramatic increase in our understanding of how diet makes a crucial contribution to human health, affecting the immune system, secretion of adipocytokines and metabolic pathways. Recent experimental evidence indicates that diet and its components are able to profoundly influence immune responses, thus affecting the development of inflammatory and autoimmune diseases. This review aims to discuss some of the main topics concerning the impact of nutrients and their relative composition on immune cell development and function that may be particularly important for regulating the balance between inflammatory and tolerogenic processes. We also highlight the effects of diet on commensal bacteria and how changes in the composition of the microbiota alter intestinal and systemic immune homeostasis. Finally, we summarize the effects of dietary compounds on epigenetic mechanisms involved in the regulation of several immune related genes.

Dietary phosphate restriction in dialysis patients: a new approach for the treatment of hyperphosphataemia

BACKGROUND AND AIM

Elevated serum phosphate and calcium-phosphate levels play an important role in the pathogenesis of vascular calcifications in uraemic patients and appear to be associated with increased cardiovascular mortality. We aimed to evaluate the effects of a partial replacement of food protein with a low-phosphorus and low-potassium whey protein concentrate on phosphate levels of dialysis patients with hyperphosphataemia.

METHODS AND RESULTS

Twenty-seven patients undergoing chronic haemodialysis were studied for a 3-month period. In the intervention group (n = 15), food protein were replaced by 30 or 40 g of low-phosphorus and low-potassium protein concentrate aimed at limiting the phosphate intake. In the control group (n = 12) no changes were made to their usual diet. Anthropometric measurements, biochemical markers and dietary interviews were registered at baseline and during the follow-up period. From baseline to the end of the study, in the intervention group, serum phosphate and circulating intact parathyroid hormone levels lessened significantly (8.3 ± 1.2 mg/dL vs 5.7 ± 1.4 mg/dL and 488 ± 205 pg/ml vs 177 ± 100 pg/ml respectively; p < 0.05) with decreasing of phosphate and potassium intake. No significant differences were found in the control group. No significant changes were observed in serum albumin, calcium, potassium, Kt/V, body weight and body composition in both the intervention and control groups.

CONCLUSION

Dietary intake of phosphate mainly comes from protein sources, so dietary phosphorus restriction may lead to a protein/energy malnutrition in a dialysis patient. A phosphorus-controlled diet plan including a nutritional substitute resulted in serum phosphate and intact parathyroid hormone decrease without nutritional status modifications in dialysis patients.

No difference in the 24-hour interstitial fluid glucose profile with modulations to the glycemic index of the diet

OBJECTIVE

Reducing the glycemic index (GI) of the diet may decrease metabolic risk, primarily through reduction and stabilization of blood glucose. The objective of this research was to investigate whether incorporation of lower or higher GI foods into mixed meals had different effects on daylong glucose profiles, measured in interstitial fluid by a continuous glucose-monitoring system.

METHODS

The study was a randomized, balanced, two-way crossover intervention of 2 x 1-wk periods of lower and higher GI diets. Participants were 12 overweight healthy adult women (mean body mass index +/- standard deviation 27.5+/-2.3 kg/m(2)). Changes in GI were achieved through substitution of key staple carbohydrate-rich foods. After a 4-d run-in on each dietary regimen, participants wore the continuous glucose-monitoring system over 2 d of identical controlled feeding in the laboratory, separated by 1 d of ad libitum consumption at home.

RESULTS

On controlled days, diets differed in GI by 15 U and provided equal energy, macronutrients, and fiber. On ad libitum days, diet diaries revealed a difference in GI of 14+/-1 U (mean +/- standard error), with no detectable difference in energy, macronutrient, or fiber intake. No differences were observed in glucose profiles between higher and lower GI interventions in the controlled or ad libitum setting. There was significant agreement in area under the glucose curve on repeated controlled feeding days (intraclass correlation 0.75).

CONCLUSION

This study indicates that a difference in dietary GI of 14-15 U is insufficient to alter daylong glycemia as measured in interstitial fluid by the continuous glucose-monitoring system.

Body mass index and bioelectrical vector distribution in 8-year-old children

OBJECTIVE

To describe bioelectrical impedance vector distribution in relation to BMI (body mass index; body weight/stature(2)) in a population of healthy children in order to detect possible changes in body composition status.

DESIGN

Observational study involving 464 healthy 8-year-old children. The subjects were divided into three groups based on their BMI: 218 normal weight (NW) children with BMI<18.4 for male and BMI<18.3 for female; 135 overweight (OW) children with BMI 18.4 to <21.6 for male and with BMI 18.3 to <21.6 for female; 111 obese (OB) children with BMI>/=21.6. Skinfold thickness was measured at the triceps using a Holtain caliper. Bioelectrical impedance analysis (BIA) measurements were performed. Total body water (TBW), fat-mass (FM), fat-free mass (FFM), body cell mass (BCM) and extra-cellular water (ECW) were estimated using conventional BIA regression equations. The resistance-reactance graph (RXc graph) method was used for vector BIA using as reference population the set of 353 children with BMI 14.0-21.5kg/m(2).

RESULTS

Mean vector displacement followed a definite pattern, with progressive vector shortening in groups with increasing BMI class, and along a fixed phase angle. This pattern indicates an increase in TBW due to an increase in soft tissue mass with an average, normal hydration. In NW children, vectors out of the right and upper half of the 75% tolerance ellipse indicating leanness, and vectors falling out of the right and lower half of the tolerance ellipse indicating undernutrition, show a significantly reduced value of BCM but no significant differences in FM or triceps skinfold thickness (TST), respectively, compared to vectors falling within the 75% tolerance ellipse.

CONCLUSIONS

Although BMI is a reliable measure to grade overweight, it cannot differentiate whether weight change is due to variation of FM, FFM or water. In our study a different impedance vector pattern has been associated with normal weight to obesity, and we have established the trajectory followed by the impedance vector of standardized age, healthy children grouped by BMI. This BIVA may be useful for clinical purposes due to ability to detect changes in hydration or body composition in children.

Role of dietary intervention on metabolic abnormalities and nutritional status after renal transplantation

BACKGROUND

In these last years, several traditional risk factors for cardiovascular disease, like obesity, dyslipidaemia, hypertension and post-transplant diabetes mellitus have been also identified as important non-immunological risk factors leading to the development of chronic allograft nephropathy, the first cause of graft loss in transplanted patients. The aim of the present study was to determine the effects of a 12-month dietary regimen on the nutritional status and metabolic outcome of renal transplant recipients in the first post-transplant year.

METHODS

Forty-six cadaver-donor renal transplant recipients (mean age 40.8 +/- 10.1-years), enrolled during the first post-transplant year (4.8 +/- 3.3 months) and followed prospectively for a 12 month period. Biochemical and nutritional markers, anthropometric measurements, body composition (by conventional bioelectrical impedance analysis) and dietary records (using a detailed food-frequency questionnaire) at baseline and after 12 months.

RESULTS

Compliance to the diet was related to sex (male better than female) and was associated with weight loss primarily due to a decrease in fat mass, with decrease in total cholesterol and glucose plasma levels and with a concomitant rise in serum albumin.

CONCLUSION

After renal transplantation, health benefits of proper metabolic balance that include reduced body fat, weight loss, lower cholesterol and triglycerides levels and an improvement, fasting glucose levels can be obtained when dietary intervention occurred.

Bioelectrical impedance analysis and age-related differences of body composition in the elderly

BACKGROUND AND AIM

Significant changes in body composition that have important health related effects may occur in the elderly. In this study, we evaluated the bioelectrical characteristics in a large group of apparently healthy Caucasian men in the age range 50-80 years, as a function of age and body mass index.

METHODS

We studied 315 men with ages ranging from 50 to 80 years. They were divided into three groups according to body mass index (kg/m(2)): 18.5-24.9 normoweight (NW); 25.0-29.9 overweight (OW); > or =30 obese (OB), and they were classified in nine age subgroups: 50-59 (young-old, YO); 60-69 (old, O); 70-80 (oldest, OS). Fat-free mass, fat mass and body cell mass were investigated using conventional bioelectrical impedance analysis. Body composition was also assessed by bioelectrical impedance vector analysis and the RXc graph method.

RESULTS

Body cell mass decreased significantly with age particularly in subgroups of the OW and OB groups (p<0.05). Mean vector displacement followed a definite pattern, with downward migration of the ellipses in the OW and OB groups, after 70 years of age.

CONCLUSIONS

Ageing was associated with a pattern of vector bioelectrical impedance analysis indicating decreased soft tissue mass (fat-free mass and body cell mass), particularly in OW and OB-OS healthy men. We suggest 70 years of age as a cut-off for significant quantitative and qualitative (tissue electrical properties) body composition modifications. This bioelectrical impedance vector analysis pattern associated with ageing and across the different body mass index categories, may be useful for clinical purposes and can be used in geriatric routine to accurately assess the body composition modifications occurring in the elderly.

Body composition and cardiovascular risk factors in pretransplant hemodialysis patients

BACKGROUND

Obesity, hyperlipemia and cardiovascular complications contribute to a significant proportion of morbidity and mortality of renal transplant patients and have negative effects on renal survival. Aim of the present study was to evaluate the main abnormalities in body composition and the prevalence of some cardiovascular risk factors in a population of hemodialyzed (HD) patients awaiting renal transplantation.

METHODS

We studied 151 HD patients, all included in a waiting list for renal transplantation, 97 males and 54 females, with mean age 47.4+/-12 years. Patients were divided into three groups according to their body mass index (BMI) (kg/m2): 18.5 to 24.9 (normoweight, NW); 25.0 to 29.9 (overweight, OW); > or =30 (obese, OB). The body composition measurements were obtained the day after the mid-week HD session using bioelectrical impedance analysis (BIA).

RESULTS

We found that 47 patients were NW (31%), while 56 were OW (37%), and 48 were OB (32%). BIA-measured body cell mass was (BCM) significantly increased in the OW as compared with the NW group (P<0.001), but, of note, no significant difference was found in OB group in comparison with the OW. Total cholesterol and triglycerides plasma levels were significantly elevated in OW and OB patients with respect to NW (P<0.05) and an increased prevalence of diabetes was seen in OB patients (NW: 6%, OW: 5%, OB: 12%).

CONCLUSIONS

These data show that a large proportion of patients awaiting renal transplant are overweight or obese and a consistent part of them have other cardiovascular risk factors associated. Furthermore, obese HD patients have a BCM lower than predicted on the basis of BMI and show an altered metabolic profile. A better understanding of the characteristics of patients included in the renal transplant waiting list is crucial in order to design prospective studies that aim to define the proper risk profile for the selection of patients.

Nutritional intervention in a hemodialysis pregnant woman: a case report

Pregnancy in dialysis patients is a rare occurrence. When pregnancy does occur, the risk of spontaneous abortion, stillbirth and neonatal complications, such as prematurity and growth retardation, are fairly high. The authors describe their experience in the follow-up of a patient with chronic renal failure who became pregnant during regular dialysis treatment and followed nutritional care. The outcomes were successful and she gave birth to a healthy baby. It is emphasized that special dedication to the nutritional control enabled a good outcome of the pregnancy. The importance of the nutritionist intervention in the follow-up of dialysis patients with the integration of a multidisciplinary staff is stressed.

Impedance vector distribution by body mass index and conventional bioelectrical impedance analysis in obese women

BACKGROUND AND AIM

To compare the body fluid status assessments provided by conventional bioelectrical impedance analysis (BIA) and vector BIA in moderate and severe obesity.

METHODS AND RESULTS

We studied 516 normotensive Caucasian women (mean age: 48 +/- 9.2 years), who were age-matched and divided into four groups on the basis of their body mass index (BMI): 99 normal weight women with a BMI of 19-25 Kg/m2; 228 preobese overweight women with a BMI of 25-30 Kg/m2; 132 women with class I-II obesity (BMI: 30-35 Kg/m2), and 57 women with class III obesity (BMI: 40-64 Kg/m2). Single-frequency (50 kHz) tetrapolar (hand-foot) bioelectrical impedance measurements were made, and total body water (TBW) and extracellular water (ECW) were estimated using conventional BIA regression equations. The RXc graph method was used for vector BIA, with the set of 327 women with a BMI of 19-30 Kg/m2 being adopted as the reference population. Mean vector displacement followed a definite pattern, with progressive vector shortening as the BMI increased, and along a fixed phase angle. This pattern indicates more TBW due to a greater soft tissue mass with average normal hydration. Short and downsloping vectors indicating fluid overload were more frequent in the group with class III obesity than in the group with class I obesity (19 vs 5%). The absolute values of TBW and ECW were significantly higher in the obese and overweight subjects than in those with normal weight subjects. TBW as a percentage of body weight was significantly lower in the obese subjects.

CONCLUSIONS

BMI influenced the impedance vector distribution pattern, which proved to be consistent up to a BMI of 64 Kg/m2. Obese women with an altered body composition can be identified and monitored using vector BIA.

HCV and GBV-c/HGV infection in HIV positive patients in southern Italy

Flaviviridae-hepatitis C virus (HCV) and GB virus C/hepatitis G virus (GBV-C/HGV)--and human immunodeficiency virus (HIV) frequently show similar modes of transmission. HCV and GBV-C/HGV infection was assessed in 134 consecutive patients with evidence of HIV infection, living in Campania, Italy. Data obtained from this cohort were compared with those obtained from 252 age- and sex-matched HCV infected patients without evidence of HIV infection (HCV control group). Following enzymatic immunoassays, samples were tested for the presence of HCV-RNA by RT-PCR. The HCV-RNA positive sera were genotyped by LiPA procedure. The prevalence of HCV infection in HIV patients was 19.40% and the largest group of HIV-HCV co-infected patients (84.62%) was represented by intravenous drug users (IVDU). The distribution of HCV genotypes in HIV-HCV patients was different, compared to that observed in HCV control group. HCV genotypes la (50%) and 3a (23.08%) were more frequently detected in HIV HCV patients, compared to HCV control group (5.16 and 5.56% for la and 3a, respectively). Conversely, HCV genotypes lb (55.70%) and 2a/2c (30.26%) were more represented in HCV control group, compared to HIV-HCV patients (15.38 and 0% for lb and 2a/2c, respectively). GBV-C/HGV seroprevalence was 41.04% in HIV patients and 6.54% in healthy control individuals. Differently from HCV, GBV-C/HGV infection did not correlate to a preferential risk behaviour in the HIV cohort. Comparative analysis of HCV and GBV-C/HGV infection indicates that the use of injecting drugs might play a key role in the epidemiology of HCV and, in particular, of la and 3a HCV genotypes, in HIV patients.