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Summary Background & aims Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disease that is characterized by neurocutaneous changes with multisystem involvement. A previous study with adults with NF1 revealed that changes in total energy expenditure were related to food consumption and body composition. Resting energy expenditure (REE), a measure of energy that the body expends to maintain vital functions, has not been assessed in NF1 populations. This study aimed to assess REE in individuals with NF1 using indirect calorimetry (IC) and evaluate its correlation with body composition and muscle strength. Methods Twenty-six adults with NF1 (14 men) aged 18–45 years underwent IC for assessing REE, respiratory quotient (RQ), and substrate utilization. Body composition was assessed by dual energy X-ray absorptiometry. Weight, height, and waist circumference (WC) were also measured. Maximum muscular strength (Smax) was measured by handgrip test using a dynamometer. Patients in the NF1 group were compared to 26 healthy controls in the control group, who were matched by sex, age, body mass index (BMI), and physical activity level. Results There were no differences in weight, WC, fat mass, and body fat percentage (BFP). Appendicular lean mass (ALM) adjusted by BMI (ALMBMI) (0.828 ± 0.161 versus 0.743 ± 0.190; P = 0.048) and Smax (37.5 ± 10.6 versus 31.1 ± 12.2; P = 0.035) was lower in the NF1 group than in the control group. No differences in body composition, strength, and anthropometric parameters were observed in men, but women with NF1 presented lower body surface area (BSA), lean body mass (LBM), ALM, ALMBMI, and Smax. REE adjusted by weight, LBM, or ALM was higher in the NF1 group than in the control group (medians, 21.9 versus 26.3, P = 0.046; 36.5 versus 41.1, P = 0.012; and 82.3 versus 92.4, P = 0.006, respectively), and these differences were observed only among women. RQ was lower in the NF1 group than in the control group (0.9 ± 0.1 versus 0.8 ± 0.1; P = 0.008), revealing that individuals with NF1 oxidized more lipids and fewer carbohydrates than controls. REE correlated negatively with BFP and positively with weight, height, BMI, WC, BSA, LBM, ALM, ALMBMI, bone mineral content, and Smax. Conclusions Individuals with NF1, particularly women, presented with increased REE (adjusted by weight, LBM, or ALM) and lower RQ compared to healthy controls. These findings were associated with lower ALMBMI and Smax, possibly indicating premature sarcopenia in this population. Further investigation concerning energy metabolism in NF1 and gender differences may be helpful in explaining underlying mechanisms of these changes.

SUMMARY BACKGROUND Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disease characterized by multisystem involvement including low bone mineral density (BMD). OBJECTIVE To assess the bone phenotype of individuals with NF1 and verify its association with nutrient intake. METHODS Twenty-six adults with NF1 underwent bone phenotype assessments using dual-energy X-ray absorptiometry (DXA) and food intake evaluations. They were compared to 26 unaffected matched control patients. Weight, height, and waist circumference (WC) were measured. DXA provided total body, spine, and hip BMDs and bone mineral content (BMC) for all patients. Food intake was evaluated for energy, macro- and micro-nutrients. RESULTS Height (1.68 ± 0.1; 1.61 ± 0.1 cm; P = 0.003) and BMC (2.3 ± 0.4; 2.0 ± 0.5 kg; P = 0.046) were lower in the NF1 group. Individuals with NF1 also presented lower total body and spine BMDs (g/cm2) (1.1 ± 0.1, 1.0 ± 0.1, P = 0.036; 1.0 ± 0.1, 0.9 ± 0.1; P = 0.015, respectively). The frequency of total body bone mass below the expected level for patients’ ages was higher in the NF1 group (7.7%; 34.6%, P = 0.016). There were no differences in energy consumption. No correlations between BMC and BMD with nutrient intake were observed in the NF1 group. CONCLUSIONS The NF1 group presented lower BMCs and BMDs. Although a lower consumption of calcium, iron, and vitamin A, and a higher intake of sodium and omega-6 were observed, there was no relationship between bone phenotype and nutrient intake. RESUMO INTRODUÇÃO A Neurofibromatose tipo 1 (NF1) é uma doença genética autossômica dominante caracterizada por envolvimento neurocutâneo e multissistêmico, incluindo baixa densidade mineral óssea (DMO). OBJETIVOS Avaliar características ósseas em indivíduos com NF1 e verificar associação com a ingestão de nutrientes. METODOLOGIA 26 adultos com NF1 submeteram-se a avaliação dos parâmetros ósseos usando absorciometria com raios-X de dupla energia (DXA), além da avaliação da ingestão alimentar. O grupo NF1 foi comparado e pareado com 26 indivíduos sem a doença. Peso, estatura e circunferência da cintura foram avaliados. DXA forneceu o conteúdo mineral ósseo (CMO) e a DMO do corpo total, coluna e fêmur. A ingestão de calorias, macronutrientes e micronutrientes foi avaliada. RESULTADOS O grupo NF1 apresentou redução da estatura (1,68 ± 0,1; 1,61 ± 0,1 cm; P=0,003) e do CMO (2,3 ± 0,4; 2,0 ± 0,5 kg; P=0,046). Indivíduos com NF1 também apresentaram redução da DMO de corpo total e coluna (g/cm2) (1,1 ± 0,1, 1,0 ± 0,1, P=0,036; 1,0 ± 0,1, 0,9 ± 0,1; P=0,015, respectivamente). A frequência de indivíduos com massa óssea abaixo do esperado para a idade foi maior no grupo NF1 (7,7%; 34,6%, P=0,016). Não houve diferenças no consumo energético. Não houve correlação entre CMO e DMO com a ingestão de nutrientes no grupo NF1. CONCLUSÕES O grupo NF1 apresentou redução do CMO e da DMO. Apesar de menor consumo de cálcio, ferro e vitamina A, e maior consumo de sódio e ômega-6, não foi observada relação entre o fenótipo ósseo e a ingestão de nutrientes.

Objects To compare insulin resistance (IR) and metabolic aspects of patients with neurofibromatosis type 1 (NF1) and individuals without the disease. Subjects and methods Forty patients with NF1 were matched by sex, age, and body mass index (BMI) to 40 controls from the community. Blood samples were collected for biochemical assessment. Homeostasis model assessment adiponectin (HOMA-AD), Homeostasis model assessment insulin resistance (HOMA-IR), and adiponectin/leptin ratio (ALR) were used to identify IR. Results The median HOMA-IR values were similar between the groups. However, the HOMA-AD value was significantly lower and the ALR significantly higher in the NF1 group. Fasting blood glucose (FBG), leptin, and visfatin levels of patients with NF1 were significantly lower, although adiponectin levels were significantly higher than those in the controls. Fasting insulin and blood glucose levels 2 hours after administration of 75 g of dextrose, glycated hemoglobin, and resistin showed no significant differences between groups. The HOMA-AD correlated with BMI, FBG, blood glucose levels 2 hours after administration of 75 g of dextrose, fasting insulin, glycated hemoglobin, adiponectin, leptin, visfatin, ALR, and HOMA-IR. The ALR correlated with BMI leptin, visfatin, and adiponectin. Conclusions Lower levels of FBG, leptin, visfatin, and HOMA-AD, and higher adiponectin levels and ALR may be related to increased insulin sensitivity and lower occurrence of type 2 diabetes mellitus in patients with NF1

Objectives To evaluate nutrient intake among adult neurofibromatosis type 1 (NF1) patients. Methods A cross-sectional study of 60 NF1 patients (29 men, 31 women) who were ≥18 y old and were evaluated from September 2012 to September 2013 in a neurofibromatosis outpatient reference center. Patients underwent nutritional assessment, including anthropometric and dietary data collection. Food intake was evaluated using three, non-consecutive, self-reported 24-h dietary recall surveys, and nutrient intake was analyzed according to the recommendations of the dietary reference intake document. Results Forty-three patients (72%) recorded energy consumption lower than the estimated daily energy requirement (EER). Men (25/29, 86.2%) were more likely to fail to meet their target EER, compared to women (18/31, 58.1%) (P = 0.016). Inadequate intake of vitamin D, magnesium, calcium, and pyridoxine was noted between men and women, and all patients consumed excess sodium. NF1 patients did not consume adequate amounts of fiber or vitamins A and C. Excessive consumption of saturated fatty acids and lipids was also observed in both male and female patients. Conclusions In this study, NF1 patients consumed an unhealthy diet that was rich in fats and sodium and lacking in fiber, vitamins, and minerals. Further studies are needed to investigate the role of these dietary and nutritional patterns in the severity of the clinical manifestations of NF1.