Mild to Moderate Food Deprivation Increases Hepcidin and Results in Hypoferremia and Tissue Iron Sequestration in Mice

Dietary Intake and Diet Quality of Female and Male NCAA Division I Cross Country Runners from a Single University

Background

Collegiate student-athletes have unique nutritional requirements to support their athletic performance and health. Few studies have comprehensively characterized the diets of National Collegiate Athletic Association (NCAA) Division I student-athletes.

Objectives

To characterize dietary intake and diet quality during a competitive season in female and male NCAA Division I cross country student-athletes from a single university.

Methods

Females and males (n = 14/sex) from the Florida State University cross country teams completed 9-d of food records across their competitive season. Nutrient intakes were compared to the Dietary Reference Intakes for the United States population [e.g., Recommended Daily Allowances (RDAs)] and athlete-specific guidelines. Diet quality was assessed according to the Dietary Guidelines for Americans (DGAs) using the 2020 Healthy Eating Index (HEI-2020). Total daily energy expenditure was estimated from training records.

Results

Carbohydrate intakes were below athlete guidelines in 43% of females (mean ± SD, 5.67 ± 1.16 g·kg-1·d-1) and 29% of males (4.95 ± 1.05, P sex = 0.096). All participants met or exceeded athlete recommendations for protein (2.09 ± 0.425 g·kg-1·d-1, 1.92 ± 0.519, P sex = 0.36) and fat (32.8 ± 5.1% kcal, 34.4 ± 3.4%, P sex = 0.36). No participants met the RDA for vitamin D (5.14 ± 1.78 μg/d, 4.91 ± 3.24, P sex = 0.83). Only 79% of females and 36% of males met the RDA for calcium (1220 ± 307 mg/d, 1010 ± 296, P sex = 0.83). Most females (n = 13) and males (n = 11) consumed iron supplements where total intakes exceeded the tolerable upper intake level (110 ± 60.1 mg/d, 66.8 ± 36.3, P sex = 0.029). HEI-2020 indicated poor adherence to the DGAs, with better diet quality in females (65.3 ± 13.7) than males (50.6 ± 10.1, P sex = 0.0034). Participants failed to meet guidelines for all HEI-2020 food group components except total protein foods. Total daily energy expenditure was greater in males and declined across the competitive season (P sex < 0.0001, P time < 0.0001, P sex∗time = 0.25).

Conclusions

NCAA Division I cross country student-athletes consumed inadequate carbohydrates, calcium, and vitamin D but met or exceeded intake guidelines for protein, fat, and iron. Diet quality was poor; HEI-2020 component scores may indicate food groups to target to improve diet quality and intake of nutrients important to runners.This trial was registered at clinicaltrials.gov as NCT04079322.

The Tolerance Model of Non-Inflammatory Immune Competence in Acute Pediatric Malnutrition: Origins, Evidence, Test of Fitness and Growth Potential

The tolerance model rests on the thesis of a physiologically regulated, albeit unsustainable, systemic attempt to adapt to the catabolic challenge posed by acute prepubescent malnutrition even in its severe forms. The model centers on the immunological component of the attempt, positing reorientation toward a non-inflammatory form of competence in place of the classic paradigm of immunological attrition and exhaustion. The foundation of the model was laid in 1990, and sixteen years later it was articulated formally on the basis of a body of evidence centered on T cell cytokines and interventions with cytokine and hormonal mediators. The benefit originally suggested was a reduced risk of autoimmune pathologies consequent to the catabolic release of self-antigens, hence the designation highlighting immune tolerance. Herein, the emergence of the tolerance model is traced from its roots in the recognition that acute malnutrition elicits an endocrine-based systemic adaptive attempt. Thereafter, the growth of the evidence base supporting the model is outlined, and its potential to shed new light on existing information is tested by application to the findings of a published clinical study of acutely malnourished children. Finally, some knowledge gaps pertinent to the model are identified and its potential for growth consonant with evolving perceptions of immunobiology is illustrated.

Seasonal and fasting induced changes in iron metabolism in Djungarian hamsters

Djungarian hamsters are small rodents that show pronounced physiological acclimations in response to changes in photoperiod, and unfavorable environmental conditions such as reduced food availability and low external temperature. These include substantial adjustments, such as severe body weight loss and the use of daily torpor. Torpor is a state of decreased physiological activity in eutherms, usually marked by low metabolic rate and a reduced body temperature. In this study, we investigated the effects of photoperiodic acclimation and food deprivation on systemic iron metabolism in Djungarian hamsters. Our study illustrates the association between liver iron levels and the incidence of torpor expression during the course of the experiment. Moreover, we show that both, acclimation to short photoperiods and long-term food restriction, associated with iron sequestration in the liver. This effect was accompanied with hypoferremia and mild reduction in the expression of principal iron-hormone, hepcidin. In addition to iron, the levels of manganese, selenium, and zinc were increased in the liver of hamsters under food restriction. These findings may be important factors for regulating physiological processes in hamsters, since iron and other trace elements are essential for many metabolic and physiological processes.

REDD1 deletion and treadmill running increase liver hepcidin and gluconeogenic enzymes in male mice

The iron-regulatory hormone hepcidin is transcriptionally up-regulated by gluconeogenic signals. Recent evidence suggeststhat increases in circulating hepcidin may decrease dietary iron absorption following prolonged exercise, however evidence is limited on whether gluconeogenic signals contribute to post-exercise increases in hepcidin. Mice with genetic knockout of regulated in development and DNA response-1 (REDD1) display greater glycogen depletion following exercise, possibly indicating greater gluconeogenesis. The objective of the present study was to determine liver hepcidin, markers of gluconeogenesis and iron metabolism in REDD1 knockout and wild-type mice following prolonged exercise. Twelve-week-old male REDD1 knockout and wild-type mice were randomised to rest or 60 min treadmill running with 1, 3 or 6 h recovery (n = 5-8/genotype/group). Liver gene expression of hepcidin (Hamp) and gluconeogenic enzymes (Ppargc1a, Creb3l3, Pck1, Pygl) were determined by qRT-PCR. Effects of genotype, exercise and their interaction were assessed by two-way ANOVAs with Tukey's post-hoc tests, and Pearson correlations were used to assess the relationships between Hamp and study outcomes. Liver Hamp increased 1- and 4-fold at 3 and 6 h post-exercise, compared to rest (P-adjusted < 0⋅009 for all), and was 50% greater in REDD1 knockout compared to wild-type mice (P = 0⋅0015). Liver Ppargc1a, Creb3l3 and Pck1 increased with treadmill running (P < 0⋅0001 for all), and liver Ppargc1a, Pck1 and Pygl were greater with REDD1 deletion (P < 0⋅02 for all). Liver Hamp was positively correlated with liver Creb3l3 (R = 0⋅62, P < 0⋅0001) and Pck1 (R = 0⋅44, P = 0⋅0014). In conclusion, REDD1 deletion and prolonged treadmill running increased liver Hamp and gluconeogenic regulators of Hamp, suggesting gluconeogenic signalling of hepcidin with prolonged exercise.