About

Professor Nicholas A. Burd is associated with the Nutrition and Exercise Performance Research Group at the University of Illinois. His research focuses on understanding how resistance exercise and dietary protein intake regulate skeletal muscle health and performance, with an emphasis on optimizing these outcomes. His work contributes to the broader field of exercise physiology and nutrition, aiming to improve performance and health through targeted nutritional and exercise interventions.

Research topics

• Medicine
• Biology
• Endocrinology
• Internal medicine
• Biochemistry
• Food science
• Neuroscience
• Environmental health
• Surgery
• Psychology
• Physical medicine and rehabilitation
• Immunology
• Physiology
• Chromatography
• Microbiology
• Chemistry

Selected publications

• Examining widely held propositions on human dietary protein needs and benefits: a critical review of the science that shapes both the data and our understanding of an essential macronutrient

  Critical Reviews in Food Science and Nutrition · 2026-05-08

  articleOpen access

  " In most instances, the experts believed additional research was warranted. For many propositions the research base was insufficient in terms of quality (rigor), quantity (sample size, study duration), or pertinence (e.g., use of surrogate markers).

  PublisherDOI

• Oral Multienzyme Supplementation Alters Postprandial Plasma Nutrient Concentrations after a Mixed Meal in Healthy Middle-Aged and Older Adults: A Randomized, Double-Blind, Placebo-Controlled, Crossover Trial

  Journal of Nutrition · 2026-02-07

  articleOpen accessSenior author

  BACKGROUND: Age-related decline in digestive function increases malnutrition risk. Supplementing meals with digestive enzymes may improve macronutrient digestion and bioavailability in adults reaching older ages. OBJECTIVES: To assess postprandial plasma nutrient concentrations after co-ingestion of a mixed meal and a mixture of 6 enzyme preparations (ENZ), including proteases, lipase, amylase, and glucoamylase. METHODS: Thirty middle-aged and older adults (56 ± 11 y; 18 females, 12 males) ingested chicken, peas, potatoes, and butter (435 kcal; 34 g protein, 51 g carbohydrate, 11 g fat) with either ENZ or placebo (PLA) in a randomized crossover fashion. Blood samples were collected at baseline and throughout a 0-5 h postprandial period for measurement of plasma amino acid, insulin, glucose, and nonesterified fatty acid (NEFA) concentrations. Clustering of postprandial amino acid responses was conducted in MFuzz, and logistic regression for response groups was conducted in JMP 18.2.0 (JMP Statistical Discovery LLC). RESULTS: Plasma amino acid concentrations were not statistically different between treatments (PLA compared with ENZ) over the postprandial period (all P > 0.05). Leucine time to maximum concentration was significantly faster (P = 0.047) with ENZ (121.2 ± 55.9 min) compared with PLA (141.0 ± 49.2 min). Postprandial plasma glucose concentrations (P = 0.04) and total NEFA (P = 0.001) were higher with ENZ compared with PLA. Three distinct response patterns (clusters) were detected within and across all postprandial amino acid categories. Differences in habitual macronutrient intake and interactions between sex, lean mass, and BMI distinguished participants with an earlier time to maximum postprandial leucine concentration when consuming ENZ compared with PLA from those with stable responses. CONCLUSIONS: Multienzyme supplementation improved macronutrient digestion of a mixed meal in middle-aged and older adults. For plasma amino acids, this benefit was most pronounced in adults with lower BMI and higher lean mass, and the effect was sex-dependent. This study was registered at clinicaltrials.gov as NCT05211440.

  PublisherDOI

• Human plasma extracellular vesicles as an exercise mimetic to preserve skeletal muscle plasticity during disuse

  npj Microgravity · 2026-03-06

  articleOpen access

  The purpose of this study was to determine the extent to which extracellular vesicles (EVs) circulating in blood after exercise training act as an effective mimetic to maintain skeletal muscle mass during unloading and/or accelerate recovery after disuse. Ten healthy males (27.7 ± 7.1 y) were recruited for a 6-week progressive resistance and endurance training program. EVs were isolated from blood before (EVs) or immediately after training (ExerVs). EVs were intraperitoneally injected into male mice (4×; 3 × 108 particles/injection) during 14 days of hindlimb unloading (HU), then the muscles were collected immediately or 7 days after HU. ExerVs did not maintain muscle mass, fiber size (fCSA), or protein synthesis but significantly reduced collagen I during HU. ExerV administration rapidly restored Type I fCSA and capillary quantity concomitant with reduced collagen during the reloading period. Overall, this study demonstrates that ExerVs may represent a novel strategy to preserve skeletal muscle health during disuse.

  PublisherOA PDFDOI

• Examining widely held propositions on human dietary protein needs and benefits: a critical review of the science that shapes both the data and our understanding of an essential macronutrient

  Figshare · 2026-05-08

  articleOpen access

  The essentiality of protein in the human diet is unequivocal. Yet researchers, clinicians, and lay people often believe numerous propositions about dietary protein despite insufficient supporting or refuting data in some instances. To address this disconnect, and to “pressure-test” current beliefs about dietary protein, the Indiana University School of Public Health-Bloomington convened a workshop in February 2025 titled “<i>Human Dietary Protein Needs and Benefits: A Critical Assessment of Postulated Propositions.”</i> More than 20 international experts discussed (1) methodologic issues affecting data acquisition and interpretation; (2) “optimal” dietary protein intakes and effects on muscle protein synthesis rates, muscle protein accretion, muscle growth, and muscle repair; (3) protein needs during weight loss; (4) acute protein intake thresholds above and below which protein is no longer related to anabolism; and (5) dietary protein intakes above which protein may be detrimental to health. The experts rated each proposition on a scale from “<i>existing evidence strongly supports the proposition</i>” to “<i>existing evidence seems sufficient to rule out the viability of the proposition.</i>” In most instances, the experts believed additional research was warranted. For many propositions the research base was insufficient in terms of quality (rigor), quantity (sample size, study duration), or pertinence (e.g., use of surrogate markers).

  PublisherDOI

• Inositol hexakisphosphate kinase 1 is implicated in the insulin response to protein ingestion in older adults

  Scientific Reports · 2026-02-18

  articleOpen access

  Abstract Age-related muscle mass is driven by a reduction in insulin sensitivity partly mediated by reduced amino acid and anabolic signalling kinetics. Insulin activates Akt-mTORC1 signalling in skeletal muscle, with inositol hexakisphosphate kinase 1 (IP6K1) shown to inhibit this signalling pathway in pre-diabetic humans. We aimed to compare muscle and plasma IP6K1 in young vs older adults and the possible role of IP6K1 in the anabolic response to protein and protein plus resistance exercise (RE). Nine young (24.9 ± 0.4 years) and nine older (66.2 ± 0.5 years), moderately active adults received primed continuous infusions of L-[ ring - 2 H 5 ]phenylalanine in basal and postprandial state. Blood and muscle biopsy samples were collected prior to and following ingestion of 25 g whey protein with or without knee extension exercise to examine skeletal muscle protein signalling and whole-body phenylalanine kinetics. Young adults had greater plasma IP6K1 at all time points. Older adults had reduced muscle IP6K1 at 120 min post-exercise. Muscle IP6K1 decreased 240 min postprandially in young adults compared with basal and there was no effect of exercise in either group. Older adults presented with reduced plasma and muscle IP6K1 in both postprandially and post-RE states, as well as reduced phenylalanine rate of disappearance for the same comparisons. IP6K1 may be involved in the reduction in amino acid metabolism , and the insulin-mediated response to protein and RE.

  PublisherOA PDFDOI

• Examining widely held propositions on human dietary protein needs and benefits: a critical review of the science that shapes both the data and our understanding of an essential macronutrient

  Figshare · 2026-05-08

  articleOpen access

  The essentiality of protein in the human diet is unequivocal. Yet researchers, clinicians, and lay people often believe numerous propositions about dietary protein despite insufficient supporting or refuting data in some instances. To address this disconnect, and to “pressure-test” current beliefs about dietary protein, the Indiana University School of Public Health-Bloomington convened a workshop in February 2025 titled “<i>Human Dietary Protein Needs and Benefits: A Critical Assessment of Postulated Propositions.”</i> More than 20 international experts discussed (1) methodologic issues affecting data acquisition and interpretation; (2) “optimal” dietary protein intakes and effects on muscle protein synthesis rates, muscle protein accretion, muscle growth, and muscle repair; (3) protein needs during weight loss; (4) acute protein intake thresholds above and below which protein is no longer related to anabolism; and (5) dietary protein intakes above which protein may be detrimental to health. The experts rated each proposition on a scale from “<i>existing evidence strongly supports the proposition</i>” to “<i>existing evidence seems sufficient to rule out the viability of the proposition.</i>” In most instances, the experts believed additional research was warranted. For many propositions the research base was insufficient in terms of quality (rigor), quantity (sample size, study duration), or pertinence (e.g., use of surrogate markers).

  PublisherDOI

• Oral amino acid tracer delivery detects feeding and exercise changes in myofibrillar protein synthesis rates in male adults

  Physiological Reports · 2026-03-01

  articleOpen access

  Abstract The efficacy of oral administration of leucine and phenylalanine tracers to measure MyoPS (LEUMyoPS and PheMyoPS, respectively) in response to varying anabolic stimuli was investigated. Participants were randomized to a rested‐fasted (FAST), rested‐fed (FED), or exercise‐fed (EXFED) condition. FED and EXFED consumed a mixed carbohydrate and AA beverage enriched with L‐[1‐ 13 C]leucine (25%) and L‐[ ring ‐ 2 H 5 ]phenylalanine (30%) at rest or after a bout of resistance exercise, while FAST consumed only the equivalent tracer dose. Blood samples were obtained every 30 min for 300 min to determine tracer precursor enrichment with muscle biopsies obtained before and at 120 and 300 min after tracer ingestion to determine MyoPS by the precursor‐product method. LEUMyoPS over 300 min was greater ( p &lt; 0.01) in EXFED (0.090 ± 0.024%/h; mean ± SD) and FED (0.067 ± 0.028%/h) compared to FAST (0.024 ± 0.015%/h). PHEMyoPS over 300 min was greater ( p &lt; 0.01) in EXFED (0.128 ± 0.034%/h) and FED (0.098 ± 0.020%/h) compared to FAST (0.056 ± 0.012%/h). There was a positive correlation ( r = 0.81, p &lt; 0.0001) between LEUMyoPS and. Oral essential amino acid tracer ingestion can be used as an alternative method to detect changes in MyoPS in response to mixed macronutrient feeding and feeding plus exercise and may be an option for the study of human muscle protein synthesis where intravenous isotope administration is logistically difficult or prohibitively expensive.

  PublisherDOI

• High protein ingestion does not affect whole-body insulin sensitivity in individuals with overweight or obesity

  Journal of the Endocrine Society · 2026-01-17 · 1 citations

  articleOpen access

  Abstract Context High protein diets (HPD), rich in branched-chain amino acids (BCAAs), are proposed to enhance glycemic control. The metabolic implications of elevated BCAAs in insulin resistance (IR) are unclear, but overactivation of ribosomal protein S6 kinase B1 (S6K1)-related signaling pathway may contribute to IR. Objective To investigate the impact of 2 dietary protein interventions on IR and molecular signaling in skeletal muscle (acutely) and adipose tissue (18-week period) in overweight/obese individuals. Methods The acute study included ingestion of 50 g protein (MPD), 100 g protein (HPD), or 50 g of protein with added fat (MPDAF) on 3 different occasions with muscle biopsies before and after. The 18-week analysis used a subset of data with available adipose tissue biopsies from a randomized, controlled, isoenergetic dietary intervention, focusing on the relevant HPD and control diets. Insulin sensitivity was assessed using labeled intravenous glucose tolerance tests acutely, and by euglycemic-hyperinsulinemic clamp in the 18-week intervention. Results Inositol hexakisphosphate kinase 1 (IP6K1) and total AMP-activated protein kinase (AMPK) protein content significantly decreased following the HPD meal (P = .048 and P = .006 respectively), alongside increased P-AktThr308/Akt2 (P = .046), while S6K1 mRNA was lower after 6 weeks of HPD, compared to the control diet group (P = .046), but not at 18 weeks. However, neither intervention changed whole-body IR. Conclusion Key proteins implicated in intracellular insulin signaling were altered with an acute HPD meal (decreased IP6K1 and AMPK, increased pAkt/Akt2 activity), indicating potential enhancement of insulin-mediated glucose signaling at the molecular level. These findings suggest that, while systemic IR was unchanged, high protein intake may have beneficial effects on cellular insulin signaling.

  PublisherDOI

• The Muscle Building Potential of Vegan Eating for Older Folks

  Journal of Nutrition · 2025-02-03

  editorialSenior authorCorresponding
  PublisherDOI

• Inositol hexakinase phosphate 1 (IP6K1) is implicated in the insulin response to protein ingestion in older adults

  Research Square · 2025-02-21

  preprintOpen access
  PublisherOA PDFDOI

Frequent coauthors

• Naiman A. Khan

  104 shared

• Hannah D. Holscher

  86 shared

• Scott A. Paluska

  University of Illinois Urbana-Champaign

  73 shared

• Caitlyn G. Edwards

  Pennsylvania State University

  65 shared

• Sarah K. Skinner

  University of Florida

  62 shared

• Joseph W. Beals

  University of Illinois Urbana-Champaign

  58 shared

• Sharon V. Thompson

  Troy University

  57 shared

• Stephan van Vliet

  Utah State University

  55 shared

Labs

• Nutrition and Exercise Performance Research GroupPI

  Research on the effects of nutrition and exercise on human performance and health.

Education

• PhD

  McMaster University

  2011

• M.S.

  Ball State University

  2007