Beetroot Juice Supplementation Does Not Improve Mitochondrial Efficiency or ADP Sensitivity in Humans
Bibliographic record
Abstract
Ingestion of sodium nitrate (NaNO3) simultaneously reduces whole-body oxygen consumption (VO2) during sub-maximal exercise while improving mitochondrial efficiency, suggesting a causal link. Consumption of beetroot juice (BRJ) elicits similar decreases in VO2 but potential effects on the mitochondria remain unknown. Therefore we examined the effects of 6 day supplementation with BRJ (280 ml/d, ~26 mmol NO3-) in young active males (n=10) who had muscle biopsies taken Pre and Post supplementation for assessments of mitochondrial bioenergetics. Subjects performed 20 min of cycling (10 min at 50% and 70% VO2Max) 48 h prior to receiving biopsies, and on day 4 of supplementation. Mitochondrial respiration in permeabilized muscle fibres showed no change in oligomycin-leak respiration, maximal substrate-supported respiration, or ADP sensitivity (apparent Km). To compare the effects of BRJ to previous findings with NaNO3, 5 subjects had muscle taken for isolation of subsarcolemmal and intermyofibrillar mitochondria. Neither subpopulation showed an improvement in mitochondrial efficiency assessed by the oxygen consumed/ATP produced (P/O Ratio), or in mitochondrial coupling assessed by respiratory control ratio (RCR). Membrane potential determined fluorometrically using safranine-O during respiration was not different Post vs. Pre supplementation. In summary, in contrast to NaNO3, BRJ supplementation did not alter key parameters of mitochondrial function. This occurred despite a decrease in exercise VO2, suggesting that the ergogenic effects are not due to a change in mitochondrial coupling or efficiency. Supported by NSERC, Canada.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".