Beware of the pickle: health effects of nitrate intake

Hematological and Hemodynamic Responses to Acute and Short-Term Creatine Nitrate Supplementation

In a double-blind, crossover, randomized and placebo-controlled trial; 28 men and women ingested a placebo (PLA), 3 g of creatine nitrate (CNL), and 6 g of creatine nitrate (CNH) for 6 days. Participants repeated the experiment with the alternate supplements after a 7-day washout. Hemodynamic responses to a postural challenge, fasting blood samples, and bench press, leg press, and cycling time trial performance and recovery were assessed. Data were analyzed by univariate, multivariate, and repeated measures general linear models (GLM). No significant differences were found among treatments for hemodynamic responses, clinical blood markers or self-reported side effects. After 5 days of supplementation, one repetition maximum (1RM) bench press improved significantly for CNH (mean change, 95% CI; 6.1 [3.5, 8.7] kg) but not PLA (0.7 [-1.6, 3.0] kg or CNL (2.0 [-0.9, 4.9] kg, CNH, p = 0.01). CNH participants also tended to experience an attenuated loss in 1RM strength during the recovery performance tests following supplementation on day 5 (PLA: -9.3 [-13.5, -5.0], CNL: -9.3 [-13.5, -5.1], CNH: -3.9 [-6.6, -1.2] kg, p = 0.07). After 5 days, pre-supplementation 1RM leg press values increased significantly, only with CNH (24.7 [8.8, 40.6] kg, but not PLA (13.9 [-15.7, 43.5] or CNL (14.6 [-0.5, 29.7]). Further, post-supplementation 1RM leg press recovery did not decrease significantly for CNH (-13.3 [-31.9, 5.3], but did for PLA (-30.5 [-53.4, -7.7] and CNL (-29.0 [-49.5, -8.4]). CNL treatment promoted an increase in bench press repetitions at 70% of 1RM during recovery on day 5 (PLA: 0.4 [-0.8, 1.6], CNL: 0.9 [0.35, 1.5], CNH: 0.5 [-0.2, 0.3], p = 0.56), greater leg press endurance prior to supplementation on day 5 (PLA: -0.2 [-1.6, 1.2], CNL: 0.9 [0.2, 1.6], CNH: 0.2 [-0.5, 0.9], p = 0.25) and greater leg press endurance during recovery on day 5 (PLA: -0.03 [-1.2, 1.1], CNL: 1.1 [0.3, 1.9], CNH: 0.4 [-0.4, 1.2], p = 0.23). Cycling time trial performance (4 km) was not affected. Results indicate that creatine nitrate supplementation, up to a 6 g dose, for 6 days, appears to be safe and provide some ergogenic benefit.

Nitrate supplementation and human exercise performance: too much of a good thing?

PURPOSE OF REVIEW

Ergogenic supplements in sport events are widely used by popular and competitive athletes to enhance performance and reduce oxygen cost. Beetroot juice and nitrate salts have been increasingly used for the past 5-6 years. The present review discusses the scientific background, the efficiency and potential adverse effects of excessive nitrate supplementation.

RECENT FINDINGS

There is clear evidence that nitrate from different food ingredients (such as beetroot juice and other vegetables) is converted into nitrite and possibly into nitric oxide, which may promote vasodilation, angiogenesis and mitochondrial biogenesis. The high affinity of nitric oxide towards different enzyme pathways inhibits excessive mitochondrial respiration and, therefore, tissue oxygen consumption. In addition, L-arginine supplements are proposed to stimulate nitric oxide synthesis in the endothelium. On the basis of these biochemical properties, nitrate supplementation has been suggested to athletes to enhance exercise performance.

SUMMARY

The recent publications in human individuals based on L-arginine, beetroot juice or nitrate supplementation revealed either a minor positive effect or no systematic effect on exercise performance, especially in trained athletes. Of note, the sugar content of whole beetroot juice might induce a slightly more pronounced effect. Although reasonable intake of nitrate salts (up to 1 g/day) has no detrimental effect on kidney function, the risk and benefit of higher nitrate intake needs to be evaluated to define the optimal range of supplementation.

A multi-ingredient, pre-workout supplement is apparently safe in healthy males and females

Background

Pre-workout supplements (PWS) have become increasingly popular with recreational and competitive athletes. While many ingredients used in PWS have had their safety assessed, the interactions when combined are less understood.

Objective

The purpose of this study was to examine the safety of 1 and 2 servings of a PWS.

Design

Forty-four males and females (24.4±4.6 years; 174.7±9.3 cm; 78.9±18.6 kg) from two laboratories participated in this study. Subjects were randomly assigned to consume either one serving (G1; n=14) or two servings (G2; n=18) of PWS or serve as an unsupplemented control (CRL; n=12). Blood draws for safety panels were conducted by a trained phlebotomist before and after the supplementation period.

Results

Pooled data from both laboratories revealed significant group×time interactions (p<0.05) for mean corpuscular hemoglobin (MCH; CRL: 30.9±0.8–31.0±0.9 pg; G1: 30.7±1.1–30.2±0.7 pg; G2: 30.9±1.2–30.9±1.1 pg), MCH concentration (CRL: 34.0±0.9–34.4±0.7 g/dL; G1: 34.1±0.9–33.8±0.6 g/dL; G2: 34.0±1.0–33.8±0.8 g/dL), platelets (CRL: 261.9±45.7–255.2±41.2×10³/µL; G1: 223.8±47.7–238.7±49.6×10³/µL; G2: 239.1±28.3–230.8±34.5×10³/µL), serum glucose (CRL: 84.1±5.2–83.3±5.8 mg/dL; G1: 86.5±7.9–89.7±5.6 mg/dL; G2: 87.4±7.2–89.9±6.6 mg/dL), sodium (CRL: 137.0±2.7–136.4±2.4 mmol/L; 139.6±1.4–140.0±2.2 mmol/L; G2: 139.0±2.2–138.7±1.7 mmol/L), albumin (CRL: 4.4±0.15–4.4±0.22 g/dL; G1: 4.5±0.19–4.5±0.13 g/dL; G2: 4.6±0.28–4.3±0.13 g/dL), and albumin:globulin (CRL: 1.8±0.30–1.8±0.28; G1: 1.9±0.30–2.0±0.31; G2: 1.8±0.34–1.8±0.34). Each of these variables remained within the clinical reference ranges.

Conclusions

The PWS appears to be safe for heart, liver, and kidney function in both one-serving and two-serving doses when consumed daily for 28 days. Despite the changes observed for select variables, no variable reached clinical significance.

28 days of creatine nitrate supplementation is apparently safe in healthy individuals

BACKGROUND

Creatine monohydrate has become a very popular nutritional supplement for its ergogenic effects. The safety of creatine monohydrate has previously been confirmed. However with each novel form of creatine that emerges, its safety must be verified. Therefore, the purpose of this study was to examine the safety of a novel form of creatine, creatine nitrate (CN), over a 28 day period.

METHODS

58 young males and females (Pooled: 24.3 ± 3.9 years, 144.9 ± 8.0 cm, 74.2 ± 13.0 kg) participated in this study across two laboratories. Subjects were equally and randomly assigned to consume either 1 g (n = 18) or 2 g (n = 20) of CN or remained unsupplemented (n = 20). Blood draws for full safety panels were conducted by a trained phlebotomist prior to and at the conclusion of the supplementation period.

RESULTS

Pooled data from both laboratories revealed significant group x time interactions for absolute lymphocytes and absolute monocytes (p < 0.05). Analysis of the 1 g treatment revealed lab x time differences for red blood cell distribution width, platelets, absolute monocytes, creatinine, blood urea nitrogen (BUN):creatinine, sodium, protein, and alanine aminotransferase (ALT) (p < 0.05). Analysis of the 2 g treatment revealed lab x time differences for BUN:creatinine and ALT (p < 0.05). BUN and BUN:creatinine increased beyond the clinical reference range for the 2 g treatment of Lab 2, but BUN did not reach statistical significance.

CONCLUSION

Overall, CN appears to be safe in both 1 g and 2 g servings daily for up to a 28 day period. While those with previously elevated BUN levels may see additional increases resulting in post-supplementation values slightly beyond normal physiological range, these results have minor clinical significance and are not cause for concern. Otherwise, all hematological safety markers remained within normal range, suggesting that CN supplementation has no adverse effects in daily doses up to 2 g over 28 days and may be an alternative to creatine monohydrate supplementation.