Keith Martin

Dr. Keith Martin

Center for Nutraceutical and Dietary Supplement Research, College of Health Sciences, University of Memphis, 495 Zach H. Curlin Street, Memphis, TN 38152, USA

Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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19 September 2018 in Food & Function
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Keith MartinKeith Martin
Keith Martin
LBLacey Burrell
Lacey Burrell
JBJennifer Bopp
Jennifer Bopp
Subclinical inflammation is frequently noted in chronic diseases such as diabetes, cardiovascular disease (CVD) and obesity. Accumulating epidemiological evidence demonstrates that diets rich in vegetables and fruits, e.g., cherries, may significantly reduce the risk of chronic disease, in part, via antioxidant and anti-inflammatory activities. In this randomized, placebo-controlled crossover study, we recruited 10 at-risk participants (38.1 ± 12.5 years; 8 females, 2 males) with BMI >25.0 kg m−2 (32.2 ± 4.6 kg m−2; 5 obese, 5 overweight) to consume 240 mL (8 ounces) daily of either 100% tart cherry juice (TCJ) or an alternate placebo beverage, for 4 weeks with a 2-week intervening washout period before switching to the alternate beverage for four weeks. Fasting blood samples were collected at the beginning and end of each arm for measurement of biomarkers of inflammation. The erythrocyte sedimentation rate (ESR), an indicator of chronic inflammation, was significantly (p < 0.05) lower with TCJ than with the placebo beverage, which increased ESR by 19%. Mean baseline hsCRP, an indicator of acute inflammation, was 7.0 ± 5.2 mg L−1 and consumption of TCJ did not affect hsCRP levels. The chemokine MCP-1 and cytokine TNF-alpha were lower in participants after consuming TCJ compared to those consuming the placebo beverage. Plasma IL-6 and IL-l0 were not different between treatments. Collectively, the data suggest that authentic 100% TCJ may reduce biomarkers of inflammation often noted in chronic disease and may be a preferable dietary selection compared to artificially flavored beverages with added sugars.

25 February 2019 in Current Developments in Nutrition
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Keith MartinKeith Martin
Keith Martin
KCKatie M Coles
Katie M Coles
Gout is a frequently occurring, complex rheumatologic form of inflammatory arthritis caused by the accumulation of serum uric acid (sUA) and deposition of uric acid crystals in the joints and tissues of the body. Hyperuricemia is also a significant independent risk factor for all-cause and cardiovascular morbidity and mortality and is associated with hypertension, diabetes, obesity, and osteoarthritis. However, patient adherence to prescribed urate-lowering therapies ranges from 20% to 70%, suggesting that other additional strategies, such as dietary intervention with specific, efficacious foods or beverages, may be necessary to mitigate the risk of arthritis, as well as other comorbidities. Tart cherry juice (TCJ) has been used for decades by some for gout based largely on anecdotal evidence of its efficacy and its antioxidant and anti-inflammatory properties. We designed this study to test the effect of TCJ on uricemia, lipidemia, glycemia, and inflammation in at-risk overweight and obese humans with a specific hypothesis that TCJ consumption would reduce sUA concentrations. In this randomized, placebo-controlled crossover study, we recruited overweight and obese participants with body mass index (BMI) >25.0 kg/m2 (n = 26, 18 women/8 men, 41 ±11 y; BMI 31.3 ± 6.0; 12 obese, 14 overweight) to consume 240 mL/d (8 oz/d) of either TCJ or placebo beverage, for 4 wk each with a 4-wk intervening washout period followed by 4 wk of the alternate beverage. TCJ significantly reduced sUA concentration by 19.2% (P < 0.05) and reduced by 19.4% (P = 0.09) and 6.3% (P = 0.08) proinflammatory high-sensitivity C-reactive protein and monocyte chemoattractant protein-1, respectively. The participants in this study displayed risk ratios indicating increased cardiovascular disease risk and insulin resistance but no differences in the pre- and postintervention groups of either placebo or TCJ groups. Collectively, the data suggest that 100% TCJ reduces sUA concentrations, mitigating hyperuricemia associated with gouty arthritis. This trial was registered at clinicaltrials.gov as NCT03636529.

22 April 2020 in Nutrients
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RBRichard Bloomer
Richard Bloomer
MMatthew Butawan
Matthew Butawan
BPBrandon Pigg
Brandon Pigg
Keith MartinKeith Martin
Keith Martin
Background: Dietary supplements purported to increase circulating nitric oxide are very popular among consumers. We determined the acute impact of two novel dietary supplements on plasma nitrate/nitrite (NOx) and nitrite alone. Methods: 20 men and women (age: 24 ± 5 years) ingested two different nitrate-rich supplements (Resync Recovery Blend at 7.5 g and 15 g; Resync Collagen Blend at 21 g), or placebo, on four different days. Fasting blood samples were obtained before and 75 min following ingestion and analyzed for NOx and nitrite. Results: Nitrite was not differently impacted by treatment (p > 0.05). The NOx response for men and women was very similar, with no sex interactions noted (p > 0.05). Condition (p < 0.0001), time (p < 0.0001), and condition x time (p < 0.0001) effects were noted for NOx. Values increased from baseline to post-ingestion for the Resync Recovery Blend at 7.5 g (11 ± 9 to 101 ± 48 µM) and at 15 g (9 ± 5 to 176 ± 91 µM), as well as for the Resync Collagen Blend (9 ± 9 to 46 ± 21 µM), while values for placebo remained stable (9 ± 7 to 8 ± 5 µM). Conclusion: While nitrite alone was not impacted by treatment, both Resync products result in an increase in plasma NOx, with the increase proportionate to the quantity of “nitric oxide blend” ingredients contained within each product. Future studies are needed to determine the physiological implications of the increased NOx, as pertaining to exercise performance and recovery, in addition to other aspects of human health.

5 June 2024 in Nutrients
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RBRichard Bloomer
Richard Bloomer
JPJacquelyn Pence
Jacquelyn Pence
JHJanine Hellenbrand
Janine Hellenbrand
DDDavis Davis
Davis Davis
SDSamantha Davis
Samantha Davis
Keith MartinKeith Martin
Keith Martin
Background: Maintaining adequate hydration is critical to optimal health, well-being, and performance. Those who are physically active in stressful environments, such as warm and/or humid scenarios, may be at particular risk for dehydration with ensuing loss of electrolytes, leading to sluggishness and impaired physical performance. Methods: We evaluated an electrolyte and amino acid product containing L-alanine and L-glutamine, as well as select vitamins [B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B12 (cobalamin), and vitamin C (ascorbic acid)]. Subjects (n = 40; four groups, n = 10) were randomized to consume either a placebo packet or one, two, or three packets daily of the test product for 4 weeks with site visits at 0, 2, and 4 weeks. We tested safety and tolerability by analyzing hematological parameters (complete blood counts), metabolic parameters (hepatic, renal, acid–base balance), urinalysis end products, thyroid status [T3 (triiodothyronine), T4 (thyroxine), TSH (thyroid-stimulating hormone)], tolerability (via questionnaire), vital signs, and dietary intake. Results: Statistical analyses displayed ten significant main effects (p < 0.05) with white blood cells, lymphocytes, neutrophils, urinary pH, thyroxine, urination frequency, calcium, calories, fat, and cholesterol. Interactions for time and group (p < 0.05) were observed for MCV, eGFR, potassium, overall tolerability, bloating, and cramping—demonstrating mild GA disturbances. Little to no change of physiological relevance was noted for any outcome variable, regardless of dosing level. Conclusions: Our results indicate the product was well-tolerated at all dosing levels and no significant adverse changes occurred in any of the test parameters compared to the placebo group, indicating relative safety of ingestion over a 4-week treatment period, at the volumes used, and outside the context of physical stress.


5 July 2023 in Processes
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Journal Article
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RBRichard J. Bloomer
Richard J. Bloomer
YZYufeng Zhang
Yufeng Zhang
JSJoshua Y. Shirazi
Joshua Y. Shirazi
COChidimma Okegbe
Chidimma Okegbe
JPJacquelyn Pence
Jacquelyn Pence
Tyler W. LeBaronTyler W. LeBaron
Tyler W. LeBaron
Alpha Hope is a dietary supplement containing pyrroloquinoline quinone and elemental magnesium, which produces molecular hydrogen (H2 gas) when dissolved in water. We determined the impact of Alpha Hope on Nrf-2, peroxisome proliferator-activated receptor-gamma coactivator (PGC-1α), and citrate synthase (CS) activity in C2C12 myoblasts. Alpha Hope was titrated to three concentrations of pyrroloquinoline quinone (PQQ) (10 nM, 100 nM, 1000 nM) and treated on C2C12 for 48 h. Nrf-2 and PGC-1α levels were measured using Western blot analysis. CS activity was measured according to previously described methods. Treatment significantly increased Nrf-2 and PGC-1α protein levels in C2C12 myoblasts, with no change for CS. For Nrf-2, values for both the 100 nM (p = 0.046) and 1000 nM (p = 0.011) concentrations were higher than control. For PGC-1α, values for both the 100 nM (p = 0.039) and 1000 nM (p = 0.017) concentrations were higher than control. In a small human pilot study, subjects consumed the Alpha Hope product daily for four weeks, with no adverse effects, with some subjects noted as “responders” to treatment. Alpha Hope can significantly increase both Nrf-2 and PGC-1α in a concentration-dependent manner. Healthy men and women who ingest the product daily can do so without adverse effects.