Nutrition and Supplementation: Systematic Review And Meta-Analysis Master List

Capsaicinoids and capsinoids are compounds found in peppers that may improve athletic performance. Capsaicin (the compound that makes spicy foods spicy) is the most well-known of these compounds, but other non-spicy compounds may also have positive effects on performance. 9 out of 14 animal studies and 5 out of 8 human studies have found that these compounds improve physical performance (some studies have looked at endurance performance, while other have looked at strength or power). The studies are too dissimilar to be worth meta-analyzing, but ~60% of studies finding significant, positive effects represents a pretty strong track record for this class of compounds, though more research is certainly needed. The potential mechanisms by which capsaicinoids and capsinoids may improve performance are summarized in the figure below.

CYP1A2 genotype and acute ergogenic effects of caffeine intake on exercise performance: a systematic review. Grgic et al. (2020)

CYP1A2 is a gene that codes for the rate-limiting protein in caffeine metabolism. People with the AA genotype (“fast metabolizers”) may experience a larger ergogenic effect from caffeine supplementation than people with AC and CC genotypes. However, that effect seems to be largest for relatively long-duration cardiovascular exercise. The effects on resistance exercise are smaller and less consistent.

The Effect of Dietary Nitrate Supplementation on Isokinetic Torque in Adults: A Systematic Review and Meta-Analysis. Lago-Rodríguez et al. (2020)

This meta-analysis found that acute nitrate supplementation doesn’t seem to significantly affect isokinetic torque. It should be noted, however, that only 5 studies were included in the analysis, and a lot of the outcomes only had one study. This is definitely an area where more research is needed before we can draw definitive conclusions.

Effects of diet interventions, dietary supplements, and performance-enhancing substances on the performance of CrossFit-trained individuals: A systematic review of clinical studies. Quaresma et al. (2020)

This paper summarizes the findings of 14 studies investigating the effects of various nutrition and supplementation interventions on CrossFit performance. The only intervention that caused significant improvements in performance was sodium bicarbonate supplementation. However, it would probably be excessively hasty to conclude that sodium bicarbonate is the only ergogenic substance for CrossFitters; we just need more research on other potential interventions.

Effect of short- and long-term protein consumption on appetite and appetite-regulating gastrointestinal hormones, a systematic review and meta-analysis of randomized controlled trials. Kohanmoo et al. (2020)

Higher protein intakes seem to suppress hunger and improve appetite regulation acutely (e.g. all else being equal, a higher protein meal promotes greater feelings of fullness and less hunger than a lower protein meal), but over time, people may habituate to the hunger-suppressing and fullness-promoting effects of elevated protein intakes.

Are There Benefits from the Use of Fish Oil Supplements in Athletes? A Systematic Review. Lewis et al. (2020)

Fish oil has a lot of effects on the human body. With that said, ergogenic effects on athletes are fairly inconsistent. Notably, however, fish oil supplementation may improve rates of recovery following muscle damage, but more research is needed.

The Effects of Intermittent Fasting Combined with Resistance Training on Lean Body Mass: A Systematic Review of Human Studies. Keenan et al. (2020)

In the eight human studies to date, intermittent fasting combined with resistance training generally allows for maintenance of lean body mass (7 out of 8 studies). One study observed an increase in lean body mass. Furthermore, most of the studies (5 out of 8) observed a decrease in fat mass, suggesting that subjects were probably in at least a slight caloric deficit.

Effects of Dietary Nitrate Supplementation on Weightlifting Exercise Performance in Healthy Adults: A Systematic Review. San Juan et al. (2020)

Realistically, this body of literature probably wasn’t quite ready for a systematic review, as only four studies met the authors’ inclusion criteria. However, three of the four studies found that nitrate supplementation successfully improved measures of resistance exercise performance (power, velocity, and reps-to-failure performance). Thus, the literature on nitrate is promising, but we need more studies before drawing any solid conclusions.

The effect of fish oil supplementation on the promotion and preservation of lean body mass, strength, and recovery from physiological stress in young, healthy adults: a systematic review. Heileson and Funderburk (2020)

Fish oil supplementation may help with preserving strength and power performance following muscle damage or immobilization, and it may support the recovery of performance following muscle damage or immobilization, but it doesn’t seem to improve performance chronically or have a notable effect on lean body mass in healthy, young adults.

Acute Effects of Citrulline Supplementation on High-Intensity Strength and Power Performance: A Systematic Review and Meta-Analysis. Trexler et al. (2019)

Citrulline supplementation has a small but significant effect on strength and power endurance tests (e.g. reps to failure tests, or similar challenges). The effect may be larger for strength endurance than power endurance.

Acute Ketone Supplementation and Exercise Performance: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Valenzuela et al. (2019)

Ketone supplementation doesn’t seem to improve exercise performance in tests ranging for short sprints to ~50 minute endurance tests.

Antioxidants for preventing and reducing muscle soreness after exercise: a Cochrane systematic review. Ranchordas et al. (2020)

Antioxidant supplementation seems to attenuate muscle soreness up to 72 hours post-training, but the magnitude of the effect probably isn’t large enough to be practically relevant.

Does Beef Protein Supplementation Improve Body Composition and Exercise Performance? A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Valenzuela et al. (2019)

The effects of beef protein supplementation on strength and muscle growth seem to be similar to the effects of whey protein supplementation.

Effect of Betaine on Reducing Body Fat—A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Xiang et al. (2019)

Betaine (TMG) supplementation may increase body fat reductions, especially when combined resistance training. This study was previously discussed in more depth in MASS.

Effect of Caffeine Supplementation on Sports Performance Based on Differences Between Sexes: A Systematic Review. Mielgo-Ayuso et al. (2019)

Caffeine seems to have similar effects on aerobic performance in both males and females, but it may have larger effects on anaerobic and resistance training performance in males.

Effect of Overnight Fasted Exercise on Weight Loss and Body Composition: A Systematic Review and Meta-Analysis. Hackett and Hagstrom (2017)

Exercise following an overnight fast doesn’t seem to produce more weight loss or more favorable changes in body composition than exercise performed in a fed state. However, there aren’t many studies to analyze (only 5), so these findings should be interpreted with caution due to low statistical power.

Effects of Arginine Supplementation on Athletic Performance Based on Energy Metabolism: A Systematic Review and Meta-Analysis

In a meta-analysis covering 15 published studies, arginine supplementation was found to significantly enhance both aerobic and anaerobic performance outcomes, with effect sizes (Hedges’ g) of 0.84 and 0.24, respectively. However, it appears as if the analysis neglected to account for the inclusion of multiple correlated outcomes from single studies, included the Harvard step test as a measurement of “performance,” included a study that combined arginine with another ingredient (which violated the exclusion criteria), and included at least a few miscalculated effect sizes. More importantly, there just isn’t a reason to supplement with arginine; oral citrulline supplementation increases blood arginine levels more effectively than oral arginine supplementation, and oral citrulline is widely accessible, similarly priced, tastes better, and has more evidence supporting its efficacy.

Effects of Curcumin Supplementation on Sport and Physical Exercise: A Systematic Review. Suhett et al. (2020)

“Eleven papers were selected for this review. Most of the studies displayed positive effects of the curcumin supplementation for athletes and physical exercise practitioners, and no side effects were reported. Participants supplemented with curcumin displayed reduced inflammation and oxidative stress, decreased pain and muscle damage, superior recovery and muscle performance, better psychological and physiological responses (thermal and cardiovascular) during training and improved gastrointestinal function. Curcumin supplementation appears to be safe and beneficial for sport and physical exercise in human beings.” Another 2020 systematic review had similar findings.

Effects of Ramadan Fasting on Physical Performance: A Systematic Review with Meta-analysis. Abaïdia et al. (2020)

Most aspects of physical performance are maintained fairly well during Ramadan fasting, but mean and peak power during Wingate tests (maximal anaerobic tests) significantly decrease. I imagine resistance training work capacity (or any long-duration activity that could be constrained by hydration) would be reduced as well, but there’s not sufficient research on that topic yet.

Effects of Sodium Bicarbonate Supplementation on Muscular Strength and Endurance: A Systematic Review and Meta-analysis. Grgic et al. (2020)

Sodium bicarbonate (baking soda) supplementation significantly increases strength endurance but not maximal strength.

Effects of vitamin C on oxidative stress, inflammation, muscle soreness, and strength following acute exercise: meta-analyses of randomized clinical trials. Righi et al. (2020)

Vitamin C supplementation may reduce some markers of exercise-induced oxidative stress (lipid peroxidation) and inflammation (IL-6), but doesn’t seem to affect the recovery markers most lifters would actually care about (soreness or strength recovery).

Impact of anthocyanin-rich whole fruit consumption on exercise-induced oxidative stress and inflammation: a systematic review and meta-analysis. Bloedon et al. (2019)

Eating a diet high in anthocyanin-rich fruits (such as blueberries and tart cherries) may reduce oxidative stress and inflammation following exercise. Another recent meta (Doma et al., 2020) had broadly similar findings. Another recent systematic review (Ortega et al., 2020) looked at tart cherry and pomegranate juice supplementation. The authors of the review conclude that higher total doses of phenolic compounds (at least 1000mg/day) and longer supplementation durations (beginning several days before strenuous exercise, and continuing through the recovery period) are more likely to have a positive effect. In other words, simply consuming anthocyanin-rich fruits or fruit supplements once before or after a workout may not have much of an effect; you need to consume them consistently, in high enough dosages, for the effect to be consistent and noticeable.

Nicotine effects on exercise performance and physiological responses in nicotine‐naïve individuals: a systematic review. Johnston et al. (2017)

There are plausible mechanisms by which nicotine could improve exercise performance, but placebo-controlled studies don’t reliably report performance benefits from nicotine supplementation for nicotine-naïve individuals.

Omega-3 Polyunsaturated Fatty Acid Supplementation for Reducing Muscle Soreness After Eccentric Exercise: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Zheng-tao et al. (2020)

Omega-3 supplementation significantly reduces muscle soreness following eccentric exercise, but doesn’t seem to improve strength recovery. However, the reduction in muscle soreness, while statistically significant, likely isn’t large enough to be clinically relevant.

Protein Intake Greater than the RDA Differentially Influences Whole-Body Lean Mass Responses to Purposeful Catabolic and Anabolic Stressors: A Systematic Review and Meta-analysis. Hudson et al. (2020)

Protein intakes that exceed the RDA (0.8g/kg per day) increase lean mass gains following resistance training, and attenuate lean mass losses following energy restriction. However, eating more protein probably won’t help you gain more lean mass when you’re in an isocaloric state and you aren’t resistance training.

Supplementation of Probiotics and Its Effects on Physically Active Individuals and Athletes: Systematic Review. Möller et al. (2018)

“Following probiotic supplementation, positive effects have been reported for several outcomes including respiratory tract infection, immunologic markers, and gastrointestinal symptoms in both athletes and nonathletes. However, published studies have distinct protocols and measured outcomes, and some of them have small sample size and failed to prove beneficial effect on probiotic supplementation, leading to inconclusive results for standardized supplementation protocols.”

The Effect of L-Carnitine Supplementation on Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. Yarizadh et al. (2020)

L-Carnitine supplementation may attenuate some markers of muscle damage, but the overall body of literature is still pretty small and findings are reasonably inconsistent. This study was previously discussed in more depth in MASS.

The Effects of Alcohol Consumption on Recovery Following Resistance Exercise: A Systematic Review. Lakićević. (2019)

Alcohol consumption post-exercise may increase cortisol, and decrease testosterone, plasma amino acids, and protein synthesis to some degree. Other markers of physiological function and recovery seem to be largely unaffected. As with anything else, the dose makes the poison; moderate drinking (1-2 standard drinks) probably won’t have a notable effect, while heavy drinking is likely to impair recovery and training adaptations to some degree.

Do multi-ingredient protein supplements augment resistance training-induced gains in skeletal muscle mass and strength? A systematic review and meta-analysis of 35 trials. O’Bryan et al. (2018)

Multi-ingredient protein supplements generally increase fat free mass and strength gains relative to placebo. However, they don’t tend to significantly outperform plain old protein supplements. With that being said, the mean effect for fat free mass leans slightly in favor of multi-ingredient supplements over plain protein supplements, likely due to the inclusion of creatine.

A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Morton et al. (2018)

Protein supplementation was found to increase gains in both strength and muscle but didn’t have a significant effect on bone mineral content. The relative benefits of protein supplementation were (unsurprisingly) larger for hypertrophy than for strength, and were larger for hypertrophy in trained individuals than in untrained individuals. The relative benefits also tended to be larger in young people than in older people. Furthermore, it was found that increases in lean body mass tended to plateau at a protein intake of around 1.6g/kg (0.73g/lb). However, the confidence intervals extended up to 2.2g/kg (1g/lb), making that the “better safe than sorry” protein recommendation. A more recent meta by Wirth et al. confirmed the finding that protein supplementation significantly increases lean body mass, though it did not find that protein supplementation significantly increased handgrip or leg press strength. However, the p-value for leg press strength in young adults was p = 0.06, which is near the classical significance threshold.

Effects of protein supplementation on increases in strength Effects of protein on increases in FFM The effect of protein supplementation on gains in FFM is influenced by age

Dose-response relationship between protein intake and muscle mass increase: a systematic review and meta-analysis of randomized controlled trials. Tagawa et al. (2020)

This meta is more-or-less an update on Morton’s meta, except that it examined the effects of total protein intake, and not just protein supplementation. In people not performing resistance training, the beneficial hypertrophic effects of higher protein intakes may more-or-less cap out at intakes of ~1.3g/kg. For people performing resistance training, higher protein intakes may lead to greater increases in fat-free mass up to intakes exceeding 3g/kg.

The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. Schoenfeld et al. (2013)

This meta-analysis examined the effects of protein intake in the immediate peri-workout window (within an hour before or after training) versus not consuming protein within that window. Protein timing didn’t significantly affect strength gains. Before adjusting for covariates, the timing did significantly increase hypertrophy. However, many studies didn’t match for total protein intake. After adjusting for higher total protein intakes in the groups consuming protein in the peri-workout window, it didn’t seem that timing significantly affected hypertrophy by itself. In other words, downing a protein shake after your workout may lead to more muscle growth if it increases total protein intake, but it probably won’t make too much of a difference otherwise.

Effect of protein timing on strength Effect of protein timing on hypertrophy, after adjusting for total protein intake

Effects of meal frequency on weight loss and body composition: a meta-analysis. Schoenfeld et al. (2015)

This meta-analysis initially found that higher meal frequencies during weight loss were associated with larger decreases in fat mass and body fat percentage, and smaller decreases in fat-free mass. However, those differences were all driven by a single study; when a sensitivity analysis was performed and that study was removed, there was no significant effect of meal frequency on fat mass, body fat percentage, or fat-free mass.

The Effect of Whey Protein Supplementation on the Temporal Recovery of Muscle Function Following Resistance Training: A Systematic Review and Meta-Analysis. Davies et al. (2018)

Protein supplementation was found to increase rate of recovery from training (defined as restoration of muscle function after a training bout). This effect was only significant (p<0.05) for time points <24 hours post-training, and 72 hours post-training; however, effect sizes favored protein supplementation at all time points (g = 0.4-0.7).

Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. Wycherley et al. (2012)

High protein diets during weight loss contributed to larger decreases in weight, fat mass, and triglycerides, and smaller decreases in fat-free mass compared to lower protein diets. However, of note, the mitigation in FFM loss only applied to studies lasting more than 12 weeks.

High protein diets lead to more fat loss Protein led to more lean mass retention in studies lasting fewer than 12 weeks

The effects of protein supplements on muscle mass, strength, and aerobic and anaerobic power in healthy adults: a systematic review. Pasiakos et al. (2015)

In terms of strength and hypertrophy, Morton (2018) provides a more up-to-date overview of the literature. However, this systematic review also adds another element. Protein supplementation also may increase gains in aerobic and anaerobic power after aerobic or anaerobic training.

Effects of protein supplements on muscle damage, soreness and recovery of muscle function and physical performance: a systematic review. Pasiakos et al. (2014)

In terms of recovery of muscle function, refer to Davies (2018). However, this systematic review also found that protein supplementation tends to decrease soreness and markers of muscle damage after training.

Threshold of Energy Deficit and Lower-Body Performance Declines in Military Personnel: A Meta-Regression. Murphy et al. (2018)

This meta-analysis found that, in military personnel, neither length of time in an energy deficit nor daily energy deficit were independently associated with decreases in lower body strength or power. However, total energy deficit was strongly associated with decreases in lower body strength and power. It’s not clear whether these findings would directly apply to strength or physique athletes trying to cut weight (while military personnel are very active, it’s not like the bulk of their exercise comes from lifting weights), but they’re at least worth taking note of. If they did apply, the implication would be that a quick cut with a large daily energy deficit and a slow cut with a small daily energy deficit would ultimately have similar impacts on performance. This is an area of research that’s been largely ignored in the context of resistance training, unfortunately (this is the only study I’m aware of, and it was pretty poorly controlled).

Does high-carbohydrate intake lead to increased risk of obesity? A systematic review and meta-analysis. Sartorius et al. (2018)

Short answer: No.

Longer answer: In studies looking at high vs. low absolute carbohydrate intake, and in studies looking at high vs. low carbohydrate intake expressed as a percentage of total calorie intake, carb intake was not associated with increased or decreased odds of obesity.

Absolute carbohydrate intake Carbohydrate intake as a percentage of total calories

The effect of glutamine supplementation on athletic performance, body composition, and immune function: A systematic review and a meta-analysis of clinical trials. Ahmadi et al. (2018)

Glutamine supplementation doesn’t seem to affect any measurable aspect of athletic performance, or any proxy for muscle damage and recovery (i.e creatine kinase). Glutamine supplementation may help a bit with weight loss (which surprised me, honestly). Interestingly, it seemed to nearly lead to a significant increase in fat mass (CI: -0.19-2.22kg), without having any effect on lean mass. This perplexing result can be explained by the fact that one particularly large study measured weight (reporting a decrease) and fat mass (reporting an increase), but didn’t measure lean mass. It had by far the largest weight in the analyses, so it really drove the results. This one study was allowed to have such undue weight because the authors used a fixed-effects model when they should have used a random-effects model. If they used a random effects model, glutamine probably wouldn’t have been found to effect body weight or body composition either.

Do ketogenic diets really suppress appetite? A systematic review and meta-analysis. Gibson et al. (2015)

A surprising outcome in obesity research is that unlike moderate energy-restricted diets, after initial increases, very low energy diets (VLED; < 800 kcal/day) actually reduce hunger (though long-term adherence is problematic). The same claim is made for very low carbohydrate diets (VLCD). This meta analysis assessed appetite response to both VLED and VLCD (< 10 % kcal or < 50 g/day, ad libitum consumption of protein and fat). VLED increased satiety and decreased hunger without changing desire to eat or the anticipated energy that would or could be eaten. VLCD increased satiety and decreased hunger, and also decreased desire to eat.

Very low energy diets vs. baseline Very low carbohydrate diets vs. baseline

Comparison of weight loss among named diet programs in overweight and obese adults: a meta-analysis. Johnston et al. (2014)

This meta-analysis included 48 RCTs in overweight individuals and categorized diets based on whether or not they were lower carbohydrate (< 40% kcal), “balanced macronutrients,” or low fat (< 20% kcal). At diet conclusion, lower carbohydrate were 83% likely to produce the most weight loss and produced significantly more weight loss than balanced macronutrient diets, but not more weight loss than low-fat diets. At 1 year follow up, low-fat diets were most likely (50%) among the three diets to result in the most weight loss retention. Adverse events incidence was higher during low-carbohydrate versus low-fat diets: constipation (68% vs 35%, respectively), headache (60% vs 40%), halitosis (38% vs 8%), muscle cramps (35% vs 7%), diarrhea (23% vs 7%), general weakness (25% vs 8%), and rash (13% vs 0%; P < .006). However, weight loss differences among diets were not clinically meaningful (1-2 kg over 6-12 months), and the authors suggested individuals follow whichever diet they can adhere to.

Weight loss intervention adherence and factors promoting adherence: a meta-analysis. Lemstra et al. (2015)

Supervised weight loss attempts tend to have about 65% higher adherence than unsupervised attempts, and interventions with a social support component tend to have about 29% higher adherence than interventions without a social support component. Furthermore, dietary interventions tend to have about 27% higher adherence than exercise interventions.

Effects of beta-hydroxy-beta-methylbutyrate supplementation on strength and body composition in trained and competitive athletes: A meta-analysis of randomized controlled trials. Sanchez-Martinez et al. (2017)

In trained athletes, HMB supplementation doesn’t seem to significantly affect either strength gains or changes in body composition (fat mass or fat-free mass). A more recent meta-analysis by Holland and colleagues had similar findings.

Effects of beta-hydroxy-beta-methylbutyrate supplementation during resistance training on strength, body composition, and muscle damage in trained and untrained young men: a meta-analysis. Rowlands et al. (2009)

Like the more recent Sanchez-Martinez meta-analysis, HMB still didn’t do anything for trained athletes back in 2009. However, this meta-analysis did find that HMB supplementation significantly increased lower body strength gains in untrained lifters, though it didn’t affect body composition.

Creatine Supplementation and Lower Limb Strength Performance: A Systematic Review and Meta-Analyses. Lanhers et al. (2015)

Creatine supplementation leads to significantly larger strength gains in both the squat and leg press. The effect was larger for squat (8%) than leg press (3%).

Squat Leg press

Does oral creatine supplementation improve strength? A meta-analysis. Dempsey et al. (2002) and Effect of creatine supplementation on body composition and performance: a meta-analysis. Branch (2003)

Creatine supplementation also significantly increases lean body mass and bench press strength, and generally improves performance in tasks lasting ≤30 seconds. It may also improve performance in some tasks lasting 30-150 seconds. It may not affect biceps curl strength. It seems to be effective in both men and women (though it may be more effective in men), and in both trained and untrained subjects. It doesn’t seem to reliably affect performance for tests lasting >150 seconds.

From Dempsey et al. From Branch et al.

Effects of Whey Protein Alone or as Part of a Multi-ingredient Formulation on Strength, Fat-Free Mass, or Lean Body Mass in Resistance-Trained Individuals: A Meta-analysis. Naclerio et al. (2016)

While both whey protein and creatine enhance strength gains and hypertrophy independently, they may have even larger effects when taken together.

Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. Martineau et al. (2017)

Vitamin D supplementation seems to decrease risk of respiratory tract infections by about 20%. The reduction in risk may be larger in people with low vitamin D levels.

Effects of Vitamin D Supplementation on Serum 25-Hydroxyvitamin D Concentrations and Physical Performance in Athletes: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Farrokhyar et al. (2017).

Even though vitamin D supplementation increases blood concentrations of vitamin D, supplementation doesn’t seem to reliably affect physical performance in athletes (though it may increase handgrip strength).

Does Fish Oil Have an Anti-Obesity Effect in Overweight/Obese Adults? A Meta-Analysis of Randomized Controlled Trials. Shichun et al. (2015)

Fish oil supplementation on top of lifestyle modification doesn’t seem to decrease body weight or BMI more than lifestyle modification alone, but it does lead to significantly larger decreases in waist circumference and waist-to-hip ratio.

β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis. Saunders et al. (2018)

β-alanine supplementation significantly increases performance for tests lasting 1-10 minutes but doesn’t significantly affect performance for tests lasting <1 minute or for tests lasting 10+ minutes. This makes sense given β-alanine’s mechanism of action – increasing muscle carnosine content, to help buffer against pH decreases. Short-duration activities (i.e. lifting) are unlikely to be limited by inadequate cellular buffering, and long-duration activities aren’t going to rely as much on anaerobic metabolism in the first place.

Subgroups from top to bottom: <1 minute, 1-10 minutes, and 10+ minutes

Effects of caffeine intake on muscle strength and power: a systematic review and meta-analysis. Grgic et al. (2018)

Acute caffeine supplementation increases maximal strength and power, though the overall effect is pretty small. The strength increase is more consistent for upper body strength than lower body strength. The average dose of caffeine used was 4.3-6.5mg/kg. A more recent meta-analysis by Ferreira et al. on the same subject had similar findings: caffeine had a statistically significant effect on bench press strength and strength endurance, but not leg press performance (though non-significant differences still leaned in favor of caffeine supplementation).

Effects of protein supplements consumed with meals, versus between meals, on resistance training-induced body composition changes in adults: a systematic review. Hudson et al. (2018)

Consuming protein supplements with meals instead of between meals may be slightly more beneficial for improving body composition. However, due to heterogeity between studies, few actual head-to-head comparisons, and lack of biological plausibility, my hunch is that it doesn’t actually matter too much, as long as you’re eating enough protein.

Effect of BCAA supplementation on central fatigue, energy metabolism substrate and muscle damage to the exercise: a systematic review with meta-analysis. Hormoznejad et al. (2019)

BCAA supplementation does seem to affect perceptions of fatigue, but it may slightly decrease the rate of metabolic fatigue, and could attenuate muscle damage following intense training. However, these results were found relative to inert control supplementation; it’s unclear if BCAA supplementation has any additional effects if someone is already supplementing with or consuming adequate amounts of protein. A 2017 meta-analysis also had broadly similar findings.

Effect of whey protein supplementation on body composition changes in women: a systematic review and meta-analysis. Bergia et al. (2018)

Whey protein supplemention seems to help increase lean mass in women. However, that effect is only significant in studies without resistance training (with resistance training, whey protein doesn’t seem to help women gain additional lean mass), and in studies imposing an energy deficit (whey protein helps women hold on to more lean mass when dieting, but it doesn’t seem to affect lean mass without a calorie deficit). Furthermore, whey protein supplementation doesn’t seem to lead to significantly greater fat loss in women. All mean effects leaned in favor of whey protein supplementation, but most comparisons simply didn’t clear the threshold of statistical significance.

Dietary fiber intervention on gut microbiota composition in healthy adults: a systematic review and meta-analysis. So et al. (2018)

Interventions involving increases in dietary fiber consumption significantly increased the abundance of intestinal bacteria strains that are generally believed to be beneficial (Bifidobacterium and Lactobacillus). Such interventions also increased fecal butyrate concentrations (which is thought to protect against colon cancer). The fibers that had the largest effect on intestinal bacteria were fructans and galacto-oligosaccharides.

Coffee, Caffeine, and Health Outcomes: An Umbrella Review. Grosso et al. (2017)

“Of the 59 unique outcomes examined in the selected 112 meta-analyses of observational studies, coffee was associated with a probable decreased risk of breast, colorectal, colon, endometrial, and prostate cancers; cardiovascular disease and mortality; Parkinson’s disease; and type-2 diabetes. Of the 14 unique outcomes examined in the 20 selected meta-analyses of observational studies, caffeine was associated with a probable decreased risk of Parkinson’s disease and type-2 diabetes and an increased risk of pregnancy loss. Of the 12 unique acute outcomes examined in the selected 9 meta-analyses of RCTs, coffee was associated with a rise in serum lipids, but this result was affected by significant heterogeneity, and caffeine was associated with a rise in blood pressure. Given the spectrum of conditions studied and the robustness of many of the results, these findings indicate that coffee can be part of a healthful diet.”

Effect of Dietary Sugar Intake on Biomarkers of Subclinical Inflammation: A Systematic Review and Meta-Analysis of Intervention Studies. Della Corte et al. (2018)

Fructose doesn’t seem to contribute to systemic inflammation to a greater degree that other dietary sugars (specifically when comparing fructose vs. glucose, and high fructose corn syrup vs. table sugar [sucrose]).

Glycemic impact of non-nutritive sweeteners: a systematic review and meta-analysis of randomized controlled trials. Nichol et al. (2018)

Overall, it doesn’t seem that non-nutritive sweeteners acutely have any meaningful impact on blood glucose, on average. The glycemic impact at some time points seems to be smaller in diabetics, smaller in people with high BMIs, and smaller in older people. By 120 minutes post-consumption, non-nutritive sweeteners significantly decrease blood glucose. All non-nutritive sweeteners seemed to have similar effects on blood glucose. A 2020 meta-analysis by Greyling and colleagues also found that low-energy sweeteners doesn’t have much of an effect on glucose or insulin post-consumption.

Effects of fasted vs fed‐state exercise on performance and post‐exercise metabolism: A systematic review and meta‐analysis. Aird et al. (2018)

Eating before exercise improves long-duration aerobic performance (but not short-duration performance). However, fasted endurance exercise leads to larger post-exercises increases in plasma free fatty acids, and may lead to larger increases in cellular signaling associated with aerobic training adaptations.

Nutritional Interventions to Improve Muscle Mass, Muscle Strength, and Physical Performance in Older People: An Umbrella Review of Systematic Reviews and Meta-Analyses. Gielen et al. (2020)

This umbrella review surveyed the results of 15 systematic reviews examining the effects of various nutritional interventions on elderly subjects. The strongest evidence was in favor of leucine supplementation and protein supplementation combined with resistance training. If you’re interested in nutritional research related to strength, muscle, or physical performance in elderly folks, this would be a good paper to mine for references to use as a jumping-off point.

Nutrition and Supplementation: Systematic Review And Meta-Analysis Master List

Nutritional practices to manage menstrual cycle related symptoms: a systematic review. Brown et al. 2023

Protein intake and body weight, fat mass and waist circumference: an umbrella review of systematic reviews for the evidence-based guideline on protein intake of the German Nutrition Society. Ellinger et al. 2023

Effects of rapeseed oil on body composition and glucolipid metabolism in people with obesity and overweight: a systematic review and meta-analysis. Yang et al. 2023

High protein provision of more than 1.2 g/kg improves muscle mass preservation and mortality in ICU patients: A systematic review and meta-analyses. van Ruijven et al. 2023

Effects of Intermittent Energy Restriction Compared to Those of Continuous Energy Restriction on Body Composition and Cardiometabolic Risk Markers – A Systematic Review and Meta-Analysis of Randomized Controlled Trials in Adults. Schroor et al. 2023

Effect of Alpha-Linolenic Acid Supplementation on Cardiovascular Disease Risk Profile in Individuals with Obesity or Overweight: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Yin et al. 2023

The Role of Vitamin D in Skeletal Muscle Repair and Regeneration in Animal Models and Humans: A Systematic Review. Agoncillo et al. 2023

Resistance Exercise and Creatine Supplementation on Fat Mass in Adults < 50 Years of Age: A Systematic Review and Meta-Analysis. Candow et al. 2023

Exploring the Nutrition Strategies Employed by Ultra-Endurance Athletes to Alleviate Exercise-Induced Gastrointestinal Symptoms—A Systematic Review. Ryan et al. 2023

β-Alanine Supplementation in Combat Sports: Evaluation of Sports Performance, Perception, and Anthropometric Parameters and Biochemical Markers—A Systematic Review of Clinical Trials. Fernández-Lázaro et al. 2023

The Effects of Flavonoids on Skeletal Muscle Mass, Muscle Function, and Physical Performance in Individuals with Sarcopenia: A Systematic Review of Randomized Controlled Trials. Wu and Suzuki 2023

Roles of citrus fruits on energy expenditure, body weight management, and metabolic biomarkers: a comprehensive review. Aslan et al. 2023

The Effect of Pre-Exercise Hyperhydration on Exercise Performance, Physiological Outcomes and Gastrointestinal Symptoms: A Systematic Review. Jardine et al. 2023

Influence of the administration form of menthol in physical performance in endurance exercise: A systematic review. Neto et al. 2023

Metabolic Adaptations to Morning Versus Afternoon Training: A Systematic Review and Meta-analysis. Galan-Lopez et al. 2023

A Little Pepper-Upper? Systematic Review of Randomized Controlled Studies on Capsaicinoids, Capsinoids, and Exercise Performance. Sukan-Karaçağıl et al. 2023

Healthy Behavior and Sports Drinks: A Systematic Review. Muñoz-Urtubia et al. 2023

The Effect of Intermittent Fasting on Appetite: A Systematic Review and Meta-Analysis. Elsworth et al. 2023

The effects of sleep disruption on metabolism, hunger, and satiety, and the influence of psychosocial stress and exercise: A narrative review. Rogers et al. 2023

Reducing meat and/or dairy consumption in adults: a systematic review and meta-analysis of effects on protein intake, anthropometric values, and body composition. Habumugisha et al. 2023

Influence of Exogenous Factors Related to Nutritional and Hydration Strategies and Environmental Conditions on Fatigue in Endurance Sports: A Systematic Review with Meta-Analysis. Caller et al. 2023

Exploring the Relationship between Micronutrients and Athletic Performance: A Comprehensive Scientific Systematic Review of the Literature in Sports Medicine. Ghazzawi et al. 2023

Effects of Dietary Nitrate Supplementation on Back Squat and Bench Press Performance: A Systematic Review and Meta-Analysis. Tan et al. 2023

Can the Substitution of Milk with Plant-Based Drinks Affect Health-Related Markers? A Systematic Review of Human Intervention Studies in Adults. Biscotti et al. 2023

The effects of carbohydrate-restricted diet on psychological outcomes: a systematic review of randomized controlled trials. Sindler et al. 2023

The effects of nutritional supplementation on older sarcopenic individuals who engage in resistance training: a meta-analysis. Song et al. 2023

Effectiveness of combined nutrition and exercise interventions on body weight, lean mass, and fat mass in adults diagnosed with cancer: a systematic review and meta-analysis. Baguley et al. 2023

Effects of weight change on taste function; a systematic review. Fathi, Javid, and Mansoori 2023

Whey protein supplementation with or without vitamin D on sarcopenia-related measures: A systematic review and meta-analysis. Nasimi et al. 2023

Moderators of Caffeine’s Effects on Jumping Performance in Females: A Systematic Review and Meta-Analysis. Grgic and Varovic 2023

Effects of Beetroot-Based Supplements on Muscular Endurance and Strength in Healthy Male Individuals: A Systematic Review and Meta-Analysis. Evangelista et al. 2023

The Effects of Creatine Supplementation Combined with Resistance Training on Regional Measures of Muscle Hypertrophy: A Systematic Review with Meta-Analysis. Burke et al. 2023

Absence of Effects of L-Arginine and L-Citrulline on Inflammatory Biomarkers and Oxidative Stress in Response to Physical Exercise: A Systematic Review with Meta-Analysis. Porto et al. 2023

The effects of vegetarian diets on glycemia and lipid parameters in adult patients with overweight and obesity: a systematic review and meta-analysis. Xu et al. 2023

Fenugreek and Its Effects on Muscle Performance: A Systematic Review. Albaker 2023

Spit It Out: Is Caffeine Mouth Rinse an Effective Ergogenic Aid? A Systematic Review and Meta-Analysis. Nabuco et al. 2023

Optimal timing of introduction of complementary feeding: a systematic review and meta-analysis. Padhani et al. 2023

Dietary pattern, food, and nutritional supplement effects on cognitive outcomes in mild cognitive impairment: a systematic review of previous reviews. Andrews et al. 2023

Genetics of caffeine and brain-related outcomes – a systematic review of observational studies and randomized trials. Kapellou et al. 2023

Effect of supplemental vitamin D3 on bone mineral density: a systematic review and meta-analysis. Kazemian et al. 2023

The Effect of Gut-Training and Feeding-Challenge on Markers of Gastrointestinal Status in Response to Endurance Exercise: A Systematic Literature Review. Martinez et al. 2023

Effectiveness of supplementation to potentiate lean mass gain during resistance training: A systematic review. Sandoval et al. 2023

Effectiveness of diet quality indices in measuring a change in diet quality over time: a systematic review and meta-analysis of randomized controlled trials. McAuley et al. 2023

Effects of creatine supplementation on memory in healthy individuals: a systematic review and meta-analysis of randomized controlled trials. Prokopidis et al. 2023

Intramuscular lipid utilization during exercise: a systematic review, meta-analysis, and meta-regression. Stokie et al. 2023

Effects of Creatine Monohydrate on Endurance Performance in a Trained Population: A Systematic Review and Meta-analysis. Fernandez-Landa et al. 2023

The Impact of High Protein Diets on Cardiovascular Outcomes: A Systematic Review and Meta-Analysis of Prospective Cohort Studies. Mantzouranis et al. 2023

Body Composition of Male Professional Soccer Players Using Different Measurement Methods: A Systematic Review and Meta-Analysis. Sebastia-Rico et al. 2023

Eating disorder risk during behavioral weight management in adults with overweight or obesity: A systematic review with meta-analysis. Jebeile et al. 2023

Dose–response effects of exercise and caloric restriction on visceral adiposity in overweight and obese adults: a systematic review and meta-analysis of randomised controlled trials. Recchia et al. 2023

Effect of exercise and antioxidant supplementation on cellular lipid peroxidation in elderly individuals: Systematic review and network meta-analysis. Ni et al. 2023

The effect of caffeine on subsequent sleep: A systematic review and meta-analysis. Gardiner et al. 2023

After Dinner Rest a While, After Supper Walk a Mile? A Systematic Review with Meta-analysis on the Acute Postprandial Glycemic Response to Exercise Before and After Meal Ingestion in Healthy Subjects and Patients with Impaired Glucose Tolerance. Engeroff et al. 2023

Intramuscular lipid utilisation during exercise: A systematic review, meta-analysis and meta-regression. Stokie et al. 2023

Sex differences in kinematics and quadriceps activity for fast isokinetic knee extension. Jeon et al. 2023

Is dieting a risk for higher weight gain in normal-weight individual? A systematic review and meta-analysis. Pellisier et al. (2022)

Ergogenic Aids to Improve Physical Performance in Female Athletes: A Systematic Review with Meta-Analysis. Lopez-Torres et al. (2022)

Effects of Caffeine Intake on Endurance Running Performance and Time to Exhaustion: A Systematic Review and Meta-Analysis. Wang et al. (2022)

Does Beetroot Supplementation Improve Performance in Combat Sports Athletes? A Systematic Review of Randomized Controlled Trials. Delleli et al. (2022)

No impact of combining multi-ingredient supplementation with exercise on body composition and physical performance, in healthy middle-aged and older adults: A systematic review and meta-analysis. Puente-Fernandez et al. (2022)

Association between animal protein sources and risk of neurodegenerative diseases: a systematic review and dose-response meta-analysis. Talebi et al. (2022)

Physiological effects of yerba maté (Ilex paraguariensis): a systematic review. José et al. (2022)

Effects of probiotic supplementation on performance of resistance and aerobic exercises: a systematic review. de Paiva et al. (2022)

Dose-response and temporal ergogenic effects of ginseng supplementation in athletes and active participants: A systematic review and meta-analysis. Khan et al. (2022)

A systematic review update of athletes’ nutrition knowledge and association with dietary intake. Janiczak et al. (2022)

Mitochondrial adaptations to calorie restriction and bariatric surgery in human skeletal muscle: a systematic review with meta-analysis. Perez-Rodriguez et al. (2022)

Effects of Nitrate Supplementation on Muscle Strength and Mass: A Systematic Review. Anderson et al. (2022)

Effects of acute nitrate supplementation against placebo on the physical performance of athletes in a time trial test: Systematic review and meta-analysis. Silva et al. (2022)

The impact of dietary protein supplementation on recovery from resistance exercise-induced muscle damage: A systematic review with meta-analysis. Pearson et al. (2022)

Effects of Capsaicin and Capsiate on Endurance Performance: A Meta-Analysis. Grgic et al. (2022)

Short-Term Creatine Supplementation and Repeated Sprint Ability—A Systematic Review and Meta-Analysis. Glaister and Rhodes. (2022)

Select Dietary Supplement Ingredients for Preserving and Protecting the Immune System in Healthy Individuals: A Systematic Review. Crawford et al. (2022)

Quercetin supplementation promotes recovery after exercise-induced muscle damage: a systematic review and meta-analysis of randomized controlled trials. Rojano-Ortega et al. (2022)

High Adherence to the Mediterranean Diet is Associated with Higher Physical Fitness in Adults: a Systematic Review and Meta-Analysis. Bizzozero-Peroni et al. (2022)

Association between adherence to plant-based dietary patterns and obesity risk: a systematic review of prospective cohort studies. Jarvis et al. (2022)

Predicting resting energy expenditure among athletes: a systematic review. Martinho et al. (2022)

Effects of Time-Restricted Feeding and Ramadan Fasting on Body Weight, Body Composition, Glucose Responses, and Insulin Resistance: A Systematic Review of Randomized Controlled Trials. Tsitsou et al. (2022)

Poultry Consumption and Human Health: How Much Is Really Known? A Systematically Searched Scoping Review and Research Perspective. Connolly et al. (2022)

Effects of the Ketogenic Diet on Muscle Hypertrophy in Resistance-Trained Men and Women: A Systematic Review and Meta-Analysis. Vargas-Molina et al. (2022)

Effect of supplemental vitamin D₃ on bone mineral density: a systematic review and meta-analysis. Kazemian et al. 2023