Research Summaries
Plain-language summaries of the most important clinical research on dietary supplements. Each summary includes key findings, study quality assessment, and practical takeaways.
We summarize 68 key clinical trials, meta-analyses, and systematic reviews on supplement efficacy.
We summarize 68 key clinical trials, meta-analyses, and systematic reviews on supplement efficacy. Each summary covers study design, participant counts, effect sizes, and practical takeaways — translating complex research into actionable guidance.
Supplement Industry Statistics 2026
50+ data points on market size, demographics, safety, efficacy, and trends — with one-click citations.
Akkermansia muciniphila for Metabolic Health: Landmark RCT
A landmark RCT of 40 overweight/obese participants found that pasteurized Akkermansia muciniphila supplementation for 3 months improved insulin sensitivity by 28% and reduced plasma LPS levels, a marker of gut barrier dysfunction, compared to placebo.
Alpha-Lipoic Acid for Diabetic Neuropathy: Meta-Analysis of 15 RCTs
A meta-analysis of 15 RCTs (n=1,058) found that alpha-lipoic acid at 600mg/day significantly reduced Total Symptom Score (TSS) for diabetic neuropathy by 2.45 points compared to placebo (p < 0.001), with meaningful improvements in pain, burning, and numbness within 3-5 weeks.
Ashwagandha and Cortisol Reduction: 2022 Meta-Analysis of 12 RCTs
A 2022 meta-analysis of 12 RCTs (n=1,002) found that ashwagandha supplementation significantly reduced serum cortisol levels by a weighted mean of 11.3% compared to placebo (p < 0.001). Effects were strongest with KSM-66 extract at 600mg/day for 8+ weeks.
Ashwagandha and Testosterone: Meta-Analysis of Clinical Trials
A meta-analysis of 4 RCTs (n=234) found that ashwagandha supplementation significantly increased testosterone levels by a weighted mean of 14.7% compared to placebo (p = 0.004), with effects most pronounced in physically active men and those with suboptimal baseline levels.
B Vitamins and Cognitive Decline in Elderly: 2022 Systematic Review
A systematic review of multiple RCTs found that B vitamin supplementation (B6, B12, folate) significantly reduced homocysteine levels by 25-30% and slowed brain atrophy by 30% in elderly adults with elevated homocysteine. The VITACOG trial showed a 53% reduction in brain atrophy rate in participants with homocysteine >13 umol/L.
Bacopa Monnieri for Memory: What the Meta-Analysis Shows
A meta-analysis of randomized controlled trials (9 studies, 437 participants) found Bacopa monnieri extract was associated with improved cognition — most clearly faster speed of attention (reaction time) — when taken consistently for about 12 weeks. Effects build gradually rather than acutely, and standardized extracts were used.
Beetroot Supplementation and Blood Pressure: 2023 Meta-Analysis of 22 RCTs
A meta-analysis of 22 RCTs (n=1,551) found that beetroot supplementation significantly reduced systolic blood pressure by 3.55 mmHg and diastolic blood pressure by 1.32 mmHg. Effects were mediated through dietary nitrate conversion to nitric oxide, which promotes vasodilation. Benefits were dose-dependent and more pronounced with supplementation lasting 2+ weeks.
Berberine and Blood Sugar Control: 2019 Meta-Analysis
A 2019 meta-analysis (n=2,569) found that berberine significantly reduced fasting blood glucose by 0.87 mmol/L, HbA1c by 0.72%, and improved insulin sensitivity. These effects were comparable to metformin in head-to-head trials. Berberine also provided additional lipid-lowering benefits not seen with metformin alone. Note: These findings do not justify replacing prescribed diabetes medication without medical supervision.
Berberine for Cholesterol: What the Meta-Analysis Shows
A 2018 meta-analysis of randomized trials (16 trials, 2,147 participants) found berberine was associated with reduced total cholesterol, LDL cholesterol, and triglycerides, and a small rise in HDL when used alone. Many included trials were of limited methodological quality, and berberine interacts with several medications — so it is best used with clinician guidance, not as a self-directed substitute for prescribed treatment.
Beta-Alanine for Exercise Performance: What the Meta-Analysis Shows
A meta-analysis of 40 studies (1,461 participants) found beta-alanine was associated with a small but significant overall improvement in exercise capacity and performance (effect size 0.18). The benefit is concentrated in sustained high-intensity efforts lasting roughly 30 seconds to 10 minutes, with typical doses of 3.2–6.4 g/day.
Beta-Alanine for Muscle Strength: What the Randomized Trials Show
In randomized trials, beta-alanine's effect on maximal muscle strength was mixed: one 5-week study reported a greater 1RM load increase with beta-alanine (24 kg vs 16 kg) [4], while trials in older adults and collegiate women found no added effect on maximal strength [5][8]. Signals were more consistent for strength-endurance and isokinetic measures [1][7].
Black Seed Oil (Nigella sativa) for Metabolic Health: Systematic Review
A systematic review of 23 clinical trials found that black seed oil (1-3g/day) significantly reduced fasting blood glucose by 17.8 mg/dL, total cholesterol by 15.6 mg/dL, and triglycerides by 20.6 mg/dL compared to placebo in adults with metabolic risk factors.
Boswellia Serrata for Osteoarthritis: RCT on Pain and Inflammation
An RCT of 60 knee osteoarthritis patients found that Boswellia serrata extract (100mg Aflapin daily) reduced WOMAC pain scores by 48.8% and improved physical function scores by 49.4% at 30 days, significantly outperforming placebo (p < 0.001).
Chromium for Blood Sugar Control: What the Meta-Analyses Show (Mixed Evidence)
The evidence is mixed. A 2020 meta-analysis found chromium was associated with reduced HbA1c and fasting glucose in type 2 diabetes, while a 2015 meta-analysis (875 participants) found most chromium forms had no significant effect on HbA1c. Any benefit appears modest and form-dependent, so chromium is not a substitute for prescribed diabetes care.
Citrulline for Strength & Power: What the Meta-Analysis Shows
A 2019 meta-analysis (12 studies, 198 participants) found citrulline supplementation was associated with a small but significant benefit to high-intensity strength and power performance versus placebo (standardized mean difference 0.20). Studied doses were at least 3 g of citrulline (or about 8 g of citrulline malate) taken before exercise.
Oral Collagen for Skin: 2021 Meta-Analysis of 19 RCTs
A 2021 meta-analysis of 19 RCTs (n=1,125) found that oral collagen peptide supplementation significantly improved skin hydration, elasticity, and reduced wrinkles compared to placebo. Skin hydration increased by a standardized mean difference of 0.53 and elasticity by 0.49 after 8-12 weeks of supplementation.
CoQ10 for Heart Failure: 2017 Meta-Analysis of 14 RCTs
A 2017 meta-analysis of 14 RCTs (n=2,149) found that CoQ10 supplementation (100-300mg/day) significantly improved left ventricular ejection fraction by 3.67% and reduced mortality in heart failure patients. The landmark Q-SYMBIO trial showed a 43% reduction in cardiovascular mortality with 300mg/day CoQ10.
CoQ10 for Migraine Prevention: What the Meta-Analysis Shows
A 2021 meta-analysis of 6 randomized controlled trials (371 participants) found coenzyme Q10 (CoQ10) was associated with a reduction of about 1.5 migraine attacks per month versus control, along with shorter attack duration. It did not significantly reduce attack severity, and certainty was limited by the small number of trials. CoQ10 is studied as a preventive option to discuss with a clinician.
Cranberry for UTI Prevention: What the Cochrane Review Shows
A 2023 Cochrane systematic review (50 randomized trials, 8,857 participants) found cranberry products were associated with a reduced risk of urinary tract infections (risk ratio 0.70 overall), with the clearest benefit in women with recurrent UTIs (RR 0.53). Benefit was small or absent in elderly institutionalized people and during pregnancy. Cranberry is for prevention in susceptible groups — it does not treat an active infection.
Creatine and Cognitive Performance: 2023 RCT in Healthy Adults
A 2023 RCT (n=281) found that 5g/day of creatine monohydrate for 6 weeks significantly improved working memory scores by 8.5% and reduced cognitive fatigue under sleep deprivation conditions. Effects were most pronounced in vegetarians and during mentally demanding tasks.
Creatine for Muscle Strength: What the Meta-Analyses Show
Meta-analyses show that creatine monohydrate, combined with resistance training, is associated with significantly greater gains in muscular strength than training alone. The effect is well established for both lower- and upper-limb strength, and creatine has a strong safety record in healthy adults at standard doses (3–5 g/day).
Curcumin for Depression: What a Meta-Analysis of 10 Trials Found
A 2020 meta-analysis of 10 randomized controlled trials (531 participants) found curcumin supplementation was associated with a significant reduction in depressive symptoms versus placebo (Hedge's g = −0.75, a large effect). Trials were short (4–8 weeks) and many used curcumin alongside standard care, so it is best viewed as a supportive option to discuss with a clinician — not a replacement for depression treatment.
Curcumin for Joint Pain and Arthritis: 2021 Systematic Review of 16 RCTs
A 2021 systematic review of 16 RCTs (n=1,810) found that curcumin supplementation significantly reduced joint pain scores (SMD = -0.93, p < 0.001), improved physical function (SMD = -0.85), and reduced inflammatory markers. Curcumin performed comparably to NSAIDs like ibuprofen and diclofenac for knee osteoarthritis pain with fewer GI side effects.
Elderberry Extract for Cold and Flu: RCT on Duration and Severity
An RCT of 312 air travelers found that elderberry extract (600mg/day) reduced cold duration by an average of 2 days and significantly lowered symptom severity scores compared to placebo (p < 0.01).
Fenugreek Extract for Testosterone and Libido: RCT Results
An RCT of 120 healthy men aged 43-70 found that 600mg/day of fenugreek extract (Testofen) significantly increased free testosterone by 46% and total testosterone by 6.57% after 12 weeks, with concurrent improvements in libido and sexual function scores (p < 0.01).
Fish Oil for ADHD in Children: What the Meta-Analyses Show
A 2011 meta-analysis (Bloch & Qawasmi) of omega-3 supplementation in children with ADHD found a small but statistically significant improvement in symptoms (standardized mean difference ≈0.31). The effect is modest and the evidence is mixed across reviews, so fish oil is best considered a possible adjunct to discuss with a clinician — not a substitute for proper ADHD evaluation and treatment.
Garlic for Blood Pressure: What the Meta-Analyses Show
Meta-analyses find garlic supplements were associated with modest reductions in blood pressure — on the order of about 5 mmHg systolic overall, and larger (around 8 mmHg systolic) in people with hypertension. Garlic may be a supportive option alongside diet and lifestyle, but it is not a replacement for prescribed blood-pressure medication.
Ginger for Nausea in Early Pregnancy: What the Meta-Analysis Shows
A meta-analysis of randomized placebo-controlled trials (6 studies, 508 pregnant women) found ginger (about 1 g/day) was associated with improved nausea and vomiting of early pregnancy. This evidence applies specifically to pregnancy-related nausea; because pregnancy is a sensitive situation, ginger should only be used after discussing it with your obstetric provider.
Ginkgo Biloba for Cognition & Dementia: What the Meta-Analysis Shows
A 2015 meta-analysis (9 trials, 2,561 patients) found standardized ginkgo biloba extract (EGb761, 240 mg/day) was associated with improved cognition in people with existing cognitive impairment or dementia. Importantly, large trials found ginkgo does NOT prevent dementia in healthy older adults — so its studied benefit is in those already affected, and it should be used with clinician guidance.
Glucosamine for Knee OA: 2018 Meta-Analysis of 25 RCTs
A 2018 meta-analysis of 25 RCTs (n=4,963) found that crystalline glucosamine sulfate (1,500mg/day) significantly reduced knee osteoarthritis pain (SMD = -0.47, p < 0.001) and improved physical function over 3-6 months. Glucosamine sulfate also slowed joint space narrowing compared to placebo.
L-Glutamine and Gut Permeability: Systematic Review of Clinical Evidence
A systematic review of 19 studies found that L-glutamine supplementation (0.3-0.5g/kg/day) significantly reduced markers of intestinal permeability and improved gut barrier integrity, with the strongest evidence in critically ill patients and those with IBS-D.
Green Tea EGCG and Fat Oxidation: Meta-Analysis of 15 RCTs
A meta-analysis of 15 RCTs (n=1,945) found that green tea catechins containing EGCG significantly increased fat oxidation by 16% and 24-hour energy expenditure by ~100 kcal/day compared to placebo, with the greatest effects during exercise.
Iron Supplementation for Anemia: 2019 Systematic Review
A systematic review found that alternate-day iron supplementation (40-80mg elemental iron every other day) achieved comparable hemoglobin recovery to daily dosing while reducing GI side effects by 36%. Fractional iron absorption was 40% higher on alternate days, making it a more efficient strategy.
L-Theanine for Anxiety: RCT on Alpha Brain Wave Activity
An RCT of 46 participants found that 200mg L-theanine daily for 8 weeks significantly increased alpha brain wave activity and reduced subjective anxiety scores by 21% compared to placebo (p = 0.019).
Lion's Mane and Nerve Growth Factor: 2023 Systematic Review
A systematic review of clinical trials (n=897) found that lion's mane supplementation significantly improved cognitive function in adults with mild cognitive impairment, stimulated NGF synthesis via hericenones and erinacines, and demonstrated a favorable safety profile. Effects required 8-16 weeks of daily supplementation to manifest.
Maca Root for Sexual Desire: Randomized Controlled Trial
An RCT of 57 men found that 1,500-3,000mg/day of maca root for 12 weeks significantly improved sexual desire scores compared to placebo (p < 0.01), without altering testosterone or estradiol levels.
Magnesium for Anxiety: 2017 Randomized Controlled Trial
An RCT (n=264) found that magnesium supplementation (248mg elemental magnesium/day as magnesium lactate) significantly reduced subjective anxiety scores on the GAD-7 scale compared to placebo over 6 weeks. A companion systematic review confirmed a positive trend across studies.
Magnesium for Migraine: What the Meta-Analyses Show (Mixed Evidence)
The evidence is mixed. A 2016 meta-analysis (789 participants) found oral magnesium was associated with reduced migraine attack frequency and intensity, and a 2025 dose-response meta-analysis reported fewer attacks — but a 2019 meta-analysis (226 participants) found no statistically significant effect and judged the evidence insufficient. Magnesium is inexpensive and low-risk, which is why some clinicians still consider it for migraine prevention.
Magnesium and Sleep: 2023 Meta-Analysis of 8 RCTs
A 2023 meta-analysis of 8 RCTs (n=2,132) found that magnesium supplementation significantly reduced sleep onset latency by an average of 17 minutes and improved subjective sleep quality scores. Effects were strongest with magnesium glycinate at doses of 200-400mg.
Melatonin and Sleep Onset Latency: 2013 Meta-Analysis of 19 RCTs
A 2013 meta-analysis of 19 RCTs (n=1,683) found that melatonin significantly reduced sleep onset latency by 7.06 minutes (p < 0.001), increased total sleep time by 8.25 minutes (p = 0.013), and improved overall sleep quality. Effects were consistent across studies with no evidence of tolerance development over weeks of use.
Milk Thistle (Silymarin) for Liver Protection: Systematic Review
A systematic review of 17 clinical trials found that silymarin (420-840mg/day) significantly reduced ALT by 14.1 U/L and AST by 9.4 U/L in patients with NAFLD, and showed histological improvement in liver steatosis and fibrosis scores across multiple trials.
Myo-Inositol for PCOS: What the Meta-Analyses Show
A 2017 meta-analysis of randomized trials found myo-inositol was associated with significant improvements in fasting insulin and insulin resistance (HOMA index) in women with PCOS, with a trend toward lower testosterone. Evidence is encouraging but mixed — some later analyses found smaller or non-significant effects — so myo-inositol is best considered with a clinician as part of a broader PCOS plan.
N-Acetylcysteine (NAC) for COPD Exacerbations: What the Meta-Analysis Shows
A 2015 meta-analysis (around 4,155 chronic bronchitis/COPD patients) found N-acetylcysteine (NAC) was associated with fewer exacerbations, particularly at higher doses (≥1,200 mg/day) over longer use. More recent analyses are mixed, and COPD is a serious medical condition — so NAC should only be considered as an adjunct under the guidance of a clinician, not as a self-directed treatment.
NMN Supplementation: RCT on NAD+ Levels and Aging Biomarkers
An RCT of 30 participants found that 250mg NMN daily for 12 weeks significantly increased blood NAD+ levels by 38% and improved aerobic capacity, while reducing biological age markers compared to placebo.
Omega-3 and Cardiovascular Events: 2019 Meta-Analysis of 13 RCTs
A 2019 meta-analysis of 13 RCTs (n=127,477) found that marine omega-3 supplementation reduced the risk of major cardiovascular events by 8% (RR 0.92, 95% CI: 0.87-0.98). Higher-dose EPA regimens (>1g/day) showed stronger reductions of up to 17% in cardiac mortality.
Omega-3s for Depression: What the Meta-Analyses Show
A 2019 meta-analysis (26 randomized trials, 2,160 participants) found omega-3 supplements were associated with reduced depressive symptoms — but the benefit was specific to formulations with at least 60% EPA (eicosapentaenoic acid). EPA-predominant omega-3 is studied as a possible adjunct, often alongside standard care, and is not a substitute for depression treatment.
Omega-3 (DHA) for Type 2 Diabetes: What the Randomized Trials Show
In randomized trials of people with or at risk of type 2 diabetes, omega-3 (EPA/DHA) supplementation produced mixed glycemic results: some trials reported lower fasting insulin, HOMA-IR, or HbA1c [1][11], while others found no change in fasting glucose, insulin, HbA1c, or inflammatory markers [2][9][4].
Probiotics for Depression & Anxiety: What the Meta-Analyses Show
Meta-analyses find probiotics were associated with reduced depression and anxiety symptoms. A 2025 meta-analysis reported moderate effects (depression SMD −0.53; anxiety SMD −0.44, anxiety analysis n=3,912), while an earlier 2019 meta-analysis found smaller effects (depression d≈−0.24). Probiotics are studied as a possible adjunct to discuss with a clinician — not a substitute for evidence-based treatment.
Probiotics for IBS: 2023 Meta-Analysis of 53 RCTs
Yes, probiotics actually work — a 2023 meta-analysis of 53 RCTs (n=5,545) found that probiotics significantly improved global IBS symptoms, with 21% more patients reporting relief vs placebo (NNT = 7). Multi-strain formulations and Bifidobacterium-containing products showed the strongest effects, also reducing abdominal pain, bloating, and flatulence scores.
Psyllium Husk for LDL Cholesterol: Meta-Analysis of 28 Trials
A meta-analysis of 28 RCTs (n=1,924) found that psyllium husk supplementation (7-15g/day) reduced LDL cholesterol by an average of 7% (0.33 mmol/L), with consistent effects across diverse populations and no significant adverse events.
Red Yeast Rice for Cholesterol: What the Meta-Analyses Show (and the Statin-Like Catch)
Meta-analyses suggest red yeast rice may lower LDL cholesterol — in one placebo-controlled analysis by about 1.02 mmol/L (~39 mg/dL), a reduction similar in size to some statins. The important catch: the key cholesterol-lowering compound in some red yeast rice products, monacolin K, is structurally identical to the statin lovastatin, so where it is present in meaningful amounts it carries statin-like safety and drug-interaction considerations — and commercial products vary enormously in how much they actually contain.
Resveratrol for Cardiovascular Health: Systematic Review
A systematic review of 24 clinical trials found that resveratrol supplementation (150-500mg/day) significantly reduced systolic blood pressure by 3.5 mmHg and improved flow-mediated dilation by 1.5%, with the strongest effects in participants with existing metabolic dysfunction.
Rhodiola Rosea for Stress-Related Fatigue: Multicenter RCT
A multicenter RCT (n=161) found that Rhodiola rosea extract (370mg/day SHR-5) significantly reduced stress-related fatigue by 20% on the fatigue index and improved cognitive function including short-term memory and associative thinking during stressful conditions, compared to placebo.
Riboflavin for Migraine: What a Randomized Trial Found
In a landmark randomized controlled trial, riboflavin (vitamin B2) at 400 mg/day was associated with a significant reduction in migraine attack frequency over 3 months versus placebo, with 59% of riboflavin users improving by at least half (vs 15% on placebo). Later meta-analysis supports a benefit on migraine days and frequency. Benefit typically builds after the first month.
Saffron for Depression: What a Meta-Analysis of RCTs Found
A 2013 meta-analysis of randomized controlled trials (5 trials, 177 participants) found saffron was associated with a large reduction in depressive symptoms versus placebo, and was comparable to standard antidepressants. Trials were small and mostly conducted in Iran, so saffron is best seen as a supportive option to discuss with a clinician — not a replacement for depression treatment.
Saw Palmetto for BPH: Meta-Analysis of IPSS and Urinary Flow
A meta-analysis of 27 RCTs (n=4,957) found that saw palmetto extract (320mg/day) reduced International Prostate Symptom Scores (IPSS) by 1.8 points and improved peak urinary flow by 1.02 mL/s compared to placebo, with effects comparable to low-dose tamsulosin.
Selenium for Hashimoto's Thyroiditis: What the Meta-Analysis Shows
A 2024 systematic review and meta-analysis of randomized trials found selenium supplementation was associated with significantly reduced thyroid peroxidase antibodies (TPOAb) in people with Hashimoto's thyroiditis (SMD −0.96), and lower TSH, independent of thyroid hormone replacement. TPOAb is a marker, however, and whether this changes clinical outcomes is less clear — so selenium should be used only under clinician supervision, not as a substitute for thyroid care.
Spirulina for Cholesterol and Triglycerides: Meta-Analysis of 12 RCTs
A meta-analysis of 12 RCTs (n=807) found that spirulina supplementation (1-8g/day) significantly reduced LDL cholesterol by 33 mg/dL (p < 0.001), triglycerides by 44 mg/dL (p = 0.001), and total cholesterol by 47 mg/dL (p < 0.001) while raising HDL by 6 mg/dL.
Tongkat Ali and Testosterone: What a Randomized Trial Found
In a randomized, double-blind, placebo-controlled trial (105 men aged 50–70 with low baseline testosterone), tongkat ali (Eurycoma longifolia) extract at 200 mg/day for 12 weeks was associated with a significant increase in total testosterone versus placebo. Evidence is mostly in ageing men with low testosterone, from small trials, so effects should not be assumed for other groups.
Tributyrin for Gut Barrier Integrity: RCT on Butyrate Delivery
An RCT of 37 adults with metabolic syndrome found that tributyrin supplementation (600mg/day for 12 weeks) significantly reduced intestinal permeability markers and plasma LPS-binding protein levels, indicating improved gut barrier function compared to placebo.
Valerian Root for Sleep Quality: Meta-Analysis of 16 RCTs
A meta-analysis of 16 RCTs (n=1,093) found that valerian root improved subjective sleep quality by 37% on average, though effects on objective sleep measures (polysomnography) were modest and not always statistically significant.
Vitamin C for Common Cold Duration: Cochrane Meta-Analysis
The Cochrane meta-analysis of 29 RCTs (n=11,306) found that regular vitamin C supplementation (≥200mg/day) did not prevent colds in the general population but reduced cold duration by 8% in adults and 14% in children, and decreased cold severity.
Vitamin D and Depression: 2022 Meta-Analysis of 41 RCTs
A 2022 meta-analysis of 41 RCTs (n=53,235) found that vitamin D supplementation significantly reduced depressive symptoms compared to placebo (ES = -0.317, 95% CI: -0.405 to -0.230, p < 0.001). Effects were strongest in those with baseline vitamin D deficiency and diagnosed depressive disorders.
Vitamin D and Fall Prevention in Older Adults: Evidence Review
Two meta-analyses of randomized trials found that daily vitamin D at roughly 700-1,000 IU (17.5-25 mcg) was associated with a modestly lower fall risk in older adults (relative risk about 0.85-0.87), with the benefit concentrated in people who are vitamin D deficient. It is not settled prevention: absolute differences were small, higher daily doses (>1,000 IU) showed no added benefit and may increase risk, and intermittent mega-doses did not help.
Vitamin D and Immune Function: 2024 Systematic Review
A 2024 systematic review of 25 trials found that vitamin D supplementation (1,000-4,000 IU/day) reduced the risk of acute respiratory infections by 12% overall, with a 42% reduction in participants who were vitamin D deficient at baseline (serum 25(OH)D < 25 nmol/L).
Vitamin K2 for Bone Density: What the Meta-Analysis Shows
A 2022 meta-analysis of 16 randomized trials (6,425 participants, mostly postmenopausal) found vitamin K2 was associated with improved lumbar-spine bone mineral density and reduced fracture incidence. Findings are strongest in postmenopausal populations and many trials came from Japan, so results may not generalize to everyone — discuss bone health with your clinician.
Zinc for Acne: What a Meta-Analysis of 25 Studies Found
A 2020 systematic review and meta-analysis (25 studies, 2,445 participants) found that people with acne had lower serum zinc levels than controls, and that zinc treatment was associated with a reduction in inflammatory acne lesions. Zinc may be a useful option for some, used alone or alongside standard acne care, and is best discussed with a clinician.
Zinc and Immune Function: 2017 Systematic Review
A systematic review of clinical trials found that zinc supplementation (75mg+/day as lozenges) reduced common cold duration by an average of 33% when started within 24 hours of symptom onset. Zinc also plays essential roles in innate and adaptive immune cell function.