The Honest Supplement Guide for Men Over 40. Creatine, Protein, and What Actually Works.

Two patients. Different weeks. Same fundamental problem.

The first was forty-four, a commercial real estate developer, who placed a printed spreadsheet on my desk before I had finished reading his chart. He had been maintaining this list for three years. Twenty-seven supplements. He wanted to know which ones were doing something. “I spend about two hundred and twenty dollars a month,” he said. “And I genuinely cannot tell you whether any of them are working.”

The second was thirty-eight, an IT project manager, who had been taking creatine monohydrate consistently for two years. He had noticed real improvements in the gym, real improvements in cognition during mentally demanding stretches. Then a colleague had told him: creatine causes hair loss. He had read about it online. He had stopped taking it three weeks ago.

These two men represent the two primary supplement failure modes in men over 40. The first is supplement sprawl: a growing stack assembled from podcasts, influencer recommendations, and longevity content, with no evidence hierarchy and no physician input. The second is supplement fear: a single well-supported supplement abandoned based on a single never-replicated study, because the correct information was not available in a usable format.

Here is the clinical hierarchy, applied with the Honesty Scale.

Creatine: The Most Studied Supplement in Existence

Creatine is the most extensively studied dietary supplement in existence. Not a marketing claim. A bibliometric fact: over 500 peer-reviewed trials have examined creatine safety and efficacy across multiple populations, spanning thirty years of research.

The mechanism is straightforward. Creatine is stored in muscle as phosphocreatine. During high-intensity, short-duration exercise, phosphocreatine donates a phosphate group to ADP, rapidly regenerating ATP. This process is rate-limiting for explosive efforts lasting 1 to 10 seconds, meaning creatine supplementation directly improves performance in resistance training and sprinting.

At 3 to 5 grams per day, creatine monohydrate consistently produces increased maximal muscle strength (effect size approximately 5 to 15%), increased lean muscle mass over 4 to 12 weeks of training, and in older adults specifically, attenuation of age-related muscle loss. Accumulating evidence also supports cognitive benefit under sleep deprivation, plausibly mediated by creatine’s role in cerebral energy metabolism. 5 / Solid

Creatine and aging: why the benefit is proportionally larger after 40.

This is where the case for creatine gets more interesting for men in this age range specifically. Brose and colleagues (Medicine and Science in Sports and Exercise, 2003) randomized elderly men to resistance training alone or resistance training plus creatine. The creatine group gained significantly more lean mass and dynamic strength. The effect size was larger than what is typically observed in younger cohorts on the same protocol.

The mechanism involves two processes beyond ATP regeneration. First, creatine increases satellite cell activity, the stem cells responsible for repairing and enlarging muscle fibers. Second, creatine upregulates IGF-1 expression in muscle tissue, a growth factor that becomes progressively more important as systemic testosterone and growth hormone decline with age. Rawson and Venezia (Journal of Nutrition Health and Aging, 2011) synthesized this evidence and concluded that creatine attenuates age-related muscle loss through mechanisms that go beyond phosphocreatine replenishment.

In practical terms: if you are forty-five and lifting, creatine is doing more for you than it would have done at twenty-five, not less.

Creatine for sarcopenia prevention in men over 40: 4 / Promising Multiple trials show benefit in older cohorts; mechanistic data on satellite cell activity and IGF-1 upregulation is consistent. Long-term sarcopenia outcome trials in community-dwelling men are still limited.

The hair loss question, specifically.

In 2009, van der Merwe and colleagues published a study in 20 male rugby players. The creatine group was loaded at 25 grams per day for 7 days, five times the standard dose, then maintained at 5 grams per day. DHT levels rose approximately 56 percent during the loading phase.

Here is what the study did not show: any participant developed hair loss. No hair loss was measured. No DHT receptor sensitivity analysis was performed. Total testosterone was unchanged. The DHT elevation remained within the normal reference range.

The van der Merwe study has never been replicated. The man who stopped taking creatine based on it made a medical decision from a single non-replicated study using an atypical dose, which measured a surrogate marker that produced no hair loss in any participant.

The Honesty Scale:

Creatine monohydrate for muscle strength and lean mass in resistance-training men: 5 / Solid Extensive replication across populations, dose ranges, and training protocols.

Creatine for cognitive performance (working memory, mental fatigue): 3 / Early Emerging but consistent evidence in cognitively demanding tasks and under sleep deprivation.

Creatine causing hair loss at standard dosing: 2 / Theoretical Zero replicated evidence. One non-replicated study using five times the standard dose measured a DHT marker that produced no hair loss in any participant.

Creatine causing kidney damage in healthy men at standard doses: 2 / Theoretical Multiple studies examining kidney function in healthy men taking creatine long-term show no clinically significant changes in eGFR or cystatin C.

Protein: The Macro Most Men Are Getting Wrong

After age 40, and accelerating after 50, muscle protein synthesis becomes less efficient per gram of protein consumed. This is anabolic resistance: the blunted muscle-building response to dietary protein that explains why a fifty-year-old man who eats the same protein as a twenty-five-year-old builds less muscle and loses more.

The evidence-based target is 1.6 to 2.2 grams of protein per kilogram of body weight per day. For an 85-kilogram man, that is approximately 136 to 187 grams daily. Most men eating a typical Western diet consume 70 to 100 grams. The gap is significant and produces measurable consequences in muscle mass and metabolic rate.

Distribution matters as much as total. The leucine threshold, approximately 2 to 3 grams per meal, is required to maximally activate mTOR-mediated muscle protein synthesis. Four meals of 40 grams outperforms eight meals of 20 grams, even at identical daily totals, because only the larger servings reliably clear that threshold.

Protein powder is a convenient method to meet these targets, not a supplement with unique properties. Whey’s advantage is its leucine content, approximately 10 to 11 percent of its amino acid composition, higher than most plant proteins.

Protein at 1.6 to 2.2g/kg/day for muscle preservation in men over 40: 5 / Solid Supported by multiple systematic reviews and the International Society of Sports Nutrition position stand.

High protein intake causing kidney damage in healthy men: 2 / Theoretical Multiple long-term studies in healthy men, including athletes consuming 3g/kg or above, show no decline in kidney function.

What the Research Actually Shows About Specific Popular Supplements

Here is the Honesty Scale applied to five supplements men over 40 are currently buying in large numbers.

Testosterone boosters (ashwagandha, D-aspartic acid, zinc as standalone).

Ashwagandha has the most credible data in this category. A 2012 RCT by Chandrasekhar and colleagues (Indian Journal of Psychological Medicine) found ashwagandha root extract at 300 mg twice daily reduced perceived stress and serum cortisol over 60 days. There is a plausible pathway: chronic cortisol elevation suppresses the hypothalamic-pituitary-gonadal axis, so reducing cortisol may preserve testosterone. Some trials have shown modest testosterone increases in men with clinical stress or subfertility. The word “modest” is doing real work.

D-aspartic acid failed in a well-designed 2013 RCT by Melville and colleagues: no effect on serum testosterone in healthy, resistance-trained men at standard doses. The signal that built the category did not hold under rigorous testing.

Zinc supplementation corrects testosterone suppression caused by zinc deficiency. It does not raise testosterone in men who are not deficient. Those are different claims, and only the first is supported.

2 / Theoretical As a category for testosterone elevation without documented deficiency: mechanism is plausible, replication is inconsistent, and effect sizes in studies showing benefit are small.

NMN and NR (NAD+ precursors).

NAD+ is a coenzyme involved in mitochondrial energy metabolism and DNA repair. NAD+ levels decline with age. Both NMN and NR raise intracellular NAD+ levels in animal models and in humans: Yoshino and colleagues (Science, 2021) demonstrated that NR supplementation increased skeletal muscle NAD+ concentrations. The human tissue-level data is real.

What does not yet exist: long-term human outcome data. Whether NAD+ precursor supplementation in humans produces the same downstream effects on aging and physical performance seen in mouse models remains unknown. The mechanism is not in question. The clinical translation is.

2 / Theoretical Compelling mechanism, early human tissue-level data, no long-term human outcome trials.

CoQ10 (coenzyme Q10).

The evidence for CoQ10 is strongest in men on statins. Statins inhibit the mevalonate pathway to lower LDL cholesterol, and the mevalonate pathway is also the biosynthetic route for CoQ10. Men on statins have measurably lower plasma CoQ10 levels. The Q-SYMBIO trial (Mortensen et al., JACC Heart Failure, 2014) found CoQ10 supplementation at 300 mg per day reduced all-cause mortality in moderate-to-severe heart failure patients. That population had documented mitochondrial dysfunction, not the typical healthy statin user.

For men on statins who experience myalgia, a trial of CoQ10 at 100 to 300 mg per day is reasonable given the mechanism. For men not on statins with no cardiac disease, the case is weaker.

3 / Early Evidence is strongest in men on statins and in heart failure patients; clinical outcome data in otherwise healthy men is limited.

Berberine.

Berberine activates AMPK and small trials have shown modest LDL reduction and glycemic benefit in metabolic syndrome patients. The concern is drug interactions: berberine inhibits CYP3A4 and CYP2D6, the same liver enzymes metabolizing many statins, metformin, and anticoagulants. A man taking berberine alongside metformin or warfarin is running an interaction risk that has not been well characterized in safety trials. GI side effects (cramping, diarrhea) are also common enough to be limiting.

3 / Early Modest LDL and glycemic data in small trials, but drug interaction concerns and GI tolerability limit the recommendation for men already on multiple medications.

Resveratrol.

Resveratrol activates sirtuins, extends lifespan in yeast, worms, and obese mice, and reduces cardiovascular markers in animal models. The supplement industry built a large market on these findings before the human data arrived.

The human data is not supportive. In a 2013 study published in Cell Metabolism, Poulsen and colleagues found that resveratrol supplementation in healthy, physically active older men blunted the cardiovascular and metabolic benefits of exercise training. Blood pressure, oxidative stress markers, and lipid profiles all improved less in the resveratrol group than in the placebo group. The likely reason: resveratrol’s antioxidant effect interfered with the reactive oxygen species signaling that drives exercise adaptation.

2 / Theoretical Compelling animal mechanism that has not translated to human outcomes; Poulsen et al. (Cell Metabolism, 2013) found resveratrol blunted exercise training benefits in older men.

Three Micronutrients Worth Addressing

Vitamin D. More than 40 percent of American men are deficient at the IOM minimum of 20 ng/mL. The evidence for cardiovascular benefit points toward a target range of 40 to 60 ng/mL. Get your level measured; the dose required to reach target varies enormously between men, from 1,000 IU to 4,000 IU or more daily. At 4,000 IU per day, vitamin D3 is safe for most adults.

The VITAL trial (Manson et al., NEJM 2019) randomized 25,871 adults to 2,000 IU of vitamin D3 per day versus placebo. The primary cardiovascular endpoint was neutral. However, vitamin D3 reduced cancer mortality by 25 percent. Critically, many participants were not deficient at baseline, meaning the effect in deficient men is likely larger. Treating documented deficiency to reach 40 to 60 ng/mL has a different evidence base than supplementing in men who are already replete. 4 / Promising

Magnesium. Dietary magnesium intake in Western populations is approximately 50 to 60 percent below the estimated average requirement. NHANES data documented by Rosanoff and colleagues in Nutrition Reviews in 2012 confirmed the majority of Americans fail to meet this threshold from diet alone. Magnesium participates in over 300 enzymatic reactions including ATP synthesis, blood pressure regulation, and cardiac rhythm regulation. Hypomagnesemia is associated with atrial fibrillation, hypertension, and insulin resistance. Magnesium oxide (the most common OTC form) has approximately 4 percent absorption. Magnesium glycinate and magnesium malate have absorption rates in the 30 to 50 percent range and are the preferred forms. Target: 200 to 400 mg elemental magnesium before sleep.

One clinical note on testing: serum magnesium stays within the normal reference range until intracellular stores are significantly depleted. Red blood cell (RBC) magnesium is a more accurate measure of true status. A normal serum magnesium does not rule out deficiency. If your diet is poor in nuts, seeds, leafy greens, and whole grains, the probability of functional deficiency is high regardless of what your serum level shows. 4 / Promising

Omega-3 fatty acids. At 1 to 2 grams EPA plus DHA per day: anti-inflammatory effect (reduced hs-CRP), modest triglyceride reduction, and probable cardiovascular mortality benefit in men with low fish intake. At 4 grams per day, the evidence sharpens, but the product matters.

The REDUCE-IT trial (Bhatt et al., NEJM 2019) enrolled 8,179 patients with established cardiovascular disease or diabetes. Participants received 4 grams per day of icosapentaenoic acid (prescription EPA only, Vascepa) or placebo over a median 4.9 years. The treatment group had a 25 percent relative risk reduction in major adverse cardiovascular events.

This was not over-the-counter fish oil. REDUCE-IT used pure EPA without DHA, at prescription doses, with pharmaceutical-grade purity. Men with elevated triglycerides or established cardiovascular disease should discuss prescription icosapentaenoic acid with their physician, not assume their daily fish oil capsule is equivalent. 5 / Solid

Beyond the Core Four

A second tier of supplements has Early or Weak evidence. Not enough to recommend them broadly, but enough to discuss them specifically, with their actual ratings.

Ashwagandha for cortisol and stress. Chandrasekhar and colleagues (Indian Journal of Psychological Medicine, 2012) randomized 64 adults with a history of chronic stress to ashwagandha root extract at 300 mg twice daily or placebo for 60 days. The ashwagandha group showed statistically significant reductions in serum cortisol and self-reported stress scores. The mechanistic pathway is plausible: sustained cortisol elevation suppresses the hypothalamic-pituitary-gonadal axis, so reducing cortisol may secondarily support testosterone. Some smaller trials in men with subfertility have shown modest testosterone increases. The evidence base is small and the populations studied are not representative of most men over 40. 3 / Early

Berberine for glucose and lipid regulation. Berberine activates AMPK, the same enzyme activated by metformin, and small trials in patients with metabolic syndrome have shown LDL reductions of 15 to 25 percent and modest fasting glucose improvement. Yin and colleagues (Metabolism, 2008) compared berberine to metformin in type 2 diabetic patients and found comparable glycemic control. The limitation for otherwise healthy men: berberine inhibits CYP3A4 and CYP2D6, the liver enzymes that metabolize many statins, anticoagulants, and other common medications. Any man on multiple medications should review interaction risk before starting. GI side effects are also common enough to be limiting in the first weeks of use. 3 / Early

CoQ10 for statin users. Statins block the mevalonate pathway to lower LDL, and that same pathway produces CoQ10. Men on statins have measurably lower plasma CoQ10. For statin users who experience myalgia (muscle aching or weakness), a trial of CoQ10 at 100 to 200 mg per day is reasonable given the documented depletion mechanism. The Q-SYMBIO trial (Mortensen et al., JACC Heart Failure, 2014) found CoQ10 at 300 mg per day reduced all-cause mortality in moderate-to-severe heart failure patients with documented mitochondrial dysfunction. For healthy men not on statins, the case is substantially weaker and the rating reflects that distinction. 2 / Theoretical for healthy non-statin-using men; the evidence is meaningfully stronger for statin users with myalgia.

The Bottom Line

For men over 40, four supplements have sufficient evidence to justify consistent use: creatine monohydrate (3 to 5g daily), protein to meet the 1.6 to 2.2g/kg target, vitamin D to reach serum 40 to 60 ng/mL, and magnesium glycinate or malate at 200 to 400 mg elemental magnesium. Add omega-3s at 2 to 4 grams EPA plus DHA if you have elevated triglycerides, elevated hs-CRP, or established cardiovascular disease. For everything else, the Honesty Scale ratings above tell you where the evidence actually stands.

The rest requires either a documented deficiency or a clinical indication. Not a podcast episode.

What to Do This Week

1. Order your 25-OH vitamin D and serum magnesium levels if you have not done so in the past year. These are the two micronutrient deficiencies most likely to apply to you, and the two where supplementation against a documented deficiency has the clearest evidence. If your physician does not routinely order these, request them specifically.

2. Calculate your current daily protein intake for one day. Use a food logging app for accuracy. Most men find they are 40 to 60 grams below the evidence-based target of 1.6 to 2.2g/kg. That gap is more consequential than any supplement in any stack, and closing it requires food planning, not more products.

3. If you are taking creatine and have been frightened by the hair loss claim, continue. If you stopped, restart. The evidence does not support the fear. The standard dose is 3 to 5 grams per day; no loading phase is required. More expensive forms (creatine HCl, buffered creatine, creatine ethyl ester) have not outperformed monohydrate in head-to-head trials.

4. Pull your current supplement list and apply the deficiency filter. For each item, ask: does this address a documented deficiency in my own labs, or am I taking it because of a mechanism I read about? Items that fail this filter are not necessarily harmful. They are likely unnecessary. The money is real.

5. If you are on a statin, ask your prescribing physician about CoQ10 at 100 to 200 mg per day. The evidence for benefit in non-statin-using healthy men is limited. For men on statins with myalgia, the mechanism is documented and the risk is low.

6. If your fasting triglycerides are above 150 mg/dL on a lipid panel and dietary modification has not moved them, ask your physician about prescription icosapentaenoic acid rather than increasing your over-the-counter fish oil dose. The REDUCE-IT trial that showed 25 percent MACE reduction used pharmaceutical-grade pure EPA at 4 grams daily. Over-the-counter fish oil at 1 to 2 grams of combined EPA and DHA is not the same intervention. Know the difference before you assume one substitutes for the other.

The Signal Check is fifteen questions mapping the cardiovascular risk pattern across the physiological domains most commonly missed in standard screenings. It produces a specific starting point for your next clinical conversation.