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VitalDecades Guides & Explainers

Supplements 12 min

Is taking iron every other day better than daily?

Iron taken every other day is absorbed better per dose than iron taken on consecutive days, because each dose raises hepcidin for about 24 hours. In treatment trials that gave the same total iron, alternate-day dosing roughly matched daily dosing on hemoglobin and ferritin, in some trials with fewer side effects. The BSG and AGA both recognize it as an option.

Supplements 13 min

Is BPC-157 legal to prescribe or buy in the US?

BPC-157 is not an FDA-approved drug and does not meet section 503A's rules for compounding ingredients. It sat in FDA's Category 2 from September 2023 to April 22, 2026. On October 28, 2026 HHS filed a draft policy not to act against licensed pharmacies and physicians compounding BPC-157 acetate for a patient under strict conditions. Research-use-only vials sold online are outside it, and WADA prohibits it.

Supplements 15 min

Does berberine lower A1C, and by how much? What the trials actually show

In placebo-controlled trials of people with type 2 diabetes, berberine lowered A1C by roughly 0.4 to 0.7 percentage points, mostly over one to three months and almost entirely in trials run in China. That is well short of semaglutide, and berberine slows liver enzymes that clear many prescription drugs.

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Supplements 12 min

Does creatine help muscle after 50? What the meta-analyses actually found

Added to resistance training, creatine gives adults over 50 a small extra gain in strength, and possibly lean mass, over training alone. Taken without training it has shown little effect on muscle, pooled trials found it added nothing to training's effect on bone density, and it raises serum creatinine on kidney tests.

Supplements 15 min

Does magnesium help you sleep? What the trials show

Magnesium has high-certainty null evidence for leg cramps, no current guideline grade for migraine, the lowest possible grade for depression, and an explicit ADA recommendation against it for glycemic benefit. The clearest effect is as an osmotic laxative at about 2.6 times the upper limit.

Supplements 14 min

Does collagen actually work? Who paid for the studies

A 2025 meta-analysis separating trials by funding source found no effect of collagen on skin hydration, elasticity or wrinkles in non-industry-funded studies. Joint-pain effects are real but roughly a third of the clinically meaningful threshold. Fat-free mass with resistance training is the one moderate-certainty finding.

Supplements 13 min

NMN and NR: what the NAD+ supplement trials actually found

NMN and NR reliably raise blood NAD+ and reliably fail to change muscle strength, gait speed or insulin sensitivity in randomized trials. The best meta-analysis says current evidence does not support them for preserving muscle. FDA reversed its position on NMN in September 2025.

Supplements 14 min

Do multivitamins do anything? What the trials actually show

The USPSTF calls the evidence insufficient for multivitamins and recommends against beta-carotene and vitamin E. COSMOS and Physicians' Health Study II missed their primary cancer and cardiovascular endpoints. Almost no randomized evidence exists for adults aged 35 to 50.

Supplements 3 min

Vitamin D supplements: who actually needs them

The 2024 Endocrine Society guideline supports empiric vitamin D beyond the standard intake for adults 75 and older, during pregnancy, and in high-risk prediabetes, and suggests daily dosing over intermittent high doses. For healthy adults under 75, it recommends against supplementing above the standard intake (600 to 800 IU/day, NASEM) to prevent disease, and against routine 25(OH)D testing, because trials found no benefit and no optimal target level.

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