The supplement aisle sells 200 ingredients. The list with real human evidence and clinically meaningful effect sizes is shorter than five. Here's the honest stack - what to take, what dose, what changes on labs, and what to skip even when the marketing is loud.
Creatine: the supplement with the most data
Creatine monohydrate, 3-5 g/day, taken any time of day. Hundreds of randomized trials across decades show consistent gains in strength, lean mass, and recovery, plus emerging cognitive benefit (working memory, fatigue resistance, mood in some populations).
Effect sizes: ~5-10% strength gain over placebo on a structured training program. ~1-2 kg lean body mass increase over 8-12 weeks (combination of muscle water and protein synthesis). Larger gains in older adults and in vegetarians/vegans.
Safety: kidney concerns are a myth in healthy individuals. Hundreds of trials, no adverse renal signal at 3-5 g/day. People with established kidney disease should consult a nephrologist before starting. Hair loss concerns trace to one small trial - meta-analysis doesn't confirm. Loading phase isn't necessary; daily dose works.
Protein: the floor that decides body composition
0.7-1.0 g protein per pound of lean body mass per day, distributed in 3-4 meals of 25-50 g each. Below the floor, lean mass loss accelerates during any caloric deficit (GLP-1, dieting, illness, aging). Above 1.0 g/lb LBM, returns plateau for most non-athletes.
Source matters less than total. Whey protein hits leucine threshold faster (good post-training); plant proteins need slightly higher total to match. "Complete protein" myths - varied diet over a day, not per meal, is what matters.
Why this is on the supplement list: most adults under-eat protein, especially women, GLP-1 users, and older adults. A 25 g whey shake closes the gap in 30 seconds. Cheap, no side effects (lactose-intolerant: isolate or plant blend), measurable impact on body composition and recovery.
Magnesium glycinate and vitamin D - when they actually help
Magnesium glycinate 200-400 mg at night: helps sleep onset and quality in many adults, especially those on caffeine, alcohol, or diuretics. Glycinate form has minimal GI effect (vs oxide which causes diarrhea). Citrate works for constipation, threonate for cognition (small data).
Vitamin D3 2000-5000 IU/day, ideally with 100-200 mcg vitamin K2 (MK-7), only when 25(OH)D is under 40 ng/mL on labs. Above 40, supplementation is unnecessary in most adults. Above 80 ng/mL, stop supplementing - hypercalcemia risk emerges in long-term excess.
These two earned the foundational stack because they tie to measurable lab outcomes (25-OH-D, sleep architecture, sometimes magnesium RBC) and have low side-effect profiles at standard doses. Most other foundational supplements (omega-3, multi) are reasonable but smaller in effect.
What to skip (or stop)
Generic "adaptogen" blends, "hormone balance" supplements, "adrenal support," "liver detox," "metabolism boosters," "thyroid support" without thyroid disease, fat burners, anything with proprietary blends. Underpowered, unstudied, or actively risky.
Mega-dosed B-complex (over 100x RDA), high-dose niacin (over 500 mg/day), and "longevity stacks" with NMN/resveratrol/spermidine all bought together: human outcome data is thin to non-existent at the doses sold. Money sinks.
Pre-workouts loaded with caffeine, beta-alanine, and proprietary stim blends: caffeine 100-200 mg from coffee or tea is just as effective for training output, costs nothing, and you know exactly what you're taking.
What to do now
Run the Advanced panel first - 25(OH)D, ferritin, B12, lipid, fasting insulin, ApoB. The labs decide what (if anything) you actually need to supplement.
Default stack for most members: creatine 3-5 g/day, protein hitting the floor, magnesium glycinate 200-400 mg at night, vitamin D3 only if 25-OH is under 40. That's the foundation. Add anything else only when a specific lab or symptom asks for it.