Supplements Basics Guide

The supplement aisle is mostly noise. A handful of products have strong evidence; the rest range from "maybe useful in a specific case" to "expensive urine". This guide cuts through the marketing and focuses on what is actually worth your money for general fitness.

The Evidence Table

SupplementDoseEffectEvidence
Whey / plant protein20-40 g per servingHits daily protein, recoveryStrong
Creatine monohydrate3-5 g/dayStrength, power, lean massStrong
Vitamin D31,000-2,000 IU/dayBone, immune, possibly performanceStrong if deficient
Omega-3 (EPA/DHA)1-3 g/day combinedCardiometabolic, anti-inflammatoryModerate
Caffeine3-6 mg/kg pre-trainingEndurance, strength, focusStrong
Beta-alanine3-6 g/day1-4 min high-intensity workModerate

How to Think About Supplements

  • Supplements are leverage on top of training, nutrition, sleep — never a substitute.
  • If a product can't tell you its dose per serving, skip it.
  • Look for third-party tested brands (Informed Sport, NSF Certified for Sport).
  • Stack effects don't multiply — most claimed synergies are marketing.
  • "Natural" doesn't mean "safe" — some herbs have real drug interactions.
  • Trial one supplement at a time so you know what's actually doing the work.

A Sensible Stack

  1. Protein powder if you struggle to hit daily protein from food.
  2. Creatine monohydrate, 3-5 g/day, taken any time.
  3. Vitamin D3 (1,000-2,000 IU) in autumn/winter or if indoors all day.
  4. Fish oil for omega-3 if you eat little oily fish.
  5. Caffeine 30-60 min pre-workout when you need a lift.
  6. Nothing else unless a specific medical or sport need justifies it.

Red Flags in Marketing

Beware of "proprietary blends" (no dose disclosure), before/after pictures with vague captions, "as seen on TV", celebrity endorsements without studies, and anything promising rapid fat loss without diet change. A clean label, transparent dosing, batch testing, and boring scientific claims are the markers of a serious product.

Timing & Dosing That Actually Matters

For most evidence-backed supplements, total daily dose matters far more than timing. Creatine works through saturation, so 3–5 g any time of day is fine — there is no need to "load" unless you want full stores within a week. Protein is about hitting your daily target (roughly 1.6–2.2 g/kg for active people); spreading it across 3–4 meals helps but the daily total dominates. Caffeine is the main exception where timing counts: take it 30–60 minutes before training and keep it at least 8–10 hours before bed to protect sleep. Vitamin D3 is fat-soluble, so take it with a meal that contains some fat.

Safety & Sourcing

Supplements are loosely regulated in most countries — the manufacturer, not a government agency, is usually responsible for safety and label accuracy before sale. That makes third-party testing the single most useful filter: look for NSF Certified for Sport or Informed Sport seals, which verify contents and screen for contaminants. If you take prescription medication, are pregnant or breastfeeding, or have a kidney or liver condition, check with a doctor or pharmacist before starting anything — some "natural" ingredients have real drug interactions. For balanced, non-commercial overviews of individual ingredients, the NIH Office of Dietary Supplements fact sheets are a reliable reference. This guide is educational and not medical advice.

Get Your Macros First

Before any supplement, lock in protein and calories. FitCalc's macro calculator helps.

Macro Calculator →

Frequently Asked Questions

Not strictly — but it's convenient and effective for hitting daily targets.
Yes — creatine monohydrate is among the most-studied sports supplements, with decades of data supporting 3–5 g/day as safe for healthy adults long-term. The common worry about kidney harm comes from misreading creatinine (a blood marker) rather than evidence of damage. If you have existing kidney disease, clear it with your doctor first.
It is the most justified "general" supplement for people who get little sun — indoor workers, northern latitudes, or darker skin in winter. 1,000–2,000 IU/day with a meal is a sensible range; a blood test removes the guesswork if you want certainty.
Yes, 3-6 mg/kg pre-training. Avoid late-day doses.
BCAAs, fat burners, detox blends, test boosters — mostly waste.