Supplement Schedule
When you take a supplement matters almost as much as what you take. This schedule is based on absorption science, circadian biology, and mineral competition research. Each recommendation links to the PubMed study behind it.
You don't need all of these — this is a reference for optimal timing of whatever you're taking. Use the filter to find your supplements.
Key Principles
Mineral competition
Zinc, iron, calcium, magnesium, copper, and manganese share transporters (DMT1). Taking them together reduces absorption of each. Separate competing minerals by 2-4 hours.
PMID: 1600930Fat-soluble vitamins need fat
Vitamins D, K2, CoQ10, astaxanthin, and curcumin require dietary fat for absorption via micelle formation. Always take with a fat-containing meal.
PMID: 20200983Splitting doses improves absorption
Water-soluble vitamins like C have saturable intestinal transporters. Splitting doses maintains higher plasma levels than one large dose.
PMID: 8623000Circadian timing matters
The gut has its own circadian clock. Gastric acid, enzyme expression, and transporter activity all follow daily rhythms. Energizing supplements morning, calming ones evening.
PMID: 24012542Taking many at once is fine — with caveats
Most supplements can be taken together without issue. The exceptions are competing minerals and certain specific interactions noted in each entry. Grouping by time block is the safest approach.
Iron is the most timing-sensitive
Iron absorption is uniquely complex — alternate-day dosing may outperform daily due to hepcidin kinetics. Always separate from calcium, zinc, coffee, tea, and turmeric.
PMID: 28389369Morning — Empty Stomach
30 minutes before breakfast. Best for amino acids, certain herbs, and compounds that compete with food for absorption.
Probiotics
Gastric acid is lowest upon waking. Taking before food gives bacteria transit through a less acidic stomach.
NAC
Only 6-10% bioavailability — food (especially protein) further reduces absorption due to competition with dietary cysteine.
L-Glutamine
Competes with other amino acids for absorption. Fasted state allows direct uptake by intestinal lining.
Sulforaphane
Activates Nrf2 antioxidant pathway. Nrf2 target gene expression has circadian gating — peaks during the morning active phase.
Alpha-Lipoic Acid
Food reduces bioavailability by ~30%. Both water and fat soluble, so no fat needed. Mildly energizing.
Berberine
Activates AMPK and blunts postprandial glucose spikes. Best 15-30 min before a carb-containing meal.
Morning — With Breakfast
Take with a fat-containing meal. Fat-soluble vitamins need micelles for absorption. This is also the time for stimulating adaptogens.
Vitamin D
32% higher absorption with a fat-containing meal. May suppress melatonin — avoid evening dosing.
Vitamin K2
Fat-soluble. Directs calcium to bones and away from arteries. MK-7 has a 72hr half-life; MK-4 is much shorter.
CoQ10
Absorption increases 3x with fat. Energizing — supports mitochondrial ATP production.
PQQ
Promotes mitochondrial biogenesis via PGC-1alpha. Energizing — morning aligns with daytime energy needs.
B-Vitamins
Energizing — participate in energy metabolism. B6 and B12 may disrupt sleep if taken in evening.
Astaxanthin
Highly lipophilic — 2.4-3x better absorption with a fat-containing meal. Accumulates over weeks.
Rhodiola
Stimulating — increases dopamine and norepinephrine by inhibiting COMT and MAO. Improves fatigue and stress.
Cordyceps
Enhances oxygen utilization and ATP production. Performance-enhancing and energizing.
Creatine
Timing isn't critical — accumulates over weeks. Carbs and protein improve uptake via insulin.
NMN / NAD+
NAD+ biosynthesis enzyme NAMPT is clock-controlled, peaking during the active phase. Morning maximizes conversion.
Iodine
Supports thyroid hormone synthesis. TSH peaks at night, T3/T4 peak in morning — provides substrate when production ramps up.
Selenium
Essential for glutathione peroxidase and thyroid deiodinases. Pairs with iodine for thyroid support.
Boron
Supports calcium/magnesium/vitamin D metabolism. May reduce SHBG, increasing free testosterone — morning aligns with peak T production.
Shilajit
Contains fulvic acid that enhances CoQ10 levels. Mildly energizing. Fulvic acid may improve absorption of other supplements.
Bacopa
Fat-soluble bacosides need dietary fat. Cognitive benefits take 8-12 weeks. Morning aligns with cognitive demand.
Vitamin C
Absorption saturates above 200mg per dose. Split dosing (morning + midday) maintains higher plasma levels than one large dose.
Midday — With Lunch
Best for minerals that compete with your morning stack. Separating minerals by 4+ hours prevents absorption competition.
Iron
Must separate from calcium, zinc, and magnesium by 2-4 hours. Alternate-day dosing may be better — hepcidin rises after ingestion and suppresses absorption for ~24 hours.
Zinc
Separate from iron and calcium. Zinc picolinate and bisglycinate have superior absorption. Nausea common on empty stomach.
Chromium
Enhances insulin signaling — potentiates insulin receptor activity. Best with a carb-containing meal.
Quercetin
Bioavailability improves with fat and is enhanced by vitamin C. Anti-inflammatory and antihistamine. Timing is flexible.
Resveratrol
Low bioavailability (~1%). Piperine can improve absorption. Activates SIRT1 (which needs NAD+ substrate).
Vitamin C (2nd dose)
Split dosing maintains higher plasma levels due to saturable intestinal absorption (SVCT1 transporters).
Evening — With Dinner
Take with a fat-containing meal. Best for calming adaptogens, anti-inflammatories, and compounds that support overnight repair.
Omega-3 (Fish Oil)
Fat-soluble — significantly higher absorption with a high-fat meal. Evening aligns with anti-inflammatory overnight repair. May improve sleep quality.
Turmeric / Curcumin
Lipophilic — needs fat. Piperine increases bioavailability by 2000%. Anti-inflammatory effects work during overnight repair phase.
Ashwagandha
Reduces cortisol by ~30%. GABA-mimetic and calming. Evening aligns with the need to lower cortisol for healthy sleep onset.
Magnesium
Calming — blocks NMDA receptors, enhances GABA. Supports sleep onset and muscle recovery. Glycinate form best for sleep.
Taurine
Inhibitory — modulates GABA-A and glycine receptors. Calming. Cardioprotective during overnight cardiovascular function.
Collagen
Collagen synthesis peaks during sleep when growth hormone is highest. Evening provides amino acid building blocks for overnight repair.
Reishi
Calming and mildly sedating. Triterpenes modulate GABA pathways. Traditional "spirit-calming" evening mushroom.
Milk Thistle
Supports liver detox. Many CYP450 enzymes peak in evening/night. Evening provides substrate during peak hepatic activity.
Holy Basil
Adaptogen with anxiolytic and cortisol-lowering properties. Reduced stress and anxiety by 39% in studies.
Bedtime
30-60 minutes before sleep. Calming amino acids, sleep-support compounds, and overnight repair substrates.
Glycine
Lowers core body temperature via NMDA receptors in the SCN, triggering sleep onset. Improved sleep quality without morning grogginess.
L-Theanine
Increases alpha brain waves within 30-40 minutes. Boosts GABA, serotonin, and dopamine. "Alert relaxation" — calming without sedation.
Melatonin
Chronobiotic — shifts circadian phase. Lower doses (0.3-0.5mg) are often more effective than high doses (5-10mg) which cause morning grogginess.
5-HTP
Immediate precursor to serotonin, which converts to melatonin at night. Supports the natural serotonin→melatonin pathway.
Valerian
Valerenic acid inhibits GABA breakdown, increasing GABA levels. Modest sleep quality improvement over 4-8 weeks.
Passionflower
GABA-A receptor modulator via chrysin and other flavonoids. Comparable to oxazepam for anxiety in one study.