Science
Science Behind OptimalNourish
Six evidence-backed principles drive every recommendation on this site. Here's the gist of each, see Sources for primary literature.
What does the research say about supplement timing?
Four principles cover most of it. Fat-soluble vitamins need dietary fat. Divalent minerals (calcium, iron, zinc, magnesium) compete and need two hours of spacing. Circadian rhythm sorts stimulating nutrients to morning and calming ones to night. Bioenhancers like piperine and vitamin C multiply absorption.
Fat solubility
Vitamins A, D, E, K and omega-3 fatty acids require dietary fat for efficient absorption. Studies show 30–300% better uptake when taken with a fat-containing meal.
Mineral competition
Divalent metals (calcium, iron, zinc, magnesium) share transporters and can block each other. Spacing doses by 2+ hours preserves absorption of both.
Circadian alignment
Cortisol peaks in the morning and melatonin rises at night. Stimulating supplements (B-complex, rhodiola) align with morning; calming ones (magnesium, glycine) with evening.
Gastric pH
Stomach acidity changes throughout the day and around meals. Probiotic survival is highest on an empty stomach; iron absorbs best in the same window.
Bioenhancers
Piperine (black pepper) increases curcumin absorption by up to 2000%. Vitamin C boosts non-heme iron uptake by ~67%. Pairings can matter more than pills.
Saturation curves
Some actives (creatine, collagen) saturate tissues over weeks of consistent dosing, daily total matters more than precise timing.
Where evidence is thin
We're upfront when claims rely on mechanism rather than outcomes, for example, much of the adaptogen literature is preclinical or small-trial. Pages flag this in their FAQs rather than overselling.
FAQ
What does the research say about supplement timing?
Four principles drive most of the evidence: fat-soluble vitamins need fat for absorption, divalent minerals compete and need spacing, circadian rhythm shifts which nutrients fit morning vs evening, and bioenhancers like piperine and vitamin C can multiply uptake several-fold.
How much does timing actually change absorption?
Calcium can cut iron absorption by roughly half when taken together (Hallberg et al.). Pairing curcumin with piperine raises bioavailability dramatically. Vitamin C boosts non-heme iron uptake by around 67%. Most timing decisions move absorption by 30 to 300 percent at the margin.
Where is the evidence still thin?
Much of the adaptogen literature is preclinical or based on small trials. Many timing recommendations for newer ingredients rely on mechanism rather than head-to-head outcomes. Pages on this site flag this in their FAQs rather than overselling.
Are the rules different for sustained-release or liposomal forms?
Yes. Sustained-release tablets blunt peak absorption windows, so timing relative to meals matters less. Liposomal vitamin C and glutathione bypass some gut absorption limits but still benefit from being taken away from competing nutrients.
Do these principles change with age, sex, or pregnancy?
Stomach acid drops with age, which slows iron and B12 absorption. Pregnancy raises iron and folate demand. Hormonal cycles shift iron needs. Individual variation is large, talk to a qualified clinician before changing a routine for a health condition.