Why Your Supplement Dose Should Be Unique to You

The supplement industry has a standardisation problem. Walk into any health shop and every bottle says the same thing: "Adults: take 1 capsule daily." But a 55kg woman with an MTHFR variant, taking an SSRI, and eating a vegan diet has completely different needs from a 90kg man who lifts weights and eats a Mediterranean diet.

Generic dosing is the default because personalisation is hard. But it doesn't have to be.

Sex matters more than most people realise

Most supplement research has been conducted predominantly on men. Dosing recommendations often don't account for fundamental biological differences:

Iron: Pre-menopausal women typically need 18mg daily; men need 8mg. Women with heavy periods may need more. Post-menopausal women's needs drop closer to men's. Supplementing iron without testing is risky for men because excess iron causes oxidative damage.

Creatine: Women may respond differently to creatine due to naturally lower baseline stores. Some research suggests women benefit from slightly higher relative doses.

Magnesium: Needs scale with body weight, but hormonal cycles also affect magnesium requirements. Many women find increased magnesium helpful during the luteal phase (the two weeks before menstruation).

B6: Can help with PMS symptoms at doses of 50-100mg during the luteal phase, a recommendation that's completely irrelevant for men.

Hormonal status changes everything

Your hormonal profile affects supplement absorption, metabolism, and requirements:

Menstrual cycle phases: Iron needs spike post-menstruation. Magnesium and B6 become more important in the luteal phase. Some adaptogenic herbs work differently depending on where you are in your cycle.

Perimenopause and menopause: Calcium and vitamin D needs increase. Magnesium becomes critical for sleep (which is often disrupted). Some women benefit from increased omega-3 for mood support.

Testosterone replacement therapy (TRT): Changes mineral metabolism, can affect zinc and magnesium requirements. Liver-supportive supplements may become more relevant.

Thyroid medication: Levothyroxine must be taken 4+ hours apart from calcium, magnesium, iron, and zinc, all common supplements. This single interaction reshapes an entire supplement schedule.

Genetics: the variants that matter

A handful of common genetic variants meaningfully affect supplement choices:

MTHFR C677T (affects ~10-15% of the population): Impairs the conversion of folic acid to its active form (methylfolate). If you have this variant, standard folic acid supplements may be ineffective or even problematic. Use methylfolate instead.

COMT Val158Met: Affects how quickly you break down catecholamines. The "worrier" variant may need to be cautious with methylated B vitamins (methyl-B12, methylfolate) as they can increase anxiety in some people.

CYP1A2: Determines how quickly you metabolise caffeine. Slow metabolisers should avoid caffeine after noon and be cautious with pre-workout supplements containing stimulants.

VDR Taq1: Affects vitamin D receptor sensitivity. Some variants require higher vitamin D doses to achieve the same blood levels.

APOE4: Affects lipid metabolism. May change the optimal omega-3 strategy and influence how you respond to saturated fat.

You don't need to get genetic testing to take supplements effectively, but if you have the data, it can meaningfully refine your protocol.

Diet creates different gaps

Your diet determines which deficiencies you're most likely to have:

Vegan/vegetarian: Almost certainly need B12 supplementation. Likely need iron (non-heme sources are poorly absorbed), omega-3 (EPA/DHA from algae, not just ALA from flax), creatine (not found in plants), and potentially zinc.

Keto/low-carb: Electrolyte needs increase dramatically, especially sodium, potassium, and magnesium. The "keto flu" is largely an electrolyte deficit.

Standard Western diet: Likely low in magnesium, vitamin D, and omega-3. May have adequate but not optimal B12 and iron.

Mediterranean: Generally fewer gaps, but still commonly low in vitamin D (especially in northern latitudes) and potentially magnesium.

Medications create interactions

Over a third of UK adults take at least one prescription medication. Common medication-supplement interactions include:

• Statins deplete CoQ10, so supplementation is strongly recommended
• Metformin impairs B12 absorption, so monitoring and supplementation are often needed
• PPIs (omeprazole, etc.) reduce magnesium and B12 absorption
• Blood thinners interact with vitamin K and high-dose fish oil
• SSRIs interact with St. John's Wort and high-dose 5-HTP

These interactions aren't theoretical. They meaningfully affect what you should and shouldn't take.

How Stack Almanac handles bio-individuality

Stack Almanac collects your bio profile progressively, not as a wall of forms, but in layers over time:

• Core profile during onboarding (sex, age, diet)
• Health conditions after your first advisor session
• Hormonal profile after the first week
• Genetic variants when you add bloodwork
• Advanced details surfaced by the advisor when relevant

Every piece of data refines the advisor's recommendations. The correlation engine factors in your cycle phase when analysing outcomes. The Stack Score includes a "bio match" component that measures how well your protocol fits your individual profile.

The result: guidance that's actually tailored to you, not to a hypothetical average adult from a clinical trial.