Supplement Jargon Explained: 30 Terms You'll See Everywhere

The supplement world has its own vocabulary. Forums, Reddit threads, podcasts, and product labels throw around terms that assume you already know the language. If you've ever felt lost reading a supplement discussion, this guide is for you.

Here are 30 terms you'll encounter, explained without the jargon.

The basics

Stack

A collection of supplements that someone takes together as part of their routine. If you take vitamin D, magnesium, and omega-3 every day, that's your stack. The word comes from the idea of "stacking" multiple supplements for complementary benefits.

You'll also hear people say "my morning stack" or "my sleep stack," meaning the specific group of supplements they take at that time or for that purpose.

Protocol

A planned supplement routine, usually with specific doses, timing, and duration. It implies more intention than casually popping a multivitamin. A protocol might include cycling on and off certain supplements, adjusting doses over time, or taking different things on training days versus rest days.

In practice, "protocol" and "routine" mean the same thing. Protocol just sounds more clinical.

Cycling

Taking a supplement for a set period, then stopping for a while, then starting again. Common cycles are 8 weeks on / 2 weeks off, or 5 days on / 2 days off.

People cycle supplements for several reasons: to prevent tolerance (your body adapting so the supplement stops working), to give organs a break from processing it, or because the research suggests periodic use is more effective than continuous use. Caffeine, ashwagandha, and creatine loading phases are commonly cycled.

Loading phase

A short period of taking a higher dose to build up levels in your body faster, followed by a lower "maintenance dose." The classic example is creatine: 20g per day for 5-7 days (loading), then 3-5g per day ongoing (maintenance).

Not every supplement needs a loading phase. For most, consistent daily dosing works fine.

Maintenance dose

The ongoing daily amount you take after an initial loading phase, or simply the regular dose you take long-term. This is the amount needed to keep levels stable once they've been built up.

How supplements work in your body

Bioavailability

The percentage of a supplement that actually gets absorbed and used by your body. If you swallow 500mg of magnesium oxide, your body might only absorb 4% of it, meaning you're getting 20mg of usable magnesium. Magnesium glycinate has roughly 80% bioavailability, so 500mg delivers around 400mg.

This is why the form of a supplement matters as much as the dose. A cheaper product with poor bioavailability can be worse value than a pricier one your body actually absorbs.

Elemental dose vs compound dose

When a label says "magnesium glycinate 2,000mg," that's the compound weight, the magnesium plus the glycine it's bound to. The elemental magnesium (the part your body actually uses) might only be 200mg. Always check which number is being reported. The elemental dose is what matters for hitting recommended intakes.

Chelated

A mineral that's been bound to an amino acid or organic compound to improve absorption. Magnesium glycinate (bound to glycine), iron bisglycinate (bound to glycine), and zinc picolinate (bound to picolinic acid) are all chelated forms. They're generally better absorbed and gentler on the stomach than non-chelated forms like magnesium oxide or ferrous sulfate.

Cofactor

A nutrient that helps another nutrient work properly. Vitamin D needs vitamin K2 to direct calcium into bones rather than arteries. Vitamin C improves iron absorption. Piperine (from black pepper) increases curcumin absorption by up to 2,000%. When someone says a supplement needs a cofactor, they mean you should take it alongside something else for best results.

Half-life

How long it takes for half of a substance to leave your body. A short half-life (like vitamin C at around 30 minutes) means you need frequent dosing or a sustained-release form. A long half-life (like vitamin D at 2-3 weeks) means daily consistency matters more than precise timing.

Fat-soluble vs water-soluble

Fat-soluble vitamins (A, D, E, K) dissolve in fat and are stored in your body. Take them with a meal containing fat for better absorption. Because they're stored, it's possible (though uncommon at normal doses) to build up too much over time.

Water-soluble vitamins (C, B-complex) dissolve in water and aren't stored. Your body uses what it needs and excretes the rest. This means you need them more frequently, but it's also harder to take too much.

Types of supplements

Adaptogen

A plant or mushroom that's claimed to help your body "adapt" to stress, whether physical, mental, or environmental. Ashwagandha, rhodiola rosea, and lion's mane are popular adaptogens. The idea is that they don't push your body in one direction (like a stimulant), but help regulate your stress response.

The evidence varies widely. Ashwagandha has decent clinical data for reducing cortisol and anxiety. Others have thinner evidence but strong traditional use.

Nootropic

Any substance taken to improve cognitive function: memory, focus, creativity, or motivation. The term covers everything from caffeine and creatine (which have solid evidence) to exotic compounds like alpha-GPC and racetams (which have varying levels of support).

"Smart drugs" is the casual term. Some nootropics are well-studied supplements; others are research chemicals with limited safety data.

Precursor

A substance your body converts into something else it needs. L-tyrosine is a precursor to dopamine. 5-HTP is a precursor to serotonin. NAC (N-acetyl cysteine) is a precursor to glutathione. The logic is: give your body more raw material and it'll make more of the end product.

This doesn't always work linearly. Your body has rate-limiting enzymes that can cap production regardless of how much precursor you provide.

Methylated

A form of a vitamin that's already in its active, usable state. Your body doesn't need to convert it. Methylfolate (active folate) vs folic acid (needs conversion), and methylcobalamin (active B12) vs cyanocobalamin (needs conversion).

This matters most for people with MTHFR gene variants who are less efficient at converting inactive forms. But even without genetic testing, methylated forms are generally considered the better choice since they skip a processing step.

Ubiquinol vs ubiquinone

Two forms of CoQ10. Ubiquinone is the oxidised form that your body must convert to the active form (ubiquinol). After about age 40, this conversion becomes less efficient. Most practitioners recommend ubiquinol for adults over 40 and ubiquinone for younger adults (it's cheaper and they convert it fine).

Measuring what works

Correlation (in the supplement context)

A relationship between taking a supplement and experiencing a change in how you feel. If your sleep quality tends to be better on days you take magnesium, that's a correlation. It doesn't prove magnesium caused the improvement (see below), but a consistent pattern across weeks of data is meaningful personal evidence.

Correlation vs causation

Just because two things happen together doesn't mean one caused the other. Maybe your sleep is better on magnesium days because you also tend to take it on less stressful days. This is why tracking multiple variables over longer periods gives better signal. Patterns that persist across different circumstances are more likely to reflect a real effect.

N-of-1

An experiment where you are the only subject. Instead of relying on population studies (which tell you what works on average), an N-of-1 approach tracks what works for you specifically. This is the core idea behind personalised supplement tracking. Your biology is unique, so your data matters more than averages.

Washout period

A break between stopping one supplement and starting another (or re-starting the same one) to let your body return to baseline. This helps you get cleaner data about whether a new supplement is actually doing something, rather than seeing lingering effects from the previous one. A common washout period is 1-2 weeks, though it depends on the supplement's half-life.

The science behind labels

RDA (Recommended Daily Allowance)

The amount of a nutrient considered sufficient for 97-98% of healthy people. RDAs are set to prevent deficiency, not to optimise health. Many practitioners argue that optimal levels are higher than the RDA for several nutrients, particularly vitamin D, magnesium, and omega-3.

Tolerable Upper Intake Level (UL)

The maximum daily amount of a nutrient considered unlikely to cause harm. Going above the UL doesn't guarantee problems, but it's where the risk of adverse effects starts to increase. For some nutrients (like vitamin C), the UL is very conservative. For others (like vitamin A), exceeding it is genuinely risky.

Third-party tested

A supplement that's been independently verified for purity, potency, and contamination. Look for certifications from NSF International, USP, Informed Sport, or ConsumerLab. Without third-party testing, you're trusting the manufacturer's label, and studies have found that many supplements contain different amounts than what's listed, or include unlisted ingredients.

Standardised extract

A plant extract that's been processed to contain a consistent percentage of the active compound. "Ashwagandha standardised to 5% withanolides" means every batch contains 5% of the compounds believed to be responsible for its effects. Without standardisation, the potency can vary wildly between batches and brands.

Proprietary blend

A mix of ingredients where the manufacturer lists the total amount but not the individual doses. This is a red flag in most cases. It makes it impossible to know whether you're getting effective doses of each ingredient or just trace amounts padded with cheap fillers. Reputable brands list every ingredient with its individual dose.

Community and culture

Biohacking

A broad term for using science, technology, and self-experimentation to optimise your biology. In the supplement world, it usually means taking a data-driven approach to supplementation: tracking outcomes, adjusting based on results, using bloodwork and wearable data to inform decisions. The term ranges from mainstream (tracking sleep with an Oura Ring) to fringe (DIY genetic engineering).

Bio-individuality

The idea that what works for one person may not work for another, because of differences in genetics, gut health, hormonal status, diet, lifestyle, and dozens of other factors. It's why your friend swears by ashwagandha but you felt nothing, and why personal data is more useful than generic recommendations.

Optimiser

Someone who doesn't just take supplements to fill gaps, but actively tries to improve specific outcomes like better sleep, more energy, sharper focus, faster recovery. Optimisers tend to track data, adjust doses, and iterate on their routines based on what they observe.

Recomp / body recomposition

Simultaneously losing fat and gaining muscle. Relevant to supplements because certain products (creatine, protein, omega-3) are marketed specifically for recomp goals, and dosing recommendations may differ from general health use.

Where to start if you're new

If you've just read through this list and feel overwhelmed, here's the good news: you don't need to know all of this to start taking supplements well. The most important concepts are:

1. Bioavailability: the form matters as much as the dose
2. Cofactors: some supplements work better taken together
3. Consistency: most supplements need weeks to show effects
4. Personal data: what works for you is what matters

Stack Almanac is built to handle the complexity for you. Add your supplements, track how you feel, and let the AI advisor and personal insights surface what's actually working, no jargon required.