All-in-one supplement vs. a separate stack: what the evidence says about the practical decision

All in one supplements vs a separate stack: what the evidence says

The honest answer is that neither format wins by default. What matters is whether the doses inside match what clinical trials actually used - and most products, in both categories, fall short on that. One meta-analysis of 159 multi-ingredient supplements found that fewer than a third contained the evidence-based dose of even their primary active ingredient. The format is almost irrelevant if the quantities are wrong.

What the evidence actually shows

Most supplement research is done on single ingredients in isolation. That's not a coincidence - it's how you isolate a signal. When you combine ingredients, you introduce variables that make it harder to attribute effects. That's the honest starting point.

That said, some combination research exists and it's worth taking seriously. A 2022 randomised controlled trial by Reber et al. (2022) looked at a multi-ingredient formula containing creatine, vitamin D, omega-3s, and protein in 130 older adults over 13 weeks. Lean mass gains were modest but statistically significant (p=0.03) compared to placebo - though the authors noted it's impossible to isolate which component drove the effect. That ambiguity is baked into multi-ingredient research.

On the other side, a systematic review by Bjelakovic et al. (2017) covering 78 trials and over 290,000 participants found that antioxidant combinations - vitamins A, C, E, selenium, beta-carotene - did not reduce all-cause mortality and some combinations were associated with harm in specific populations. The lesson isn't that antioxidants are dangerous. It's that combining ingredients without understanding their interactions is not a neutral act.

A separate analysis by Maughan et al. (2018), commissioned by the IOC, concluded that for most people, single well-dosed ingredients with strong evidence bases are preferable to multi-ingredient products where individual doses are often diluted to fit a serving size. That's a real constraint. You can't fit ten ingredients at clinical doses into one scoop without the scoop becoming impractical.

The biology of absorption: does combining ingredients help or hinder?

Some ingredient combinations genuinely improve bioavailability. Vitamin C co-administered with non-haem iron roughly doubles iron absorption - that's well-established. Fat-soluble vitamins (A, D, E, K) absorb better when taken with dietary fat, so including them in a meal-replacement style product makes biological sense.

But some combinations work against each other. Calcium and magnesium compete for the same intestinal transporter (TRPM7), meaning high doses of one can suppress absorption of the other. Zinc and copper interact similarly - supplementing zinc without copper can deplete copper over time. These aren't theoretical concerns. A study by Sandstrom et al. (1995) demonstrated measurable reductions in zinc absorption when calcium was co-administered in doses above 300mg.

The practical implication: the formula design matters more than the format label. An all-in-one product designed with these interactions in mind can outperform a carelessly assembled stack. A stack assembled without understanding these interactions can actively work against you.

The dosing problem - and why it's the central issue

This is where most all-in-one products fail, and it's worth being specific about why.

Take creatine. The most replicated dose in resistance training research is 3-5g per day of creatine monohydrate. A 2017 meta-analysis by Lanhers et al. (2017) across 22 RCTs confirmed this range produces meaningful increases in upper and lower body strength (effect size d=0.83 for bench press, d=0.94 for leg press). That's a 5g dose - by weight, it's a significant portion of a serving. If your all-in-one product contains creatine alongside nine other ingredients in a 10g total serving, the maths don't work.

Vitamin C is similar. The evidence for immune support, collagen synthesis, and reduction of tiredness and fatigue - all of which are authorised health claims - is built on doses typically ranging from 200mg to 1000mg daily. A product containing 30mg of vitamin C as a token inclusion isn't doing much. The EU authorised claims require a meaningful contribution to daily intake, not a trace amount.

At Kojo, the formula contains 5000mg of micronised creatine monohydrate and 500mg of vitamin C - both at or above the doses used in the trials that generated the evidence. That's not a coincidence. It's the point. If you're going to include an ingredient, include it at a dose that does something.

A separate stack, in theory, lets you dose each ingredient precisely. In practice, most people don't do the research to know what dose to use, and they often end up with a collection of products each containing sub-clinical amounts. The format advantage of a stack disappears if you don't know what you're doing with it.

What a well-designed all-in-one actually needs to get right

I've looked at a lot of these products. The pattern of failure is consistent: too many ingredients, too little of each, and a label that reads impressively without delivering anything clinically meaningful. This is the proprietary blend problem in its most common form - if you want to understand how labelling practices obscure this, the piece I wrote on why supplement labels lie covers it in detail.

A well-designed all-in-one needs to do a few things right:

• Prioritise depth over breadth. Fewer ingredients at meaningful doses beats a long list of ineffective ones.
• Account for interaction effects. Both synergistic (vitamin C + iron) and antagonistic (calcium + zinc) interactions should inform the formula.
• Be transparent about what's unproven. Some ingredients have plausible mechanisms and early-stage human data without the RCT evidence to make strong claims. That's fine - but it should be stated clearly.
• Match doses to the trials, not to the label. If the evidence was generated at 5g, use 5g.

The all-in-one supplements UK guide I put together goes into more detail on what to look for when evaluating specific products in this category.

The honest case for a separate stack

There are real situations where a separate stack makes more sense, and I'd be misrepresenting the evidence if I didn't acknowledge them.

If you have a specific, well-characterised deficiency - say, clinically confirmed low vitamin D, or iron-deficiency anaemia - a targeted single-ingredient supplement at a therapeutic dose is the right tool. No all-in-one product is going to contain 1000-4000 IU of vitamin D3, which is what the evidence supports for correcting deficiency. Heaney et al. (2012) demonstrated that serum 25(OH)D levels respond in a dose-dependent manner, and the doses needed to correct deficiency are simply too large to include in a multi-ingredient product without crowding everything else out.

Similarly, if you're an athlete with specific performance requirements - creatine loading phases, beta-alanine at 3.2-6.4g/day for carnosine buffering - you may need doses that exceed what any combined product can practically deliver. The evidence for beta-alanine at those doses is solid: Hobson et al. (2012) meta-analysed 15 studies and found significant improvements in exercise capacity lasting 60-240 seconds (effect size 0.374, p<0.001). You need 3.2g+ to replicate that. Most all-in-one pre-workouts contain 1-1.5g.

The stack also wins on flexibility. You can adjust doses, cycle individual ingredients, or remove something if you have a reaction. That granularity matters for some people.

The honest case against a separate stack

The counterargument is adherence. A stack of six to eight individual supplements requires six to eight decisions per day, six to eight products to run out of at different times, and six to eight opportunities to get the timing wrong. The behavioural science on this is consistent: complexity reduces compliance.

There's also a cost argument that's often overlooked. Individual products have individual packaging, fulfilment, and retail margins. A well-designed all-in-one, bought direct from a transparent manufacturer, can deliver the same or better ingredient quality at lower total cost than assembling equivalent doses from separate products. Not always - but often.

And there's the research literacy problem. Most people assembling their own stack are doing so based on marketing, not primary literature. They end up with products that contain impressive-sounding ingredient lists at doses that were never tested. The stack format doesn't protect you from that - it just distributes the problem across more products.

Polyphenols and plant extracts: what the evidence actually supports

This is where I need to be careful, because the marketing in this space runs well ahead of the evidence.

Aged garlic extract, olive leaf extract, grape seed extract, and pine bark extract all appear in the Kojo formula. The mechanistic rationale for each is plausible - they contain polyphenolic compounds with demonstrated antioxidant activity in cell and animal models, and some human trials exist. But I won't overstate it.

For aged garlic extract, a meta-analysis by Ried et al. (2016) across 12 trials found modest but statistically significant reductions in systolic blood pressure (mean reduction 5.1mmHg, p<0.001) in hypertensive subjects. That's a real signal - but it's in a specific population, and large-scale trials in healthy adults are limited. The research on aged garlic extract is ongoing and I'd be overstating it to claim more than that.

The same honest caveat applies to olive leaf extract, grape seed extract, and pine bark extract. The human data on these ingredients is thin compared to the mechanistic literature, and I'd be doing you a disservice to present them as established interventions. They're included because the early evidence is interesting and the safety profile is good - not because the RCT evidence is settled.

Who this matters most for: a note on specific populations

The all-in-one vs stack question lands differently depending on who's asking it. For someone managing multiple health priorities simultaneously - energy, immune function, cardiovascular health, physical performance - a well-designed all-in-one offers genuine practical advantages. For someone with a single specific goal and the knowledge to pursue it precisely, a targeted stack may be more efficient.

For women navigating perimenopause, for instance, the nutritional picture is genuinely complex - multiple systems are affected simultaneously, and the supplement evidence in that context involves a different set of considerations entirely. I've written about this separately: the piece on perimenopause supplements UK goes through what the evidence actually supports in that context.

The broader point is that there's no universal answer. The question "all-in-one or separate stack?" is only answerable once you know what you're actually trying to address and what the evidence-based dose for each ingredient actually is.

Frequently asked questions

My honest take

I started Kojo because I was frustrated with exactly this problem. I'd spent years assembling my own stacks, reading the literature, trying to work out what was actually worth taking. And I kept running into the same wall: either the products were transparent about doses but contained one or two ingredients, or they contained interesting combinations but hid the doses in proprietary blends.

The formula I built is an all-in-one. I made that choice deliberately, because I think the adherence advantage of a single daily product is real, and because I think most people aren't going to spend their evenings cross-referencing PubMed to build a personalised stack. But I also know that an all-in-one is only defensible if the doses are right - otherwise it's just convenient nonsense.

The evidence doesn't declare a winner between formats. It declares a winner between products that dose correctly and products that don't. Most products in both categories don't. That's the honest read.

If you're building your own stack, start with the primary literature, not the label. If you're buying an all-in-one, ask for the doses and check them against the trials. The format is almost beside the point.