Learn

Walk down any supplement aisle in October and you'll find D3 on one shelf and D3 with K2 on the next, usually a few pounds dearer and wrapped in the language of synergy. Fair question: is the K2 doing something, or is it a tidy way to charge more for the same sunshine vitamin? Short version: the biology makes sense, the human evidence is thinner than the marketing, and the thing that matters most is getting your D3 dose right in the first place. Why the two get paired The NHS says everyone should consider a daily vitamin D supplement of 10 micrograms from autumn through winter, when the sun isn't strong enough for your skin to make it.[1] Vitamin D has authorised health claims for contributing to the normal absorption and use of calcium and phosphorus, the maintenance of normal bones, and normal muscle and immune function. Vitamin K is authorised for contributing to normal blood clotting and the maintenance of normal bones.[2] The NHS puts adult need at roughly 1 microgram per kilogram of body weight a day, mostly from leafy greens, vegetable oils and cereal grains.[3] 10 micrograms The daily vitamin D the NHS suggests for adults through autumn and winter — 400 IU The case for combining them goes like this. D3 helps you absorb calcium; vitamin K helps activate proteins, osteocalcin among them, involved in getting calcium into bone. It's a plausible mechanism. Plausible isn't proven, and the review we lean on most here says exactly that.[4] What the trials actually found The best-known K2 study followed 244 postmenopausal women aged 55 to 65 for three years. Those taking 180 micrograms of MK-7 a day lost less lumbar spine bone density than those on placebo, roughly 0.5% against 1.5%, as reported in Osteoporosis International.[5] Worth knowing: it tested K2 alone, and the manufacturer of the MK-7 funded it. It doesn't tell us what happens when you add K2 to a D3 you're already taking. On the combination itself, a 2020 meta-analysis of eight randomised trials (971 people, mostly women) found moderate-quality evidence that vitamin D plus vitamin K can improve bone mineral density, with K2 looking stronger than K1.[6] Then the caveats. The trials are small and short, they measure density rather than fractures, and the benefit seems to sit with postmenopausal women who already have low bone mass. No large trial has shown fewer fractures in the general population.[4] So do you actually need K2? Not in the way you need D3 in January. If you eat greens most days you're already getting vitamin K, and K2 is an option, not a requirement. It's most worth a conversation with your GP if bone health is a particular concern for you, for instance after the menopause. One firm caution: if you take warfarin or another vitamin K antagonist, don't add K2 without speaking to your doctor or pharmacist. Vitamin K can blunt those drugs, which is why people on them are told to keep their intake steady.[4] What to check on the label Micrograms of D3 per serving — and whether the serving is one tablet or two. Compare it with 10 micrograms, not with the biggest number on the pack. The form of K — MK-7 is the K2 used in the trial research above; K1 is the plant form. Total K in micrograms — the NHS says 1mg or less a day from supplements is unlikely to cause harm.[3] Where our own tablet sits Strength is where D3 and K2 products differ most, so here are our numbers. Our Vitamin D3 & K2 Tablets give 4,000iu (100 micrograms) of D3 and 150 micrograms of K2 as MK-7 across a two-tablet daily serving, with coconut MCTs. That D3 figure is the NHS upper limit, not a starting point.[1] It's a high-strength option for people whose GP or blood test points that way, and you shouldn't stack it with another vitamin D supplement. For everyone else, 10 micrograms is the number to aim for, and we've written that up in Vitamin D3 Dosage UK: How Much Do You Actually Need?. If a higher-strength D3 with K2 is what you and your GP have landed on, this is the one built to those label numbers: The Golden Pick Vitamin D3 & K2 Tablets 4,000iu D3 · 150µg K2 (MK-7) · Coconut MCTs · 120 tablets £9.95● IN STOCK Shop Vitamin D3 & K2 Tablets → The gold standard is boring Know your D3 dose, decide whether K2 earns a place next to it, and be honest about what the trials do and don't show. That's the whole routine. Get the D right first; the K2 is a refinement. Frequently asked questions Can you take vitamin K2 and D3 together? Yes, and they're commonly sold together. The one real exception is anyone taking warfarin or a similar vitamin K antagonist, because vitamin K can reduce how well those medicines work. If that's you, speak to your GP or pharmacist before adding K2. How long does vitamin D3 with K2 take to work? Bone is slow tissue. The trials behind the bone-density findings ran from six months to three years, so think in seasons rather than weeks. There's no quick-result version of this story, and no supplement should replace a conversation with your GP if you have concerns about your bones. How much vitamin D3 should I take with K2? The NHS suggests 10 micrograms (400 IU) a day for adults through autumn and winter, and says not to go above 100 micrograms (4,000 IU) a day. Most people sit nearer the first number. Our full breakdown is in Vitamin D3 Dosage UK: How Much Do You Actually Need?. Is it safe to take vitamin K2 every day? The NHS says 1mg or less of vitamin K a day from supplements is unlikely to cause harm, though it also says there isn't enough evidence on higher doses. Check with your GP first if you're on blood-thinning medication or have a health condition. Sources NHS — vitamin D: 10 micrograms a day through autumn and winter, and the 100 microgram upper limit. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ Commission Regulation (EU) No 432/2012 — list of permitted health claims, including the vitamin D and vitamin K claims referenced. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32012R0432 NHS — vitamin K: adult need, food sources and the 1mg supplement guidance. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-k/ Science-Based Medicine (Gavura, June 2025) — review of vitamin D plus K co-supplementation, plausibility of the mechanism, limits of the trial evidence and the warfarin caution. https://sciencebasedmedicine.org/should-you-take-vitamin-k-with-your-vitamin-d/ Knapen et al., Osteoporosis International (2013) — three-year MK-7 trial in 244 postmenopausal women, as reported by NutraIngredients (manufacturer-funded). https://www.nutraingredients.com/Article/2013/03/27/Vitamin-K2-shows-extremely-important-improvements-in-clinical-outcomes-for-bone-health/ Examine.com summary (July 2020) — meta-analysis of 8 randomised trials, 971 participants, on combined vitamin D and K and bone mineral density. https://examine.com/summaries/study/g983b0/ At Oxford Origins, your wellbeing is our priority, and although we pride ourselves on our expertise in nutrition and supplementation, it's important to acknowledge the individuality of each person. Articles published by Oxford Origins are not intended to treat, diagnose, cure or prevent any disease, or replace the advice of your GP. We always recommend consulting with a healthcare provider if you encounter any health concerns, and we'll always be here to support you so you're never alone on your journey.

Three years ago, creatine was still a locker-room supplement — something you scooped into a shaker after leg day and forgot about until the next one. Now it's turning up in conversations about perimenopause, cognitive ageing and bone health, championed by physicians who've never set foot in a CrossFit box. That's a big shift for a compound that costs about ten pence a gram. So what does the actual research say, once you strip away the enthusiasm? From gym bag to bathroom cabinet: why creatine got rebranded The shift happened for a reason. Most of the original creatine research was done on young men lifting weights, which meant an entire population — women, particularly those past 40 — were left out of the picture for decades. Newer trials have started closing that gap, and what they've found isn't uniformly flattering. Some of it holds up well. Some of it doesn't. It's worth knowing which is which before you spend money on it. What creatine is actually doing in your body Creatine isn't a stimulant, a hormone, or anything exotic. Your liver and kidneys make a small amount of it daily from amino acids, and you top the rest up through red meat and fish — though not much, since a typical diet supplies roughly 1g a day. It's stored mostly in skeletal muscle, where it helps regenerate ATP, the molecule your cells burn for quick bursts of energy. That's why the oldest, strongest evidence for creatine concerns short, hard efforts: a sprint, a heavy lift. Everything newer builds outward from that same mechanism. The muscle evidence, and the one number worth remembering On strength, the research is about as settled as supplement science gets. Creatine increases physical performance in successive bursts of short-term, high-intensity exercise — an effect established enough that it's one of the few creatine claims formally authorised on the EU health claims register, at a daily intake of 3g.[1] That's not a figure picked out of the air, either — it's exactly the dose our own tablets are built around. 3g the daily intake behind every authorised creatine claim in the EU register There's a second authorised claim that matters more if you're over 55: taken alongside regular resistance training, daily creatine has been shown to enhance the effect of that training on muscle strength specifically in older adults.[2] That's a meaningfully narrower claim than "creatine makes you stronger" — it only holds alongside the resistance training. The tablet isn't doing the lifting for you. Brain health: what the memory trials actually found This is the part most of the recent headlines are about, and the honest answer is promising, but early. A 2023 systematic review and meta-analysis in Nutrition Reviews pooled ten randomised controlled trials and found creatine supplementation improved measures of memory compared with placebo — with the effect notably stronger in adults over 66 than in their younger counterparts.[3] "The effect was notably stronger in older adults than in their younger counterparts." A separate 2024 meta-analysis in Frontiers in Nutrition reached a similar conclusion for broader cognitive function, though the authors were careful to note that study designs, doses and durations varied enough that larger, more consistent trials are still needed before this becomes settled science.[4] Read that as a real signal, not yet a guarantee. Bone density: where the hype has outrun the evidence Here's where it's worth being honest rather than convenient. The most rigorous test of creatine and bone health to date is a two-year, placebo-controlled trial in 237 postmenopausal women, who took 3g of creatine daily alongside a structured resistance and walking programme. At the end of two years, creatine made no measurable difference to bone mineral density at the femoral neck, hip or spine compared with placebo.[5] It did produce some modest, more technical improvements in bone geometry — the shape and load-bearing structure of bone, rather than its density — but that's a narrower result than "creatine builds bone." If bone health is your main reason for taking it, weight-bearing exercise, calcium and vitamin D are still doing most of the actual work. How much to actually take, and what's worth checking on the label The dose that shows up across nearly every trial above — muscle, brain and bone alike — is 3g a day, taken consistently. There's no meaningful benefit to cycling on and off, and no real need to "load" with higher doses first unless you're chasing faster saturation ahead of a specific event. Creatine monohydrate, the plain, unbuffered form used in essentially all of the research cited here, remains what most sports scientists still reach for. Newer forms like HCL or buffered creatine are marketed on absorption claims the evidence doesn't yet back up. Check the form — monohydrate is what the research above actually used; other forms haven't caught up on the evidence. Check the dose — 3g is the figure behind every claim in this piece; anything meaningfully lower is unlikely to do much. Check the consistency — daily, ongoing use is what the trials tested, not occasional or pre-workout-only dosing. Three tablets a day gets you there without a scoop, a shaker or a chalky aftertaste — which is the whole idea behind our Creatine Monohydrate Tablets: one gram of monohydrate per tablet, formulated to the same 3g threshold the research keeps landing on. The Golden Pick Creatine Monohydrate Tablets 1g monohydrate per tablet · 90 tablets · 30-day supply £14.95● OUT OF STOCK View Creatine Monohydrate Tablets → It's currently between batches — worth using the notify option on the product page rather than hunting down a powder tub in the meantime. The bit worth remembering Creatine monohydrate has been studied for three decades, which is longer than almost anything else on a supplement shelf, and it keeps landing on the same handful of numbers: 3g, taken daily, alongside whatever you're already doing — lifting, walking, or just trying to think a little more clearly. It isn't a shortcut for any of that. It's a small, well-evidenced nudge underneath them, about as close to the gold standard as a supplement claim is actually allowed to get. Frequently asked questions How long does creatine take to start working? Most trials see measurable strength changes within two to four weeks of daily use, once muscle stores reach saturation. Loading with a higher dose for the first five to seven days can get you there slightly faster, though it isn't necessary — a steady 3g a day reaches the same point within about three to four weeks. Do you need to cycle creatine, or take breaks from it? No trial evidence supports cycling. The studies behind the claims in this piece used continuous daily dosing for anywhere from eight weeks to two years, with no washout periods built in and no reported need for one. Is it safe to take creatine long-term? The longest controlled trial on record ran for two years with no serious adverse effects reported, and creatine is one of the more extensively studied supplements in sports nutrition. The usual caveat applies if you have existing kidney disease or reduced kidney function: talk to your GP before starting, since creatine is processed by the kidneys and long-term data in that specific group is limited. What's the difference between creatine monohydrate and newer forms like creatine HCL? Monohydrate is the form used in essentially every trial referenced in this article, including the muscle, memory and bone research. Creatine HCL and other buffered forms are marketed on claims of better absorption or less bloating, but the EU health claims register doesn't recognise any absorption advantage for these forms, and independent trials haven't shown them to outperform monohydrate. If it's label-reading you're after more generally, our piece on whether women need a different multivitamin than men covers similar ground. Sources Commission Regulation (EU) No 432/2012 — EU-authorised health claim: creatine increases physical performance in successive bursts of short-term, high-intensity exercise, at a daily intake of 3g. https://www.legislation.gov.uk/eur/2012/432/annex Commission Implementing Regulation (EU) 2017/672 — EU-authorised health claim: creatine in combination with resistance training and improvement in muscle strength in adults over 55. https://www.legislation.gov.uk/eur/2017/672/2020-12-31/data.html Prokopidis et al., Nutrition Reviews (2023) — systematic review and meta-analysis of randomised controlled trials on creatine supplementation and memory in healthy individuals. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9999677/ Frontiers in Nutrition (2024) — systematic review and meta-analysis of creatine supplementation and cognitive function in adults. https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2024.1424972/full Chilibeck et al., The Journals of Gerontology: Series A (2020) — two-year randomised, placebo-controlled trial of creatine supplementation and bone health in postmenopausal women. https://academic.oup.com/biomedgerontology/article-abstract/75/5/931/5525440 At Oxford Origins, your wellbeing is our priority, and although we pride ourselves on our expertise in nutrition and supplementation, it's important to acknowledge the individuality of each person. Articles published by Oxford Origins are not intended to treat, diagnose, cure or prevent any disease, or replace the advice of your GP. We always recommend consulting with a healthcare provider if you encounter any health concerns, and we'll always be here to support you so you're never alone on your journey.