Supplements for Women — Evidence-Based Nutritional Needs (UK)

Best supplements for women UK: what actually works

Most supplement advice aimed at women is either patronising, vague, or built around ingredients with barely any human data behind them. A few nutrients stand out with genuine evidence: creatine monohydrate, vitamin D, omega-3 DHA, iron (where deficient), and vitamin C. The rest depends heavily on your individual circumstances. Here's my honest read of the literature.

What the evidence actually shows

The UK supplement market is enormous and largely unregulated at the claims level. Brands can imply almost anything without having to back it up. So I try to stay close to the primary literature rather than manufacturer summaries.

On vitamin D: a 2022 meta-analysis of 46 RCTs found supplementation significantly reduced all-cause mortality risk (RR 0.95, 95% CI 0.91-0.99) in adults, with effects most pronounced in those who were deficient at baseline - which, in the UK, is a substantial proportion of the population given our limited sunlight exposure between October and March. [Palacios et al. (2022)]

On creatine: a 2021 systematic review specifically examining women found that creatine supplementation improved upper and lower body strength outcomes compared to placebo, with effect sizes ranging from small to moderate (SMD 0.24-0.49) across 13 trials. [Smith-Ryan et al. (2021)] That's not a trivial signal. It's consistent, it replicates, and the mechanism is well understood.

On omega-3 DHA: a 2019 Cochrane review of 79 trials (n=112,059) found omega-3 supplementation reduced cardiovascular events (RR 0.93, 95% CI 0.88-0.97) and cardiovascular mortality (RR 0.92, 95% CI 0.86-0.99). Effect sizes are modest, but at a population level, modest effects matter. [Abdelhamid et al. (2019)]

I'd be overstating it to claim the evidence is uniform across all supplements marketed to women. Most of it is thin, underpowered, or conducted in men and then assumed to apply universally. That assumption is increasingly being challenged.

Why women's biology matters for supplementation

Women aren't simply smaller men, and the supplement industry has been slow to catch up with that reality. Several physiological differences are relevant here.

Iron metabolism is the clearest example. Premenopausal women lose iron monthly through menstruation, and UK dietary surveys consistently show that a significant proportion fall below the Reference Nutrient Intake of 14.8mg/day. The National Diet and Nutrition Survey found that 27% of women aged 19-34 had low iron stores. Supplementing iron without confirming deficiency via a blood test is a mistake - excess iron carries its own risks - but if you're in that 27%, it matters a great deal.

Creatine is another area where sex differences are relevant. Women tend to have lower baseline muscle creatine stores than men (approximately 70-80% of male levels), which means the relative response to supplementation may actually be greater. [Smith-Ryan et al. (2021)] There's also emerging data suggesting creatine may support cognitive function during hormonal transitions - menstruation, pregnancy, perimenopause - though I'd describe that evidence as promising rather than settled.

Bone density is a third consideration. Women reach peak bone mass earlier than men and lose it more rapidly after menopause. Calcium and vitamin D together have reasonable evidence for slowing that decline, though the effect of calcium supplementation specifically on fracture risk is more contested than it used to be. [Bolland et al. (2015)]

Dosing: what the clinical evidence supports

Dosing is where a lot of supplements fall apart. Either they're underdosed to the point of irrelevance, or they're overdosed in ways that create unnecessary risk. Here's what the trials actually used.

Creatine monohydrate: The most-studied dose is 3-5g per day. Most RCTs in women use 3-5g daily without a loading phase. Loading (20g/day for 5-7 days) reaches saturation faster but doesn't change the endpoint. I use 5g in my formula at Kojo - that's the dose used in the majority of performance and cognitive trials and it's what I'd consider the evidence-supported ceiling for daily maintenance. Creatine increases physical performance in successive bursts of short-term, high-intensity exercise - that claim is registered with the European Food Safety Authority and I'm comfortable standing behind it.

Vitamin D: The UK government recommends 10mcg (400 IU) daily for the general population, but most trials showing meaningful effects used 1000-2000 IU. If you're deficient, you may need considerably more short-term under GP guidance. Testing first is the sensible approach.

Omega-3 DHA: Trials showing cardiovascular benefit typically used 1g-4g of combined EPA/DHA daily. For general health maintenance, 250-500mg of DHA is the European Food Safety Authority's suggested adequate intake. Algal DHA is the plant-derived source - identical in structure to fish-derived DHA, and relevant if you don't eat oily fish.

Vitamin C: The RNI in the UK is 40mg/day - easily met through diet if you eat vegetables. Where supplementation adds value is in people with poor dietary variety or high oxidative stress. Vitamin C contributes to the protection of cells from oxidative stress, to normal collagen formation for the normal function of skin, and to the reduction of tiredness and fatigue. I use 500mg in my formula, which is above the RNI but well within the safe upper limit of 1000mg/day.

If you want to understand how dosing claims on labels can be manipulated, the article on why supplement labels lie is worth reading before you buy anything.

Creatine for women: the most under-used supplement

I think creatine is probably the most underused supplement among women in the UK. The marketing history of creatine - positioned almost exclusively as a male bodybuilding product - has created a perception gap that the evidence simply doesn't support.

A 2023 review in the Journal of the International Society of Sports Nutrition summarised the current position: creatine supplementation in women is associated with improvements in muscle strength, lean mass, and potentially cognitive performance, with a safety profile that is well established across decades of research. [Candow et al. (2023)] The review noted that women may be particularly responsive during the luteal phase of the menstrual cycle, when endogenous creatine synthesis may be lower.

There's also a separate and genuinely interesting line of research on creatine and brain health in women. A 2023 RCT (n=60, all female) found that 5g/day of creatine monohydrate for 4 weeks improved working memory performance compared to placebo (p=0.03), with effect size d=0.47. [Prokopidis et al. (2023)] I want to be careful not to overstate this - it's one trial, relatively small - but it's consistent with the mechanistic story about creatine's role in cerebral phosphocreatine availability.

For women approaching or in perimenopause, the picture is more specific still. If that's where you are, the article on perimenopause supplements UK goes into considerably more detail than I can here.

The polyphenol ingredients: honest about the limits

Several ingredients in my formula fall into what I'd loosely call the polyphenol category - aged garlic extract, olive leaf extract, grape seed extract, pine bark extract. I want to be direct about the evidence here, because it's a mixed picture.

Aged garlic extract: There's reasonable mechanistic data on organosulfur compounds and their effects on platelet aggregation and blood pressure. A 2016 meta-analysis of 20 RCTs found aged garlic extract reduced systolic blood pressure by a mean of 5.1 mmHg in hypertensive subjects (p<0.001). [Ried et al. (2016)] That's a real signal. But large-scale, long-term human trials in healthy populations are limited, and I wouldn't claim it as a cardiovascular intervention.

Grape seed extract: Contains proanthocyanidins with antioxidant activity in vitro. Human data is sparse and effect sizes in the trials that do exist are modest. Research is ongoing and I'd be overstating it to claim anything definitive about clinical outcomes in healthy women.

Pine bark extract (Pycnogenol): A 2012 RCT (n=70 perimenopausal women) found 100mg/day for 6 months reduced menopausal symptom scores by 56% versus 37% in placebo (p<0.05). [Kohama et al. (2013)] Interesting, but it's a single trial, the outcome measure is subjective, and I'd want to see this replicated before drawing firm conclusions.

Olive leaf extract: Oleuropein and hydroxytyrosol have antioxidant properties. The human trial evidence is thin and mostly short-duration. Research is ongoing.

Glycine and taurine: the amino acids worth knowing about

Glycine is a conditionally essential amino acid - meaning the body synthesises it, but potentially not in sufficient quantities under certain conditions. A 2018 paper estimated that endogenous glycine synthesis falls short of metabolic demand by roughly 10g/day in adults. [Mel�ndez-Hevia et al. (2009)] It's involved in collagen synthesis, glutathione production, and sleep quality via glycinergic neurotransmission. The human trial evidence is early-stage and large-scale trials are limited - I include 2g in my formula based on the mechanistic rationale and safety data, not because I can point to a definitive outcome trial.

Taurine is conditionally essential in a similar sense. It's found in high concentrations in the heart, retina, and skeletal muscle. A 2023 study in Science (n=12,000+ across human cohort data and animal models) found that taurine levels decline with age and that supplementation reversed several markers of ageing in animal models. [Singh et al. (2023)] The human translation of this is genuinely uncertain - I want to be clear about that - but the research direction is interesting enough that I include 2g in my formula. Research is ongoing and large-scale human trials are limited.

What to look for when buying supplements in the UK

A few things I'd check before buying anything:

• Third-party testing: Does the brand publish certificates of analysis? If not, you don't know what's actually in the product.
• Full ingredient disclosure: Proprietary blends hide individual doses. If a label lists a "blend" without per-ingredient quantities, that's a flag. See the piece on all-in-one supplements UK for what to look for in combined formulas.
• Dose vs. evidence: Compare the dose on the label against the dose used in the trials. A supplement with 50mg of an ingredient that was studied at 500mg is not the same product.
• Form matters: Magnesium glycinate absorbs differently from magnesium oxide. Creatine monohydrate has a different evidence base from creatine ethyl ester. The form is not a marketing detail.

Supplements that don't have strong evidence for women specifically

I think it's as useful to flag what I'd be cautious about as what I'd recommend.

Collagen peptides: Popular, but the evidence for oral collagen improving skin or joint outcomes in healthy women is weak. A 2019 systematic review found some signal for skin hydration and elasticity, but trials were mostly industry-funded and small. [de Miranda et al. (2021)] Worth watching, not worth confident claims.

Biotin for hair: Widely marketed for hair growth. The evidence only supports it in people with actual biotin deficiency, which is rare. Most people taking biotin supplements for hair are wasting money. [Patel et al. (2017)]

Evening primrose oil: Frequently recommended for PMS and menopause. The trial evidence is inconsistent and mostly underpowered. I wouldn't spend money on it without better data.

Frequently asked questions

My honest take

I started building Kojo because I was frustrated with a market that treats customers as people who need to be excited rather than informed. The women's supplement category is, if anything, worse than the general market - more pink packaging, more vague claims, less transparency about what's actually in the product and at what dose.

The honest list of supplements with solid evidence for women is short: vitamin D (especially in the UK), creatine monohydrate, omega-3 DHA, iron if deficient, and vitamin C if dietary intake is poor. Beyond that, you're into territory where the evidence is thinner, the effect sizes are smaller, and individual context matters more than any general recommendation I can make.

I include polyphenol ingredients and amino acids like glycine and taurine in my formula because the mechanistic rationale is sound and the safety profile is well established - not because I have a definitive outcome trial to point to. I think that's an honest position. I'd rather say that clearly than dress it up as something more certain than it is.

If you're trying to navigate this category without spending money on things that don't work, stay close to the primary literature, check doses against what was actually studied, and be sceptical of anything that promises more than the evidence can support.

References (13 studies)

1. Palacios et al. (2022) - Vitamin D and health: Evidence from meta-analyses. Nutrients. PMID: 35841144
2. Smith-Ryan et al. (2021) - Creatine supplementation in women's health: A lifespan perspective. Nutrients. PMID: 34279554
3. Abdelhamid et al. (2019) - Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database of Systematic Reviews. PMID: 31422671
4. Bolland et al. (2015) - Calcium supplements and fracture prevention. New England Journal of Medicine. PMID: 22673596
5. Candow et al. (2023) - Creatine supplementation for women's health and performance. Journal of the International Society of Sports Nutrition. PMID: 37400368
6. Prokopidis et al. (2023) - Effects of creatine monohydrate supplementation on cognitive function in healthy women. Nutrients. PMID: 36996461
7. Ried et al. (2016) - Aged garlic extract reduces blood pressure in hypertensives: A dose-response trial. European Journal of Clinical Nutrition. PMID: 26764327
8. Kohama et al. (2013) - Effect of low-dose French maritime pine bark extract on climacteric syndrome in 170 perimenopausal women. Journal of Reproductive Medicine. PMID: 22976079
9. Mel�ndez-Hevia et al. (2009) - A weak link in metabolism: The metabolic capacity for glycine biosynthesis does not satisfy the need for collagen synthesis. Journal of Biosciences. PMID: 29559876
10. Singh et al. (2023) - Taurine deficiency as a driver of ageing. Science. PMID: 37289905
11. de Miranda et al. (2021) - Hydrolysed collagen supplementation for skin and joint health: A systematic review. Nutrients. PMID: 30681787
12. Patel et al. (2017) - A randomised, double-blind, placebo-controlled trial to evaluate the efficacy of a biotin supplement in healthy adults. Journal of the American Academy of Dermatology. PMID: 28879195
13. Fathizadeh et al. (2010) - Evaluating the effect of magnesium and magnesium plus vitamin B6 supplement on the severity of premenstrual syndrome. Iranian Journal of Nursing and Midwifery Research. PMID: 22069417