Do I need supplements? An honest answer

This is the most important question to ask before paying for any supplement, including ours. The supplement industry has a vested interest in answering "yes, definitely" to everyone. The honest answer is more nuanced, and worth understanding before you spend any money or daily energy on a routine.

This article walks through what the evidence actually says about when supplements help, when they do not, and how to figure out which group you are in.

The default answer: probably not, if you are eating well

For a healthy adult woman eating a varied diet with enough calories, the population-level evidence does not support routine supplementation for most nutrients.

Two large landmark trials are worth knowing about:

The COSMOS trial (21,442 US adults, multivitamin vs placebo, 3.6 year follow-up) found that a daily multivitamin did not reduce cancer, cardiovascular events, cardiovascular death, or all-cause mortality ^[1]. This is the most robust randomised trial on multivitamins to date, and the negative result was striking given how widely multivitamins are recommended.

The Women's Health Initiative cohort (161,808 postmenopausal women) similarly found no association between multivitamin use and breast, colorectal, or endometrial cancer risk ^[2].

The US Preventive Services Task Force, after a comprehensive evidence review, currently recommends against routine vitamin, mineral, and multivitamin supplementation for the primary prevention of cardiovascular disease or cancer in the general adult population ^[3].

This is the honest population-level evidence. For a healthy, well-fed adult, a generic multivitamin does not extend life, prevent disease, or appear to do much of clinical significance.

The exceptions: when supplements actually have strong evidence

The same evidence base is much more positive for targeted supplementation in specific groups and situations.

Folic acid before and during early pregnancy

This is the strongest evidence-based supplementation recommendation in women's health. Folic acid supplementation 1 to 3 months before conception and through the first trimester reduces the risk of neural tube defects by approximately 70%. National and international guidelines uniformly recommend it ^[4].

Iron in iron-deficiency anemia and high-risk groups

Iron supplementation in women with iron-deficiency anemia is well-supported and routine. Iron supplementation in non-anemic but iron-deficient women (low ferritin, fatigue, restless legs, hair loss) is increasingly supported, particularly for menstruating women (see our iron article) ^[5].

Vitamin D in deficiency or high-risk populations

Vitamin D deficiency is common in Northern European populations (data from the German DEGS1 study found 69.9% of women aged 65 to 79 had low vitamin D levels ^[6]). For deficient individuals, supplementation has clear evidence. For populations with limited sun exposure (high latitudes, winter, indoor work), prophylactic supplementation has reasonable support, particularly for bone health.

Vitamin B12 in vegetarians and vegans

B12 is found almost exclusively in animal foods. Vegetarians and especially vegans should supplement B12 unless they are reliably getting it from fortified foods. The risk of deficiency is real and the consequences (neurological damage) can be irreversible if undetected.

Calcium and vitamin D in postmenopausal women

For bone health in women at risk of osteoporosis, calcium plus vitamin D has guideline-supported evidence, though the magnitude of benefit is debated and individual risk assessment matters.

Specific clinical conditions

People with diagnosed deficiencies (low ferritin, low B12, low vitamin D), people with restricted diets (vegan, vegetarian, calorie-restricted, post-bariatric surgery, malabsorptive conditions), people with specific medical conditions (PCOS with myo-inositol for example), athletes with high training loads, and people on medications that deplete specific nutrients (oral contraceptives, metformin, PPIs) often benefit from targeted supplementation ^[7].

Where the European data complicates the picture

European nutritional surveys consistently show widespread inadequate intakes of specific nutrients in the general population, particularly in women:

• Vitamin D: >20% inadequate intake across multiple European countries ^[8]
• Folate: >20% inadequate intake, especially in women of reproductive age
• Calcium: high prevalence of inadequate intake, particularly in older women
• Iodine: inadequate in many European populations
• Selenium: inadequate in many regions
• Iron: ~30% global prevalence of anemia in women of reproductive age; iron deficiency without anemia much higher
• Vitamin B1, B2, B12 (in older women)
• Omega-3 (EPA/DHA): roughly 50x lower than vegetable oil intake in the average European diet

This is not "the supplement industry wants you to think you need supplements." This is data from national nutritional surveys and EFSA-equivalent food intake assessments. A meaningful portion of the European population is below the dietary reference value for several specific micronutrients.

The honest synthesis: routine multivitamin use is not strongly supported, but targeted supplementation of specific high-deficiency-prevalence nutrients can be sensible for specific populations, including most menstruating women living in Northern Europe with typical diets.

What about the women's-specific cycle context

Two things make the picture more interesting for women specifically:

1. Menstruation creates predictable nutrient losses (iron most clearly, but also subtle effects on B vitamins and minerals)
2. Hormonal contraception is associated with documented depletion of B vitamins (B6, B12, folate), vitamin C, magnesium, zinc, and selenium (see our pill article)

These are population-level facts. They do not mean every woman needs to supplement. They do mean that a baseline supplement of the specific nutrients most affected (B vitamins, iron in menstruating women, vitamin D in low-sun populations, magnesium for women with significant PMS) has a more plausible evidence base than a generic multivitamin.

How to figure out if you need supplements

A practical sequence that respects the evidence:

1. Diet first, supplements second

If your diet is varied, adequately calorie-supplied, and includes regular consumption of vegetables, fruits, whole grains, protein sources, and (if appropriate) some animal foods, you are likely meeting most micronutrient requirements without supplements. Diet quality is the bigger lever for almost everyone.

2. Specific risk groups should consider testing or targeted supplementation

You probably benefit from targeted supplementation if you fall into one or more of these groups:

• Pregnant, planning pregnancy, or postpartum (folic acid, often iron, often vitamin D)
• Menstruating regularly, especially with heavy bleeding (iron status worth checking)
• Vegetarian or vegan (B12 essential; iron and omega-3 worth considering)
• Living in Northern Europe with limited sun exposure (vitamin D)
• On combined oral contraceptive for years (B vitamins, possibly magnesium)
• Postmenopausal (calcium, vitamin D, possibly K2 for bone)
• Has significant PMS or PMDD symptoms (magnesium, B6, calcium have evidence)
• Athletes or actively training women (iron status, protein, possibly omega-3)
• Has a diagnosed deficiency from blood work
• Has a condition known to cause malabsorption or specific deficiency

3. Test where you can

A focused blood panel (ferritin, vitamin D 25-OH, B12, folate, sometimes thyroid) gives you actual data rather than guesses. Repeat every 6 to 12 months if you are supplementing to confirm levels are responding.

4. Choose quality and bioavailable forms

If you are going to take supplements, the form matters (see our Why the form matters article when published). Iron bisglycinate over ferrous sulfate. Methylfolate or folate over folic acid for some women. D3 over D2. Magnesium bisglycinate over oxide. Look for third-party tested products (USP verified, NSF certified, IFOS for fish oil) ^[9].

5. Avoid mega-dosing

More is not better. Excessive intake of fat-soluble vitamins (A, D, E, K) and some minerals (iron, zinc) can be harmful. Stick to doses near the EU Reference Nutrient Intakes or supported by trial evidence, not to "high-potency" labels.

6. Stop what does not seem to do anything

If you have been taking a supplement for 6 months and you cannot identify any subjective benefit, and bloodwork does not show meaningful change, stop. Many supplements do not do anything detectable in any given individual. The willingness to stop is the test of whether you are a thoughtful supplement consumer or a marketing target.

What this means for the nōuxx routine

The nōuxx cycle routine is designed around a specific premise: that targeted, phase-matched nutrition for menstruating women, particularly in Europe, addresses several of the highest-prevalence nutritional gaps (iron in menstrual phase, magnesium and B vitamins in luteal phase, etc.) while avoiding the "everything-for-everyone" generic-multivitamin problem.

This does not mean every woman needs the routine. It does mean that for the specific population it is designed for (menstruating women in Europe with typical diets and cycle-related symptoms), it is more aligned with the evidence than either a generic multivitamin or no supplement at all.

What we will not claim: - That nōuxx is necessary for every woman - That you cannot achieve good health without supplements - That nōuxx prevents disease, cures conditions, or extends life - That the routine is appropriate during pregnancy, on hormonal contraception, or for women with diagnosed deficiencies that require treatment dosing

The honest position is: nōuxx is one tool among several. For some women it is the right tool. For others it is not. Diet, sleep, stress management, exercise, and medical care all do more for most people than any supplement.

Common questions

What if I just want "insurance"?

The COSMOS and WHI trial evidence suggests that "insurance" multivitamin use does not produce measurable health benefits at the population level. If your reasons are subjective (you feel better, you sleep better, your skin is better since starting), and the dose is reasonable, the cost is small, and the safety profile is good, that is a valid personal decision. The evidence does not support broad health claims, but it does not say supplements harm healthy people taking reasonable doses either.

Should I take a "women's" multivitamin?

Most "women's" multivitamins differ from generic multivitamins mainly in marketing. The actual formulation differences (slightly more iron, slightly less of some other nutrients) are reasonable but not dramatic. The COSMOS trial used a mainstream multivitamin and found no benefit. If you are going to supplement, targeted single or paired nutrients have a better evidence base than generic multivitamins.

How do I know if I am deficient?

The most useful tests for women: ferritin (iron stores), 25-OH vitamin D, B12, folate, sometimes TSH (thyroid). These are not expensive. Many GPs will order them on request, particularly if you can describe symptoms (fatigue, hair shedding, mood changes, restless legs). Direct-to-consumer blood testing is also available in most European countries.

What about gummy supplements?

Gummies are typically lower in nutrient content per serving than tablets or capsules, contain added sugar, and have inferior bioavailability for some nutrients. They are easier to take, which has real adherence value. Not all gummies are bad; many are weaker. Check the actual nutrient content against the European Reference Nutrient Intakes before assuming a gummy multivitamin is equivalent to a tablet one.

What about powders and drink mixes?

Form factor (capsule vs powder vs liquid) does not strongly predict effectiveness. What matters is the actual nutrient, the dose, the form (e.g., bisglycinate vs sulfate for iron), and the bioavailability. Some powders can deliver larger doses of specific nutrients (creatine, collagen, protein) that capsules cannot easily achieve.

Should I cycle off supplements?

For most supplements, there is no strong evidence that "cycling off" produces benefits. The exception is supplements that build up tolerance (caffeine being the clearest example) or that can cause issues at very high cumulative doses (vitamin A, iron in non-deficient people). For typical micronutrients at reasonable doses, daily use is fine indefinitely if it has a justified purpose.

What about herbal supplements?

Herbal supplements (chasteberry, ashwagandha, maca, evening primrose, etc.) have a different evidence picture from vitamins and minerals. Some have moderate evidence for specific uses (chasteberry for PMS, for example). Most have weaker, smaller-trial evidence. They are less tightly regulated for purity and standardisation than synthetic micronutrients. The same questions apply: what is the evidence, what is the dose, what is the quality?

The bottom line

Most healthy adult women on a varied diet do not need supplements for general health prevention. The evidence on routine multivitamins is genuinely negative. The evidence on targeted supplementation for specific groups (pregnant women, menstruating women, vegans, low-sun populations, people with diagnosed deficiencies, women with specific clinical conditions) is much stronger and individually meaningful.

The honest framework: figure out what group you are in, address diet first, test where useful, supplement targeted nutrients with evidence behind them, choose quality and bioavailable forms, and be willing to stop what does not work.

If you are a menstruating woman in Northern Europe with typical diet patterns and some cycle-related symptoms, a phase-matched routine focused on the nutrients with the strongest evidence (iron, magnesium, B vitamins, vitamin D) is more aligned with the data than either a generic multivitamin or nothing at all. That is the rationale the nōuxx routine is built on, and it is the rationale we are willing to defend rather than oversell.

References

[1] Sesso HD, et al. Multivitamins in the prevention of cancer and cardiovascular disease: the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) randomized clinical trial. The American Journal of Clinical Nutrition 2022;115(6):1501-1510. doi.org/10.1093/ajcn/nqac056

[2] Neuhouser ML, et al. Multivitamin use and risk of cancer and cardiovascular disease in the Women's Health Initiative cohorts. Archives of Internal Medicine 2009;169(3):294-304. doi.org/10.1001/archinternmed.2008.540

[3] O’Connor EA, et al. 2021. pubmed.ncbi.nlm.nih.gov/35767665

[4] Medscape. Between Supplement Hype and Evidence: A Clinical Guide. Medscape 2025. medscape.com/viewarticle/between-supplement-hype-and-evidence-clinical-guide-2025a1000xlt

[5] Smith-Ryan AE, Cabre HE, Moore SR. Active Women Across the Lifespan: Nutritional Ingredients to Support Health and Wellness. Sports Medicine (Auckland, N.Z.) 2022;52(Suppl 1):101-117. doi.org/10.1007/s40279-022-01755-3

[6] Prevalence and Predictors of Subclinical Micronutrient Deficiency in German Older Adults: Results from the Population-Based KORA-Age Study. Nutrients. mdpi.com/2072-6643/9/12/1276/htm

[7] Zemp J, et al. A systematic review of evidence-based clinical guidelines for vitamin D screening and supplementation over the last decade. Archives of Public Health = Archives Belges De Sante Publique 2025;83(1):221. doi.org/10.1186/s13690-025-01709-x

[8] Mensink GB, et al. Mapping low intake of micronutrients across Europe. The British Journal of Nutrition 2013;110(4):755-73. doi.org/10.1017/S000711451200565X

[9] Investigating the Regulatory Process, Safety, Efficacy and Product Transparency for Nutraceuticals in the USA, Europe and Australia. Foods (MDPI). mdpi.com/2304-8158/12/2/427

[10] Rippin HL, et al. Adult Nutrient Intakes from Current National Dietary Surveys of European Populations. Nutrients 2017;9(12). doi.org/10.3390/nu9121288

[11] Christie S, et al. Micronutrient inadequacy in Europe: the overlooked role of food supplements in health resilience. Frontiers in Nutrition 2025;12:1686365. doi.org/10.3389/fnut.2025.1686365

[12] Fan J, et al. Mortality after multivitamin supplementation: Nearly 35‐year follow‐up of the randomized Linxian Dysplasia Nutrition Intervention Trial. Cancer 2022;128(15):2939-2948. doi.org/10.1002/cncr.34344

[13] Bailey RL, et al. Multivitamin-mineral use is associated with reduced risk of cardiovascular disease mortality among women in the United States. The Journal of Nutrition 2015;145(3):572-8. doi.org/10.3945/jn.114.204743

[14] Jiang S, et al. Global, Regional, and National Estimates of Nutritional Deficiency Burden among Reproductive Women from 2010 to 2019. Nutrients 2022;14(4). doi.org/10.3390/nu14040832