Which nutrients do women fall short on in the US and other countries?

Iron is the one nutrient that turns up as a problem for women of reproductive age almost everywhere, including the US. WHO's 2023 estimates put anemia at 15.0% of American women aged 15 to 49, close to Canada (14.0%), Germany (14.0%) and Spain (15.6%), lower than Japan (18.7%) and Brazil (21.3%), and about half the world figure of 30.7% ^[1,2]. Beyond iron, the gaps depend on the country. Vitamin D is low wherever people get little winter sun and eat little oily fish, iodine is a weak spot in parts of Europe, and folate looks different in countries that add folic acid to flour, like the US, than in those that don't ^[3,4,5]. The surveys behind these numbers use different methods and years, so treat the comparison as a rough sketch rather than a ranking.

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Why survey numbers from different countries don't line up

It's tempting to put every country's survey side by side, but they measure different things. Some record what people ate, others test blood. The reference amounts differ too. A menstruating woman is advised to get 18 mg of iron a day in the US, while Japan's recommendation is 10.0 to 10.5 mg ^[6,7], so "below the recommendation" means something different in each place. Years and age ranges vary as well.

That's why this article starts from one shared yardstick. WHO estimates the share of women aged 15 to 49 with anemia for almost every country, using the same hemoglobin cutoffs (below 120 g/L if not pregnant, below 110 g/L if pregnant) and a statistical model built on national survey data ^[2]. National findings are added after that, with their own caveats.

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Anemia in women, country by country

The US sits in the middle of this group. The differences between neighbouring rows are small, and since these are modeled estimates, a gap of a point or two doesn't tell you much. The CDC's own blood test figure for women aged 20 to 59 (14.0%) is close to the WHO estimate but not identical, because the ages, years and methods aren't the same ^[11].

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Iron is short almost everywhere

In every country here with intake data, women ate less iron than their national recommendation. Italian women averaged 10.4 mg a day ^[9], Spanish women 9.8 mg ^[10], and Japanese women in their 20s and 30s 6.3 mg ^[6]. US women aged 20 and over averaged 11.0 mg ^[17]. A comparison of national diet surveys across eight European countries found more than half of women below the average requirement for iron in six of them, especially between ages 14 and 50 ^[3].

The reason is the same everywhere. Monthly bleeding means steady iron losses, and a typical diet doesn't make up for them. What differs is where the iron comes from. In the US, about half of dietary iron comes from bread, cereal and other grain products, much of it from iron added to enriched flour and breakfast cereals ^[18]. In Spain, cereals supply about 27% of iron and meat about 20 to 23% ^[10]. Brazil has required iron in wheat flour and cornmeal since 2004, at a minimum of 4.2 mg per 100 g ^[19], and UK flour has had iron added for decades ^[20].

Fortified flour can raise average intake, but it doesn't close the gap for a woman with heavy periods. That's a question for a blood test, wherever you live.

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Folate looks different in countries that fortify flour

The US was the first country to require folic acid in flour, in 1998, and 78 countries had followed by 2021 ^[5]. Canada made it mandatory the same year, Brazil in 2004, and Mexico mandated it in 2008 ^[12,19,15]. In the US, NIH reports that neural tube defect rates have fallen by 28% since fortification began ^[18].

Europe took a different path. Mandatory folic acid fortification of flour had not been introduced anywhere in Europe as of 2021 ^[5]. The UK has since decided to require folic acid in non-wholemeal wheat flour from the end of 2026, and expects about 200 neural tube defect cases a year to be prevented ^[20]. Before that change, the UK's national survey found that 89% of women aged 16 to 49 had red blood cell folate below the level linked to a higher risk of neural tube defects ^[14]. In France, the share of women aged 18 to 49 at risk of folate deficiency nearly doubled, from 7% in 2006 to 13% in 2015 ^[16].

Fortification doesn't make the advice go away, even in the US. Anyone who could become pregnant is still advised to get 400 mcg of folic acid a day from supplements, fortified foods or both ^[18]. Mexico shows why. Despite fortified flour, 9 to 28% of women aged 19 to 39 got less folate than WHO recommends, and rural women who buy tortillas from small makers using unfortified flour were less likely to benefit ^[15].

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Vitamin D depends on sun, season and fish

Few diets anywhere provide much vitamin D. In Italy, no adults in the national survey reached the reference of 15 mcg from food ^[9], and Brazil's survey found inadequate intake in more than 85% of people ^[8]. In the US, most milk is fortified with about 3 mcg per cup ^[21], yet women still averaged only 4.0 mcg from food and drinks ^[17].

So blood levels depend heavily on sunlight, and sunlight depends on latitude. In Boston, at about 42 degrees north, winter sun produced no vitamin D in skin from November through February ^[22]. Germany lies further north still, and its national survey found low levels in 55.9% of women aged 18 to 44, with a quarter of women below 30 nmol/L from November to May ^[13]. In the UK, 16% of adults aged 19 to 64 had low vitamin D status after accounting for the season ^[14].

For an American reader, that means the answer depends on where you live in the country, how much time you spend outside and your skin tone, not just on what you eat ^[21].

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Iodine is a European worry, and a US pregnancy worry

Iodine comes mostly from dairy, seafood, eggs and iodized salt, and countries handle salt very differently. In Germany, only 9% of the salt in processed foods was iodized, and WHO's European office warned in 2024 that the shift to plant-based milks and falling dairy intake are raising the risk of iodine deficiency across the region ^[4]. German women aged 18 to 60 had the lowest average iodine intake of eight countries compared, at 105 mcg a day ^[3]. In the UK, median urinary iodine among women aged 16 to 49 was 98 mcg/L, with 21% below 50 mcg/L ^[14].

The US is in a similar spot. Iodizing table salt is voluntary, processed foods almost always use noniodized salt, and the median urinary iodine of pregnant women in 2007-2014 was 144 mcg/L, just under the WHO cutoff for adequacy in pregnancy ^[23]. If you're pregnant or planning to be and you eat little dairy or fish, it's worth asking your doctor whether your prenatal vitamin contains iodine.

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What US women can take from the comparison

Being in the middle of the international table doesn't mean American women are fine. US intake data show the same shortfalls in iron, calcium and vitamin D seen elsewhere, and the details for each nutrient, with the American foods that supply them, are in Which nutrients do American women most often fall short on?.

If your periods are heavy, you're tired all the time, or you're planning a pregnancy, talk to your primary care doctor or OB-GYN. A blood test says more about you than any country average.

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Common questions

Q1. Do American women have more anemia than women in Europe?

Not according to WHO's 2023 estimates. The US figure of 15.0% is close to Spain (15.6%), Germany (14.0%) and the UK (13.6%), a little higher than France (13.1%) and lower than Italy (16.4%) ^[1]. Differences this small aren't meaningful, because the numbers are modeled estimates.

Q2. Why is Japan's anemia rate higher than the US rate?

WHO estimates 18.7% for Japan and 15.0% for the US ^[1]. Japan's 2024 survey found women in their 20s to 40s eating 6.3 to 6.6 mg of iron a day ^[6], well below the 11.0 mg averaged by US women aged 20 and over, while in the US about half of dietary iron comes from grain products, much of it enriched ^[17,18]. Lower intake may be part of the story, but neither survey can show the cause.

Q3. If US flour already has folic acid, do I still need a supplement before pregnancy?

Yes. US advice is that anyone who could become pregnant gets 400 mcg of folic acid a day from supplements, fortified foods or both, and the USPSTF recommends a daily supplement starting at least a month before conception ^[18]. Fortified food alone doesn't guarantee that amount.

Q4. Can I compare my own blood test with these country figures?

Not really. The figures describe populations, and countries use different cutoffs and methods ^[2]. Your doctor will interpret your own results against the reference ranges your lab uses.

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References

Sources (23)

1. World Bank. World Development Indicators: Prevalence of anemia among women of reproductive age (% of women ages 15-49), indicator SH.ANM.ALLW.ZS (source: WHO Global Health Observatory), 2023 values. https://data.worldbank.org/indicator/SH.ANM.ALLW.ZS
2. World Health Organization, Global Health Observatory. Anaemia in women of reproductive age (aged 15-49), prevalence (%), by pregnancy status. https://www.who.int/data/gho/data/indicators/indicator-details/GHO/prevalence-of-anaemia-in-women-of-reproductive-age-(-)
3. Mensink GBM, et al. Mapping low intake of micronutrients across Europe. British Journal of Nutrition 2013;110(4):755-773. https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/mapping-low-intake-of-micronutrients-across-europe/3030D01830361125149A3BD9514F5A61
4. WHO Regional Office for Europe. People in the WHO European Region at greater risk of iodine deficiency due to changing diets. 28 June 2024. https://www.who.int/europe/news/item/28-06-2024-people-in-the-who-european-region-at-greater-risk-of-iodine-deficiency-due-to-changing-diets
5. Morris JK, et al. Prevention of Neural Tube Defects in Europe: A Public Health Failure. Frontiers in Pediatrics 2021;9:647038. https://www.frontiersin.org/journals/pediatrics/articles/10.3389/fped.2021.647038/full
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7. Japan Foundation for Aging and Health (Kenko Choju Net). Iron: functions and daily intake (based on Dietary Reference Intakes for Japanese, 2025). https://www.tyojyu.or.jp/net/kenkou-tyoju/eiyouso/mineral-tetsu.html
8. Verly Junior E, et al. Evolution of energy and nutrient intake in Brazil between 2008-2009 and 2017-2018. Revista de Saúde Pública 2021;55(Suppl 1):5s. https://scielosp.org/article/rsp/2021.v55suppl1/5s
9. Le Donne C, et al. The National Food Consumption Survey IV SCAI: Nutrient Intakes and Related Dietary Sources in Italy. Nutrients 2026;18(1):88. https://pmc.ncbi.nlm.nih.gov/articles/PMC12787946
10. Samaniego-Vaesken ML, et al. Iron Intake and Dietary Sources in the Spanish Population: Findings from the ANIBES Study. Nutrients 2017;9(3):203. https://eprints.ucm.es/70191/1/nutrients-09-00203 (1).pdf
11. Williams AM, Ansai N, Ahluwalia N, Nguyen DT. Anemia Prevalence: United States, August 2021-August 2023. NCHS Data Brief No. 519. National Center for Health Statistics; 2024. https://www.cdc.gov/nchs/products/databriefs/db519.htm
12. Liu S, West R, Randell E, et al. A comprehensive evaluation of food fortification with folic acid for the primary prevention of neural tube defects. BMC Pregnancy and Childbirth 2004;4:20. https://pmc.ncbi.nlm.nih.gov/articles/PMC524178
13. Rabenberg M, et al. Vitamin D status among adults in Germany: results from the German Health Interview and Examination Survey for Adults (DEGS1). BMC Public Health 2015;15:641. https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-015-2016-7
14. Office for Health Improvement and Disparities, Food Standards Agency. NDNS: results from years 9 to 11 (2016 to 2017 and 2018 to 2019), combined statistical summary. https://www.gov.uk/government/statistics/ndns-results-from-years-9-to-11-2016-to-2017-and-2018-to-2019/ndns-results-from-years-9-to-11-combined-statistical-summary
15. Columbia University Mailman School of Public Health. Tortillas Tell the Story of Folate Deficiency in Mexico: Study (on Orjuela-Grimm M, et al., American Journal of Clinical Nutrition 2019). 17 September 2019. https://www.publichealth.columbia.edu/news/tortillas-tell-story-folate-deficiency-mexico-study
16. Santé publique France. Esteban 2014-2016: chapitre dosages biologiques des vitamines et minéraux. 6 December 2019. https://www.santepubliquefrance.fr/les-actualites/2019/esteban-2014-2016-chapitre-dosages-biologiques-des-vitamines-et-mineraux-pas-de-deficit-important-ou-de-carence-a-grande-echelle
17. U.S. Department of Agriculture, Agricultural Research Service. Nutrient Intakes from Food and Beverages: Mean Amounts Consumed per Individual, by Gender and Age, in the United States, August 2021-August 2023. What We Eat in America, NHANES. https://ars.usda.gov/ARSUserFiles/80400530/pdf/2123/Table_1_NIN_GEN_2123.pdf
18. NIH Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals; Iron: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/ and https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
19. Britto JC, Cançado R, Guerra-Shinohara EM. Concentrations of blood folate in Brazilian studies prior to and after fortification of wheat and cornmeal (maize flour) with folic acid: a review. Revista Brasileira de Hematologia e Hemoterapia 2014;36(4):275-286. https://scielo.br/j/rbhh/a/m6yT4S6Ycz8CjMZvPWWmcXw/?lang=en
20. UK Department of Health and Social Care. Birth defects prevented by fortifying flour with folic acid. 14 November 2024. https://www.gov.uk/government/news/birth-defects-prevented-by-fortifying-flour-with-folic-acid
21. NIH Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
22. Webb AR, Kline L, Holick MF. Influence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin. Journal of Clinical Endocrinology and Metabolism 1988;67(2):373-378. https://pubmed.ncbi.nlm.nih.gov/2839537/
23. NIH Office of Dietary Supplements. Iodine: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/

This article provides general health information and is not a substitute for diagnosis or treatment. If you have symptoms that concern you, please see a healthcare provider.

This article is general information and doesn't replace advice from a doctor or dietitian.