Food fortification means adding vitamins or minerals to staple foods, such as iodine to salt or folic acid to flour, to prevent deficiency. It works best for iodine and folic acid: US flour fortification since 1998 prevents about 1,326 neural tube defects a year. From 13 December 2026, non-wholemeal wheat flour in England and Scotland must contain folic acid.
What food fortification is, and why governments use it
Most nutrition advice relies on people changing what they eat. Fortification takes the opposite approach: it changes the food supply so that people get more of a nutrient without having to do anything differently. The World Health Organization and FAO describe it as an approach that can "deliver nutrients to large segments of the population without requiring radical changes in food consumption patterns" (WHO and FAO, Guidelines on food fortification with micronutrients, November 2006).
Three versions are worth separating, because the debates about them are different:
- Mass or large-scale fortification. A nutrient is added to a staple that almost everyone eats, such as salt, wheat flour, maize flour, rice or cooking oil. This is usually mandatory and set out in law.
- Targeted fortification. Foods for a specific group, such as infant formula, complementary foods for young children or products for older people in care, are fortified to meet that group's needs.
- Market-driven (voluntary) fortification. Manufacturers choose to add nutrients to products such as breakfast cereals, plant drinks and spreads, within limits set by regulators.
Mass fortification is the public health tool, and it is the focus of this article. It suits nutrients where deficiency is widespread, the consequences are serious, the safe range is reasonably wide, and the nutrient can be added cheaply without changing taste or colour.
How many countries fortify
Fortification has spread steadily over the past two decades. The Food Fortification Initiative (FFI), which tracks national laws with partners including the Global Fortification Data Exchange (GFDx), reports that 86 countries now have legislation mandating fortification of at least one industrially milled cereal grain. Of these, 85 mandate wheat flour, alone or with other grains, and one, Papua New Guinea, mandates only rice. When FFI was founded in 2002, only 38 countries had such mandates (Food Fortification Initiative, Global Progress).
The Global Fortification Data Exchange holds the country-by-country detail on which foods and nutrients are covered. One caution when reading it: GFDx classes a food as mandatory or voluntary, not each nutrient, so a country listed as having mandatory wheat flour fortification may require iron but leave folic acid optional. Our compare countries tool is a quick way to see how national nutrition profiles differ before you dig into the fortification databases.
| Nutrient | Usual food vehicle | Main problem it targets | Strength of evidence for benefit | Key safety point |
|---|---|---|---|---|
| Iodine | Salt | Goitre, hypothyroidism, impaired brain development | Strong; a long-established public health success | Excess intake in some countries; must fit with salt reduction |
| Folic acid | Wheat and maize flour | Neural tube defects such as spina bifida | Strong; consistent falls in birth prevalence | Very high intakes can mask vitamin B12 deficiency |
| Iron | Wheat flour, maize flour, rice | Iron deficiency and anaemia | Low certainty for anaemia reduction | Little adverse-effect data in children |
| Vitamin D | Milk products and fat spreads | Low vitamin D status in low-sunlight countries | Good for raising blood levels; less clear for disease outcomes | Total intake from supplements also matters |
The big successes
Iodine and salt
Iodine is needed to make thyroid hormones, and deficiency early in life can cause goitre, delayed growth and development of the central nervous system, and intellectual impairment (Velasco and colleagues, Cochrane Database of Systematic Reviews 2026). Iodising salt is the main way countries tackle it. In 2014 WHO issued a guideline on fortifying food-grade salt with iodine for the prevention and control of iodine deficiency disorders, aimed at the people who design and scale up salt-iodisation programmes (WHO guideline, October 2014).
The results are visible in global monitoring. The Iodine Global Network's 2025 scorecard, which uses median urinary iodine concentration in school-age children, classes 102 of WHO's 194 member states as having adequate iodine intake and 10 as having excess intake. A further 82 are listed as insufficient, but 59 of those have no recent data, so only 23 have recent survey evidence of deficiency (Iodine Global Network, Global Scorecard of Iodine Nutrition 2025).
That data gap is itself a finding. Iodine programmes need regular monitoring, because both deficiency and excess are possible, and because reformulated processed foods may use non-iodised salt.
Folic acid and neural tube defects
Neural tube defects (NTDs), mainly spina bifida and anencephaly, happen in the first weeks of pregnancy, often before a woman knows she is pregnant. Supplements before conception work, but many pregnancies are unplanned, which is why fortification matters.
The United States mandated folic acid fortification of enriched cereal grain products at 140 micrograms per 100 grams from 1998. A CDC analysis of 19 birth defect surveillance programmes found that, in programmes that capture prenatal diagnoses, the prevalence of spina bifida and anencephaly fell from 10.7 per 10,000 live births in 1995 to 1996 to 7.0 in 1999 to 2011. It estimated that about 1,326 babies a year are born without an NTD who would otherwise have been affected, with a 95% confidence interval of 1,122 to 1,531 (Williams and colleagues, CDC MMWR 2015). The same report noted remaining opportunities for prevention among women with lower folic acid intakes, especially Hispanic women.
The UK folic acid decision
The United Kingdom debated mandatory folic acid fortification for more than two decades before deciding to go ahead. The government's 2022 consultation said that about 1,000 pregnancies a year in the UK are affected by NTDs, and that fortification could prevent around 200 cases a year, about 20% of the total. It noted that Australia, New Zealand and Canada already had similar policies (UK government press release, 1 September 2022).
What the new law requires
The government confirmed its decision in a response updated in January 2024. Non-wholemeal flour from common wheat must contain 250 micrograms of folic acid per 100 grams. Small mills producing under 500 tonnes a year are exempt, and wholemeal and gluten-free flour fall outside the requirement, which keeps unfortified options available. The minimum levels of calcium carbonate, iron and niacin also rise to 15% of the nutrient reference value per 100 grams, while thiamin is unchanged (UK government response to the bread and flour consultation).
In England, the Bread and Flour (Amendment) (England) Regulations 2024 were made on 13 November 2024. The provisions that add folic acid, at 0.250 milligrams per 100 grams, to the essential ingredients of flour come into force on 13 December 2026 (legislation.gov.uk, SI 2024/1162). Scotland made its own amending regulations in December 2024, with the folic acid change also starting on 13 December 2026 (legislation.gov.uk, SSI 2024/387).
The safety debate
The arguments against mandatory folic acid have mostly been about safety and choice rather than effectiveness. The UK government response records that the Committee on Toxicity found chronic exposure from non-wholemeal flour at the planned level would not exceed guidance levels, that the European Food Safety Authority's draft tolerable upper intake level of 1 milligram a day for folic acid matches the UK guidance level, and that masking of vitamin B12 deficiency is the key concern at intakes above that level. A UK-wide monitoring group will track both benefits and harms. For readers worried about B12, our guide to vitamin B12 deficiency covers the groups most likely to run low and the blood tests used to check.
Fortified flour does not replace folic acid supplements. The NHS advises taking a folic acid supplement for the first 12 weeks of pregnancy, starting ideally three months before conception, and notes that the folic acid added to foods is much lower than the amount in supplements. Some women need a higher dose, so check with a pharmacist, midwife or doctor (NHS, Folic acid).
Where fortification falls short
Iron: a weaker evidence base
Iron is the most common nutrient added to flour, yet the evidence for its effect is less certain than for iodine or folic acid. A 2021 Cochrane review of 10 trials with 3,319 participants found that iron-fortified wheat flour "may reduce" the risk of anaemia by about 27% (risk ratio 0.73), based on low-certainty evidence. The effects on iron deficiency and haemoglobin were uncertain, and the trials reported almost no data on adverse effects in children (Field and colleagues, Cochrane Database of Systematic Reviews 2021).
One reason is that anaemia has many causes besides low iron intake, including infections, inherited blood disorders and other deficiencies, so adding iron alone cannot solve it. The trials also used very different iron doses, from under 40 to over 60 milligrams per kilogram of flour, and a law on paper does not guarantee that the flour people buy meets the standard. For individuals, iron needs are better assessed clinically; our guide to iron supplements covers who might need them.
Reach: the people who need it most
Mass fortification only reaches people who buy industrially processed staples. Rural households who grow their own maize or take grain to a small local mill can miss out, and the UK's own small-mill exemption shows that even rich countries accept some gaps. The people with the poorest diets are often those least reached by industrial food chains, which links fortification closely to food insecurity.
Vitamin D: good for blood levels, less clear for outcomes
Vitamin D shows both the promise and the limits. Finland began systematic vitamin D fortification of fluid milk products and fat spreads in 2003. In nationally representative surveys of adults aged 30 and over, mean blood 25-hydroxyvitamin D rose from 48 nmol/L in 2000 to 65 nmol/L in 2011; supplement use also rose, from 11% to 41%, and the authors attributed the improvement mainly to fortification, especially of milk, together with greater supplement use (Jääskeläinen and colleagues, American Journal of Clinical Nutrition 2017). Raising blood levels is not the same as proving fewer fractures or infections, though. For individual advice, see our guide to vitamin D supplements.
Policy fit
Fortification can pull against other goals. Salt iodisation has to coexist with campaigns to cut salt intake, which means iodine levels may need adjusting as salt consumption falls. Fortifying foods that are otherwise unhealthy, such as sugary cereals, can give a "health halo" that labelling rules then have to manage. That is why debates about fortification sit alongside those on front-of-pack labelling and the sugar tax: each changes the food environment rather than relying on individual education.
Can fortification cause too much intake?
Yes, in theory, and in a few cases in practice, which is why programmes need monitoring rather than a "set and forget" approach.
- Iodine. The 2025 IGN scorecard lists 10 countries with excess iodine intake among school-age children. Concerns have been raised about thyroid autoimmunity during salt iodisation, although a 2024 review of studies over as long as two decades found thyroid function stayed normal and judged the programmes safe, while calling for better long-term studies. The same review estimated that well-run programmes have cut the prevalence of iodine deficiency by 75% (Atapattu and colleagues, Nutrients 2024).
- Folic acid. The UK Committee on Toxicity concluded that long-term exposure from fortified non-wholemeal flour at the planned level would not exceed guidance levels. People who also take high-dose supplements and eat many fortified products are the group to watch.
- Several fortified products at once. Someone who eats fortified cereal, fortified plant milk, fortified bread and also takes a multivitamin can add up more of some nutrients than they realise. This is mostly a voluntary-fortification issue rather than a mass-fortification one.
Dietitians are well placed to check this in practice, particularly for children, pregnant women and people taking several supplements. Our supplements hub explains how supplement intakes add to diet.
Whose data to trust
Fortification statistics come from different kinds of source, and they do not always agree. Legal mandates are tracked by FFI and GFDx; compliance, the share of flour or salt that actually meets the standard, comes from market surveys and is often missing; and health outcomes come from birth defect registries, urinary iodine surveys or blood tests. A country can have a strong law and poor compliance, or good outcomes because people already eat enough of a nutrient. When you read a claim that fortification "works" or "fails" in a given country, check which of these three it is talking about.
National guides also differ on whether fortification is mentioned at all. Our explainer on the new US food pyramid covers the latest American advice, and our country guides for the United Kingdom and the United States describe how dietitians in each system fit fortification into practice. Fortification and environmental sustainability also intersect, for example when plant-based drinks are fortified to replace dairy nutrients; our article on the sustainable diet looks at that trade-off.
What it means for practice
For dietitians and nutrition professionals, a few practical points follow:
- Know your country's mandates. Which staples are fortified, with what, and at what level, changes your assessment of a patient's likely intake.
- Ask about wholemeal, gluten-free and home-milled flour. People who avoid fortified staples, including those with coeliac disease, may need other sources of folate, iron or calcium.
- Keep recommending pre-conception folic acid. Flour fortification lowers risk but does not remove the need for supplements.
- Watch for stacking. Add up fortified foods and supplements in children and heavy supplement users.
- Support monitoring. Programmes improve when dietitians and public health teams report gaps, from non-compliant flour to falling iodine status.
For more global policy resources, start at our global nutrition hub. If you want personal advice on whether your diet covers folate, iron, iodine or vitamin D, especially before pregnancy or on a restricted diet, you can book a session with a registered dietitian.
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Frequently asked questions
What is food fortification?
Food fortification is the deliberate addition of vitamins or minerals to foods. Mass fortification adds nutrients to staples nearly everyone eats, such as iodine to salt or folic acid and iron to flour, usually by law. Targeted fortification focuses on foods for groups like infants, and voluntary fortification is when manufacturers add nutrients to products such as cereals and plant drinks.
Which countries fortify flour with folic acid?
Many countries do, including the United States since 1998, Canada, Australia and New Zealand. The Food Fortification Initiative reports that 85 countries mandate wheat flour fortification, but not every one requires folic acid, so check the Global Fortification Data Exchange for each country. In England, folic acid becomes mandatory in non-wholemeal wheat flour from 13 December 2026.
Can fortification cause too much intake?
It can, which is why programmes are monitored. The Iodine Global Network's 2025 scorecard lists 10 countries with excess iodine intake in school-age children. For folic acid, the UK's toxicity experts found fortified flour at the planned level would not push long-term intakes above guidance levels, but people also taking high-dose supplements should check their total. Stacking many fortified products with supplements is the main risk.
Why is folic acid being added to flour in the UK?
To reduce neural tube defects such as spina bifida, which affect about 1,000 UK pregnancies a year. The government estimated fortification could prevent around 200 cases a year. Because many pregnancies are unplanned and the neural tube forms very early, adding folic acid to non-wholemeal wheat flour protects women who are not taking supplements.
Does fortified flour mean I do not need folic acid tablets in pregnancy?
No. The NHS says the folic acid added to foods such as bread is much lower than the amount in supplements, and advises a folic acid supplement for the first 12 weeks of pregnancy, ideally starting three months before you conceive. Some women need a higher prescribed dose, so check with a pharmacist, midwife or doctor.
Is fortified food as good as getting nutrients naturally?
Fortification has a strong track record for nutrients such as iodine and folic acid, and Finland's experience shows fortified milk and spreads can raise vitamin D levels across a population. It does not make an otherwise poor diet healthy, though. A fortified sugary cereal is still high in sugar, so it is best to see fortified staples as a safety net within a varied diet.
