Iron, Vitamin D and B12 Deficiency: The Signs to Know (and Who's Most at Risk)
Iron, vitamin D and vitamin B12 are by far the most common nutrient deficiencies, both in France and worldwide. They don't show up on the scale or in a calorie counter: they tend to show up as general signs — fatigue, paleness, tingling — that many people put down to being overworked or under-slept. Here's what health authorities (ANSES, HAS, French Public Health agency, WHO) say about these 3 deficiencies: their signs, who's most at risk, and where to find them in food. Read with one essential caveat, repeated throughout this article: only a healthcare professional can confirm a deficiency, through a blood test.
Why these 3 deficiencies specifically?
Our micronutrients article covers the 14 benchmarks Radish tracks (vitamins, minerals, fiber, sugar, saturated fat). This one takes a different angle: among all micronutrients, three deficiencies show up far more often than the rest in public-health data. According to the WHO, iron deficiency is the most common nutritional deficiency in the world, affecting menstruating women, pregnant women and young children above all. In France, Public Health France's Esteban study found a shortfall or insufficiency in vitamin D across a large share of adults. And vitamin B12 is structurally at risk for anyone excluding animal products, according to ANSES.
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The benchmark. ANSES sets iron need at around 11 mg/day for most adults, rising to 16 mg/day for women of childbearing age with heavy menstrual losses.
How many people are affected. According to a HAS report drawing on the ENNS survey, 20 to 25% of women of childbearing age in France have low ferritin (depleted iron stores), and 5 to 10% have confirmed iron-deficiency anemia.
General signs, per ameli.fr (the French national health insurance): fatigue, paleness, breathlessness on exertion, headaches, dizziness, difficulty concentrating — and more specifically, dry skin and hair, brittle nails. Early on, the deficiency is often silent, which is exactly why it can go unnoticed for a long time.
Who's most at risk: women of childbearing age (especially with heavy periods), pregnant women, children and teens in active growth, people following a vegetarian or vegan diet (plant-based iron is less well absorbed), regular blood donors, endurance athletes, and people with chronic inflammation or a condition affecting intestinal absorption.
Where to find it. Heme iron — the best absorbed form — comes exclusively from animal products: red meat, organ meat (especially liver), fish, shellfish. Non-heme iron, less well absorbed, comes from legumes, nuts, grains, egg yolk and leafy greens; pairing these with a vitamin C source (citrus, peppers) improves absorption.
Vitamin D: signs, at-risk groups, sources
The benchmark. Since 2016, ANSES has recommended 15 µg/day for adults.
How many people are affected. The Esteban study (2014-2016) from Public Health France, run on thousands of adults and children in France, found that around 7% of adults and 4% of children are deficient, rising to 13% among teenagers. Only one adult in four reaches an adequate status, and nearly two-thirds of adults show a moderate insufficiency or deficiency. Public Health France concludes there's no mass deficiency severe enough to justify urgent public-health policy, but flags several points of vigilance, notably among men aged 55 to 74.
Signs, per the MSD Manual: muscle pain and weakness, bone pain, fatigue. In severe, prolonged cases, deficiency can cause rickets in children (bone deformities, delayed walking) or osteomalacia in adults, with a higher fracture risk — notably hip fractures in older adults.
Who's most at risk: older adults (particularly those with little sun exposure or living in care facilities), infants, pregnant and breastfeeding women, people with darker skin, people living in northern regions during winter, people with obesity, and people with intestinal absorption disorders.
Where to find it. The main source remains brief, regular sun exposure; on the food side, oily fish, fortified dairy and cereals, egg yolk and fish liver oils all contribute. In France, supplementation is commonly offered to infants and frail older adults — always by prescription, never on your own initiative.
Vitamin B12: signs, at-risk groups, sources
The benchmark. ANSES sets the adequate intake at 4 µg/day for adults, 4.5 µg for pregnant women and 5 µg for breastfeeding women.
A structural deficiency without supplementation. Vitamin B12 is only naturally found in animal products. ANSES is explicit: for people following a strict vegan diet, deficiency is essentially inevitable without supplementation.
Signs, per the MSD Manual: on one hand, anemia-related signs (fatigue, paleness, weakness, and in advanced cases breathlessness and dizziness); on the other, neurological signs that can appear even before the anemia — tingling and numbness in the hands and feet, loss of sensation in the extremities, balance problems, and with prolonged deficiency, irritability or memory issues.
Who's most at risk: people following a strict vegan or vegetarian diet without supplementation, older adults (whose stomach acid declines, reducing absorption), people who've had bariatric or gastric surgery, people with chronic digestive conditions (Crohn's, celiac disease), people on long-term metformin or certain antacids, and breastfed infants of unsupplemented vegan mothers.
Where to find it. Meat (liver and organ meats top the list), fish, shellfish, eggs, dairy, and some fortified cereals. No natural plant source covers the need — a central point of vigilance for anyone excluding animal products.
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⚠️ The one thing to remember. The fatigue, paleness or tingling described here can have many other causes besides these 3 deficiencies — poor sleep, stress, another condition. Recognizing yourself in these signs doesn't make a diagnosis. Only a blood test ordered by a doctor (ferritin and hemoglobin for iron, 25-OH vitamin D, B12 level depending on the case) confirms or rules out a deficiency. Never start supplementation on your own initiative: too much iron or vitamin D can be harmful, and untargeted supplementation can delay the diagnosis of a more serious underlying condition. If in doubt, the first step is always to talk to a healthcare professional.
How Radish helps you track these benchmarks
In Radish, iron, vitamin D and vitamin B12 are among the 14 benchmarks shown every day, calculated from the official CIQUAL and USDA data tied to each food in your log — no manual math required. The app even raises the iron target for women of childbearing age. But Radish stays a food-tracking tool, not a diagnostic one: it helps you see whether your diet covers these benchmarks, and it never replaces a blood test. For the full breakdown of all 14 benchmarks and their food sources, see our micronutrients article.
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How do I know if I have an iron, vitamin D or B12 deficiency?
Only a blood test ordered by a doctor can confirm a deficiency (ferritin and hemoglobin, vitamin D or B12 level depending on the case). The general signs described here — fatigue, paleness, tingling — can have other causes and are never enough, on their own, to make a diagnosis.
Can I take supplements without medical advice if I recognize these signs in myself?
This isn't recommended. Too much iron or vitamin D can be harmful, and untargeted supplementation can delay the diagnosis of an underlying condition. A healthcare professional determines whether supplementation is needed, and at what dose.
Who's most at risk of these 3 deficiencies?
For iron: women of childbearing age, pregnant women, growing children, and vegetarian/vegan diets. For vitamin D: older adults with little sun exposure, infants, and people with darker skin. For B12: people on a strict unsupplemented vegan diet and older adults.
Can Radish diagnose a deficiency?
No. Radish shows food-intake benchmarks calculated from what you eat (CIQUAL/USDA data); it replaces neither a blood test nor medical advice.
The one thing to remember: iron, vitamin D and B12 are the 3 most common deficiencies, but their signs (fatigue, paleness, tingling) stay non-specific. Radish helps you track your food intake against official data (CIQUAL, USDA), for free and offline — diagnosis, meanwhile, always stays a healthcare professional's job. nutri-track.fr
General information, not medical advice. Does not replace a consultation or a blood test.
🔎 Methodology & sources. Every nutrition figure in this article is cross-checked against official sources (ANSES, HAS, French Public Health agency, WHO, MSD Manual, ameli.fr), and health topics are reviewed before publication against our internal reference framework. See our full methodology →
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