Nutrient deficiencies in Switzerland – why you could also be affected

You live in Switzerland, have access to fresh food and may even consciously pay attention to your diet. And yet: fatigue that cannot be explained, more frequent infections or a level of performance that is no longer what it used to be. Such unspecific complaints are often not caused by burnout or a serious illness – but by a micronutrient deficiency. Even in one of the richest countries in the world, this is more common than most people assume.

Why a nutrient deficiency does not mean that you eat poorly

Micronutrient deficiency does not necessarily result from obvious poor nutrition. More often, the cause lies in a one-sided food selection, increased requirements during life phases such as pregnancy, breastfeeding, intensive sport or older age – or in reduced absorption in the gut.

The Swiss Federal Food Safety and Veterinary Office (FSVO/BLV) explicitly points out that dietary supplements are only useful in cases of insufficient intake or increased requirements. The foundation remains a varied diet. However, anyone who belongs to a risk group – whether due to dietary habits, life phase or season – should know the most relevant nutrients.

Vitamin D – the deficiency that begins with winter

Vitamin D has a special status among micronutrients: it is not primarily obtained through food, but produced in the skin through UV-B radiation. This is exactly where the problem lies in Switzerland. From October to March, sunlight at Switzerland’s latitude is not sufficient to ensure adequate endogenous production – even with regular time spent outdoors.

An analysis published in Nutrients (PMC7987506) on vitamin D status in the Swiss population shows that a considerable proportion of the population – especially older people and those with little sun exposure – has insufficient serum levels. The Federal Commission for Nutrition (FCN/EEK) has summarised the available data and reached similar conclusions.

The context is important: while targeted supplementation is useful for risk groups (older people, people with dark skin, people who hardly go outdoors), more recent large studies – including the VITAL trial – show that routine supplementation in healthy middle-aged adults provides no proven additional benefit. Vitamin D also does not act in isolation: bones and the immune system require interaction with calcium and magnesium.

Vitamin D is central for:

• Bone health and calcium utilisation
• Muscle function and fall prevention in older age
• Normal function of the immune system

Vitamin B12 – an invisible risk with plant-based nutrition

Vitamin B12 occurs naturally almost exclusively in animal-based foods – meat, fish, eggs and dairy products. People who follow a vegetarian or vegan diet cannot cover their requirements through food alone and rely on supplementation. This is not a marginal issue: plant-based diets are also becoming more common in Switzerland.

A scoping review in Nutrients (2024, PMC 11124153), evaluating 70 studies, came to a clear conclusion: vitamin B12 supplementation is not optional for vegans, but necessary. A cross-sectional study from the German-speaking region (Annals of Medicine, 2023) confirmed that non-supplementing vegans had significantly lower B12 biomarker values – while supplementing vegans achieved an adequate status.

However, people with plant-based diets are not the only ones affected. Older people produce less stomach acid and intrinsic factor – both of which are necessary for B12 absorption in the gut. People who take proton pump inhibitors or metformin long term also have an increased risk.

A prolonged deficiency may manifest as:

• Persistent fatigue and exhaustion
• Concentration and memory problems
• Tingling or numbness in the hands and feet
• Anaemia (megaloblastic anaemia)

Iron deficiency – the most common nutrient deficiency among women in Switzerland

Iron deficiency is the most widespread nutrient deficiency worldwide – and in Switzerland it is by no means limited to low-income population groups. A study by ETH Zurich published in 2025 in the European Journal of Clinical Nutrition (Herter-Aeberli et al., DOI 10.1038/s41430-025-01685-z) evaluated data from 26 Swiss studies involving 2709 women aged 18 to 54. The result: almost 19% of women had an iron deficiency – nearly one in five.

Women with heavy menstrual bleeding, pregnant women, breastfeeding women and women who do intensive sport are particularly affected. A vegetarian or vegan diet also increases the risk, as plant-based iron (non-haem iron) is absorbed much less efficiently than animal-based iron.

Typical symptoms include:

• Persistent fatigue and reduced performance
• Paleness, dizziness, shortness of breath during exertion
• Poor concentration and irritability
• Brittle nails and hair loss

Calcium, iodine and omega-3 – three further supply gaps at a glance

Nutrient	Main risk group	Common cause	Function
Calcium	People with low dairy intake, lactose intolerance, older women	Low dietary intake, poor absorption without vitamin D	Bones, teeth, muscle and nerve function
Iodine	People with reduced salt intake, vegans	Low use of iodised table salt, no sea fish	Thyroid function, metabolism
Omega-3 (EPA/DHA)	People who rarely eat oily fish	Low dietary intake; plant-based sources provide only ALA	Heart, brain, regulation of inflammatory processes

The same applies to calcium as to vitamin D: the two nutrients depend on each other. Without sufficient vitamin D, calcium utilisation in the gut is impaired – isolated intake is less useful than the interaction of both substances.

Why micronutrient deficiencies remain undetected for so long

The difficulty with micronutrient deficiencies lies in their lack of specificity. Fatigue, susceptibility to infections, concentration problems – these symptoms can have dozens of causes. A deficiency is often not the first thing that comes to mind, neither for the person affected nor for the doctor.

In addition, many deficiencies remain for a long time in the area of so-called subclinical deficiency: blood values that are still within the normal range, but already so low that bodily functions may be impaired. Only a targeted blood test provides clarity – especially if complaints persist over a longer period.

What you can do in practical terms

The foundation remains a varied, as natural as possible diet with plenty of vegetables, legumes, nuts, wholegrain products and – depending on dietary habits – high-quality animal-based sources. No supplementation replaces a good nutritional foundation.

In certain life situations, targeted supplementation is useful and supported by the data:

• Vitamin D in autumn and winter, especially for risk groups
• Vitamin B12 with vegetarian and vegan diets – consistently and long term
• Iron in women with heavy menstruation – after blood test control
• Omega-3 with low fish consumption, also available from algae oil

Important: not all nutrients should be supplemented routinely. Too much iron, for example, can be harmful; high-dose vitamin D should also not be taken uncritically. A blood test before starting supplementation is recommended – and provides the best basis for an individual decision.

Conclusion

Nutrient deficiency is not a problem limited to developing countries or extreme poor nutrition. It affects people in Switzerland – due to season, dietary habits, life phases or simply everyday food choices. Vitamin D in winter, vitamin B12 with plant-based diets and iron in women of childbearing age are the three best-documented supply gaps in our environment. Anyone who pays attention to warning signs and clarifies them in a targeted way creates a solid foundation – for today and for the long term.

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This article is for general information only and does not replace medical advice. If complaints persist, we recommend consulting a doctor.

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