When should you opt for a course of food supplements?

Why consider a course rather than a daily intake?

What exactly is a course of food supplements?

A course of food supplements is a temporary, targeted intake of a specific nutrient — in the form of a soft capsule, capsule, tablet or oil — over 1 to 3 months to fill an identified deficit. It differs from a long-term daily supplementation by its limited duration and its corrective aim. The FSVO defines food supplements as foodstuffs intended to complement the diet through a concentrated intake of vitamins, minerals or other substances with a nutritional or physiological effect^[1].

The one-off course responds to a passing or seasonal physiological need of the body, whereas daily supplementation accompanies a lasting state such as a strict vegan diet or a diagnosed malabsorption. Confusing the two logics exposes you to an unjustified use of food supplements useful elsewhere, and to a risk of cumulative overdose.

How does it differ from continuous supplementation?

The course targets a one-off deficit, continuous supplementation covers a permanent need. This difference is not only a matter of course duration: it changes the posology, the medical follow-up and the associated risk. A course of iron after a confirmed vitamin deficiency will last 3 months with a blood test check; vitamin B12 supplementation in a strict vegan will stretch over years without interruption, in addition to a varied diet.

The 2023 FSVO national survey established that two-thirds of the supplements consumed by Swiss adults (66.7%) contain vitamins or minerals^[2], often in combination — multivitamins, combined packs or routine multivitamin courses. This stacking makes the duration of use even more decisive: a moderate-dose product taken for a few weeks remains safe; the same product taken continuously for years can lead to exceeding the tolerable upper intakes.

Why does the limited duration change the benefit-risk ratio?

Limiting the duration reduces the risk of overdose and allows the effectiveness of courses on the body to be assessed. The fat-soluble vitamins A, D, E and K build up in the liver and adipose tissue: prolonged intake at a high dose can lead to chronic intoxication^[3]. Calcium and iron taken in the long term without a deficiency also create digestive or metabolic disturbances. A break between each course thus protects the working of the body.

A course framework allows regular reassessment. After a 1- to 3-month course, a blood test or a symptom review guides the decision to continue, stop or change the active molecule. This logic of a limited time window is the same as the one used for optimal intake timing, where the moment and the frequency influence effectiveness as much as the dosage itself.

When do a seasonal change or fatigue justify a course?

Why does a seasonal change in Switzerland call for vitamin D supplementation?

The FSVO indicates that about 60% of the Swiss population is not sufficiently supplied with vitamin D during winter months^[4]. The country’s latitude — between 45° and 47° North — and the drop in sunlight between October and April strongly limit cutaneous synthesis. The FSVO recommends that people aged 3 to 60 cover their winter needs through a diet rich in vitamin D, enriched foods or supplement intake — beyond the specific recommendations for children up to 3 years, seniors aged 60 and over, and pregnant or breastfeeding women after consultation with a professional.

A clinical study published in the European Journal of Nutrition in 2025 showed that winter supplementation reduced by 17% the number of days with respiratory symptoms in children aged 6 to 8 in Copenhagen (55° North)^[5], compared with placebo. Needs vary according to lifestyle habits: a course adapted to the Swiss climate takes into account altitude, remote working and the time actually spent outdoors between November and March.

Is a course relevant in case of persistent severe fatigue?

Yes, but only after identifying the cause. Fatigue that lasts more than three to four weeks should trigger an examination, not blind supplementation. The most frequent nutritional causes are iron deficiency in women of childbearing age^[10], lack of vitamin D in winter, and combined magnesium and B-vitamin deficits in people whose state of health is marked by prolonged stress. Reducing fatigue begins by identifying what is missing.

A Cochrane review published in 2024 on postpartum anaemia concluded, with moderate certainty, that intravenous iron slightly reduces fatigue in the 8 to 28 days following childbirth compared with oral iron tablets^[7], with no notable difference beyond four weeks. For other profiles, a course for severe fatigue first rests on a blood test, then on a targeted vitamin course — iron, vitamin D, folic acid, B-group vitamins according to the result — rather than on generic multivitamins.

Which objective signs distinguish a true deficiency from a simple dip in energy?

A confirmed deficiency shows itself through measurable signs, not just by a feeling. Clinical warning signs include cutaneous and conjunctival pallor, hair loss, visible effects on the skin and brittle nails, repeated night cramps, breathlessness on moderate effort or a measurable drop in performance at work as in training. These signals are not enough to diagnose but they justify the examination.

The FSVO stresses that healthy people who eat in a varied and balanced way do not, as a rule, need food supplements^[1]. Biological diagnosis therefore remains the step that changes everything — without it, the course is guesswork and may needlessly prolong the problem, regardless of the quality of the products chosen.

Chronic stress, sport and convalescence: three specific cases

Does chronic stress justify a magnesium course?

Yes in certain profiles, particularly when prolonged stress comes with measurable physical symptoms. A single-blind randomised controlled trial published in Frontiers in Nutrition in 2023 documented that a combination of magnesium, B6/B9/B12 vitamins, green tea and rhodiola, taken for 28 days, lowered the stress score measured by the DASS-42 scale in 40 chronically stressed adults^[8]. The improvement remained moderate but consistent with clinical observations, and magnesium contributes to the normal functioning of the nervous system.

Another placebo-controlled crossover trial published in 2025 in the Journal of Psychopharmacology confirmed an improvement in working memory and attentional performance with a supplement based on magnesium, chromium and plant extracts (Scutellaria baicalensis and Crataegus laevigata) taken for 15 days by 43 stressed adults^[9]. A course tailored to chronic stress typically mobilises a well-tolerated form of magnesium, complemented by the B-group vitamins that contribute to nervous regulation — often available in soft capsules or capsules depending on the chosen formula.

Is a course before a sporting effort or competition useful?

It depends on the nutrient, the sport and the athlete’s profile. A 2023 review published in Sports Medicine established that iron and the B-group vitamins contribute to haematological adaptation, while calcium and vitamin D are essential to the bone health of an athlete subjected to intense physical activity^[6]. For these nutrients, a course justified by a biological examination improves performance or injury prevention.

For ergogenic aids such as creatine or beta-alanine, the mechanism is different: these are performance tools, not deficiency correctors. A 2024 review in Nutrients confirmed the effectiveness of creatine at 3-5 g/day for strength and high-intensity efforts, with a safety profile documented over prolonged use^[11]. The timetable of a course before competition therefore depends on the product chosen and the discipline targeted — capsule packs, soft capsules or powder according to use preferences.

Is a course needed during or after convalescence?

Yes in most post-operative or post-infectious situations, under medical follow-up. The human body’s needs for protein, zinc, vitamin D and sometimes iron increase during the healing phase and the recovery of the immune system. ERAS (Enhanced Recovery After Surgery) protocols now include pre- and post-operative nutritional optimisation to reduce complications and length of stay, alongside the usual dietary regimen.

The 2024 Cochrane review on postpartum anaemia, cited above, documented that intravenous iron slightly reduced fatigue in the first 8 to 28 days compared with oral iron in women who had had a post-birth haemorrhage, with moderate certainty^[7]. A course during convalescence distinguishes which nutrients to favour according to the type of surgery, age and initial nutritional health status — vitamins, minerals, marine collagen or omega fatty acids according to documented cases.

What precautions should you take before starting a course in Switzerland?

Why is a biological examination preferable to intuition?

Because the symptoms of fatigue, weakened immunity or sleep disturbances are not very specific and steer the choice of course poorly. A blood test allows measurement of 25-hydroxyvitamin D, ferritin, haemoglobin, vitamin B12 and sometimes erythrocyte magnesium. Without this data, a course becomes a guess — and no pack or label information can replace a dosage. The FSVO recalls that food supplements are not medicines: they are not intended for the prevention or treatment of a human disease and must not carry claims promoting such purposes^[1].

• ①Vitamin D: 25(OH)D dosage, ideally between October and March in Switzerland to catch the lowest value of the year.
• ②Iron: ferritin and haemoglobin, to be requested in case of chronic fatigue, heavy menstruation or a meat-free diet.
• ③Vitamin B12: dosage indicated for strict vegan diets, seniors and people on metformin or long-term PPIs.

What overdose risks should you be aware of?

Overdose is not a theoretical exception: the 2023 FSVO survey established that 25% of magnesium consumers exceed the tolerable upper intake of 250 mg/day and 6% of vitamin D consumers exceed the UL of 100 µg/day^[2]. The fat-soluble vitamins A, D, E and K build up in the liver and adipose tissue and can become toxic at a prolonged maximum dose. Vitamin B6 taken at a high dose for several months is associated with a risk of reversible peripheral neuropathy documented by EFSA^[12]. Health safety therefore calls for sustained attention to the quantity actually absorbed, regardless of the product’s quality or natural character.

• ⚠Stacking several multivitamin products exposes you to exceeding the tolerable upper intake.
• ⚠Over-the-counter supplements can interact with medical treatment, in particular anticoagulants, antihypertensives and levothyroxine.
• ⚠Health claims are strictly regulated by the Ordinance on Food Information in Switzerland: “cures”, “relieves” or “prevents” a disease are forbidden on a supplement.

How do you frame an effective course over time?

Three markers structure a useful course: a measurable goal, a defined duration, a check point. The goal is expressed biologically (raising ferritin above a threshold) or symptomatically (reducing the frequency of cramps). The FSVO indicates that taking food supplements for a limited time can be advisable when certain nutrients cannot be ingested in sufficient quantity through diet^[12]. The standard duration of 1 to 3 months for minerals and of the whole dark period for vitamin D gives a clear framework. The check point is a medical appointment, a fresh blood test or a symptom diary. Following these markers is one of the main pieces of advice for a successful course.

Without this framework, the course drifts into unjustified chronic consumption. The physiological working of food supplements reinforces this need for discipline: most active ingredients produce an effect within 4 to 8 weeks when they have a real target, and bring nothing more beyond that period if the deficit has been filled. The logic of a course therefore protects the wallet, hepatic safety and observed effectiveness alike.

Frequently asked questions about courses of food supplements