Which food-supplement course during convalescence?

Why does the body consume more nutrients during convalescence?

What happens in the body after illness or surgery?

An acute illness, an infection or a surgical procedure triggers an inflammatory reaction that mobilises the body’s energy, proteins and micronutrients. Protein requirements can rise from 0.8 g per kilo in a healthy adult to 1.2 or even 1.5 g per kilo per day during convalescence, according to the ESPEN guideline on the nutrition of multimorbid hospitalised patients^[1].

This prolonged mobilisation empties the reserves of minerals such as zinc and iron, as well as those of vitamin D and vitamin C, which play a role in tissue repair and in regulating the immune system. Without a suitable intake, fatigue persists and post-operative healing can slow down, particularly in elderly people or those already weakened.

What are the most frequent deficiencies during recovery?

Three profiles of deficiency recur most often during convalescence: a protein-energy deficit, a lack of zinc and a low vitamin D. The review by Hill and colleagues published in the British Journal of Nursing^[2] identifies protein, zinc, iron, copper, manganese and vitamins A, C, E and K as central nutrients in the healing process.

The FSVO Swiss nutrition bulletin, based on 1,282 adults^[6], indicates that 30% of Swiss people use food supplements without necessarily meeting a documented deficiency. Taking food supplements blindly can lead to excess: the same survey observes the tolerable upper intake being exceeded for magnesium (25.4% of consumers) and vitamin D (6.2%)^[6].

Which nutrients really support recovery?

Why is protein the pillar of a convalescence?

Proteins, sources of amino acids, form the basic material for tissue repair and muscle rebuilding after a period of bed rest. The ESPEN guideline^[1] recommends, in hospitalised or recently ill patients, a protein intake between 1.2 and 1.5 g per kilo per day, compared with 0.8 g in healthy adults.

A South Korean retrospective study in seniors operated on for a hip fracture^[4] shows that a post-operative oral nutritional supplement reduces the drop in albumin, shortens the length of hospital stay and lowers post-operative confusion. The muscle loss linked to bed rest, called acute sarcopenia, can be marked if the protein intake remains insufficient.

What do recent studies say about vitamin C, vitamin D and zinc?

Vitamin C is an indispensable cofactor for the synthesis of collagen, the main structural protein of skin and connective tissues under repair. The review by Bhoot and colleagues published in Cureus^[5] summarises its role in immunity, healing and bone formation.

Zinc, for example in the form of zinc bisglycinate for better bioavailability, plays a role at the level of cell proliferation, wound closure and the immune response, which can promote healing. A review by Espírito Santo and colleagues covers nine clinical studies bringing together 741 patients with chronic wounds^[3]: several trials report a reduction in wound surface with a high-protein formula enriched with zinc and vitamins A, C and E.

Vitamin D, the deficit of which is frequent in Switzerland in winter, also plays a role in the working of the immune system. A meta-analysis published in Nutrients^[7] describes a reduction in the risk of Covid-19 infection and of intensive-care admission in people supplemented preventively. None of these nutrients “cures” a convalescence on its own: their effect is documented in case of a deficit, not as a universal stimulant.

How do you organise a convalescence course in practice?

How long does it take to feel the effects of a course?

The time to action of a food supplement during convalescence generally lies between 2 and 8 weeks, depending on the targeted nutrient, its dosage and the size of the initial deficit. For magnesium, a German randomised trial published in Nature and Science of Sleep^[8] observes a moderate improvement in sleep after 4 weeks at 250 mg of elemental magnesium per day, more pronounced in people with a low dietary intake at the start.

For vitamin D, the rebuilding of adequate reserves often takes 4 to 12 weeks depending on the initial status. For protein and zinc, the effect on healing and muscle mass becomes measurable in 2 to 4 weeks according to the ESPEN guideline^[1]. Regularity in the frequency of intake matters more than the dose: a forgotten tablet is not made up for by doubling the next day.

What precautions should you take before supplementing?

A poorly steered course can lead to an overdose, particularly in people who are already on several treatments. The FSVO Swiss nutrition bulletin^[6] documents, in food-supplement consumers followed over seven days, instances of the tolerable upper intake being exceeded mainly for magnesium and vitamin D, and more marginally for zinc and folic acid.

Some supplements interact with common medicines — vitamin K with anticoagulants, iron with certain antibiotics, calcium with thyroid hormones. The Swiss rule of the Swiss Food Supplements Ordinance (repealed in 2017) recalled that food supplements are foodstuffs presented as a concentrated source of nutrients intended to complement a normal diet, not medicines. Any intake of food supplements during convalescence should be discussed with a health professional — doctor or pharmacist — especially in case of a chronic condition, pregnancy, breastfeeding or an ongoing treatment.

Frequently asked questions about courses during convalescence