The novel coronavirus outbreak has had some unexpected side effects, including a sales boost for manufacturers of immunity-focused foods and supplements – although there is no evidence that any product can protect against the virus itself.

The market for products that support immunity was already one of the strongest segments in functional foods and supplements, and in the context of Covid-19, consumers are turning to products that promise to improve their immune systems more than ever, with companies and brands around the world reporting significant sales spikes in view of the ongoing crisis.

Globally, vitamin C is one of the most well-known nutrients for its role in immune support, and many companies have reported increased demand. For instance, Singapore supermarket chain Fairprice and Chinese e-commerce giant JD both reported up to a five-fold rise in sales of the vitamin in February, while JD said other products intended to boost immunity, such as herbal formulas and those based on Traditional Chinese Medicine have also seen increased demand.

DSM has a vitamin C production site in Jiangshan, China, and shipped 50 tonnes from its facility to Hubei in February to help improve residents’ immune response in the face of the outbreak. It also has a facility in Scotland, wher demand has been higher than usual, according to the company. Chinese company Angel Yeast reported increased demand for glucan, lactoferrin and selenium-enriched yeast, while some suppliers of CBD oil, probiotics and mushroom extracts positioned for immune support have also said sales have risen.

Eating a healthy diet and ensuring sufficient intake of micronutrients is linked to greater resilience to infection and illness in general, as good nutrition helps ensure that the body has the tools it needs to produce an appropriate immune response. Someone with a suppressed or weakened immune system is more likely to suffer serious repercussions from any infection – and poor diet is one factor among many that could lead to a weaker immune response. That said, it is important to note that nothing can prevent a person from contracting Covid-19, other than avoiding exposure to the virus.

Nutrients thought to be beneficial for the immune system include vitamins A, B6, B9, B12, C and E, and certain minerals like zinc, copper, iron and selenium. For all of these nutrients, EFSA considers that a cause and effect relationship has been established between dietary intake and their contribution to the normal function of the immune system. Other promising nutrients, including probiotics, have not been successful in convincing EFSA of their efficacy for immune support – although many studies have linked increased gut microbial diversity with improved immune regulation.

Food and supplement manufacturers should take care that their products do not make any kind of unapproved implied health claim when it comes to immunity, however, particularly during the ongoing outbreak, as they could find themselves in regulatory hot water. Regulators worldwide, including the US Food and Drug Administration and European Food Safety Authority, have issued warnings to manufacturers making false claims in relation to the novel coronavirus.