If we were to compile a list of Boris Johnson’s achievements as prime minister, it would surely include … er… well, his war on obesity might be successful.

He declared it last week, expressing the belief that being overweight was instrumental in Covid-19 hitting him so hard. Our 5ft 9in PM reportedly weighed 17-and-a-half stone when the virus put him in intensive care last month.

Johnson’s concerns about his weight are well-founded. Studies by both the New York University Grossman School of Medicine and NYU Langone Health have warned that obese people are at high risk of hospitalisation from coronavirus.

It’s the sort of scientific research BoJo, details man that he is, will have pored over following his abrupt conversion to the so-called nanny state he long opposed. The specifics of his drive to make the nation thinner have yet to be revealed – but they’re no doubt only days away.

When they arrive, they’ll be very zeitgeisty indeed. Because housebound Brits are, understandably, going wellbeing crazy. They’re gobbling down yoghurt for gut health, filling their shopping baskets with functional food and drink, and maintaining their pre-Covid dedication to healthier snacks.

And their bathroom cabinets are overflowing with vitamin supplements. Sales skyrocketed by 19.5% to £48.5m in the run-up to lockdown [Kantar 4 w/e 22 March 2020], most likely because people sought an immunity boost.

What they favoured is interesting. There’s no evidence that vitamin C promotes immunity from any sort of virus. Its main purposes, according to the NHS, are “helping to protect cells and keep them healthy; maintaining healthy skin, blood vessels, bones and cartilage; helping with wound healing”. And yet vitamin C sales more than doubled during panic-buying.

At the same time, vitamin D added 29.8% to its value sales. It’s a nutrient highly necessary right now given the fewer opportunities we have to soak up sun, our main source of vit-D. A lack of it could pose a serious health risk during the pandemic, research from Queen Elizabeth Hospital Foundation Trust and the University of East Anglia suggests. “The most vulnerable group for Covid-19 is also the one that has the most deficit in vitamin D.”

But a sufficiency won’t prevent illness. “There have been some news reports about vitamin D reducing the risk of coronavirus,” the NHS website notes. “However, there is no evidence that this is the case.”

Meanwhile, vitamin E, which actually does actually strengthen the body’s natural defences against illness, shed 46.1% of its value in March. Probably because it’s a lesser-known nutrient, and has received little attention from the health columnists.

Herein lies an opportunity for the whole of grocery – not just supplement suppliers – to educate consumers about the real benefits and efficacy of vitamins. Not only is it the right thing to do, especially during a health crisis like no other, it’s the astute one: people will likely be concerned about their vitamin intake for a long time to come. Increased on-pack messaging about vitamin content, for instance, will surely drive sales.

The industry will need to be proactive with this, of course. It can’t wait for a lead by government ministers. After all, they’re about to be very busy with their fight against flab.