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Got a cold? Eat caterpillars

Why medinical zinc is not all it's cracked up to be.

How’s this for impact? At the end of January, a research group in Manchester published a paper on the essential role of zinc in the human immune system. A week later, the price of zinc rose on the international metals markets after its longest slump in 25 years.

Amazing? Of course not. These are two entirely unrelated events. But it’s the ability to separate coincidence from causality that allows us to distinguish old wives’ tales from useful information.

Zinc has been in medical use since at least the 2nd century BC. A set of pills found in the remains of a ship wrecked off the Tuscan coast in 140BC are 75 per cent zinc. They were almost certainly used to treat eye and skin disorders, a practice documented by the Roman polymath Pliny in the 1st century AD.

Zinc is still used for this purpose. It has antiseptic and antiviral properties, which is why it is often embedded in dressings for wounds. What’s more, anecdotal evidence has long suggested that taking zinc supplements helps fight the common cold. But anecdotal evidence isn’t the most trustworthy: sometimes it sees cause and effect where there is none.

Even individual studies haven’t been enough to give us the answer; depending on how they are carried out, they can produce conflicting results. Fortunately, we’ve developed even more sophisticated techniques: dissection, analysis and pooling of the scientific studies themselves. This has allowed us to draw a firm and reliable conclusion. In the case of zinc, it’s this: take at least 75mg a day and “there is a significant reduction in the duration of cold”, according to a gold-standard Cochrane Review, which looks at primary research in health care. Ancient wisdom, in this case, has some validity.

What the ancients didn’t know is the mechanism involved. Zinc deficiency, it turns out, causes more than 3,000 types of protein in the body to function inefficiently or not at all. The body responds to this as stress, causing the immune system to leap into action. Specifically, according to researchers at Manchester University, zinc deficiency unleashes a molecule called interleukin-1-beta. This is part of the armoury of the immune system. The trouble is that, in the absence of any infection to clear, firing the immune response’s weaponry just causes damage.

The zinc deficiency, as the researchers point out, could easily be resolved using dietary supplements. And this increased medical use of zinc could have an economic impact.

Not, it has to be said, in the metals markets, where the rising price of zinc is linked to China’s construction boom. But zinc use for medical purposes could be worth about $25bn a year in the US alone. That is the estimated annual impact of common colds, in terms of lost productivity. The Cochrane Review has found that taking zinc supplements for at least five months can reduce that. It certainly reduces school absences and the prescription of antibiotics for children with the common cold.

Because colds are caused by a virus, antibiotics do nothing for sufferers, yet doctors prescribe them as a placebo to get worried parents out of their surgery. So zinc supplementation also slows the spread of antibiotic resistance. Here’s a final tip in case the price of zinc lozenges skyrockets: a daily 100g of cooked caterpillars contains all the zinc you need.

You’re welcome.
 

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 19 February 2014 issue of the New Statesman, The Space Issue

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Why the Liberal Democrats by-election surge is not all it seems

The Lib Dems chalked up impressive results in Stoke and Copeland. But just how much of a fight back is it?

By the now conventional post-Brexit logic, Stoke and Copeland ought to have been uniquely inhospitable for the Lib Dems. 

The party lost its deposit in both seats in 2015, and has no representation on either council. So too were the referendum odds stacked against it: in Stoke, the so-called Brexit capital of Britain, 70 per cent of voters backed Leave last June, as did 62 per cent in Copeland. And, as Stephen has written before, the Lib Dems’ mini-revival has so far been most pronounced in affluent, Conservative-leaning areas which swung for remain. 

So what explains the modest – but impressive – surges in their vote share in yesterday’s contests? In Stoke, where they finished fifth in 2015, the party won 9.8 per cent of the vote, up 5.7 percentage points. They also more than doubled their vote share in Copeland, where they beat Ukip for third with 7.3 per cent share of the vote.

The Brexit explanation is a tempting and not entirely invalid one. Each seat’s not insignificant pro-EU minority was more or less ignored by most of the national media, for whom the existence of remainers in what we’re now obliged to call “left-behind Britain” is often a nuance too far. With the Prime Minister Theresa May pushing for a hard Brexit and Labour leader Jeremy Corbyn waving it through, Lib Dem leader Tim Farron has made the pro-EU narrative his own. As was the case for Charles Kennedy in the Iraq War years, this confers upon the Lib Dems a status and platform they were denied as the junior partners in coalition. 

While their stance on Europe is slowly but surely helping the Lib Dems rebuild their pre-2015 demographic core - students, graduates and middle-class professionals employed in the public sector – last night’s results, particularly in Stoke, also give them reason for mild disappointment. 

In Stoke, campaign staffers privately predicted they might manage to beat Ukip for second or third place. The party ran a full campaign for the first time in several years, and canvassing returns suggested significant numbers of Labour voters, mainly public sector workers disenchanted with Corbyn’s stance on Europe, were set to vote Lib Dem. Nor were they intimidated by the Brexit factor: recent council by-elections in Sunderland and Rotheram, which both voted decisively to leave, saw the Lib Dems win seats for the first time on massive swings. 

So it could well be argued that their candidate, local cardiologist Zulfiqar Ali, ought to have done better. Staffordshire University’s campus, which Tim Farron visited as part of a voter registration drive, falls within the seat’s boundaries. Ali, unlike his Labour competitor Gareth Snell and Ukip leader Paul Nuttall, didn’t have his campaign derailed or disrupted by negative media attention. Unlike the Tory candidate Jack Brereton, he had the benefit of being older than 25. And, like 15 per cent of the electorate, he is of Kashmiri origin.  

In public and in private, Lib Dems say the fact that Stoke was a two-horse race between Labour and Ukip ultimately worked to their disadvantage. The prospect of Nuttall as their MP may well have been enough to convince a good number of the Labour waverers mentioned earlier to back Snell. 

With his party hovering at around 10 per cent in national polls, last night’s results give Farron cause for optimism – especially after their near-wipeout in 2015. But it’s easy to forget the bigger picture in all of this. The party have chalked up a string of impressive parliamentary by-election results – second in Witney, a spectacular win in Richmond Park, third in Sleaford and Copeland, and a strong fourth in Stoke. 

However, most of these results represent a reversion to, or indeed an underperformance compared to, the party’s pre-2015 norm. With the notable exception of Richmond’s Sarah Olney, who only joined the Lib Dems after the last general election, these candidates haven’t - or the Lib Dem vote - come from nowhere. Zulfiqar Ali previously sat on the council in Stoke and had fought the seat before, and Witney’s Liz Leffman and Sleaford’s Ross Pepper are both popular local councillors. And for all the excited commentary about Richmond, it was, of course, held by the Lib Dems for 13 years before Zac Goldsmith won it for the Tories in 2010. 

The EU referendum may have given the Lib Dems a new lease of life, but, as their #LibDemFightback trope suggests, they’re best understood as a revanchist, and not insurgent, force. Much has been said about Brexit realigning our politics, but, for now at least, the party’s new normal is looking quite a lot like the old one.