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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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Donald Trump vs Barack Obama: How the inauguration speeches compared

We compared the two presidents on trade, foreign affairs and climate change – so you (really, really) don't have to.

After watching Donald Trump's inaugural address, what better way to get rid of the last few dregs of hope than by comparing what he said with Barack Obama's address from 2009? 

Both thanked the previous President, with Trump calling the Obamas "magnificent", and pledged to reform Washington, but the comparison ended there. 

Here is what each of them said: 

On American jobs

Obama:

The state of our economy calls for action, bold and swift.  And we will act, not only to create new jobs, but to lay a new foundation for growth.  We will build the roads and bridges, the electric grids and digital lines that feed our commerce and bind us together.  We'll restore science to its rightful place, and wield technology's wonders to raise health care's quality and lower its cost.  We will harness the sun and the winds and the soil to fuel our cars and run our factories.  And we will transform our schools and colleges and universities to meet the demands of a new age.

Trump:

For many decades we've enriched foreign industry at the expense of American industry, subsidized the armies of other countries while allowing for the very sad depletion of our military.

One by one, the factories shuttered and left our shores with not even a thought about the millions and millions of American workers that were left behind.

Obama had a plan for growth. Trump just blames the rest of the world...

On global warming

Obama:

With old friends and former foes, we'll work tirelessly to lessen the nuclear threat, and roll back the specter of a warming planet.

Trump:

On the Middle East:

Obama:

To the Muslim world, we seek a new way forward, based on mutual interest and mutual respect. To those leaders around the globe who seek to sow conflict, or blame their society's ills on the West, know that your people will judge you on what you can build, not what you destroy. 

Trump:

We will re-enforce old alliances and form new ones and unite the civilized world against radical Islamic terrorism, which we will eradicate completely from the face of the earth.

On “greatness”

Obama:

In reaffirming the greatness of our nation we understand that greatness is never a given. It must be earned.

Trump:

America will start winning again, winning like never before.

 

On trade

Obama:

This is the journey we continue today.  We remain the most prosperous, powerful nation on Earth.  Our workers are no less productive than when this crisis began.  Our minds are no less inventive, our goods and services no less needed than they were last week, or last month, or last year.  Our capacity remains undiminished.  

Trump:

We must protect our borders from the ravages of other countries making our product, stealing our companies and destroying our jobs.

Protection will lead to great prosperity and strength. I will fight for you with every breath in my body, and I will never ever let you down.

Stephanie Boland is digital assistant at the New Statesman. She tweets at @stephanieboland