Peter K. Dearden
This week I was astounded to discover this. Over 80% of a random sample of Americans support mandatory labelling on foods containing DNA. Ouch. Presumably everyone is worried that if you ingest DNA from a sunflower, you will become a sunflower.
So, here are my top tips for avoiding the consumption of (or indeed contact with) DNA.
- Don’t Eat.
Our food contains DNA. It’s kind of simple, but mashed potato contains potato DNA, beef contains cow DNA, flour contains wheat DNA. It’s really hard to think of a food which won’t contain small traces of DNA from the organisms that it is made from. Even in highly processed food there is enough DNA to be detectable . That mouthful of crisp salad, tender meat or mouth-watering chocolate then BAM – DNA.
- Don’t drink (even water).
Lots of drinks are made from things that had DNA, and still carry detectable DNA. Water, however should be O.K. right? Well the problem here is microbes. Water contains microbes (even the cleanest drinking water), and those microbes contain DNA, and as soon as they hit your stomach they will start being digested and release that DNA. Even if the water is newly sterilised and you drink it from a sterilised bottle, you will pick up microbes from your mouth, fingers and lips, and then BAM – DNA.
When it comes down to it, everything is covered in microbes – rocks, trees, dogs, toasters – all strewn with the little blighters. People too are covered in them, estimates (for which I can’t find a decent reference) suggest bacteria on/in our body outnumber our own cells 10 to 1. Don’t touch or you may inadvertently ingest some and then BAM – DNA.
- Don’t breathe.
Sorry folks, air also contains microbes. Lots of them. Apparently one person coming into a room adds 37 million bacteria to the air . Up to 1.8 living bacteria can be found in every litre of urban air, but even in rural and wilderness areas there are plenty . Take a deep cleansing breath of fresh country air and then BAM – DNA.
If you are avoiding DNA its probably worth mentioning that you need to eat it to produce the building blocks of your own DNA.
Joking aside, do we have a problem here? Is eating DNA a precursor to having DNA from the things we eat shoved into our cells?
Well, we have sequenced several thousand Human genomes (all the DNA in a human) and I am yet to see a report showing that there is some plant DNA inserted in one of those genomes. Cancerous cells are another popular target for DNA sequencing, and again I can’t find anything suggesting DNA from food is associated with those cells. We have really good mechanisms, mainly the digestion of food, to stop us picking up DNA from food and using it as anything but materials to make our own cells.
But what would happen if we did pick up DNA from our environment? Would we run the risk of disease or turning into what we eat? Well, while we don’t pick up DNA and stick it in our genomes, I know of one animal that does. It turns out that Bdelloid (pronounced with a silent b) rotifers have a load of DNA they have picked up from their environment shoved into their own DNA. We think this is because of the sad state of Bdelloid sex lives. Bdelloids have been asexual for at least 80 million years, reproducing without sex for a massively long time. Biologists have been surprised by this because sexual reproduction is vital to help organisms get rid of bad mutations and defects in their DNA. Without sex, Bdelloids should have dropped dead years ago. A few years ago, the genome of Bdelloids was sequenced, and found to have lots of bits of DNA from fungi, bacteria and plants. Indeed a follow-up study shows that about 10% of active genes in Bdelloids are borrowed. To live on borrowed time, it looks like you need to borrow DNA.
So, are Bdelloid rotifers becoming fungi, bacteria or plants because they have picked up their DNA? No, still rotifer, still Bdelloidy, for at least 80 million years.
We like to say that we are what we eat, but only in a metaphorical sense. Eating a banana doesn’t make you one, even if you do eat banana DNA.
A Bdelloid Rotifer.