Judging Risk, And Benefit

The Royal College of Obstetricians and Gynaecologists this last week released a report offering advice to pregnant women which advised mothers to be to avoid things like tinned food or food in plastic packaging because of unquantified and unidentified fears. This has got me thinking, not for the first time, about risk and how our society is ridiculously risk averse and has forgotten that we should assess risks in a risk-benefit analysis, something we are equipped to do naturally. Every time you approach a corner in the road in your car you are doing this in assessing how fast you should take it. Back in New Zealand corners on open roads in the countryside have speed advisory boards on them giving a suggested safe speed to help. It means when you see 20 (km/hr) you know the corner is a hairpin, and there are some.

What the RCOG report writers have forgotten is to factor in the benefits of food packaging and what life was like before we started to use it, especially for pregnant women. One risk in particular is Listeria which can cause miscarriages. Campylobacter and a new one E. coli 0157 which are both nasty. All of these, and more, can be caught from food. Packaging has not removed these risks entirely, which is why you should wash store bought salad leaves, but they have lowered them enormously. To the benefit of many, but especially the very young, the old, pregnant women and the immune compromised.

To ignore the benefits of the packaging, less handling from humans some of whom will carry viruses and bacteria. Remember the norovirus that causes winter vomiting needs just 9 virus particles to start an infection.

So if anything pregnant women are better off buying fresh veg, fruit and meat in plastic packaging than loose material that could have been handled by anyone.

We tend to live in a world where no risk can be accommodated just like nothing bad can happen without someone being held responsible.

And that is before we get to popular media reports of statistical scientific risks. They shout X doubles the risk of Y but often fail to point out that your risk of Y is a fraction of a percent.

Life is never risk free, you might choke on a pretzel, or just about anything but you have to eat. Too much water can kill as happens to some back markers in warm weather marathons who overestimate how much they are sweating and drink too much, yet we have to drink to stay alive. We must breathe but the air is full of microparticles and they don’t have to be viruses. Polluted air such as in London gives me asthma, yet when we lived there I had to breathe it. There were benefits from living where we lived, the jobs my wife and I did and the schools the kids went to. Having said that we were also happy to leave.

So next time some report, even from a Royal College tells you about a risk, think about benefits too, and ask what the absolute risk is and if it is some fraction per 1,000 people or whatever. Go about your life worry free.


Can B Vitamins Help in Alzheimer’s?

Recent media reports on new research suggest taking B Vitamins (B6, B12, Folic Acid) can prevent the mental decline in Alzheimer’s. This piqued my interest so I decided to find out more. The original research is here (full text behind paywall). Reports in the popular media are here and here. But they are, unsurprisingly, a bit too upbeat and as we shall see the study does not look at the impact on Alzheimer’s. The excellent NHS Choices site has a much better report here and I would urge anyone wondering about a popular media health report to check NHS Choices. There are a couple of problems with that though.

So, what’s the story? 270 men and women over 70 with mild cognitive impairment were randomly split into two groups. One group got high dose B Vitamins (B6, B12, Folic Acid) while the other got a placebo. As NHS Choices says this is the best experimental design for this study. They took those B Vitamins or the placebo for 2 years and their brains were scanned at the start and end of the study. This is a secondary study, the first looked at whole brain shrinkage while this one used the same data to look at which brain regions were most affected. Brain shrinkage is associated with the mental decline seen in dementias and Alzheimer’s in particular. This study looked particularly at grey matter, cells rather than axon tracts (in electronic terms transistors not the wires that connect them). They found that the B Vitamin treated group had smaller shrinkages in brain regions associated with Alzheimer’s symptoms than the placebo group. It’s important to note that the vitamins did not stop the shrinkage, they just slowed it. They further found that patients with high homocysteine levels had the biggest effects in terms of shrinkage reduction. The brain regions the shrinkage was found in are those that shrink and are affected most in Alzheimer’s.  Continue reading