Personalised Medicine

The era of personalised medical advice is arriving at last. Australia's new sun guidelines vary the advice by 3 skin types. Well, it's a start.

I enjoy the talks that Dr Paul Mason gives on the LowCarbDownUnder youtube channel, such as the last two:

and

.

Not that I always agree with his theories (such as that the benefit of sunshine is mostly about nitric oxide and that vitamin D is relatively unimportant). But I certainly admire him for taking on the medical establishment which needs shaking up. However we need to get past the current situation where experts shout contradictory views without proper consideration of each other's evidence, and where health advice is hard to change because some important person said something once and we mustn't contradict them.

Returning to the current topic: Dr Mason seems to share the desire of health advisors to give the same advice for everyone. In the second of those two videos he tells us about a plant chemical which is very similar to human cholesterol. He then tells us how most people handle this well and mostly get rid of that chemical without it causing too many problems. However some people incorporate significant amounts of the chemical in places where cholesterol is meant to be, leading to malfunction of the insulin receptors of cells. Yet we don't hear how much of the bad heart statistics from seed oil consumption is because of those people. Maybe he has an alternative diet that is better for everyone, but the advantage might not outweigh other factors for people without the specific problem. He is not slow to claim that other things he opposes have limited benefit.

Skin colour is an obvious case where your origins lead to differences which now affect the best health advice. Here's another.

Suppose your ancestors lived near the sea and ate a lot of seafood. They, and you, probably have a very good system for getting rid of excess salt. And they don't have a working system for retaining salt in case of a future shortage. Now if you wisely decide to stop eating processed food, then you need to get your salt in other ways, and if you don't then you could easily suffer health effects from that.

Now suppose your ancestors lived inland in a low salt area, buying salt when possible. Now their system for getting rid of salt may not work so well. Indeed they may be inclined to retain salt when they get it, despite the resultant health problems. And now you, with those genes, are not well suited for our modern high salt diet.

It is mind-blowing that advice on sun exposure took so long to take skin colour into account. And it still doesn't advise artificial UV for those who can't get enough sun, even though, as Dr Mason would be quick to say, vitamin D tablets don't do the same job. Of course artificial UV is illegal in Victoria, where it is most needed in mainland Australia.

We need to identify more hidden differences that should impact health advice, then develop and fund testing for those differences. In future we might be able to use genetic testing. For the moment we need to look for things that can be tested more cheaply. I expect that this should include the two cases mentioned here: handling salt and handling plant chemicals the imitate cholesterol.

Mixed strategies in Bridge

BBO (Bridge Base Online) has a lovely system for practicing declarer play. Here is the B-8 problem in level 4:

The suggested solution says "we need to avoid losing 2 club tricks", and suggests leading twice to the KQ. The trouble is that we also need to make 4 tricks in clubs, there being no other likely source of tricks. Leading twice to the KQ fails this extra test when clubs break 4-1, unless East's singleton is the J. So I think it is better to play West for the J and finesse the 10, then return to hand to finesse the 9. On 4-1 breaks this gains when East's singleton is the A, 4, 5, or 6, only losing when it is the J.

The suggested solution goes on to say (approximately) "If East has Ax of clubs they will duck on the first lead to the K, to give declarer a problem next time. So if East wins the K with the A you should play East for AJ doubleton and just play the Q on the 2nd round." Well that can't be right. If declarer always cashed the Q after the K lost to the A initially, then East would always play the A with Ax so that partner will score their J with Jxx.

So clearly declarer should finesse the 10 on the 2nd round often enough that it is not an easy win for East to play the A with Ax. If both declarer and defender understand all this then each party has an optimal mixed strategy. This is called the Nash Equilibrium. It is simple in this case where each side has 2 options. For each player, both strategies must have the same reward. So I think that means that:

1. With Ax, East should play the A a third of the time, so that when the A is played it is equally likely to be Ax or AJ.
2. Declarer should finesse the 10 50% of the time and play the Q 50% of the time.

If either player departs from their equilibrium position then the other can improve their average result. For example if declarer finesses the 10 next less than 50% of the time then East gains by always playing the A with Ax. Or if East plays A from Ax more than a third of the time then declarer gains by always finessing the 10 next.

Of course most such equilibrium solutions are likely to be more complex.

In real life knowledge of opponents and smoothness of play is likely to be the deciding factors, but if you can work out the equilibrium position then you know what mistake you're playing the opponent for.