Tag Archives: Health

Why Not Walking Talks?

Most people see exercise as healthy, and see walking as a reasonably comfortable form of exercise. Some think that they should spend precious exercise time doing something more athletic, and others just can’t find the time to walk. But most seem to enjoy walking and see it as healthy, if only they could find the time.

I’ve been spending a lot of time giving talks lately, mostly on my book. I’m also back to teaching now that summer is over. Usually, these events all happen in a room, where I stand in front while everyone else sits. Sometimes I teach my class out on the grass instead of in a room. And so I wonder: why can’t we give talks while walking outside?

Yes, you’d have to forego visual aids, unless someone works out some pretty fancy tech. And yes, you’d need to pick a walking route that is quiet enough so that the audience could hear the speaker, and so a full-throated speaker won’t bother others along the route. Sometimes the weather isn’t agreeable. The audience would find it harder to see the speaker’s face, and a bigger group would need a louder speaker and more tolerant neighbors. And those who can’t walk might need someone else to push them in a wheelchair.

But none of these seem insurmountable barriers. We already manage to schedule lots of shared activities outdoors. We already have walking talks when guides take groups through battlefields, museums, and other special places. Is it so hard to have talks not focused on the immediate physical surroundings?

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Is US gun control an important issue?

After the shocking massacre in Connecticut it looks like gun control is going to draw a lot of attention from Obama and Congress this year. This got me thinking about how important gun control might be as a political cause. The potential good achieved by focussing on this policy is in large part determined by the damage done by guns in the first place. In that light, does it deserve it?

A natural measure of the importance of the problem is the number of years of healthy life lost due to gun violence. At  the moment there are a bit over 8,000 murders with firearms each year in the US, some two thirds of the total. If we guess that the typical age of death from gun violence is 30, then the average survivor would have enjoyed another 50 years or so of healthy life. Firearm homicides would than lead to the loss of 400,000 years of healthy life each year. We would then have to add health problems among survivors of gun violence. To confirm that these figures are sensible I looked up the World Health Organisation’s Global Burden of Disease, which suggest ‘intentional violence’ as a whole cost the US and Canada about 1,100,000 years of healthy life each year. Two thirds of this would be 650,000 years, a figure which amounts to about 0.8% of the total burden of disease and injury in the US.

Another even larger problem than murder – at least as far as years of healthy life lost – is suicide. Easy access to guns makes suicide attempts more likely to succeed. The US suicide rate is 12 per 100,000; tragically high, though sadly unexceptional by international standards. If the typical suicide victim would have lived another 45 healthy years, this amounts to an annual burden of 1,600,000 each year, roughly the WHO’s figure. [1]  Firearms are used for about half of these suicides, so we’ll say they have a burden of 800,000 years of healthy life, or about 1% of the total burden of disease and injury.

How much could the US hope to reduce these figures? Of course the relationship between the number of guns and violence is contested, and I don’t really want to get drawn into that debate. I will just assume, for the sake of argument, that gun control policies could indeed help reduce violence. For that purpose, let’s imagine it could get firearm violence and suicide down to the average of other OECD countries. [1] Doing so would reduce the gun death rate (and I will assume injuries too) by 80% from ~10 to ~2 per 100,000. This is wildly optimistic given the other drivers of violence and suicide in the US, and the timidity of any likely gun control laws under the Second Amendment. Even if guns did become hard to access, we would expect to see substitution to other weapons. Nonetheless, it offers a useful upper bound.

An 80% drop in firearm deaths and injuries would prevent the loss of 1.15 million years of healthy life each year, or around 1.4 per cent of all the damage done by disease and injury in the US. This falls inconveniently between ‘very little’ and ‘quite a bit’. How can we put this figure in perspective? One option would be to consider how much people claim to value their lives, while another would be to compare it to other available options for saving lives. Here I will use the latter to give some idea of how focussing on gun control compares to other policies or causes that might improve the health of Americans.

How much does it cost to save a life in the US?  The NHS in Britain conveniently uses £30,000 (around $US50,000) for each year of healthy life as the highest price at which a treatment is worth funding. The US has no central body for making these decisions, so no generic ‘marginal cost’ exists. A conclusion of the classic paper, Five-hundred life-saving interventions and their cost-effectiveness, is that the cost of extending lives varies across several orders of magnitude depending on the approach you take. Nonetheless, many interventions in medicine and general safety fell between $5-50,000 for a year of life, at least in the mid-90s. A quick search turns up vaccination of US girls against HPV, which buys a year of healthy life for about $44,000, total knee arthroplasty for $18,300, HIV screening for under $25,000 and flu vaccination at $8,000-52,000. The availability of all of these could be expanded. At a rounded $50,000 figure, the equivalent of 1.15 million years of healthy life could be saved for $57 billion, or 0.38% of US GDP – a significant sum, though under a fifth of long run annual growth. By comparison, the US Federal Government already spends about 24% of US GDP, and all healthcare spending accounts for some 15%. Based on Robin’s work on the inefficacy of much US healthcare spending, redirecting some of that enormous budget to truly life-saving activities would go a long way.

If American activists or voters currently preoccupied with gun control were willing to look farther afield in their desire to prevent unnecessary death, directing government spending to provide bed nets to protect children in developing countries against malaria could save 30,000 kids for a meagre $70 million, or 0.00000046% of GDP. Sadly, the effectiveness and size of US foreign aid is barely discussed.

Of course this health story is not the full picture of the damage done by gun violence. We ought also consider the:

  • Costs incurred in trying to stay safe
  • Costs of caring for the injured
  • Loss of human capital from adults dying
  • Resulting distress and fear
  • Reduced urbanisation as a result of crime (which lowers productivity, among other things).

I would appreciate attempts to quantify these costs but don’t have time to pursue them myself right now. I would note in passing that many other interventions that improve health and safety would also reduce these harms to some extent.

My interpretation of the above is that gun violence is a serious issue in the US. It is not being blown out of proportion like shark attacks or terrorism. At the same time, the impact of guns on US health-span is modest, and lower than many common and avoidable diseases or accidents which fail to inspire a national conversation. Guns have become a hot issue because of their grisly and visible results, as well as fierce identity politics, rather than the absolute scale of the damage they do. If the main goal of gun control advocates were to save lives, their cause would not stand out as low-hanging fruit, especially if they cared about foreigners as well as Americans. Given the host of major problems facing the US, the limited attention of Congress and the White House, and the improbability of achieving a significant reduction in the number of dangerous weapons available, it is not a cause I would jump on.

[1] Some would say that a death by suicide isn’t as bad as a murder, because someone who is preventing from committing suicide probably has a low quality of life. There is some truth to this but I will ignore it, consistent with my desire to define an upper bound.

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Which supplements should a healthy person take?

I have recently been looking into which, if any, nutritional supplements I should start taking. I am in good general health so am looking for supplements that are likely to maintain or improve that health, not cure any particular condition. I have been using three excellent sources for this project, which I can recommend checking out: [1]

For those who want to save time, I will outline my key conclusions here in the hope that doing so will help you. I have decided to start taking:

  • Vitamin D3 (10µg or so a day)
  • Creatine (5g a day)
  • Zinc (30-160mg and Vitamin C (>1g)  each day for the duration of colds.

Tyrosine and potassium are also both cheap and so I will trial them to see if they improve my concentration. I don’t consider them likely to work, but they are at least worth testing. Fluoride mouthwashes also seem a cheap way to reduce the risk of cavities.

Vitamin D has a large evidence base suggesting it significantly lowers ‘all-cause mortality’ and improves both general and bone health. It is especially important now that I am living in the UK, where it is much harder to get Vitamin D from sun exposure.  It is also inexpensive. [2] Basically, it is a no-brainer. The 10µg is twice the daily recommended dietary dose in the UK. For some reason, Gwern is taking a very large 125µg each day. Personally I am tempted to err on the low side due to recent research suggesting too much Vitamin D can raise mortality.

Creatine is best known as a supplement for body-builders, but I am taking it primarily because I hope it will improve my cognition. The evidence to back this is thin, and only finds a significant effect among subgroups like vegetarians, perhaps because they get less creatine from meat consumption. However, the effect size identified was very large, it is cheap and largely safe. I am an almost-vegetarian and lift weights so it is more likely to be worthwhile for me. I will also be able test whether it improves my energy and concentration and stop using it if it doesn’t. This review also finds a range of other worthwhile positive impacts on health.

There is compelling evidence that zinc helps reduce the intensity and duration of colds. As summarised by Cochrane:

Zinc inhibits rhinoviral replication and has been tested in trials for treatment of the common cold. This review identified 15 randomized controlled trials, enrolling 1360 participants of all age groups, comparing zinc with placebo (no zinc). We found that zinc (lozenges or syrup) is beneficial in reducing the duration and severity of the common cold in healthy people, when taken within 24 hours of onset of symptoms.

There are some concerns about side effects, but they do not seem significant in the scheme of things. The tablets can also be obtained cheaply and easily. The appropriate dose is unclear, but studies included in the meta-analysis used between 30-160mg. I will probably choose a figure in the middle of that, and keep some tablets at work and home so I can always take them immediately at the onset of symptoms.

Despite a large number of studies, evidence to back an effect of Vitamin C on colds in the general population is mixed, with positive effects only reliably found on those engaging in extreme exercise. I worry that positive results on such sub-populations could just be the result of data mining, publication bias or other chicanery. Nonetheless, there are no side effects and the tablets are cheap. I consider it worth taking at the onset of colds, even if the probability of any real effect is under a third. Furthermore, effervescent vitamin C tablets are tasty and comforting to drink, and being as conspicuous as they are, may produce a larger than usual placebo effect.

Incidentally, most infection by common colds is caused by surface to surface contact. Using an ethanol handwash after touching shared surfaces, and reducing how often you touch your face with your hands, is likely to significantly reduce their occurrence. If you didn’t already have one, the desire not to get colds is a good selfish reason to wash your hands after using the bathroom. Poor general health is not the problem, as even healthy people who are exposed to the virus are highly likely to become infected.

If I were particularly worried about my blood pressure or cardiovascular health I would start

However, I am young, and consider heart disease to be a problem for the future.

I am keen to hear if I am making mistakes in the above, or missing out on other valuable chances to improve my life. Thanks to Seb Farquhar and Will Crouch for help with this research.

[1] Cochrane’s ‘house effect’ is to frequently find that there is insufficient evidence to draw any conclusion. Where they do make a recommendation, the evidence backing it is likely to be compelling. Gwern’s advice extends to unusual supplements about which there is little other information. Unfortunately, is in based in significant part on personal experiences. While he has tried to do blind and controlled trials  on himself with sufficient sample sizes, I don’t consider one individual’s experiences to be compelling evidence relative to large trials and meta-analyses. He often doesn’t have a statistically significant effect, in part due to small samples. Nonetheless, if the cost of a supplement is low, and it is safe, it can be worth taking even with a low probability of an effect. Snake-Oil Supplements falls somewhere in the middle.

[2] Reasonably cheap sources of: creatine, Vitamin D, Vitamin C and Zinc, tyrosine and potassium. Mouthwashes with over >200ppm of fluoride are widely available, but you should check the label.

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