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Can Science Help You Stay Warm?

by on 2013/12/19

The seasonably cold weather motivated this second entry in my series of Infographic Analyses. I’m originally from Michigan (the photo is me with my dad in a slightly snowier-than-normal Michigan winter) and spent a few years in Ontario, Canada, so I don’t need any help handling the relatively mild Scottish winters, but Jones Oil has produced a infographic on The Science of Staying Warm to help those with less experience with the cold. So let’s have a look at the evidence behind their claims.

The Science of Staying Warm

Does cold kill?

The most egregious error on this infographic is right at the top. Flu, pneumonia and the common cold are caused by viruses, not the cold. The relationship between cold weather and infection rates is complicated, but there is little evidence for a strong link between cold temperatures and decreased immune function.

The NHS Choices webpage on the common cold is very clear on the issue:

The only thing that can cause a cold or flu is a cold or flu virus. Getting cold or wet won’t give you a cold. However, if you are already carrying the virus in your nose, it might allow symptoms to develop.

Researchers at Cardiff Common Cold Research shed some light on why colds are more common in the winter. They dismiss outdated ideas about increased indoor crowding in the winter and cite a new theory that cooling the nose lowers resistance to infection, suggesting that covering your nose with a scarf might reduce your susceptibility to infection.

The infographic is absolutely correct that cold is a leading cause of hypothermia, though.

Are 180 pensioners killed by the cold every day?

This is an accurate estimate of excess winter mortality in England and Wales, which is a complicated concept comparing death rates from December to March to the previous August to November and the subsequent April to July.

However, there are several problems with the reporting of these numbers. Infographic writers love to feature big, round numbers, but often leave out important context. For example, is this excess mortality worldwide, or within a specific country like the US or UK? Actually, it is the statistic for England and Wales. This context-less number also doesn’t allow for any perspective. Do you know how many pensioners die each day in England and Wales each day in the summer? I had to look this up from data tables available from the Office for National Statistics: 255,778 people age 65+ died between April and November 2010, which is 1044 pensioners each day. A 17% increase in mortality rate is nothing to dismiss, and fuel poverty is a serious issue, but sensationalised statistics with no context don’t help to communicate the actual scope of these problems.

The characterisation of these 180 pensioners each day as having been “killed by the cold” is also a bit sensationalised. Most of the excess winter mortality (EWM) is not directly due to the cold. Indeed, the Office for National Statistics includes this warning about interpreting EWM statistics:

Previous research has shown that although mortality does increase as it gets colder, temperature only explains a small amount of the variance in winter mortality, and high levels of excess winter mortality can occur during relatively mild winters (Brown et al, 2010). Curwen and Devis (1988) showed that both temperature and levels of influenza were important predictors of excess winter mortality. Thus, the relationship between temperature, influenza and winter mortality is complex.

Can food and hot drinks make you warmer?

Holding a hot drink can make your judgements of others ‘warmer’, but I found no evidence that simply holding a hot drink can make a significant difference to body temperature. In fact, Cambridge neuroscientist Peter McNaughton suggests the opposite; hot drinks can actually cool you down by inducing sweating.

While I don’t want to spoil the comfort that comes from a hot cuppa, I must take serious exception to the next statement, “Perspiration induced by drinking hot drinks can flush toxins from the body, helping to purify the bloodstream.” This is an unreferenced claim from a ‘blog‘ that seems to be an advert for Aquasana water filters. They suggest that, “Additionally, drinking hot water helps remove deposits in the nervous system. These deposits are believed to have a negative effect on thoughts and emotional responses.” I don’t have the space to explain everything that is wrong with these statements, but Ben Goldacre’s excellent Bad Science website has a whole section on this detox codswallop.

I couldn’t find much information in the scientific literature about the warming properties of complex carbohydrates, but this advice was echoed in an interview of Washington State University food scientist Barry Swanson.

Do spices “boost your metabolism”? A quick Google search showed that bloggers certainly seem convinced of the metabolism-boosting properties of spicy food, but what does the scientific research conclude? A well-referenced article on the benefits of spices suggests that capsinoids (non-spicy compounds in some sweet chilis) can increase thermogenesis, but that these effects require very large doses, have very small effects, last a very short time, and the effects are only present in those who do not eat spices regularly. However, there is evidence that ginger may really warm you up.

So does drinking water make you warmer, as claimed in the infographic? First of all, the word hydration has nothing to do with ions. It comes from the Greek hydr- meaning water and the noun-forming suffix -ion. I ran the next sentence, “Our bodies are full of ions, and when ions dissolve in water, the stabilising reactions release heat. This is known as the heat of hydration.” past our resident chemical expert, Ross Forgan, who confirmed that the infographic’s statement is “an incorrect interpretation of a fundamental physical property of ionic compounds.”  Our bodies really are full of ions, such as sodium and calcium, which are important for many biological processes, and the heat of hydration really is the change in energy when ions dissolve in water, but the ions in your body are already in solution unless you’re dehydrated to the point of mummification. While drinking plenty of water can have real health benefits, the heat of hydration is just a sciency-sounding justification for baseless pseudo-medical advice on staying warm.

So how can I stay warm?

You can usually rely on government health organisations to provide sensible, non-sensationalised advice based on science or common sense. Age UK and the BBC have sensible, concrete advice on making your self and your home winter-proof. Also see an excellent and well-referenced article on Huffpost, Everything you know about getting warm is wrong.

Breakdown of Citations in the Infographic

  1. Cold kills 180 British pensioners a day: Accurate, but sensationalised.
  2. Nine pensioners died from cold every hour: This Daily Mail article does contain this statistic, but I’m not entirely sure how they arrived at it. 9/hour * 24 hours/day * 120 days/winter = 25920 deaths/winter. They cite numbers for excess winter deaths (EWD) as 25400 for England and Wales, and 2760 for Scotland, totaling 28160. The office for National Statistics only provides figures for England and Wales, but they listed 25810 EWD in 2009/10, with 23710 of those being pensioners. However, the reporter was probably working with estimated numbers when this article was published, so this statistics is relatively accurate, if sensationalised (see above). This article is also the source of the stat, “More than 300,000 UK pensioners have died of cold related illnesses since 1997”.
  3. Excess winter deaths: This website provides EWD stats for over-65s by region. They have this to say about the measure: “Overall adequacy of the indicator: medium.  Whilst the data sources used here are reliable ones, there is no data providing evidence of a direct causal relationship between winter deaths and energy inefficient housing.”
  4. Science of staying warm: This is the source of, “Ways in which a body loses heat are conduction, convection and radiation. “These are three methods of heat transfer you might have learned about in physics class, but the images give little explanation how they relate to the human body (as opposed to products sold by Jones Oil). If you’re actually interested in the mechanisms of heat loss, this backpacking site gives a good overview of these three mechanisms, plus evaporation and respiration, and how they relate to the human body.
  5. Thermal Conductivity: This physics website does confirm that air has very low thermal conductivity.
  6. Staying Warm: (the link in the infographic has a typo) This science podcast is the source of, “About sixty to eighty percent of the chemical activity that takes place inside our cells has no other purpose than to release heat”, an unreferenced statement by Yaël Ksander, co-host of A Moment of Science and MFA in painting. I had a difficult time determining the veracity of this statement. A Google search only flags a text version of this infographic by Ajay Murmu. While this sort of statistic really triggered my skeptic alarm, it’s certainly not always right, and would appreciate more information for any readers with expertise in this area.
  7. Convection: Dictionary definition of convection.
  8. Foods that keep you warm: These seem to be the opinion of a food blogger, rather than based on any scientific findings.
  9. Heat of Hydration: “The heat that is released by hydration of one mole of ions at a constant pressure. The more the ion is hydrated, the more heat is released.”
  10. Cold weather hydration: This website provides techniques for staying hydrated while hillwalking in cold weather (e.g., how to avoid the tubes in your camelback freezing).
  11. Skier froze to death and lived to tell the tale: The “How to freeze to death and survive…” section of this infographic is a pretty accurate summary of the reporting in this blog post, except the infographic has substituted hyperthermia for hypothermia.
  12. Benefits to drinking hot water: This is the source of “Perspiration induced by drinking hot water flushes toxins from your body, helping to purify your bloodstream.”
  13. Whole Grain: This Wikipedia page seems to have no information relevant to the infographic, except confirming that whole grains contain complex carbohydrates and that brown rice, quinoa, oats, barley and buckwheat are, in fact, whole grains.
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