Thursday, July 28, 2011

Life Expectancy - the Blue to Red Zones

There is a lot of interest in increasing life expectancy. Who after all doesn’t wish to live longer? Since life expectancy differs markedly across countries researchers have naturally tried to tease out the reasons. Some obvious findings are that high levels of infectious diseases lower life expectancy, and wealth and good medical care increase it.

One of the ideas being bandied about is that dietary differences are important. The reasoning is that once you control infectious diseases life span depends on the lack of degenerative diseases like heart attacks or cancer, and there is a fair amount of evidence that unhealthy diets are a major cause of degenerative diseases. The appealing thing about the focus on diet is that it is something we can control.

Unfortunately there is disagreement (even among experts) about what the ideal diet would be. Some look at the association between saturated fat consumption and degenerative diseases and emphasize a plant based diet. Others insist that large quantities of carbohydrates, not fats, are the central cause of degenerative disease. Some swear by good fats e.g. olive oil, nuts and seeds and fish, and red wine. Some blame dairy products for a lot of health problems while other researchers say that milk consumption actually lowers belly fat and that Sardinians live long lives on a lot of goat or sheep milk. There seems to be no end to the arguments. One way to sort this out is to look at which populations live long healthy lives and note what they eat. The problem with this approach is that there are always confounding factors that muddy the picture. So I applied my mind to ways of isolating the effect of diet.

The first thing that occurred to me was that infant mortality reflects disease load, hygiene and quality and availability of medical care. So life expectancy - controlling for infant mortality - should isolate the relevant lifestyle and dietary factors. The second thing that occurred to me was that although the effect of wealth on disease control, health care and hygiene is captured by infant mortality it also plays a role beyond medical factors e.g. safety. So it would be worthwhile to control for GDP per capita too. The third thing that occurred to me is that mean IQ is strongly correlated to infant mortality, life expectancy and GDP per capita. IQ would be a major confounding factor so I controlled for mean IQ too. IQ and GDP per capita might be called ‘means to health’ factors. IQ alone accounts for 54% of the variance in life expectancy and GDP per capita adds another 3%.

I initially ran a regression on life expectancy with infant mortality, IQ and GDP per capita as predictors, and looked at the residuals. What struck me was that all the countries with high AIDS rates were clustered at the bottom. So I added AIDS prevalence (and then later smoking) rates, as additional predictors.

Interestingly I found that the ‘means to health’ factors do not add much to predicting life expectancy, once the effect of infant mortality is controlled for. This doesn’t mean that the ‘means to health’ factors only work by reducing infant mortality. It means that the ‘means to health’ factors work on what infant mortality and life expectancy have in common. I think it lends credence to my initial assumption – that infant mortality is a good proxy for disease load, hygiene and the availability and quality of medical care.

The regression was extremely accurate – accounting for 92.4% of the variance in life expectancy in 185 countries. Infant mortality and AIDS alone accounted for 90.2% of the variance. Clearly life expectancy is mainly about avoiding diseases and getting good medical care. Improving disease control and medical care, to the extent that every country would have an infant mortality equal to the current minimum and a zero AIDS rate, would move average country life expectancy from 70 to 78 and reduce the standard deviation from 10 to 3.8. There would still be a good 5 years difference in their life expectancies of the top and bottom 20% of countries. These differences would mostly be accounted for by diet and community – in other words, lifestyle differences.

So lets look at which countries have the healthiest lifestyles (outside of disease control, hygiene and wealth and safety). The map shows the results according to the following color codes. The figures are years above or below expected.

Red - <=-4 years Orange -4 to -2 years Yellow -2 to 0 years
Green 0 to +2 years Light blue +2 to +4 years Dark blue => +4 years

You can see that certain regional trends are evident. Firstly there is a tendency for bad lifestyle countries to be in the same regions. Most of Asia; South, Central and West African; and the Arabian Peninsula, would have below average life expectancies if all countries had the same IQ, disease and AIDS rates, wealth, medical care and smoking habits. East and Northern Europe would also be below average. You can’t see it on the map but all the Pacific Islands would tend to be bad too. I call the worst of these, Red Zones. They are of course red on the map.

On the other hand South Western (or Mediterranean) Europe would have above average life expectancy residuals. North Africa, the Middle East and the South West Asia and Caucasus region are good. So are East Africa, and Japan, Thailand and Cambodia. The whole of the Americas are good - especially the Central and South parts. Not seen on the map is that the Caribbean Islands are also above average to good.

Some of this isn’t a surprise. The so called Blue Zones (Sardinia, Italy; Okinawa, Japan; Loma Linda, California; Nicoya Peninsula, Costa Rica, and Icaria, Greece) all fall within the latter group of countries. Blue Zones are places where high percentages of the adult population live to very advanced ages – at least 90 and often 100 - in good health and in a functional state. The really good areas are therefore blue on the map, with dark blue being outstanding.

There is a literature on these Blue Zones which is well worth studying. However the map suggests that places other than the already identified Blue Zones should be looked at too. Spain, Portugal and North Africa stand out and have some dietary and lifestyle affinities with Sardinia, Icaria and the Mediterranean region in general. So too does the Middle East (outside the Arabian Peninsula) and South West Asia/Caucasus region. East Africa is another region (with Middle Eastern influences) worth studying. Georgia is particularly interesting for several reasons. It is an especially good zone (dark blue) and was once it was rumored to be the location of a Blue Zone. The Caucasus area in general is good but transitions to very bad as soon as one gets to the non Caucasus parts of Russia.

Then there are a host of Central and South American countries other than Costa Rica that come up as blue on the map, so the dietary and lifestyle traditions of this whole region bears looking at. An interesting finding is that adult Hispanics in the US live longer than the much wealthier US white adults. Presumably they maintain some of their diet and lifestyle traditions after emigrating.

The USA is usually the poster child of bad lifestyles and diets. The USA is in fact bad relative to the best but it turns out that so many countries are even worse that the USA turns out to be above average.

On the other side of the picture are those sad countries who diets and lifestyles one would do well to avoid – the Red and Orange (and maybe even yellow) Zones. What is wrong with the diets and lifestyles of Southern, Western and Central Africa? Why are Russia and the former Soviet Union so bad? Why is Northern and Eastern Europe below average? Why are India and China below average?

The Blue Zones have certain things in common. They all favor plant based foods - particularly legumes (from Fava, soy and pretty much any beans to chickpeas and lentils), whole grain cereals (wheat, corn and maybe rice), high nutrient fibrous vegetables, starchy yellow vegetables (sweet potato and pumpkin) and nuts. Fruit seems to be something consumed in moderation. Yogurt is also common in these regions. Of course their consumption of foods not on the list is very low. They all have high levels of moderate activity and some sunshine as part of their daily lives. Their lifestyles are ‘chilled’ rather than time urgent and they have very high levels of social engagement within extensive and supportive social networks. Red wine and olive oil (oily fish) is a common factor around Christian Mediterranean areas. Smoking is something they all avoid.

Georgian cuisine is built on wheat and corn, beans, olive oil, walnuts, lean poultry, some red meat (mostly lamb but also beef and pork), freshwater fish, vegetables (mainly eggplant, a variety of spinach and mushrooms) and a strong yogurt and some cheese. The alcohol is wine or a grape based spirit. In short it is very much a Middle East/Mediterranean diet i.e. plenty of low glycemic index carbohydrates, healthy fats, yogurt and wine and few bad fats, refined carbohydrates or root vegetables. Living in the mountains makes for plenty of exercise whether you like it or not.

The unfortunate thing about these diets and lifestyles is that are generally those of the poor, and most of those very people would prefer not to eat and live like that. As soon as they become a little wealthier they start eating a lot more meat, fat, refined carbohydrates and calories overall.

That’s all very interesting but if the Red Zones follow similar diets and lifestyles the importance of those commonalities falls flat. Fortunately there are differences. The Russian diet is a case in point and is pretty bad. It is high in fatty meat, oil (not olive or fish), root vegetables (potato and beets), eggs (typically fried), salt, vodka and refined wheat and is low on vegetables, fruit and legumes. It emphasizes high calories – something regarded as self evidently good and healthy in Russia. This is in direct contradiction to experiments showing that lower calories (provided nutrient levels are high) result in longer life spans.

The staple diet of much of Southern, West and Central Africa are heavily based on starch – either root vegetables or grain (mostly refined) – and fatty meat (in stews or grilled). Although meat is favored many of them don’t get much (through poverty) and suffer protein deficiencies even though they eat enough calories to get fat. East Africa and the Horn use more legumes and milk and less meat in their diet. The Arabian Peninsula differs from the rest of the Middle East in that they eat relatively more meat (mostly chicken, sheep and goat). Northern European diets are heavy of fatty meat, cheese, potatoes and bread. The South Sea Islanders eat a lot of meat (and not as much fish as you would expect) and also starchy root vegetables like cassava. These Islands have some of the highest proportions of people overweight in the world. The Chinese and Indian diets have too little variety – rice is eaten for almost every meal – and too little protein. They eat so little protein in fact that the amount provided by hapless insects in the unhygienic vegetarian fare of poor Indians is enough to make them appreciably healthier than vegetarian Indians in countries where the insect load in food is lower.

The common denominators are high starch (root vegetables) and refined grain (and sugar) levels – and sometimes just too much rice - and a lot of meat (especially fatty meat). Too little protein plays a role in some places.


If you want to live longer then you would do well to try and adapt the Blue Zone principles to a modern and wealthier lifestyle but you don’t really want to live like the poor if you can help it. Try to take the traditional Middle Eastern/North African/ Mediterranean or Central/South American or Thai/Japanese (Okinawa) cuisine and give it a more gourmet twist. Develop a collection of 20 or so recipes from those cuisines. They should be simple to make and appeal to you i.e. be soul food rather than elaborate. Typically people only eat 10 different recipes over their whole lives so you don’t need to be endlessly creative. One good way is to substitute the ingredients of your habitual meals with ingredients emphasized in the Blue Zones and map areas.

The main ingredients are legumes of all kinds, whole grains, fibrous and leafy vegetables, nuts, yellow starchy vegetables (pumpkin/butternut or yellow/orange sweet potato), peppers, spices, olives (olive oil), yogurt (goat or sheep’s milk) and moderate amounts of low fat meats, fruit and red wine. No vitamin pills are involved but you probably wouldn't do yourself any harm taking a reasonable dose wide spectrum vitamin and mineral supplement regularly.

On the other hand any refined grain or carbohydrate is a no-no. Curiously root vegetables (especially potato) don’t seem to be good either. A recent study showed potato consumption accounted for 2/3 of bodyweight gains in the USA, and countries that have it as a staple tend to be Red and Orange Zones. Refined carbohydrates (bread and sugar) accounted for much of the rest of the USA bodyweight gains. Vegetable oils (other than olive oil) that don’t need to be refrigerated are also very bad. Very low protein is bad.

Try to exercise. Expensive gym memberships or formal workout programs aren’t necessary and aren’t part of the lifestyles of Blue Zones. Walking works and is a low stress convenient activity that can be combined with other purposes from just getting somewhere to thinking or walking the dog. There are lots of fun activities one can try too e.g. roller blades, physical games, even sex. In particular make sure you don’t spend much time sitting – especially when being passive, as in watching TV. Research shows sitting really does subtract the years off your life. A little flexibility and strength work is important too.

Develop your network of supportive relationships – friends, family and community. One can learn how to find people who interest you, to make more friends and how to cultivate them once they are formed. Increase the level of low level socializing i.e. not necessarily clubbing or going to expensive restaurants. Try to end bad relationships of all kinds – by either repairing rifts or dropping them altogether – because bad relationships are worse than no relationship. Help people regularly (because research shows that helping activities do increase happiness and welfare) but don’t let it become a duty that binds and weighs heavily on you.

While it helps to have a purposeful life (where your existence matters to other people) be careful not to let your purposeful life turn into a high pressure one. Try to trim the pressure and urgency from your life and adopt a more “chilled” approach to your purposive and necessary activities. Try to eliminate what isn’t necessary or important. Deliberate relaxation is very beneficial and socializing is better means than TV for many reasons. Yoga is something that can help to relax and some forms are also excellent sources of flexibility and strength work.

1 comment: