Monday, December 29, 2008

Hostels vs hotels vs couchsurfing

We Don't Speak The Language is a series of video travel blogs "for the young and the broke". It's the work of Sean Blanda and Chris Wink, freelance journalists from Philadelphia, who recently completed a three-month trip around Europe. Unfortunately, the series has come to end now the guys are back home, but check out this episode below, offering lots of good tips in the pros and cons of backpacking accommodation options: hostels, hotels and couchsurfing.

It's a two-parter and the couchsurfing tips follow in the second video. They're spot on about making couchsurfing requests personal to increase your chances of finding a suitable and willing host. Cut-and-paste efforts are instantly recognisable, expose you as having made no effort to read the person's profile and are not likely to elicit a response. Watch on for more advice...

Part one: hostels

Part two: hotels and couchsurfing

Sunday, December 28, 2008

Local travel: future trends

Geographical magazine coined all sorts of new buzzwords for their December “future of tourism” issue. Most include the prefix “geo” as a subtle reminder of where you heard it first.

First up is the “geotourist”. According to the term’s inventor, Jonathan Tourtellot of National Geographic Traveler, this is someone who “gets off a cruise ship and discovers an interesting town, then decides to come back and explore it another time”.

Tourists who like places and aren’t satisfied with a couple of hours docking in a cruise port? This didn’t strike me as anything new, but, reading on, the underlying point gets more interesting.

Geotourists are those who look beyond just ticking places off a list and want to build connections with the destinations and their people. Their aim is to "sustain or enhance the geographical character of a place: the environment, heritage, aesthetics, culture and well-being of its residents”.

Sustainable, or conscious, tourism may not be a brand new concept, but here's hoping Geographical are right and it will continue to spread. After all, something's got to give.
Tourtellot points out there could be seven billion tourists rooming our planet in next decade and “if four billion people decide to see the Mona Lisa, it would take 309 years, even with groups of 25 viewing it for one minute, 24 hours a day”.

So what else does the future hold? According to Geographical, travel by 2020 will also be “geo-local”. Basically, this means holidaymakers will travel closer to home. "We'll begin to travel more within our own countries and continents, and less frequently beyond them. A British family might head to Cornwall to stay in a locally run Cornish cottage, shop for Cornish crafts and enjoy a cream tea.”

Perhaps. Although, as the economic crisis takes hold, I’d say people aren’t going to wait until 2020 until they start holidaying closer to home.

So, it's buzzword number three that is arguably the most innovative of the lot: hyper-local sourcing. "
By 2020, we'll also see the majority of hotels getting their produce, employees, materials, services and the like from sources within their immediate vicinity," they say. They also predict a new type of hotel - 'the ten-kilometre hotel' - for which all food and materials will have been sourced from within a ten-kilometre radius. Hotels will offer energy and water for guests on a metered system, and there will be discounts for visitors who keep their consumption below average.

For me, "geotourism" and "geo local" travel are already in full swing, but I'll be interested to see if the "hyper local" prediction comes true. I can see the potential. My first, and only, such experience was when
received a discount for arriving by public transport at a tree-climbing centre on the Isle of Wight.

The hotel or excursion bill of the future ('s mock-up is pictured), which offers discounts rather than just piling on unexpected extras would certainly make a welcome change.

Saturday, December 27, 2008

Butter, Margarine and Heart Disease

Shortly after World War II, margarine replaced butter in the U.S. food supply. Margarine consumption exceeded butter in the 1950s. By 1975, we were eating one-fourth the amount of butter eaten in 1900 and ten times the amount of margarine. Margarine was made primarily of hydrogenated vegetable oils, as many still are today. This makes it one of our primary sources of trans fat. The consumption of trans fats from other sources also likely tracked closely with margarine intake.

Coronary heart disease (CHD) resulting in a loss of blood flow to the heart (heart attack), was first described in detail in 1912 by Dr. James B. Herrick. Sudden cardiac death due to CHD was considered rare in the 19th century, although other forms of heart disease were diagnosed regularly by symptoms and autopsies. They remain rare in many non-industrial cultures today. This could not have resulted from massive underdiagnosis because heart attacks have characteristic symptoms, such as chest pain that extends along the arm or neck. Physicians up to that time were regularly diagnosing heart conditions other than CHD. The following graph is of total heart disease mortality in the U.S. from 1900 to 2005. It represents all types of heart disease mortality, including 'heart failure', which are non-CHD disorders like arrhythmia and myocarditis.

The graph above is not age-adjusted, meaning it doesn't reflect the fact that lifespan has increased since 1900. I couldn't compile the raw data myself without a lot of effort, but the age-adjusted graph is here. It looks similar to the one above, just a bit less pronounced. I think it's interesting to note the close similarity between the graph of margarine intake and the graph of heart disease deaths. The butter intake graph is also essentially the inverse of the heart disease graph.

Here's where it gets really interesting. The U.S. Centers for Disease Control has also been tracking CHD deaths specifically since 1900. Again, it would be a lot of work for me to compile the raw data, but it can be found here and a graph is in Anthony Colpo's book The Great Cholesterol Con. Here's the jist of it: there was essentially no CHD mortality until 1925, at which point it skyrocketed until about 1970, becoming the leading cause of death. After that, it began to fall due to improved medical care. There are some discontinuities in the data due to changes in diagnostic criteria, but even subtracting those, the pattern is crystal clear.

The age-adjusted heart disease death rate (all forms of heart disease) has been falling since the 1950s, largely due to improved medical treatment. Heart disease incidence has not declined substantially, according to the Framingham Heart study. We're better at keeping people alive in the 21st century, but we haven't successfully addressed the root cause of heart disease.

Was the shift from butter to margarine involved in the CHD epidemic? We can't make any firm conclusions from these data, because they're purely correlations. But there are nevertheless mechanisms that support a protective role for butter, and a detrimental one for margarine. Butter from pastured cows is one of the richest known sources of vitamin K2. Vitamin K2 plays a central role in protecting against arterial calcification, which is an integral part of arterial plaque and the best single predictor of cardiovascular death risk. In the early 20th century, butter was typically from pastured cows.

Margarine is a major source of trans fat. Trans fat is typically found in vegetable oil that has been hydrogenated, rendering it solid at room temperature. Hydrogenation is a chemical reaction that is truly disgusting. It involves heat, oil, hydrogen gas and a metal catalyst. I hope you give a wide berth to any food that says "hydrogenated" anywhere in the ingredients. Some modern margarine is supposedly free of trans fats, but in the U.S., less than 0.5 grams per serving can be rounded down so the nutrition label is not a reliable guide. Only by looking at the ingredients can you be sure that the oils haven't been hydrogenated. Even if they aren't, I still don't recommend margarine, which is an industrially processed pseudo-food.

One of the strongest explanations of CHD is the oxidized LDL hypothesis. The idea is that LDL lipoprotein particles ("LDL cholesterol") become oxidized and stick to the vessel walls, creating an inflammatory cascade that results in plaque formation. Chris Masterjohn wrote a nice explanation of the theory here. Several things influence the amount of oxidized LDL in the blood, including the total amount of LDL in the blood, the antioxidant content of the particle, the polyunsaturated fat content of LDL (more PUFA = more oxidation), and the size of the LDL particles. Small LDL is considered more easily oxidized than large LDL. Small LDL is also associated with elevated CHD mortality. Trans fat shrinks your LDL compared to butter.

In my opinion, it's likely that both the decrease in butter consumption and the increase in trans fat consumption contributed to the massive incidence of CHD seen in the U.S. and other industrial nations today. I think it's worth noting that France has the highest per-capita dairy fat consumption of any industrial nation, along with a comparatively low intake of hydrogenated fat, and also has the second-lowest rate of CHD, behind Japan.

Thursday, December 25, 2008

The Fundamentals

I heard an interview of Michael Pollan yesterday on Talk of the Nation. He made some important points about nutrition that bear repeating. He's fond of saying "don't eat anything your grandmother wouldn't recognize as food". That doesn't mean your grandmother specifically, but anyone's grandmother, whether she was Japanese, American or African. The point is that commercial food processing has taken us away from the foods, and traditional food preparation methods, on which our bodies evolved to thrive. At this point, we don't know enough about health to design a healthy synthetic diet. Diet and health are too complex for reductionism at our current level of understanding. For that reason, any departure from natural foods and traditional food processing techniques is suspect.

Mainstream nutrition science has repeatedly contradicted itself and led us down the wrong path. This means that traditional cultures still have something to teach us about health. Hunter-gatherers and certain other non-industrial cultures are still the healthiest people on Earth, from the perspective of non-communicable disease. Pollan used the example of butter. First we thought it was healthy, then we were told it contains too much saturated fat and should be replaced with hydrogenated vegetable margarine. Now we learn that trans fats are unhealthy, so we're making new margarines that are low in trans fats, but are still industrially processed pseudo-foods. How long will it take to show these new fats are harmful? What will be the next industrial fat to replace them? This game can be played forever as the latest unproven processed food replaces the previous one, and it will never result in something as healthy as real butter.

The last point of Pollan's I'll mention is that the world contains (or contained) a diversity of different cultures, living in dramatically different ways, many of which do not suffer from degenerative disease. These range from carnivores like the Inuit, to plant-heavy agriculturalists like the Kitavans, to pastoralists like the Masai. The human body is adapted to a wide variety of foodways, but the one it doesn't seem to like is the modern Western diet.

Pollan's new book is In Defense of Food. I haven't read it, but I think it would be a good introduction to the health, ethical and environmental issues that surround food choices. He's a clear and accessible writer.

Merry Christmas, happy Hanukkah, and happy holidays to everyone!

Wednesday, December 17, 2008

Local tips on trekking in Peru

Picture the scene: you’re high in the Peruvian Andes. It’s 5,000 metres above sea level, the air is thin, and you’re doing your best to keep altitude sickness at bay. You’re surrounded by snow-capped mountains and the rain is relentless.

This is when you happen upon a teary eyed backpacker, who has been separated from the rest of her group. She’s wearing cotton trousers, two T-shirts and a jacket that isn’t waterproof. She’s so cold that she’s verging on hypothermia and she’s even started to hallucinate.

This is what my group came across a few weeks ago on the week-long Salkantay trek through Peru’s sacred valley.

Fortunately, we were able to take her to a nearby lodge, where we dried her off the best we could, and gave her some hot food and dry clothes. Finally, her exceedingly casual guide showed up, accompanied by her shivering friend, who was similarly under-prepared with plastic bags on her feet to combat leaking boots.

This article isn’t meant to scare people out of trekking in Peru. The point is just because so many people are doing it (up to 500 people a day embark on the famed Inca Trail), it doesn’t make it a walk in the park. Altitude and weather conditions can make it tough, so preparation is essential.

I’ve been speaking to the experts (namely Jose from, Dameiro from Mountain Lodges of Peru and Jose at and getting their tips on what people should know before starting their big Peruvian trek.

If you’ve been trekking in Peru, feel free to add your own.

To combat altitude sickness
Keep hydrated by drinking lots and lots of water.
Don’t drink alcohol or caffeine.
Do drink coca tea - locals swear by it.
Go to bed early, as your sleep will be interrupted at high altitude.

What to pack
Decent trekking boots (fully broken in and making sure toes don’t touch the end)
Sock liners to go inside trekking socks to prevent blister-inducing friction (available from outdoor shops, or ordinary thin socks should do)
Blister plasters
Insect repellent
A warm hat
A sunhat/cap
Longsleeved T-shirt (to protect against insects/sunburn)
Waterproof jacket and trousers
Non-cotton trekking clothes (they dry faster)
Sleeping bag suitable for the season (or you can often hire one)
Consider taking or hiring walking poles, which, according to Cusco Guides, "reduce up to 30% off your legs' effort and also give more confidence when you walk downhill".

Book ahead if you want to do the Inka Trail
(at least six weeks). The trail is closed in February, which is the height of the rainy season. It’s not all about the Inka Trail though. Consider taking an alternative and less busy route. The Salkantay - which traverses nine bio zones and gives an unusual, distant view of Machu Picchu - is highly recommended.

Sunday, December 14, 2008

U.S. Weight, Lifestyle and Diet Trends, 1970- 2007

For this post, I compiled statistics on U.S. weight, health and lifestyle trends, and graphed them as consistently as possible. They span the period from 1970 to 2007, during which the obesity rate doubled. The data come from the National Health and Nutrition Examination Survey (NHANES), the Behavioral Risk Factor Surveillance System (BRFSS), and the U.S. Department of Agriculture (USDA). Some of the graphs are incomplete, either because the data don't exist, or because I wasn't able to find them. Obesity is defined as a body mass index (BMI) of 30+; overweight is a BMI of 25+. Yes, it's frightening. It has affected adults and children (NHANES).
The percentage of Americans who report exercising in their spare time has actually increased since 1988 (BRFSS).
We're eating about 250 more calories per day, according to NHANES.
The 250 extra calories are coming from carbohydrate (NHANES).

We're eating more vegetables and fruit (USDA).
We're eating more meat by weight, although calories from meat have probably gone down because the meat has gotten leaner (USDA). This graph represents red meat, fish and poultry. The increase comes mostly from poultry. Boneless, skinless chicken breasts anyone?
We're eating more sugar (USDA). The scale of the graph doesn't allow you to fully appreciate that sweetener consumption had increased by a full 100 calories per day by 1999, although it has dropped a bit since then. This is based on food disappearance data. In other words, the amount consumed is estimated using the amount sold domestically, minus a percentage that approximates waste. High-fructose corn syrup has seized nearly 50% of the sweetener market since 1970.
Again, the scale of the graph doesn't allow you to fully appreciate the magnitude of the change here. In 2000, we ate approximately 2.5 ounces, or 280 calories, more processed grains per day than in 1970 (USDA). That has since decreased slightly (34 calories). You might be saying to yourself right now "hey, that plus the 100 calories from sugar adds up to more of an increase than the NHANES data show!" Yes, and I think that points to the fact that the data sets are not directly comparable. NHANES data are self-reported whereas USDA data are collected from vendors. Regardless of the absolute numbers, our processed grain consumption has gone way up since 1970.

Wheat is still king. Although we grow a lot of corn in this country, most of it gets fed to animals. We prefer eating wheat without first feeding it to an intermediary. In absolute quantity, wheat consumption has increased more than any other grain (not including corn syrup).
Bye bye whole milk. Hello skim milk (USDA).

This graph represents "added fats", as opposed to fats that occur naturally in meat or milk (the USDA does not track the latter). Added fats include salad oil, cooking oil, deep fry oil, butter, lard, tallow, etc. We are eating a lot more vegetable oil than we were in 1970. It comes chiefly from the industrial, omega-6 rich oils such as soybean, corn and canola. Added animal fats have increased slightly, but it's pretty insignificant in terms of calories.

There is an artifact in this graph that I have to point out. In 2000, the USDA changed the way it gathered vegetable oil data. This led to an abrupt, apparent increase in its consumption that is obvious on the graph. So it's difficult to make any quantitative conclusions, but I think it's clear nevertheless that vegetable oil intake has increased considerably.

Between 1970 and 1980, something changed in the U.S. that caused a massive increase in obesity and other health problems. Some combination of factors reached a critical mass that our metabolism could no longer tolerate. The three biggest changes in the American diet since 1970:
  • An increase in cereal grain consumption, particularly wheat.
  • An increase in sweetener consumption
  • The replacement of meat and milk fat with industrial vegetable oils, with total fat intake remaining the same.
Mainstream America has done to itself what it did to native American and other indigenous cultures worldwide, with the same result.

Thursday, December 11, 2008

Going local with the lingo

I've just spent a week in Santiago, living with a friend of mine, hanging out with her mates and generally getting a feel for Chilean life. People would pay a lot of money for that sort of language immersion. But for me, it was free. Xili was a contact from

Xili (pictured far right) and I met earlier in the year when was visiting her hometown, Panama City. She had listed herself on Couchsurfing as willing to show travellers around town and her profile carried an abundance of glowing references. We ended up spending the best part of two weeks together and got along so well that we vowed to meet up again in Santiago, where she was heading to study.

Our reunion was a testament to how travel-networking can accelerate language learning. The first time we met, back in March, we spoke almost entirely in English. This time, the tables had turned. I'd been travelling across South America pretty much ever since, hanging out with locals, and generally doing my best to get off the standard Gringo trail. All the while, my confidence and vocab have been growing.

For the past week, we have conversed entirely in Spanish, which is hugely exciting progress for me. This doesn't mean Xili's English isn't still far superior to my faltering efforts in her language. For example, I still have a tendency to speak in uncertain, approval-seeking questions when using the past tense - ie "I saw? the film", "I had? lunch already". However, ever-patient, she gave nods of encouragement where appropriate and ensured I retained confidence not to give up.

What I love most about learning Spanish in Latin America is that people are delighted when you have a go and are ultra patient, even when you make a mess of it. I remember it being rather different when I lived in France, where I'd often get "Quoi?" barked back at me, accompanied by a semi-disgusted wrinkling of the nose. I'm a big fan of French people, but it was tough at times and it took much longer to feel comfortable communicating. Although, the fact that I was a self-conscious 18-year-old may have been a factor too.

Spending the best part of this year hanging out - and, in some cases, living - with locals has worked wonders for my Spanish. It goes without saying that it's far better than learning it from a book or even in classroom setting - where, as soon as you get into the "real world", you often seize up. Or at least I do. When I first arrived in France - after seven years of lessons - I may have been able to discuss the films of François Truffaut but I didn't have a clue how to say "You're welcome".

I'd highly recommend travel-networking sites to keen linguists as a way to learn how a language is used on a real, day-to-day basis., for example, clearly shows you which languages members speak and many specifically use it to get extra practice with native speakers. So, you might find yourself in Milan, speaking Italian with your host over your morning cappuccino and then switching to English when you take an impromptu shopping tour.

My only criticism is that insists on dividing competence levels into just three categories: beginner, intermediate, or expert. I'd argue there's a big leap between the upper two levels. Could they not slot "fluent" in between? Fluent is a much better description for those who can communicate effectively, but would never claim perfection.

There are a range of travel-networking sites you can use to meet local hosts. Or, if you're rooted to the spot, why not have people come to you? When in London, my Couchsurfing profile specifically states that "patient French and Spanish speakers are particularly welcome". Alternatively, if you're feeling particularly shy, you can do it all via your computer with sites such as, and (incorporating what was Friends Abroad). Many of these also offer "voice chat", providing invaluable conversation practice.

You could also meet with a group of other enthusiasts through (Michael Muszlak runs a great Anglo-Franco get-together in Paris every Saturday night.) Or you could try a skill exchange via community sites such as Last year, Luz Marina became my Spanish teacher in London, thanks to Gumtree; this year, I visited her in her native Bogota.

Recently, in a gringo-friendly cafe in Sucre, Bolivia, I saw a good-old fashioned noticeboard request. "Looking for someone to practice English with. Nothing weird. I'm just planning to move to the US." My Couchsurfing contact in the town, Laura, noticed it too. "I used to do that," she said. "Until I discovered Couchsurfing."

I think I might try the old-fashioned note in a cafe when I get to Buenos Aires, or I'll revisit the local Couchsurfing group. I'm also hoping Xili will come and visit me while I'm there. That way I can finally return some of her hugely appreciated hospitality.

Monday, December 8, 2008

Paris Hilton is not your friend

What happens to members of elite travel-networking site that break the strict rules of conduct? Those, for example, who after gaining much sought-after membership simply can't restrain themselves from sending a wishful friend request to the site's celebrity contingency, such as Paris Hilton or Naomi Campbell?

Immediate expulsion followed by profile deletion was the worst I imagined. But no, it's much more humiliating than that.

ASW wrong-doers get relegated to a purgatory otherwise know as A Big World. Next time they log in, they find the normally blue welcome screen has turned a shameful green, access to the forums and other profiles is denied, and all they can read are the "what did I do wrong?" lamentations from other ejectees.

An old article from Wired details an anecdote from one reluctant Big World member: a 20-something
from Geneva called Talal bin Laden, who admits he's "distantly, distantly related to that guy no one likes".

"One guy posted some anti-Arab racist slurs, and I responded with a polite deconstruction of why I felt that was inappropriate," says bin Laden. "For that, I was evicted to hell."

Saturday, December 6, 2008

Peripheral vs. Ectopic Fat

I went to an interesting presentation the other day by Dr. George Ioannou of the University of Washington, on obesity and liver disease. He made an interesting distinction between the health effects of two types of body fat. The first is called subcutaneous fat (or peripheral fat). It accumulates right under the skin and is evenly distributed over the body's surface area, including extremities. The second is called ectopic fat. Ectopic means "not where it's supposed to be". It accumulates in the abdominal region (beer belly), the liver, muscle tissue including the heart, the pancreas, and perhaps in lipid-rich deposits in the arteries. Subcutaneous fat can be measured by taking skinfold thickness in different places on the body, or sometimes by measuring arm or leg circumference. Ectopic fat can be measured by taking waist circumference.

It's an absolutely critical distinction, because ectopic fat associates with poor health outcomes while subcutaneous fat does not. In
this recent study, waist circumference was associated with increased risk of death while arm and leg circumference were associated with a reduced risk of death. I think the limb circumference association in this particular study is probably confounded by muscle mass, but other studies have also shown a strong, consistent association between ectopic fat and risk of death, but not subcutaneous fat. The same goes for dementia and a number of other diseases. I think it's more than an epidemiological asssociation. Surgically removing the abdominal fat from mice prevents insulin resistance and prolongs their lifespan.

People with excess visceral fat are also
much more likely to have fatty liver and cirrhosis. It makes sense if you think of them both as manifestations of ectopic fat. There's a spectrum of disorders that goes along with excess visceral fat and fatty liver: it's called the metabolic syndrome, and it affects a quarter of Americans (NHANES III). We already have a pretty good idea of what causes fatty liver, at least in lab animals: industrial vegetable oils and sugar. What's the most widely used animal model of metabolic syndrome? The sugar-fed rat. What are two of the main foods whose consumption has increased in recent decades? Vegetable oil and sugar. Hmm... Fatty liver is capable of causing insulin resistance and diabetes, according to a transgenic mouse that expresses a hepatitis C protein in its liver.

You want to keep your liver happy. All those blood tests they do in the doctor's office to see if you're healthy-- cholesterol levels, triglycerides, insulin, glucose--
reflect liver function to varying degrees.

Abdominal fat is a sign of ectopic fat distribution throughout the body, and its associated metabolic consequences. I think we know it's unhealthy on a subconscious level, because belly fat is not attractive whereas nicely distributed subcutaneous fat can be. If you have excess visceral fat, take it as a sign that your body does not like your current lifestyle. It might be time to think about changing your diet and exercise regime.
Here are some ideas.

Thursday, December 4, 2008

Tourists in Japan must dance to a different tuna

It was Tokyo's ultimate local travel experience: get up early and head to the world's biggest fish market, Tsukiji. See the giant tuna roll in, catch the auction action, and try some of the freshest sushi in town. It was a everyday life that few tourists had seen before. Until, that is, everyone caught on to the idea...

When 200 and 300 people started packing into the auction area, it became too much. Earlier this year authorities called for tourists to show voluntary restraint and stay away, but, of course, that was never going to work. So now the ban is complete. For at least a month.

As soon as tourism becomes a mass activity, problems usually follow. The main issue with "must sees" is that people usually go through the motions and forget their common sense - especially, perhaps inevitably, when getting up at 4am. There have been reports of tourists obscuring auction hand signals with flash photography, walking around in high heels and compromising hygiene by prodding the fish.

However, couldn't such stupidity be avoided without a total ban? Tsukiji's restaurants and shops must surely hope so.

"As far as sushi restaurants are concerned, I think more than 50 percent of their customers are [outsiders] on weekdays. On Saturdays, they probably account for more than 90 percent," Susumu Isono, director of local sushi chain Isonoya, told the Japan Times.

So is this just a clever PR scam? If the authorities create a storm of publicity by making such a drastic move, guidebooks and tour operators will be obliged to change their info. "Arrive at 5am to catch the action," says Lonely Planet. Expect an update soon.

Photograph: Derek Mawhinney/ Wikipedia images

Wanted: a friendly Parisian

Parisians rude and unfriendly? No, you´ve got it all wrong. In fact, to prove it, Paris Greeters will get a extra-friendly resident to give you a free city tour. Or, at least, that´s the theory. In reality, it seems all 11 million of them are a little busy right now. One will get back to you though. Maybe. If you´re very persistent.

Journalist Agnès Poirier waited six weeks to get a response - and only then after tipping them off that she was journalist. She wrote an entertaining blog about it over at Guardian Travel.

But friendly Parisians can´t be in that short supply, can they? My recent trip there showed that the best way to get behind closed doors - literally and metaphorically - is to stay with a local via a B&B network, such as or Alcôve & Algapes. Pictured left is my host, Françoise - a professional laughter coach living in the eastern suburb of Vincennes - with the equally friendly Jenny Johnson from 2binParis.

Or you could try meeting a Couchsurfer. Paris is the world´s largest Couchsurfing city, with over 15,000 local members.

And before you despair in all greeter schemes. Check out this follow-up blog, Pleased to Greet You, which covers more successful greeting experiences in Jamaica and Argentina, among others.

I'll add links to these greeter sites to the Going Local Travel sidebar. And thanks to Stephen Chapman of MakeTravelFair for making me aware of many of them.

Wednesday, December 3, 2008

Polyunsaturated Fat Intake: What About Humans?

Now we know how to raise a healthy pig or rat: balance omega-6 linoleic acid (LA) and omega-3 alpha-linolenic acid (LNA) and keep both relatively low. LA and LNA are the most basic (and shortest) forms of omega-6 and omega-3 fats. They are the only fats the body can't make on its own. They're found in plant foods, and animal foods to a lesser extent. Animals convert them to longer-chain fats like arachidonic acid (AA; omega-6), EPA (omega-3) and DHA (omega-3). These long-chain, animal PUFA are involved in a dizzying array of cellular processes. They participate directly as well as being further elongated to form eicosanoids, a large class of very influential signaling molecules.

AA is the precursor of a number of inflammatory eicosanoids, while omega-3-derived eicosanoids tend to be less inflammatory and participate in long-term repair processes. A plausible explanation for the negative health effects of LA-rich vegetable oils is the fact that they lead to an imbalance in cellular signaling by increasing the formation of AA and decreasing the formation of EPA and DHA. Both inflammatory and anti-inflammatory signaling are necessary in the proper context, but they must be in balance for optimal function. Many modern diseases involve excess inflammation. LA also promotes oxidative and nitrosative damage to organs, as explained in the last post. This is an enormous oversimplification, but I'll skip over the details (most of which I don't know) because they could fill a stack of textbooks.

How do we raise a healthy human? Although I think pigs are a decent model organism for studying diet and health as it relates to humans, they don't have as much of a carnivorous history as we do. You would expect them to be more efficient at converting plant nutrients to their animal counterparts: carotenes to vitamin A, vitamin K1 to K2, and perhaps short-chain polyunsaturated fats (PUFA) to long-chain fats like AA, EPA and DHA. I mention it simply to point out that what goes for a pig may not necessarily go for a human when it comes to fatty acid conversion.

I've dug up a few papers exploring this question. I don't intend this post to be comprehensive but I think it's enough to get a flavor of what's going on. The first paper is an intervention trial comparing the effect of flax oil and fish oil supplementation on the fat composition of red blood cells. Investigators gave volunteers either 1.2 g, 2.4 g or 3.6 g (one teaspoon) flax oil per day; or 0.6 g or 1.2 g fish oil per day. The volunteers were U.S. firefighters, who otherwise ate their typical diet rich in omega-6. Flax oil supplementation at the two higher doses increased EPA, but did not increase DHA or decrease AA significantly. This suggests that humans can indeed convert some ALA to long-chain omega-3 fats, but adding ALA to a diet that is already high in omega-6 does not reduce AA or increase the all-important DHA.

The fish oil supplement, even at one-sixth the highest flax oil dose, increased EPA and DHA to a greater extent than flax oil, and also decreased AA. This shows that fish oil has a greater effect than flax oil on the fat profile of red blood cells in the context of a diet rich in omega-6. Another study also found that ALA intake is not associated with EPA or DHA in blood plasma. This could suggest either that humans aren't very good at converting ALA to longer n-3 fats, that the pathways are blocked by excessive LA or some other factor (a number of things block conversion of omega-3 fats), or that our bodies are already converting sufficient omega-3 and fish oil is overkill.

What happens when you reduce omega-6 consumption while increasing omega-3? In one study, participants were put on a "high LA" or "low LA" (3.8% of calories) diet. The first had an omega-6 : omega-3 ratio of 10.1, while the second had a ratio of 4.0. As in the previous intervention study, EPA was higher on the low LA diet. Here's where it gets interesting: DHA levels fell precipitously throughout the study, regardless of which diet the participants were eating. This has to do with a special requirement of the study diet: participants were not allowed to eat seafood. This shows that most of the DHA in the blood is obtained by eating DHA from animal fat, rather than elongating it from ALA such as flax oil. This agrees with the finding that strict vegetarians (vegans) have a low level of DHA in blood plasma.

In another intervention study, researchers achieved a better omega-6 : omega-3 ratio, with participants going from a baseline ratio of 32.2 to an experimental ratio of 2.2 for 10 weeks. The change in ratio was mostly from increasing omega-3, rather than decreasing omega-6. This caused an increase in serum EPA and DHA, although the DHA did not quite reach statistical significance (p= 0.06). In this study, participants were encouraged to eat fish 3 times per week, which is probably the reason their DHA rose. Participants saw a metabolic shift to fat burning, and an increase in insulin sensitivity that was on the cusp of statistical significance (p= 0.07).

I think what the data suggest is that humans can convert short-chain omega-3 (ALA) to EPA, but we don't efficiently elongate it to DHA. At least in the context of a high LA intake. Another thing to keep in mind is that serum PUFA are partially determined by what's in fat tissue. Modern Americans have an abnormally high proportion of LA in their fat tissue, sometimes over 20%. This contributes to a higher proportion of omega-6 and its derivatives in all tissues. "Wild" humans, including our paleolithic ancestors, would probably have values in the lower single digits. LA in fat tissue has a half-life of about 2 years, so restoring balance is a long-term process. Omega-3 fats do not accumulate to the same degree as LA, typically comprising about 1% of fat tissue. At this point, one could rightly ask: we know how diet affects blood polyunsaturated fats, but what's the relevance to health? There are multiple lines of evidence, all of which point in generally the same direction in my opinion.

There are associations between omega-6 intake (from vegetable oils), low omega-3 intake, and a number of health and psychiatric problems. Another line of evidence comes from intervention trials. The Lyon diet-heart study was one of the most successful intervention trials of all time. The experimental group increased their intake of fish, poultry, root vegetables, green vegetables, bread and fruit, while decreasing intake of red meat and dairy fat. A key difference between this study and other intervention trials is that participants were encouraged to eat a margarine rich in omega-3 ALA. In sum, participants decreased their total PUFA intake, decreased omega-6 intake and increased intake of ALA and long-chain omega-3s. After an average of 27 months, total mortality was 70% lower in the intervention group than in the control group eating the typical diet! This effect was not seen in trials that encouraged vegetable and grain consumption, discouraged red meat and dairy fat consumption, but didn't alter PUFA intake or the omega-6 : omega-3 ratio, such as the Women's Health Initiative.

As usual, the most important line of evidence comes from healthy non-industrial cultures that did not suffer from modern non-communicable diseases. They invariably consumed very little omega-6 LA (3% of calories or less), ate a roughly balanced amount of omega-6 and omega-3, and had a source of long-chain (animal) omega-3. They did not eat much omega-3 from plant sources (such as flax), as concentrated sources are rare in nature. Dr. Weston Price observed that cultures throughout the world sought out seafood if available, sometimes going to great lengths to obtain it. Here's an exerpt from Nutrition and Physical Degeneration about Fiji islanders:
Since Viti Levu, one of the islands of this group, is one of the larger islands of the Pacific Ocean, I had hoped to find on it a district far enough from the sea to make it necessary for the natives to have lived entirely on land foods. Accordingly, with the assistance of the government officials and by using a recently opened government road I was able to get well into the interior of the island by motor vehicle, and from this point to proceed farther inland on foot with two guides. I was not able, however, to get beyond the piles of sea shells which had been carried into the interior. My guide told me that it had always been essential, as it is today, for the people of the interior to obtain some food from the sea, and that even during the times of most bitter warfare between the inland or hill tribes and the coast tribes, those of the interior would bring down during the night choice plant foods from the mountain areas and place them in caches and return the following night and obtain the sea foods that had been placed in those depositories by the shore tribes. The individuals who carried these foods were never molested, not even during active warfare. He told me further that they require food from the sea at least every three months, even to this day. This was a matter of keen interest, and at the same time disappointment since one of the purposes of the expedition to the South Seas was to find, if possible, plants or fruits which together, without the use of animal products, were capable of providing all of the requirements of the body for growth and for maintenance of good health and a high state of physical efficiency.
Price searched for, but did not find, vegetarian groups that were free of the diseases of civilization. What he found were healthy cultures that put a strong emphasis on nutrient-dense animal foods, particularly seafoods when available. I think all this information together suggests that the optimum, while being a fairly broad range, is a low intake of omega-6 LA (less than 3% of calories) and a modest intake of animal omega-3 for DHA.

I believe the most critical element is reducing omega-6 LA by eliminating industrial vegetable oils (soybean, corn, cottonseed, etc.) and the foods that contain them from the diet. Fats from pasture-raised ruminants (butter, beef, lamb etc.) and wild fish are naturally balanced. We no longer commonly eat the most concentrated land source of DHA, brain, so I think it's wise to eat seafood sometimes. According to the first study I cited, 1/4 teaspoon of fish oil (or cod liver oil) per day is enough to elevate plasma DHA quite significantly. This amount of omega-3 could be obtained by eating seafood weekly.

Tuesday, December 2, 2008

London shopping: keeping it local

Wards Corner is the latest London market to come under threat. The Latin American enclave in Tottenham is the being earmarked for "development".

Londoners have already lost a large chunk of Spitalfields and Camden´s future has been looking dubious for sometime. And what have we gained in their place? That monstrous shrine to excessive consumerism: the Westfield Centre.

But all hope is not yet lost. Big up to the site that celebrates London´s independent traders: Good luck to them and their New York branch.

And "suerte" to the Wards Corner community. If you´re in London, show your support at their Christmas party on Dec 5.