Interesting Articles in the AJCN

I just received an RSS alert for the American Journal of Clinical Nutrition's latest articles. This upcoming issue is full of very interesting material:

1. Dr. Neil D. Barnard reviews food consumption patterns in the US from 1909 to 2007 (1). This is something I've written about a number of times. The most notable change is that industrial seed oil use has increased by more than 3-fold in the last 40 years, and even more in the last 100 although he doesn't provide those numbers. Butter and lard use declined sharply. Meat consumption is up, but the increase comes exclusively from poultry because we're eating the same amount of red meat we always have. Grain consumption is down, although it peaked around 1900 so it may not be a fair comparison with today:

In the late 1800s, wheat flours became more popular and available due to the introduction of new [high-gluten] wheat varieties, [low extraction] milling techniques, and transport methods, and during this time new breakfast cereals were introduced by John Harvey Kellogg, CW Post, and the Quaker Oats Company. Thereafter, however, per capita availability of flour and cereal products gradually dropped as increased prosperity, improved mechanization, and transport (eg, refrigerated railway cars) increased competition from other food groups. [Then they partially rebounded in the last 40 years]

2. Dr. S.C. Larsson published a paper showing that in Sweden, multivitamin use is associated with a slightly higher risk of breast cancer (2).

3. Soy protein and isoflavones, which have been proposed to do everything from increase bone mineral density to fight cancer, are slowly falling out of favor. Dr. Z.M. Liu and colleagues show that soy protein and/or isoflavone supplementation has no effect on insulin sensitivity or glucose tolerance in a 6 month trial (3). This follows a recent trial showing that isoflavones have no effect on bone mineral density.

4. Dr. Ines Birlouez-Aragon and colleagues showed that high-heat cooked (fried and sauteed) foods increase risk factors for diabetes and cardiovascular disease (insulin resistance, cholesterol, triglycerides), compared to low-heat cooked foods (steamed, stewed) in a one-month trial (4). The high-heat diet also reduced serum levels of long-chain omega-3 fatty acids and vitamins C and E.

5. Dr. Katharina Nimptsch and colleagues showed that higher menaquinone (vitamin K2) intake is associated with a lower cancer incidence and lower cancer mortality in Europeans (5). Most of their K2 came from cheese.

6. And finally, Dr. Zhaoping Li and colleagues showed that cooking meat with an herb and spice blend reduced the levels of oxidized fat during cooking, and reduced serum and urinary markers of lipid oxidation in people eating the meat (6).

The take-home message? Eat stewed beef with herbs, but don't pre-brown it in vegetable oil. Throw out the tofu and have some artisanal cheese instead.

New Review of Controlled Trials Replacing Saturated fat with Industrial Seed Oils

Readers Stanley and JBG just informed me of a new review paper by Dr. Dariush Mozaffarian and colleagues. Dr. Mozaffarian is one of the Harvard epidemiologists responsible for the Nurse's Health study. The authors claim that overall, the controlled trials show that replacing saturated fat with polyunsaturated fat from industrial seed oils, but not carbohydrate or monounsaturated fat (as in olive oil), slightly reduces the risk of having a heart attack:

These findings provide evidence that consuming PUFA in place of SFA reduces CHD events in RCTs [how do you like the acronyms?]. This suggests that rather than trying to lower PUFA consumption, a shift toward greater population PUFA consumption in place of SFA would significantly reduce rates of CHD.

Looking at the studies they included in their analysis (and at those they excluded), it looks like they did a very nice job cherry picking. For example:

• They included the Finnish Mental Hospital trial, which is a terrible trial for a number of reasons. It wasn't randomized, appropriately controlled or even semi-blinded*. Thus, it doesn't fit the authors' stated inclusion criteria, but they included it in their analysis anyway**. Besides, the magnitude of the result has never been replicated by better trials, not even close.
  
• They included two trials that changed more than just the proportion of SFA to PUFA. For example, the Oslo Diet-heart trial replaced animal fat with seed oils, but also increased fruit, nut, vegetable and fish intake, while reducing trans fat margarine intake! The STARS trial increased both omega-6 and omega-3, reduced processed food intake, and increased fruit and vegetable intake! These obviously aren't controlled trials isolating the issue of dietary fat substitution. If you subtract the four inappropriate trials from their analysis, which is half the studies they analyzed, the result disappears. Those four just happened to show the largest reduction in heart attack mortality...
  
• They excluded the Rose et al. corn oil trial and the Sydney Diet-heart trial. Both found a large increase in total mortality from replacing animal fat with seed oils, and the Rose trial found a large increase in heart attack deaths (the Sydney trial didn't report CHD deaths, but Dr. Mozaffarian et al. stated in their paper that they contacted authors to obtain unpublished results. Why didn't they contact the authors of this study?).

The authors claim, based on their analysis, that replacing 5% of calories as saturated fat with polyunsaturated fat would reduce the risk of having a heart attack by 10%. Take a minute to think about the implications of that statement. For the average American, that means cutting saturated fat nearly in half to 6% of energy, which is a real challenge if you want to have a semblance of a normal diet. It also means nearly doubling PUFA intake, which will come mostly from seed oils if you follow the authors' advice.

So basically, even if the authors' conclusion were correct, you overhaul your whole diet and replace natural foods with bland unnatural foods, and...? You reduce your 10-year risk of having a heart attack from 10 percent to 9 percent. Without affecting your overall risk of dying! The paper states that the interventions didn't affect overall mortality at all. That's what they're talking about here. Sign me up!


* Autopsies were not conducted in a blinded manner. Physicians knew which hospital the cadavers came from, because autopsies were done on-site. There is some confusion about this point because the second paper states that physicians interpreted the autopsy reports in a blinded manner. But that doesn't make it blinded, since the autopsies weren't blinded. The patients were also not blinded, so the study overall was highly susceptible to bias.

** They refer to it as "cluster randomized". I don't know if that term accurately applies to the Finnish trial or not. The investigators definitely didn't randomize the individual patients: whichever hospital a person was being treated in, that's the food he/she ate. There were only two hospitals, so "cluster randomization" in this case would just refer to deciding which hospital got the intervention first. Can this accurately be called randomized?

Fatty Liver: It's not Just for Grown-ups Anymore

The epidemic of non-alcoholic fatty liver disease (NAFLD) is one of my favorite topics on this blog, due to the liver's role as the body's metabolic "grand central station", as Dr. Philip Wood puts it. The liver plays a critical part in the regulation of sugar, insulin, and lipid levels in the blood. Many of the routine blood tests administered in the doctor's office (blood glucose, cholesterol, etc.) partially reflect liver function.

NAFLD is an excessive accumulation of fat in the liver that impairs its function and can lead to severe liver inflammation (NASH), and in a small percentage of people, liver cancer. An estimated 20-30% of people in industrial nations suffer from NAFLD, a shockingly high prevalence (1).

I previously posted on dietary factors I believe are involved in NAFLD. In rodents, feeding a large amount of sugar or industrial seed oils (corn oil, etc.) promotes NAFLD, whereas fats such as butter and coconut oil do not (2). In human infants, enteric feeding with industrial seed oils causes severe liver damage, whereas the same amount of fat from fish oil doesn't, and can even reverse the damage done by seed oils (3).

So basically, I think sugar and industrial oils are major contributors to NAFLD, and if you look at diet trends in the US over the last 40 years, they're consistent with the idea. Industrial oils are harmful due (at least in part) to their high omega-6 content, which is problematic partially because it disturbs normal omega-3 metabolism. A potential solution to fatty liver is to reduce sugar, replace industrial oils with natural fats, and ensure a regular source of omega-3. I've posted two anecdotes of people rapidly healing their fatty livers using diet changes* (4, 5).

I recently came across a study that examined the diet of Canadian children with NAFLD (6). The children had a high sugar intake, a typical (i.e., high) omega-6 intake, and a low omega-3 intake. The authors claimed that the children also had a high saturated fat intake, but at 10.5% of calories, they were almost eating to the American Heart Association's "Step I" diet recommendations**. Busted! Total fat intake was also low.

High sugar consumption was associated with a larger waist circumference, insulin resistance, lower adiponectin and elevated markers of inflammation. High omega-6 intake was associated with markers of inflammation. Low omega-3 intake was associated with insulin resistance and elevated liver enzymes. Saturated fat intake presumably had no relation to any of these markers, since they didn't mention it in the text.

These children with NAFLD, who were all insulin resistant and mostly obese, had diets high in omega-6, high in sugar, and low in omega-3. This is consistent with the idea that these three factors, which have all been moving in the wrong direction in the last 40 years, contribute to NAFLD.


* Fatty liver was assessed by liver enzymes, admittedly not a perfect test. However, elevated liver enzymes do correlate fairly well with NAFLD.

** Steps I and II were replaced by new diet advice in 2000. The AHA now recommends keeping saturated fat below 7% of calories. Stock up on those skinless chicken breasts! Make sure there isn't any residual fat sticking to the meat, it might kill you. I do have to give the AHA credit however, because their new recommendations focus mostly on eating real food rather than avoiding saturated fat and cholesterol.

Interview on Bizymoms

I recently did a written interview for the website Bizymoms.com. It was the first time I had been invited to do an interview, so I figured what the heck. They bravely posted the interview, despite the fact that my responses could be seen as controversial. You can find it here.

A False Dichotomy

In the discussion section of the last post, the eternal argument about non-industrial people arose: were their lives (a) "nasty, brutish and short" (Hobbes), or were they (b) "noble savages" (Shaftesbury) living in Eden? The former argument states that they had awful lives, and we should be glad we're living int he 21st century. The latter argument implies that we should emulate them as much as possible. Each side is bursting with anecdotes to support their position.

Any time the discussion reaches this point, it stops providing us anything useful. The argument is a false dichotomy, one in which neither answer is correct. The correct answer is (c): none of the above. Some aspects of hunter-gatherer life are preferable to ours, and some aspects of our lives are preferable to theirs. Understanding that we spent a lot of evolutionary time as hunter-gatherers, as well as a few thousand years in small, tightly knit agricultural communities, may be useful in understanding how to work constructively with our own bodies and minds in the modern world.

So please, let's leave behind the false dichotomy and foster a more nuanced understanding of hunter-gatherer life.

The Paleolithic Mind

I went to a meditation retreat this week with the Red Cedar Zen community in Bellingham. It was a good experience. Staring at a wall from 6 am to 9 pm for a few days gives you the opportunity to learn a few things about your mind. Some of these are things you already know on some level, but you just need to have them reinforced. For example, the weight of psychological stress that we carry in modern societies like the US. It's only when it goes away for a while that you can see how heavy it was.

I'm totally ignorant of the scientific literature on this, but the way I see it, there are at least two main sources of psychological stress in the modern world for which we aren't well equipped as human beings:

• Being eternally and inescapably subordinate in a large social structure
  
• Having too many responsibilities such as possessions and obligations
  

I recently read an excellent article by Michael Finkel in National Geographic magazine on the Hadza of Tanzania. The Hadza are a hunter-gatherer group living in a way that may resemble how our ancestors lived for most of the last million years. Here are a few characteristics of the Hadza lifestyle as described by the author:

The Hadza do not engage in warfare [although they do have homicide]. They've never lived densely enough to be seriously threatened by an infectious outbreak. They have no known history of famine; rather, there is evidence of people from a farming group coming to live with them during a time of crop failure. The Hadza diet remains even today more stable and varied than that of most of the world's citizens. They enjoy an extraordinary amount of leisure time. Anthropologists have estimated that they "work"—actively pursue food—four to six hours a day. And over all these thousands of years, they've left hardly more than a footprint on the land.

This isn't intended to idealize their lifestyle, but to point out that being a hunter-gatherer has its advantages. One of these is a minimal social structure in which each person is has full authority over himself:

The Hadza recognize no official leaders. Camps are tra­ditionally named after a senior male (hence, Onwas's camp), but this honor does not confer any particular power. Individual autonomy is the hallmark of the Hadza. No Hadza adult has authority over any other. None has more wealth; or, rather, they all have no wealth. There are few social obligations—no birthdays, no religious holidays, no anniversaries.

Even "marriage" doesn't carry much obligation. The author describes the Hadza as "serial monogamists". The idea of an eternal bond between two individuals doesn't exist. Women are not subordinate to men:

Gender roles are distinct, but for women there is none of the forced subservience knit into many other cultures. A significant number of Hadza women who marry out of the group soon return, unwilling to accept bullying treatment. Among the Hadza, women are frequently the ones who initiate a breakup—woe to the man who proves himself an incompetent hunter or treats his wife poorly. In Onwas's camp, some of the loudest, brashest members were women.

Contrast this with modern civilizations in which everyone has a boss-- whether it's at a job, in a marriage or under your country's legal system. I think this feeling of perpetual subordination is destructive to an animal such as ourselves, that has spent so much of its existence mostly free of these pressures.

The author says this about their possessions:

Traditional Hadza, like Onwas and his camp mates, live almost entirely free of possessions. The things they own—a cooking pot, a water container, an ax—can be wrapped in a blanket and carried over a shoulder.

This resembles other African hunter-gatherer groups that have few and simple tools. From the book The !Kung San: Men, Women and Work in a Foraging Society:

!Kung tools are few in number, lightweight, made from locally available materials, and multipurpose.

Again, this is in sharp contrast to the modern world, where we have so many belongings it's impossible to keep track of them all. We have giant houses that we "need" to store all these things, and still it doesn't seem like enough. Many of our possessions are indispensable if we want to fit in to society. We need (or feel we need) clothes, cookware, identification, money, transportation, furniture, tools, sports gear, et cetera. Having to be responsible for this extraordinary quantity of possessions (by evolutionary standards) is a heavy weight on our minds.

Unfortunately, we have more than just possessions on our minds. To live in the modern world is to be pricked to death by a thousand small responsibilities. Remember to make your lunch. Remember to make a doctor's appointment, shop for groceries, tie your shoes, get your oil changed, send that e-mail, make dinner, go for a jog, vacuum the floor, take a shower, pick up the kids-- the list is endless. Are our memories as defective as we think they are, or are we simply not designed to keep track of so many details?

In hunter-gatherer times, we had stress. Homicide, accidents, infectious disease and predation were always stalking us. But it was a totally different kind of stress-- it was occasional, powerful and brief rather than a constant flow of obligations clogging the paths of our minds. Most days were leisurely, with plenty of time for gossiping, staring at the clouds and dozing off.

Those times are gone for us, but perhaps keeping them in mind can help us live more constructively in the modern world. I find that meditation helps keep the thousand pricks of modern life in perspective, perhaps bringing my mind closer to the paleolithic state.