Scientific Studies

Are Low-Carb Diets Killing Sweden? (Also: New Interviews and Raw Vegan Immortality)

I’m occasionally stricken by a wave of crippling, all-consuming terror. Sometimes it’s because I can’t find my wallet. Sometimes it’s because I hear the unmistakable sound of Smitty throwing up on my bed. Sometimes it’s because I take a few wrong turns on Youtube and accidentally learn what Piccinini animal-human hybrids are (what is seen cannot be unseen). But these days, it’s usually because I’ve looked at the calendar and realized that—along with being 25 and really old now—I haven’t posted anything on this blog in almost four months.

What madness!

As most of you probably know, I’ve been chugging away on an upcoming book called “Death By Food Pyramid,” which is the main reason Raw Food SOS has been hosting more tumbleweeds than blog entries lately. Thanks to finding some unexpected political shenanigans to investigate (which I’m really excited to tell you guys about), the release date for “Death By Food Pyramid” is now September 2013. More details to come.

Earlier this month, I recorded an interview that touches upon the USDA’s seamy, pyramid-shaped underbelly (mostly in the second half):

I’ll be writing more about the book soon (and resuming my previous rapid-blogging schedule of six posts a year instead of four), but in the meantime, here’s a new installment of Bad Science Du Jour!

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The Truth About Ancel Keys: We’ve All Got It Wrong

(Note: This post was inspired by the “Ancel Keys” section in a recent series of paleo-challenging YouTube videos, which I may critique in the future. The anonymous videomaker “Plant Positive” highlighted some important misconceptions about Keys and his research that I’d like to broadcast to a larger audience, but didn’t address some equally important points tangled in the Keys saga, and likewise made some arguments I believe are incomplete or misleading. This blog post is an attempt to address those misconceptions in a more balanced and thorough way, and provide a broader context for how we view the infamous Mr. Keys.)

This is one of those “gotta bust me some myths no matter where they come from” blog posts. And by that, I mean I’m about to challenge a story that’s been so well-circulated among paleo, low carb, and real-food communities that most of us have filed it away in a little brain-folder called “Things We Never Have to Question Because They’re So Ridiculously True.”

I’m talking about the late, great Ancel Keys, and his equally late (but maybe not as great) role in the history of heart disease research. The oft-repeated tale goes something like this:

Once upon a time, a scientist named Ancel Keys did an awful thing. He published a study about different countries that made it look like heart disease was associated with fat intake. But the truth was that he started out with 22 countries and just tossed out the ones that didn’t fit his hypothesis! When other researchers analyzed his data using all the original countries, the link between fat and heart disease totally vanished. Keys was a fraud, and he’s the reason my mom made me eat skim milk and Corn Chex for breakfast instead of delicious bacon and eggs. LET HIS SOUL BURN. BURN! BUUUUUURN! (more…)

One Year Later: The China Study, Revisited and Re-Bashed

Lest this blog sink further into its eery two-month silence, I think it’s high time for an update!

First item of business: The Ancestral Health Symposium. Due to some serendipitous events, it turns out I’ll be presenting at this hyperventilation-inducingly-awesome event next week. My lecture is at 10:00 AM on August 6th in the Rolfe 1200 auditorium. If you’re lucky enough to have a ticket, I hope to see you there, and to verify my existence for anyone who still thinks I’m a meat industry puppet. Otherwise, unless PETA pops in and sets fire to UCLA, all the presentations should be available online for free shortly after the symposium is over. Woohoo!

Second item of business: Now that he’s outed the project himself, I feel safe in announcing that Mark Sisson is going to be publishing the book I mentioned working on in an earlier blog post, and that it’ll be released mid-2012. I’m super excited, and couldn’t ask for a better publisher to work with. Or one with more impressive abs (see link above). More details to come in the near future.

Now on to the real point of this post. (more…)

New Study: Will Omega-3s Boost Your Risk of Prostate Cancer?

Two yesterdays ago, I said I was going to “post this tomorrow.” On one hand, that didn’t happen. On the other hand, a one-day delay is still more timely than usual for me, so I’m counting this as a blogging victory. Whip out the kazoos!

As some of you’ve already seen, a major study came out this week with some unexpected findings about DHA, an omega-3 fat abundant in fish. The study linked high blood levels of DHA to aggressive prostate cancer (and trans fats to lower prostate cancer rates). To date, it’s the biggest fat-and-prostate-cancer study of its kind—which makes these findings all the more peculiar. Given the widespread use of fish oil supplements for quelling inflammation and boosting cardiovascular health, it’s a little spooky to think DHA is really a double-edged sword. But is this study really a slam against fish fat?

This analysis wound up as a guest post for Mark’s Daily Apple, so head over there to read the full thing:

Overall, the study itself isn’t too shabby—and the researchers readily admitted their findings surprised them. But this study is far from a harbinger of doom for seafood lovers. The take-home points, and some additional thoughts:

  • Serum fatty acids aren’t a perfect mirror of diet—and the men with higher levels of DHA weren’t necessarily eating more fish. In fact, it seems low-fat diets can actually increase DHA status in the blood the same way omega-3 supplementation can.
  • The “highest levels of serum DHA” reported here were based on percentage of fatty acids—not absolute value. Here’s a great explanation of why percentage-based measurements may be misleading in studies like these.

Another major study, the European Prospective Investigation into Cancer and Nutrition, also found a slight (but non-statistically-significant) link between prostate cancer and DHA levels in the bloodbut at the same time, found zero association between dietary fish fat and the disease. And as I wrote in the post on Mark’s Daily Apple, nearly all previous studies have shown fish consumption to have either a neutral or protective association with prostate cancer. Blood levels of DHA and dietary intake don’t seem to follow the same pattern in relation to this disease.

That said: I’m pretty weary of long-term mega-dosing of fish oil for other reasons. Thanks to all their double bonds, omega-3s are relatively unstable and prone to oxidation, just like other polyunsaturated fats. It’s quite possible that the anti-inflammatory benefits appearing short term could eventually collide with a new set of problems that take longer to appear: those stemming from oxidative stress. Moderate supplementation probably won’t cause harm, but regularly taking huge doses of fish oil should probably be done with caution. The best strategy for achieving a great omega-3/omega-6 ratio is reducing your intake of high-omega-6 foods like grains and industrial oils, rather than simply chugging back more omega-3 to compensate.

Edit: Paul at Perfect Health Diet has a more technical discussion of omega-3s, angiogensis, and cancer that does make DHA seem a little fishy. Highly worth reading!

The New USDA Dietary Guidelines: Total Hogwash, and Here’s Why

A few days ago, the USDA finally unveiled their (fashionably late) 2010 dietary guidelines—the first update they’ve made since 2005. Are you as excited as I am? Can we live without bread yet? Leave the fat on our dairy? Ditch the rancid vegetable oils? Gobble down butter and coconut oil without fearing imminent death? By golly, has the USDA finally pulled its head out of the soybean fields and given us something useful, emerging as a reliable authority instead of a food industry puppet?

Nah.

Contrary to my title, though, the new guidelines aren’t total hogwash. Just mostly. A few of their recommendations are passable, like these:

  • Prevent and/or reduce overweight and obesity through improved eating and physical activity behaviors. (Duh.)
  • Increase physical activity and reduce time spent in sedentary behaviors. (Duh.)
  • Keep trans fatty acid consumption as low as possible by limiting foods that contain synthetic sources of trans fats, such as partially hydrogenated oils. (Duh.)
  • Limit the consumption of foods that contain refined grains, especially refined grain foods that contain solid fats, added sugars, and sodium. (Yes!)

Unfortunately, the rest of the guidelines are the regurgitated—and often unsubstantiated—snippets we’re already inundated with. Case in point:

  • Consume less than 10 percent of calories from saturated fatty acids by replacing them with monounsaturated and polyunsaturated fatty acids.
  • Consume less than 300 mg per day of dietary cholesterol.
  • Consume at least half of all grains as whole grains. Increase whole-grain intake by replacing refined grains with whole grains.
  • Increase intake of fat-free or low-fat milk and milk products, such as milk, yogurt, cheese, or fortified soy beverages.
  • Use oils to replace solid fats where possible.

According to the guideline packet, these recommendations provide “information and advice for choosing a healthy eating pattern” and are “based on the most recent scientific evidence review.” If you’ve read anything else on this blog, you probably know by now that I’m weary of trusting second-hand interpretations—the original data often tells a different story than the mouths claiming to interpret it. So instead of taking the USDA’s word as gospel, why not see what they’re basing their recommendations on?

Luckily, the USDA has a Nutrition Evidence Library, where they’ve compiled the studies they used to create their latest guidelines. Let’s dig in. (more…)

Vegetarians and Heart Disease: Will Ditching Meat Really Save Your Arteries?

Welcome to 2011! (Why don’t we have flying cars yet?) My new year’s blogolutions are to 1) write here more often and 2) actually answer emails. So far, I’m failing at both, but I’ve got 359 days left to clean up my act.

Sometimes, when I feel like I don’t have enough stress in my life and start craving a blood-pressure boost, I go to my old vegan haunts to read gems like these:

The only way meat can be digested is by putrefaction, our stomach acid is only 5% of that of a carnivore or omnivore so instead of being digested it basicly [sic] rots in your intestines which leaves toxic gases and waste to be absorbed into the blood. (From here.)

we know what’s happening. we’ve known for decades. however, we also have found that when we talk about the health detriments associated with eating the products of the corpse industries, people don’t believe us. (From here.)

[T]here is a single, sole cause to heart disease: cholesterol. If your total cholesterol is below 150 and LDL is below 70, you are essentially heart attack proof. What is the cause of high cholesterol? Saturated fat and animal products. (From here.)

Don’t you love this stuff? But I digress. What I want to talk about right now is one of the most oft-cited perks of being a vegetarian: an apparently lower risk of heart disease compared to omnivores. A recent paper called Chemistry Behind Vegetarianism sums it up by saying “Omnivores have a significantly higher cluster of cardiovascular risk factors compared with vegetarians, including increased body mass index, waist to hip ratio, blood pressure, plasma total cholesterol (TC), triacylglycerol and LDL-C levels, serum lipoprotein(a) concentration, plasma factor VII activity, ratios of TC/HDL-C, LDL-C/HDL-C and TAG/HDL-C, and serum ferritin levels.”

This is a trend that some folks translate as “meat causes heart disease”—a sentiment I saw plastered all over the veggie message boards during my most recent lurking spree. I assume this belief is bolstered by all the perfectly-preserved chunks bacon found in meat eaters’ arteries during heart biopsies. (more…)

Hot Off the Press: A New “China Study” Links Wheat with Weight Gain

You’re going to hate me. This isn’t the wheat post, which means I’ve broken my “wheat is next” promise for the 80th time and should never be trusted with anything again ever. But during my nightly Pub(Med) crawl, I saw this nearly-new gem of a study glimmering in the dust and said to myself, “Wow. Wow! Wow.” By the third wow, a blog post was inevitable. So here it is. I promise this is truly interesting (not that me promising things matters anymore).

But first, some background.

A few years ago, a study hit the stands with the audacious title Vegetable-rich food pattern is related to obesity in China. The paper showed that among four diet patterns—“macho” (meat and alcohol), “sweet tooth” (sugary drinks and cake), “traditional” (rice, vegetables, pork, and fish), and “vegetable-rich” (vegetables, wheat, whole grains, and fruit)—only one had any relationship to obesity: the vegetable-rich pattern.

The study didn’t exactly receive a lot of press, probably because no one wants to think vegetables make people fat (including the researchers, who hummed and hawed their way to a half-baked conclusion—check out this post by Michael Eades). And as Stephan Guyenet explained, the study really showed a trend between wheat intake and weight gain, with the pounds rising as wheat replaced rice as a staple.

I mention this because the new study is actually a follow-up to the old one. It tracked changes in the participants’ weight over the span of five years, using the same method of divvying up food consumption into distinct diet patterns. In fact, here’s the table with their “factor loading” system, showing how various foods were weighted to determine adherence to each diet pattern. (Go ahead, click on it. You know you want to.)

I’m going to explain this study point-by-point before getting to the good stuff, because it’s a little complicated (but totally worth understanding).

Note that only two patterns use wheat as a factor: the “traditional” and “vegetable-rich” diets. The traditional pattern loaded inversely on wheat flour and positively on rice, whereas the vegetable-rich pattern loaded inversely on rice and positively on wheat. In simpler terms, that means the “traditional” pattern is rice based and the “vegetable-rich” pattern is wheat based. These two patterns are polar opposites in terms of their staple grain. The “macho” and “sweet tooth” patterns don’t take grain consumption into account.

After the researchers schemed up these diet patterns, they divided everyone into quartiles of adherence. Folks in the first quartile of any pattern had the lowest adherence to it, whereas folks in the fourth quartile ate diets most in line with that particular pattern. The paper only gives a detailed breakdown of the “traditional” diet quartiles and smaller summaries of the other three, but you can still see how food intake changes from quartile to quartile:

From the paper:

A clear increasing trend of the intake of fat was seen across quartiles of the ‘traditional’ pattern from low to high. Participants in the first quartile of this pattern had the highest intake of wheat flour and dietary fibre compared with the other groups. … There was a significant negative association between the ‘traditional’ pattern and energy density.

Darn right. The first quartile boasts an average wheat intake of 298 grams per day, versus only 21 grams in the fourth quartile. And fat intake rises from 75 to 87 grams per day from the first to fourth quartile. Energy density (calories per gram of food) also drops, although the researchers don’t mention that total energy intake (calories) is actually highest in the fourth quartile.

The researchers also note that “across quartiles of the ‘vegetable-rich’ pattern, the intake of energy, wheat flour and vegetable oil increased.” Most of that info didn’t make it into any tables, so we’ll just have to take their word for it.

Now here’s where it gets interesting.

The following table shows the five-year weight change for the different quartiles of each diet pattern. Remember that the “traditional” and “vegetable-rich” diets are the only ones defined—at least in part—by wheat consumption (or lack thereof). (A) is the traditional pattern, (B) is the macho pattern, (C) is the sweet-tooth pattern, and (D) is the vegetable-rich pattern.

What stands out here? How about this:

After adjustment for age, sex and baseline weight, the ‘traditional’ dietary pattern was inversely associated with weight gain, while the ‘vegetable-rich’ pattern was positively associated with weight gain. … No significant associations of the ‘macho’ and ‘sweet tooth’ patterns with weight gain were found.

What interests me is that the largest change in weight out of any of the graphs—1.4 kilograms—occurs between the first and second quartile in the “traditional” pattern. This corresponds with a drop in average wheat intake from 298 to 40 grams per day. (Without knowing the actual per-quartile numbers for the “vegetable-rich” pattern, it’s impossible to say how changes in wheat consumption match up with that graph, although the researchers already stated that wheat consumption rises throughout the quartiles.)

The inverse relationship between the “traditional” pattern and weight (and therefore wheat and weight) doesn’t seem to be confounded by other factors, either:

In the stratified multivariate analyses, an inverse association between the ‘traditional’ dietary pattern and weight gain was present in subjects aged < 40 years and ≥ 40 years, in non-smokers and smokers, in overweight and normal-weight subjects, in alcohol drinkers and non-drinkers, and in men and women. There were no significant interactions between any of the above factors and the ‘traditional’ dietary pattern with weight gain.

The connection between wheat and weight was so prominent in this study that the researchers (who carefully tiptoed around the subject in their 2008 writeup) couldn’t beat around the bush any longer. They slammed the “discussion” section with a giant wall of wheat text. Since I’m not sure how long the study will be available for free, I’ll quote the relevant parts right here (interspersed with some commentary):

A large difference in the intake of rice and wheat flour was found across quartiles of the ‘traditional’ dietary pattern. It represented two different sub-patterns with two different staple foods in inverse proportions, i.e. rice and wheat.

(No quibbles there. But the next part is where they try painfully hard to rationalize the wheat-weight connection.)

Rice is a low-energy food that contributes to the bulk of the traditional diet. Compared with wheat, rice absorbs more water when cooked. In addition, different cooking methods are used in preparing these two staple foods. For instance, steamed rice contains twice the amount of water and half of the energy compared with steamed bread(17). Thus, the energy density of the rice staple diet is usually lower than the one based on wheat.

(Regardless of energy density, the fourth quartile for both diet patterns show that the rice-based pattern had a higher average calorie intake than the wheat-based pattern, yet lower five-year weight gain—0.0 kilograms versus 1.6 kilograms.)

Since the content of wheat was only predominant in the first quartile of this dietary pattern, this may partly explain the negative association between the ‘traditional’ pattern and weight gain in the present study.

(Ding, ding, ding. But is it because wheat has lower water content, as they suggest, or does our favorite grain somehow wreak metabolic havoc? The weight changes in the “traditional” pattern echo wheat consumption more consistently than total energy intake.)

Also, this association could not be explained by fat intake, since a higher intake of the ‘traditional’ pattern was associated with a higher intake of fat. Intake of fibre was the highest among people in the first quartile of the ‘traditional’ pattern. Thus, the benefit of weight maintenance of the traditional dietary pattern was not related to dietary fibre.

(Blasphemy! How did such nonsense pass peer-review?)

The reason I find this so fascinating is that it perfectly corresponds with the patterns in the Oxford-Cornell China Study, which showed that wheat was the single biggest contributor to BMI out of any diet variable. Calories didn’t matter. Fat didn’t matter. Weight followed the wheat.

I recommend reading the full study before the Powers That Be shove it behind a pay wall (or before the wheat industry files a lawsuit). And I’d say my real wheat/heart disease post is coming up next, but I don’t want to jinx myself. It’s on the way, though. I promise (?).

Brand-Spankin’ New Study: Are Low-Carb Meat Eaters in Trouble?

We interrupt your regularly scheduled wheat broadcast for an important announcement!

A few of you lovely readers emailed me today (thanks!) about the study Low-Carbohydrate Diets and All-Cause and Cause-Specific Mortality just published in the Annals of Internal Medicine. This paper compares mortality rates for folks eating a so-called “animal-based diet” versus a so-called “vegetable-based diet,” both of them so-called “low carbohydrate.” I finally got a chance to look at it, and indeed, a glance at the abstract looks a little spooky for any low-carb omnivores out there:

A low-carbohydrate diet based on animal sources was associated with higher all-cause mortality in both men and women, whereas a vegetable-based low-carbohydrate diet was associated with lower all-cause and cardiovascular disease mortality rates.

Oh noes! This abstract sounds vaguely China-Study-esque, with the conclusion that plant-based diets are healthier than ones featuring more animal foods. Was this study really comparing hardcore meat eaters with plant noshers, like the abstract implies? Is animal protein poison after all? Is it time to ditch the steaks and bow down in phytoestrogenic reverence to the almighty tofu? (more…)