Science Diet

Science is all the rage in our modern age, taking the place of religion and philosophy in many people’s lives.  But because science has become the one-size-fits-all replacement for intellectual pursuit, the abuse of science has blossomed.  And to be honest, even much of the science we cite in support of our low carb / paleo / primal diets falls far from the ideal of the scientific method.

You might think I’m fretting about questionable statistical methods by qualified researchers, the mass media’s mangling of science stories to imply that fructose causes cancer, or emphasis on the USDA’s Food Pyramid by people who should know better, but that’s not my main concern today.  What bothers me most is the improper use of science to support a particular position or sell a product.  Science is not used for inquiry and discovery, but as a sales method to impart a patina of respectability to otherwise dubious claims.

On Low Carb Daily, our news aggregator for low carb, paleo and primal articles and news, we categorize the articles according to the author’s expertise.  The Medical Blogs category is reserved for degreed medical doctors with current or past practice with actual patients.  Researchers are degreed individuals with doctorates or master’s degrees in a related field, with the idea that they at least understand human biology.  Advocates are those of us who may have a specialty in another field, but are interested in the low carb way of life, and contribute a lot to the community through published books, movies or websites that go beyond personal blogging.  Two categories address the “regular people” that contribute, Personal Sites and Recipe Sites.  We are not attempting to impose a hierarchy of importance, as some of the most useful low carb information is found in the personal experiences of regular people.   But when you read an article making a scientific claim, you want to know more about the background of the person making the claim.  The scientific opinions of doctors and researchers should carry more weight than personal trainers, dietitians and the rest of us mere mortals.

Paleo and primal diets are becoming more popular, and many new adherents are excited about trying to match modern day diets to what is called “evolutionary eating”.  But there is an almost religious fervor being expressed about it, with some claims that don’t pass the smell test, such as:  grass fed beef is much better than grain fed beef because of the Omega 3 to Omega 6 ratio.  When you look at the actual amounts of either fatty acid in both types of beef, you see that it really doesn’t matter which one you eat for your body’s overall Omega 3 / Omega 6 ratio, as the difference in total intake is about 30 mg.  While there may be philosophical or ethical reasons to prefer one over the other, emphasizing the minor difference in Omega 3 / Omega 6 ratios is pseudo-science.

Dan, at the blog At Darwin’s Table, is a biologist who understands both science and the on-line community.  He identifies one of the problems with the way lay people approach the idea of evolutionary eating:

Just because an organism possesses a certain trait does not mean that this trait is adaptive. Or was evolved for that purpose. Which brings me to the paleo diet. Too many people make bold statements about what humans are adapted to eat. They do this often by simply making judgments based off what they think or have heard. Although the idea of the paleolithic diet is very much rooted in scientific theory, when people do this it starts to become more of a belief. In other words people will find examples to confirm what they want to believe.

For example, are Inuit adapted to eating lots of fat or did they do it because thats all they had access to? This is just an example and certainly easily investigated by looking at fat metabolism in Inuit people. But until that research is done (if it has been done) people should be careful when saying that some hunter gatherer group is adapted to eat lots of fat. Or worse that humans are adapted to eating lots of fat.

Dan recently had a guest post from JP, a student studying to be a kinesiologist, who expanded on the problem from his perspective:

I’m concerned about the future of evolutionary eating. I was attracted to paleo eating because of its scientific component. The evolution theory is still, after all those years of scientific progress, one of the most popular theories. It’s really hard to scientifically (not religiously) argue against evolution, natural selection and the concept of adaptation. This gave me the strong foundation I needed to build my lifestyle on. Obviously, whenever you build a house, you want to make sure it stands on solid ground. No one wants to have to start back again every couple of years. On top of that, evolutionary eating is based on anthropology – which happens to be my favourite science. Anthropology has a lot to offer in  the nutrition debate.

[…]

As evolutionary eating became more popular, people forgot about some of its important parts, or made up new concepts that I would argue are pseudo-science at best. Indeed, more often than not, people reinterpret some data and make it look like it’s optimal.

There is more there in JP’s post, so I encourage you to read the original.

You can find a ton of information on-line.  And a lot of misinformation.  I have become more aware of the abuse of science, but finding the balance between healthy skepticism and outright cynicism is difficult.  I hope  more people with science backgrounds help clarify issues, as Dan and JP have done. And I hope those making claims are a bit more circumspect in their pronouncements (but alas, that may be too much to ask!)

Cancer, Fructose and Ketogenic Diets

Dana at Hold the Toast has several articles on the problems with fructose, including the hidden fructose in Agave Nectar. Her latest post repeats the wide-spread media analysis of a recent study where fructose shows itself to be a superior fuel for pancreatic cancer cells. Unlike most of the media accounts, Dana focuses on the important part of the story:

It was the first sentence in the abstract that really caught my eye: Carbohydrate metabolism via glycolysis and the tricarboxylic acid cycle is pivotal for cancer growth, and increased refined carbohydrate consumption adversely affects cancer survival. Got that? Carbohydrates are pivotal for cancer growth. Eating carbs means you’re less likely to survive cancer. Remember that next time someone tells you you’re courting cancer by eating meat and eggs instead of grains and fruit.

Unlike some reports in the press and blogosphere elsewhere, the study doesn’t show that fructose causes pancreatic cancer or feeds cancer cells in the body. The researchers used pancreatic cancer cells for the test, isolated in petri dishes, and then added more glucose or fructose to the solutions. They were then able to measure the rate at which the cells divided and grew, and found that:

In comparison with glucose, fructose induces thiamine-dependent transketolase flux and is preferentially metabolized via the nonoxidative pentose phosphate pathway to synthesize nucleic acids and increase uric acid production.

Ah. I always suspected fructose was preferentially metabolized via the nonoxidative pentose phosphate pathway. I’ll have to have biologist or doctor sort out that sentence for me.

My understanding of the way fructose is metabolized by the liver leads me to believe a cancer cell in your pancreas would never see fructose. It would see glucose in the blood stream, which it uses to divide and grow just fine. Dr. Briffa explains:

The study in question found, in summary, that feeding cancer cells fructose caused them to proliferate. Obviously, this is not a good state of affairs. The authors of the study suggest that reducing intake of refined fructose may disrupt cancer growth.

When fructose is consumed it travels to the liver. The vast majority, if not all, of it is metabolised in the liver, meaning that little or any reaches the general circulation. However, there is always the potential that uric acid might exert a considerable direct effect on the liver. We can perhaps see the potential for fructose to be directly toxic to the liver in some evidence linking its consumption with ‘fatty liver’ (a build-up of fat within the tissue of the liver).

But what about other tissues in the body?

One of the effects of fructose is to cause a ramping up of uric acid in the liver. Uric acid is, as its name suggests, acidic. And the relevance of this is that some cancer cells grow better in an acidic environment. Now, the body has processes by which it regulates the pH (acidity/alkalinity) of the bloodstream within quite a narrow range. However, there is the potential for the pH to drop (become more acidic) and this might perhaps encourage cancer growth.

I’m not aware of any evidence linking fructose consumption and cancer in the scientific literature. However, this recent study, I think, gives us another potential reason for giving fructose and high fructose corn syrup a miss.

Those wanting to read more about fructose can follow this MegaSearch Link for all the articles by our Low Carb Daily index of websites. We select only low carb / paleo / primal sites for this search, targeting the results to the interests of our readers.

I am as eager as the next low carber to pounce on a media story that equates fructose with cancer, but let’s be honest: this study doesn’t say that. We have a duty to try and report things accurately, although for us laypeople, it can be difficult. Remember, we are critical of the old idea that eating cholesterol added cholesterol to the bloodstream. It makes sense on one level, and that would be great, except it simply isn’t true. We know that now. Why are we so quick to say eating sugar feeds cancer? We need our theory validated with research.

On the other side, the Corn Refiner’s Association (CRA) has already weighed in with a critique of the study, so the battle is engaged. And you know what? Some of their criticisms are valid.

Dietary science is the bastard son of real science, yet the mass media treats every new study like it’s E=MC2.

As Dana pointed out, the real problem is that cancer cells use glucose, and a high blood glucose level may assist in their growth. And carbs lead to high blood glucose levels. It sounds reasonable that a low carb diet would help slow cancer growth, but are there any studies showing that effect?

Well, the University of Würzburg Hospital has recommended a low carb, ketogenic diet for cancer patients since 2007. And they link a few studies on their site.

At least one other study shows that starving cancer with a very low calorie, ketogenic diet may work. This isn’t the type of diet we are on: calories were limited to 600 per day, and the ratio of fat to carbs and protein was 4:1. Italian and American researchers used this extreme, ketogenic diet and traditional treatments (radiation and chemotherapy) and mapped the progress of a particularly bad cancer: glioblastoma multiforme (brain cancer):

After two months treatment, the patient’s body weight was reduced by about 20% and no discernable brain tumor tissue was detected using either FDG-PET or MRI imaging. Biomarker changes showed reduced levels of blood glucose and elevated levels of urinary ketones. MRI evidence of tumor recurrence was found 10 weeks after suspension of strict diet therapy.

This is one study, on one patient, with a very strict dietary regime that showed promise. It doesn’t mean that staying in ketosis prevents cancer, or that a different type of cancer would be slowed by the same ketogenic diet. It does point out the need for further research.

Needless to say, someone with cancer would want to discuss this approach with their doctor as an adjunct to standard treatment, and not risk “going it alone” based on this one study.

Lies, Damn Lies and Statistics

The title of this article refers to the phrase Mark Twain popularized, that he attributed to Disraeli. There is a touch of irony in that no one can actually pinpoint where Disraeli said any such thing. But you get the point.

Sometimes, even when its good news for low carbers, the stats are manipulated in such a way to mask the true advantage.

Dietary science is the bastard son of science, with correlation in cohort studies trumpeted as “proof” by the media. A randomized controlled study is a better model as it helps eliminate various types of bias.

We were all excited to see the new study that compared low fat to low carb dieting, and found that cardiovascular risk factors were not greater with a low carb diet … in fact, they were lower! And this was a randomized controlled trial, with over 300 participants who were followed over a two year period; that’s a very long time in dietary science!

But in scouring the web for more authoritative voices to add to our new low carb news aggregator LowCarbDaily.com, I found something shocking. From a layman’s perspective, the study is horribly flawed, and grossly underestimates the beneficial impact of a low carb diet. How so? The researchers used a statistical method called “Intention To Treat” (ITT). This method uses the results from all the participants, even those that drop out, diluting the true impact of the diet on those that continue to follow it. As Pål Jåbekk writes in the Ramblings of a Carnivore blog:

Now, intent to treat analysis is a perfectly fair method to use. But it means that the results cannot tell us which dietary approach is the more effective. If we want to know which diet causes the greatest weight loss we must look at the data from the participants that actually followed the diet, and only those. What the results of this recent study tells us, is the effect of being put on a diet as opposed to the effect of following one. Is it really so bloody impossible to include data on compliers vs non compliers? As interesting as it is to know the effect of being put on a diet I for one would also like to know the actual effect of following the diets.

Jåbekk links to a paper by Richard D Feinman on ITT where the curious practice is further explained:

In ITT, the data from all subjects who are randomized to treatment are analyzed regardless of whether subjects followed the protocol or not (“analyze as randomized”). At first hearing, the idea of ITT is counter-intuitive if not completely irrational – why would you include in your data, people who are not in the experiment? – suggesting that a substantial burden of proof rests with those who want to employ it. No such obligation is usually met and, particularly in nutrition studies, such as comparisons of isocaloric weight loss diets, ITT is frequently used without justification. ITT analyses are typically reported in a way that implies that they have the final say on efficacy and it is even argued that, once assigned to an experimental group, all data must be included in the analysis even if subjects do not comply with the protocol.

Feinman’s article includes this table, showing how ITT masks the true response of those that follow a low carb diet in two prior studies:

Table 1

Weight Loss in Diet Comparisons and the Effect of Analysis.

Data for 12 months Weight Loss (kg)

With Drop-outs SD Only Study Subjects SD

Foster, et al. low carb 4.4 6.7 7.3 7.3
low fat 2.5 6.3 4.5 7.9
difference 1.9 2.8

Stern, et al. low carb 5.1 8.7 7.3 8.3
low fat 3.1 8.4 3.7 7.7
difference 2 3.6

Feinman Nutrition & Metabolism 2009 6:1   doi:10.1186/1743-7075-6-1

Keep in mind that in these prior studies, the end result reported in the paper was that weight loss was just about equal with either a low carb or low fat diet. That’s the message if you use the numbers that include the people who dropped out of the diet, in the “With Drop Outs” column, where the low carb group in the “Foster, et. al.” study only lost 1.9 kg more than the low fat group. But look at the column titled “Only Study Subjects”, comparing those that actually followed the low carb or low fat diet, and you find that the low carb dieters actually lost 2.8 kg more than the low fat dieters (47% more weight). For the “Stern, et. al.” study, we find even greater numbers: a difference of 2 kg between the diets using ITT and 3.6 kg when counting those that actually followed the diet plans. That’s 80% more weight loss. Feinman continues:

Thus, the conclusion that weight loss is the same at 1 year on low-carbohydrate diets and conventional diets comes from an ITT analysis and, as stated, is misleading. Because dieters and practitioners reasonably want to know the potential of a diet, it seems that authors must be very circumspect about describing results. The ITT analysis, again, only answers the question about assignment to a diet in a particular experimental setting, and does not address the question as to which is the more effective diet if adhered to. The fact that it is acknowledged that the substantially greater improvement in plasma triglycerides on the low carbohydrate diet compared to the low fat diets persisted for one year should have been taken as a sign that it would be surprising if the diets were the same.

While the news about the good results was welcome, it is disheartening to see that the results are still not being reported in an easy to understand manner. It appears the new study did not include the results only from the people who adhered to the diet, but only reported the “Intention to Treat” numbers.

Free Paleo e-Book

Douglas Robb is a personal trainer with a health and fitness blog, Health Habits. Robb is an advocate of a paleo diet for his clients, but he saw a problem with the proliferation of different paleo diets, with some eschewing cooked food, some advocating periods of fasting, modern blood-letting, etc. The normal person researching the lifestyle can find exactly the situation Robb describes:

. . . what started out as a very simple, very healthy way of eating has splintered into a million and one different tribes – some with very restrictive rules and others much more relaxed.

Robb’s solution is a basic, flexible diet he dubs “A Paleo Diet for the 21st Century”. He attempts to incorporate the most important parts of the less and more restrictive paleo plans out there to provide some guidelines that normal, mortal humans can follow. And he gives it away. Register on his site for a free copy and he will email you the link to download the 27 page e-book.

I’m a low carb guy, for very specific medical reasons (metabolic syndrome, primarily). Reducing carbs also helped me lose 50 pounds, eliminated my GERD, and reduced my blood pressure. The paleo lifestyle appeals to me, but the restrictions found in some advocate’s blogs seem to go too far. In my view the value of the paleo approach to what is, essentially, lower carb eating, is this: it provides a philosophical framework for the diet.

Most long term dieters have more than fat around the middle. Like everyone else, they have a brain, which is comprised mainly of water and fat (see, not all fat is bad!) And in that fatty tissue of the brain is the record of every failed diet and broken promise. Addressing the “fat between the ears” is at least as important as the fat around the middle.

Low carb dieters use books like The Protein Power Lifeplan to provide an intellectual framework for the new way of eating. Beyond the important studies and plethora of scientific facts the dieter knows some very simple precepts: keep carbs low and eat enough protein.

But what I’ll call the Paleo Philosophy can provide the same intellectual framework. Looking in the supermarket, you can ask yourself if a caveman would have had access to the food you see. Meat, fruit, and veggies all make the grade, and the majority of them are just fine for most people. Like a dedicated low carber, you would avoid the center aisles, knowing that Grog would not have had access to Twinkies.

And there’s nothing wrong with combining the two approaches if you like; reduce carbs while adopting the basic premise that if it wasn’t a food 10,000 years ago, you shouldn’t eat it. And Robb’s free e-book can help you navigate the maze of paleo approaches to find one that is flexible and suitable for life in the 21st century.

New Site: Low Carb Daily

Low Carb Daily is a new concept in Low Carb news; an aggregator that previews the most recent stories in the Low Carb blogosphere. The entire article is not reprinted, just the headline and lead paragraph. Links to the original article allow you to click through and read what interests you, on the original author’s site. This provides the easiest way to review the dozens of personal stories, articles and news generated every day in the Low Carb world.

Several features make the site unique:

  • Site Search: Search the latest articles for any current topic
  • MegaSearch: Search all Contributor’s Sites, and only their sites, for any topic, past or present
  • Categories: Sort all articles by the author’s category

The front page always displays the most recent articles, but you can sort the collection several different ways. The search method works, of course, but you can also display articles written by members of a particular category.

There are six categories based on the author. Advocates are low carb enthusiasts who contribute a tremendous amount of information to the low carb world. The Low Carb News category tracks the latest news in popular media about low carb topics, direct from Google News. Medical Blogs presents low carb articles written by medical doctors. In a similar vein, the Researchers category includes those with doctorates, or other advanced degrees. Personal Sites presents the posts by bloggers on their own low carb journey and Recipes shows you the latest from the low carb recipe sites.

Low Carb Daily also features a new Forum, not tied to a specific company or organization. Charter members can help design and build the community as an independent forum. As the site is brand new, there is no activity there yet.

Low Carb Daily is ad-supported, with free membership. Membership is only required to post in the Forum, but all of the rest of the site’s features can be enjoyed anonymously. Advertising on the site is intended to be non-intrusive and clearly marked. A Google ad is placed at the top of the page, and an Amazon Associate store features books and products for low carbers. Two ads appear in the sidebars for products from the store, clearly marked as “Shop!” items.

Low Carb Daily is sponsored by Low Carb Age and HOSTkabob.

Outcomes After 2 Years Compared

A 2 year comparison of reduced calorie, low fat diets and low carb diets, with counseling and medical intervention, was published today in the Annals of Internal Medicine:

Successful weight loss can be achieved with either a low-fat or low-carbohydrate diet when coupled with behavioral treatment. A low-carbohydrate diet is associated with favorable changes in cardiovascular disease risk factors at 2 years.

The study was a randomized, parallel group trial spread over three medical centers and consisting of 307 participants, lasting two years.

For the low carbohydrate group, the study limited the intake of carbohydrates to 20 grams per day for 3 months. There was no restriction on the amount of fat or protein the low carb participants could eat. After three months, the low carb participants increased their carb intake by 5 grams per day for a week, then increased in the next week by another 5 grams, monitoring the results until they reached a point where they were not losing weight. The counselors fine-tuned the diet for each individual and gave them encouragement.

For the low fat group, daily calories were slashed to 1200 to 1800 kcal per day, with less than 30% of the calories from fat. Like the low carb group, the low fat dieters were given “comprehensive behavioral treatment”.

Weight loss was approximately 11 kg (11%) at 1 year and 7 kg (7%) at 2 years. There were no differences in weight, body composition, or bone mineral density between the groups at any time point. During the first 6 months, the low-carbohydrate diet group had greater reductions in diastolic blood pressure, triglyceride levels, and very-low-density lipoprotein cholesterol levels, lesser reductions in low-density lipoprotein cholesterol levels, and more adverse symptoms than did the low-fat diet group. The low-carbohydrate diet group had greater increases in high-density lipoprotein cholesterol levels at all time points, approximating a 23% increase at 2 years.

The low carb group had better blood pressure, triglyceride levels, vLDL, and higher levels of the good cholesterol, HDL. Plus, they were eating BACON.

It would be interesting to see if the low carb group was happier with their new eating regime than the low fat group. The study did say that the attrition rate was pretty high for both groups at the two year mark.

The study was funded by the National Institutes of Health.