Assorted Thoughts About the 2010 Dietary Guidelines

In the past week, I've been rooting through the USDA's 2010 Dietary Guidelines (1). Here are a few of my thoughts.

Positive

One of the things I've been enjoying recently is watching health authorities shift away from a nutrient-oriented philosophy in favor of a more food-oriented philosophy. For example, I recently read a nice editorial by Drs. Dariush Mozaffarian and David S. Ludwig (not associated with the USDA) that encapsulates this (2). Here's a quote:

Nutritional science has advanced rapidly, and the evidence now demonstrates the major limitations of nutrient-based metrics for prevention of chronic disease. The proportion of total energy from fat appears largely unrelated to risk of cardiovascular disease, cancer, diabetes, or obesity. Saturated fat—targeted by nearly all nutrition-related professional organizations and governmental agencies—has little relation to heart disease within most prevailing dietary patterns. Typical recommendations to consume at least half of total energy as carbohydrate, a nutrient for which humans have no absolute requirement, conflate foods with widely divergent physiologic effects (eg, brown rice, white bread, apples). Foods are grouped based on protein content (chicken, fish, beans, nuts) despite demonstrably different health effects. With few exceptions (eg, omega-3 fats, trans fat, salt), individual compounds in isolation have small effects on chronic diseases. Thus, little of the information found on food labels’ “nutrition facts” panels provides useful guidance for selecting healthier foods to prevent chronic disease.

In contrast with discrete nutrients, specific foods and dietary patterns substantially affect chronic disease risk, as shown by controlled trials of risk factors and prospective cohorts of disease end points

Although this approach may seem radical, it actually represents a return to more traditional, time-tested ways of eating. Healthier food-based dietary patterns have existed for generations among some populations.

Tell it! Although he doesn't use the word nutritionism, that's basically what he's arguing against. Dr. Mozaffarian seems to represent the less reductionist school of nutrition, which is a more informed version of what nutrition pioneers such as Sir Edward Mellanby, Dr. May Mellanby, Dr. Weston Price and Sir Robert McCarrison advocated.

Although the 2010 guidelines are too focused on nutrients for my taste, they do spend some time talking about food groups and eating patterns, for example, recommending an increase in the consumption of vegetables, fruit, whole grains and seafood. They also recommend Mediterranean and plant-focused eating patterns. Although I don't think their recommendations quite hit the mark, they do reflect a shift in thinking.

Another thing I enjoyed about the Guidelines is the table on page 12 of chapter 2, which shows just how messed up the average American diet is. The number one source of calories in all age groups is "grain-based desserts". The next five in adults are yeast breads, chicken dishes, soda/sports drinks, alcohol and pizza. To see typical American food habits presented like this just blows me away. They call this the "obesogenic environment"; the idea that we're surrounded by tasty but unhealthy food and situations that favor the consumption of it. I agree.

The Guidelines also contain a surprisingly accurate one-sentence review of the glycemic index literature:

Strong evidence shows that glycemic index and/or glycemic load are not associated with body weight; thus, it is not necessary to consider these measures when selecting carbohydrate foods and beverages for weight management.

Negative

The first problem is the creation of the category "solid fats and added sugars", abbreviated SoFAS. With the creation of this term, they lump pastured butter together with Crisco and Red Hots. If they've been hiding the evidence that pastured butter, virgin coconut oil or red palm oil contribute to heart disease, I'd like to see it so I can stop eating them!

Another problem is their list of recommendations to curb the obesity epidemic. They say:

The current high rates of overweight and obesity among virtually all subgroups of the population in the United States demonstrate that many Americans are in calorie imbalance—that is, they consume more calories than they expend. To curb the obesity epidemic and improve their health, Americans need to make significant efforts to decrease the total number of calories they consume from foods and beverages and increase calorie expenditure through physical activity.

Looks like we have Sherlock Holmes on the case. Now that we have this information, all we have to do is tell overweight people to eat less and they'll be lean again! What's that, they already know and it's not working?? Someone should tell the USDA.

Jokes aside, I do think energy balance is a huge issue, perhaps even the central issue in chronic disease risk in affluent nations. The basic problem is that Americans are eating more calories than is optimal, and they have a very hard time stopping. It's not because they have less willpower than their stoic ancestors, it's because their bodies have decided that overweight/obesity is the new lean, and they defend that higher level of fat mass against changes. Simply telling an overweight person to eat fewer calories, without changing the dietary context, is not very effective in the long term, due to compensatory mechanisms including hunger and increased metabolic efficiency (fewer calories burned for the same muscular exertion).

What does the USDA recommend to lose fat or maintain leanness?

• Count calories. Doesn't work for most people, although I acknowledge that it is physically possible to lose fat (and lean mass) by restricting calories.
• Reduce sweetened beverages. Thumbs up.
• Serve smaller portions. As far as I know, this rests exclusively on very short-term studies that showed that food consumed at a single meal or three is reduced if portion size is smaller. I guess it can't hurt to try it, but I'm not convinced it will have any effect on long-term body fatness. I think restaurant portion sizes have probably increased because people eat more, rather than the other way around, although both could be true.
  
• Eat foods that are less calorie dense. I think vegetables are healthy, but is it because they're less calorie-dense? Why is dietary fat intake generally not associated with obesity if it's the most calorie-dense substance? Why do many people lose body fat eating energy-dense low-carbohydrate diets? Not convinced, but I'm feeling open minded about this one.
• Exercise more and watch less TV. Exercise is good. But don't let it make you hungry, because then you'll eat more!

Overall, I think their recommendations for fat loss are not very satisfying because they don't address the core reasons Americans aren't in energy balance. Eliminating sweetened beverages and exercising are the most solid advice they offered in my opinion. The rest strikes me as wishy-washy advice that's offered because they have to say something.

At one point, they talk about changes in the US diet that have corresponded with the obesity epidemic:

Average daily calories available per person in the marketplace increased approximately 600 calories, with the greatest increases in the availability of added fats and oils, grains, milk and milk products, and caloric sweeteners.

Let me edit that so it's more complete:

Average daily calories available per person in the marketplace increased approximately 600 calories per day, 250 calories of which were actually consumed (USDA and NHANES). Added fats increased, due to a large increase in seed oil intake, but total fat intake remained approximately the same because of a roughly equal decrease in fatty meat and whole milk consumption (USDA and NHANES). Grain intake, predominantly wheat, increased, as did the consumption of refined sweeteners, predominantly high-fructose corn syrup (USDA).

It reads a bit differently once you have a little more information, doesn't it? Animal fat intake declined considerably, and was replaced by seed oils, in parallel with the obesity and diabetes epidemics. Maybe it contributed, maybe it didn't, but why not just be forthright about it? People appreciate honesty.

Conclusion

Although the 2010 USDA Dietary Guidelines show some promising trends, and contain some good information, I hope you can find a better source than the USDA for your nutrition advice.

Cryptocontributions

John Regehr of Embedded in Academia has a great post about Cryptocontributions in writing:

Even when interesting and unexpected results make it into a paper (as opposed to being dismissed outright either by the PI or by a student doing the work) the discussion of them is often buried deep in some subsection of the the paper. When this happens — and the interesting development is not even mentioned in the abstract or conclusion — I call it a “cryptocontribution.” Sometimes these hidden gems are the most interesting parts of what are otherwise pretty predictable pieces of work. When authors are too focused on getting the thing submitted, it’s really easy to shove interesting findings under the rug. Certainly I’ve done it, though I try hard not to.

I like that in his post, there is a little bit of a cryptocontribution, and that is - by being so conference deadline-driven, Computer Science is, as a Science, still a bit immature. If I have time I'll write more about this topic next week, because it's an idea I've been pondering for awhile.

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PS - A note to John and other bloggers who run WordPress type-things - I seem to be unable to leave IP-anonymous comments on your blogs via Tor. I try, and try, and try, and am thwarted. So I've given up! But do know I'd love to comment if I could. Maybe this summer if I have some free time I'll write a Tor browser plugin that works with WordPress.

What are you missing? AIX

Happy February Readers,

I didn't want to miss last week's posting, but I also didn't have the time to make a quality post before leaving on a trip. So quality over quantity will hopefully gain favor with you. I'm taking a break in the What was wiped series to give myself some more time to gather what I need and instead I am continuing the What are you missing series in this post.

Doing forensics on specialized servers, which I will define as anything non wintel and whose file systems have no parsers supported in forensic tools, is an interesting challenge. You have to:

1. Research where the system log files exist

2. Determine what format the logs are in

3. Capture the metadata of the file system

4. Determine if the file system can be parsed by anything but the running OS

5. Determine if it's feasible to image the server via DD

6. Determine if here is any hardware specific evidence that exists

A good example of this would be an older AIX system as detailed below

Read more »

yea, yea

i know, i said i would show y'all this week but it's taking a lot longer then anticipated to get my kitchen back in order.  painting is done and my kitchen is no long bright green, and i think, i kind of like her :)  hope your week is going peachy!

John Nash's Thesis

You know those games where you pick the street you grew up on and add on your cousin's middle name and your first pet's name and then you have the name for a band?

This post isn't actually about that. (Though I do think "John Nash's Thesis" would be a great name for a band). This post is about those myths and legends you hear as a nascent researcher. Probably the first of these I ever heard was: "John Nash's dissertation was only four pages long."

This really is one of those legends that seems to have suffered a whisper-down-the-lane effect. Wikipedia claims it weighs in at 28 pages, on Princeton's website it is 32. Some forum contributor on degreeinfo.com claims it was only 23 pages long.

In any case, it was short, sweet, and revolutionary.

I really respect that. I've slogged through CS dissertations that were approaching 250 pages in length. By the middle you start pulling your hair out and wishing they had the brevity of John Nash.

My dissertation will not be 23 pages long. Why, the table of contents alone is pushing 30! (Just kidding!) (mostly).