Monday, June 29, 2009

Did following the experts' diet advice make us any healthier?

To kick things off at my new blog devoted only to health, food, and nutrition, I'm going to show how what we've been eating has dramatically changed in the past 100 years. Most nutrition experts tell us to cut back on red meat and dairy -- and to eat white meat or fish if we must -- while increasing our intake of grains and fruits and vegetables. Since we know that obesity, type II diabetes, and the other symptoms that make up Metabolic Syndrome have been shooting up since roughly the 1970s, we can see whether our changing diet has anything to do with it.

Did we follow the experts' advice? And if so, did it do us any good? Let's see.

The data come from the USDA (see here for the spreadsheets), and they measure the availability of various food types for each year. This isn't the same thing as consumption, but because availability (supply) reflects the demand for it (consumption), when availability goes up or down, we're safe to conclude that consumption is doing so too. The data are all per capita, so we've already accounted for America's changing population size.

We'll start with the demonized foods: red meat (saturated fat! -- actually, most of it is monounsaturated), dairy (more saturated fat! -- which explains why the cheese-eating French have such awful health), and eggs (cholesterol! -- you know, that stuff that gets turned into your pesky sex hormones and vitamin D).

We've been throwing red meat overboard since about 1970. Dairy has been way down since 1940, although there's a moderate rise starting in 1980 (my guess is that it's mostly cheese for pizza). And eggs have plummeted since 1950.

But even the fruits and nuts people will admit that we need some protein -- we should just get it from white meat (chicken breasts with 0 g of fat) or fish (which, unless you eat sardines or salmon, probably won't have any fat either). Have we been choosing these more supposedly healthy forms of protein? You bet. Here are the graphs for poultry and fish:

Poultry has been skyrocketing exponentially since 1940, and fish too has been increasing since 1960.

And what about those cure-all fruits and vegetables? Eat mostly fruits and vegetables, we're told, and you'll be as robust and affable as any PETA member. Unfortunately these data only go back to 1970 instead of 1910, but the trend is still clear -- we've been scarfing down more spinach and blueberries (hopefully not together) than ever before. I've also included graphs for specific foods like the starchy potato vs. the more nutritious dark, leafy green vegetables.

And of course, any healthy diet requires grains -- after all, they form the solid foundation of the Food Pyramid. It's just plain common sense that you can't thrive unless you crunch your way through a sack full of Grape Nuts every morning, isn't it? Here's the graph for grains:

Starting at least in 1910 (and perhaps earlier), we started putting grains to better use -- as bird feed -- but since 1970, we've been steadily reversing that practice. Now when we eat out, it's bread, breadsticks, pasta, rice, noodles, and more bread.

Finally, the one food that everyone agrees is bad for your health -- caloric sweeteners like sugar:

From the mid-1960s through the mid-1990s, we found it necessary to dump more and more sugar on our food -- probably because we'd switched to a tasteless diet of spinach and Special K. Still, for the past 15 years, we've been letting it go (likely as a result of switching to non-caloric sweeteners like Equal). So, we'd misbehaved for awhile, but we've been good -- honest! -- more recently.

To sum up, we've done everything the nutrition experts have told us to do -- and have so for decades. Aside from eating less sugar, all of these supposedly health-promoting changes began no later than 1970, with some beginning as far back as 1940. Surely that's enough time for the benefits to show up in national health statistics, right? Well, let's see what the end results of this gigantic national experiment are.

The experts began telling us what to eat in order to lower rates of heart disease, although once obesity and related metabolic problems became huge, they extended their guidelines to help us get thinner too. Here is a graph showing the incidence of heart disease during the period when all of these dietary changes had begun (from this AHA pdf):

Huh, that's odd -- our hearts seem to stubbornly resist the supposedly heart-healthy food we've been eating. These are total numbers, not per capita rates. Still, the number of people suffering from heart disease doubled from 1970 to 2000, even though the US population was only 1.4 times as big in 2000 (at 282 million) as in 1970 (at 205 million). Therefore, there was a real increase in heart disease rates that cannot be explained simply by a larger population.

Why do we need to look at "hospital discharges with CVD as first listed diagnosis" rather than deaths due to heart disease? Because we could be getting better at saving lives when a person already has heart disease -- in that case, the death statistics will make those sufferers of heart disease invisible. Checking into a hospital due to heart disease sheds better light on the group of people with CVD.

And as if you needed me to tell you what the obesity rates have been like recently, here's a graph showing the prevalence of obesity and overweight:

That's odd -- the lines are pretty flat before the mid-1970s, at least back to 1960 (and possibly before), and they only shoot up sometime in the mid-'70s. Looks like loading up on Total ceral, non-fat salad dressing, and potatoes hasn't done us much good in trimming our waistlines.

So, even though we've been scrupulously following the experts' advice about what to eat -- and those graphs above prove that -- we're more likely to suffer from heart disease, obesity, and other symptoms of Metabolic Syndrome. Does that mean that these so-called experts don't have the foggiest idea what they're talking about? Yes -- that's exactly what it means.

I doubt that eating more spinach has harmed us, obviously. The main culprits are eating more carbohydrates (potatoes, grains, and sweeteners) and eating less of the fatty animals products (red meat, dairy, and eggs). I won't go through the reasons why since, if you're reading a blog called Low Carb Art and Science, I assume you already know why.

But for those of you who, like most of us, weren't aware of how bogus the experts' advice was, here are three links that provide plenty of information in an easily understandable form:

Gary Taubes' lecture at Berkeley
, where he reviews the material in his encyclopedic book Good Calories, Bad Calories.

Tom Naughton's Fat Head blog, where you can buy the DVD of Fat Head, his hilarious spoof of Supersize Me, which lays out how different types of food promote or discourage obesity, depression, and so on. The movie is currently #1 in Amazon's comedy documentary section. (Imagine that -- a documentary that isn't maudlin or obnoxiously political.)

Michael Eades' blog, where the co-author of excellent Protein Power regularly explains the science behind many health and nutrition concerns that we have, especially when new studies come out.

Tuesday, June 23, 2009

New low carb blog

Just a place-holder post to make sure everything is working fine.