Sunday, July 24, 2011

Don't Believe What Dietitians Tell You About Diet

In just the past year, I've seen a lot of articles in mainstream publications refuting long-cherished dietary doctrine, and supporting many of the ideas put forward by "alternative" health systems. Here are a few.

First, according to Scientific American: "It's Time to End the War on Salt. The zealous drive by politicians to limit our salt intake has little basis in science." They cite articles in the American Journal of Hypertension and the Journal of the American Medical Association pointing to this, and go on to say that "the evidence linking salt to heart disease has always been tenuous".

Next, the LA Times comes around to the idea that carbs are the problem, not fat: "A reversal on carbs. Fat was once the devil. Now more nutritionists are pointing accusingly at sugar and refined grains… 'The country's big low-fat message backfired,' says Dr. Frank Hu, professor of nutrition and epidemiology at the Harvard School of Public Health… Some…would argue that we haven't evolved to adapt to a diet of refined foods and mass agriculture—and that maybe we shouldn't try."

The New York Times brings us an article arguing that counting calorie intake is not an effective way to lose weight. It matters more what we eat than how much we eat. "'There are good foods and bad foods, and the advice should be to eat the good foods more and the bad foods less,' (a cited doctor) said. 'The notion that it’s O.K. to eat everything in moderation is just an excuse to eat whatever you want.'". The "worst" food, by their measure, was french fries; the "best" was yogurt, with nuts close behind. (I guess I can keep eating yogurt with nuts for breakfast!)

Finally, a study showing that bacterial imbalance in the large intestine may affect the brain. "For the first time, researchers at McMaster University have conclusive evidence that bacteria residing in the gut influence brain chemistry and behaviour." (Citation.) Of course, Natasha Campbell-McBride has been saying this for years. (For much more on this subject, check out this post on Food Renegade's blog.)

Here are my (perhaps rhetorical) questions:

1. In the case of salt, how and why was the salt-hypertension connection elevated from a tenuously-supported hypothesis to a "fact"? And in the case of fat and carbs, what led to the promotion of the low-fat, high-carb diet? What went wrong with our scientific process?

2. How long will it take for the above-cited research to affect, say, the low-fat, high-carb food that patients are given in hospitals? The french fries and bread that kids are given in schools? How long will it be before educators, dietitians, and regulators catch up to the true best practices in the field of nutrition?

I am not asking these questions to be negative or show how clever and cynical I can be—I am asking them to open the door to questioning dietary authorities like the USDA and the various medical guilds. "Alternative" nutrition movements, while by no means perfect, are sometimes way ahead of the mainstream on important issues.

(This post is part of Health Home Economist's Monday Mania blog carnival. Please visit her great blog!)


Anonymous said...

It's quite simple. It takes a few years for those in power to shift their investments, first they have to see if the trend is long term, if it is then they begin to move their funds, and eventually claim that it was their idea in the first place.

Alex Lewin said...

Sad but true.

Heather said...

1. Read "Good Calories, Bad Calories", by Gary Taubes. I'm about 1/3 of the way through it right now, and he answers such questions. As for what went wrong: follow the money. There's a LOT more money in processed carbs than there really is in grassfed beef.

2. That stuff is supposed to be FOOD?! Hubs spent a week in the hospital a few years ago, and Burger King had tastier and more nutritious food. The Vietnamese place down the street had MUCH better food, considering that pho shops often make their own broths (pho is Vietnamese soup--VERY yummy!)

Alex Lewin said...

Heather, agreed that it's clear why it's easier to profit from industrial carbs than from grass-fed beef. But what's with the salt thing? Was salt a scapegoat, to distract us from the real issues? (I feel like cholesterol is a scapegoat...but that's another post for another time!)

And as far as pho goes, I know it well, and I love it too! I made it myself and blogged about it a while ago...I'm getting hungry now rereading my post:

Nancy said...

Hello Alex,

Ok, on the "salt/hypertension" issue here goes. There IS a connection between sodium and hypertension - numerous studies have proved that. Now, having said that, remember that this is NOT TRUE for the entire population - i.e. think of a bell curve - each person falls somewhere on that bell curve so each individual's response to sodium is going to be different - not to mention that other factors do come into play regarding hypertension - family history, weight, other components in the diet, etc., etc. and at this point, we can't test to see exactly what factor or factors are responsible and to what degree.

So, in light of this connection and the dramatically increasing rates of hypertension, the health care industry had a few choices. If the health care community had said "well, some people could reduce their risk of hypertension by reducing sodium intake" most people would simply ignore it, right? I mean everyone would think "not me" and thus not be motivated to change their diet. So, given that reducing salt intake has no negative impact (unless it's extreme) the health care community decided that in order to help that percentage of people who are "sodium sensitive" they'd take a more generalized approach - i.e. that everyone should reduce their sodium intake - (some believed that it would also lead to a decline in processed food intake which would (theoretically) have an impact on weight as well. From their standpoint their was no downside to taking this position and definitely some upside.
Given that we can't tell who benefits and who doesn't via a simple test, this is the best that can be done with this information to try and combat our increasing rates of hypertension and heart disease.
Imperfect, confusing and frustrating... as someone who is in the dietetics field "I feel your pain". The best advice - which hasn't changed - is to have regular physical check ups and with the case hypertension it's unfortunately trial and error. Some people, through changes in diet (i.e. adopting the DASH diet for example) can control their hypertension without medication. Others will not and unfortunately medical science hasn't progressed to the point where we know why. But we are getting there!

Hope this explanation makes some sense - it's always good to keep asking questions!!!

Shane said...

Hi Alex.

Love the info and insights. I read a really interesting article on salt from Dr. Mercola's website. It said that its not the salt itself but the source. Apparently most table salt is a byproduct of refineries. The negative health impact comes from the toxic chemicals present in the salt due to its source. He recommends sea salt or Himalayan salt.
Interesting theory isn't it?
Keep up the great work!

Alex Lewin said...

Nancy, thanks for your thorough and insightful comment! It raises a question that I think is fascinating:

Is it right, or perhaps more to the point is it effective, for health professionals and public health officials to lie (or at least fudge) if they think that it's in the best interests of the general public?

The potential benefit is that it may help decrease salt intake for those who are in fact hypersensitive to salt.

Some potential costs I can think of are (1) encouraging food-related anxieties, obsessions, and neuroses, which are already pretty bad in this country; and (2) reducing the general population's faith in the "experts", when the "truth" comes out.

Is it worth it? I don't know.

Beyond that, you flatly state that "There IS a connection between sodium and hypertension - numerous studies have proved that," yet you do not cite studies. The Scientific American article I mention does cite studies, and explains why some studies do not prove what they claim to prove.

Would you like to back up your claim? :-)

Alex Lewin said...

Shane, yes, I think there's something to that. Regular old table salt has a lot of bad stuff in it, which may in fact lead to problems. I believe that if the body is functioning properly, the kidneys should regulate the sodium level, so extra salt should be excreted. And if you're concerned about it, drink lots of water and do some power yoga! For better or for worse, I can sweat out 2 or 3 pounds in one yoga session...

Unknown said...

Hi Alex, great post on some key health issues of our time! You wanted some extra information on salt being bad for some people, I actually wrote a blog post not too long about salt, many of the links in it link either to a page that contains scientific study links or directly to them. There are too many to re-post here so if you don't mind I will link to the post;
Other than the conditions I mention, there is a theory about people being "salt sensitive" but as you notice there are no studies to back this up. That doesn't mean there aren't people who need to watch their salt intake, though I would be more inclined to believe they need to switch to unrefined salt, it just means that no studies have been done on it. I often say that you need to listen to your body and do what is right for it, and this is no exception. I hope this helps clarify some things!