In last week’s post, we saw how media shills for the Save The Grains Campaign have been warning us that if we ditch the grains, we’ll develop diabetes, fill up with mercury, then get sick and die. And lest we assume they’re being overly dramatic, they assure us these claims are backed up by research.
Well, it’s true … really lousy research in the form of weak observational studies. The SBC News article that flatly declared we need whole grains to avoid diseases and death, for example, cited this study as proof:
Methods
The study included 367,442 participants from the prospective NIH-AARP Diet and Health Study (enrolled in 1995 and followed through 2009). Participants with cancer, heart disease, stroke, diabetes, and self-reported end-stage renal disease at baseline were excluded.
Results
Over an average of 14 years of follow-up, a total of 46,067 deaths were documented. Consumption of whole grains were inversely associated with risk of all-cause mortality and death from cancer, cardiovascular disease (CVD), diabetes, respiratory disease, infections, and other causes.
Same old garbage. Researchers send out food questionnaires over a period of years and follow up by examining medical records. Then they look for correlations – and by gosh, they tend to find exactly the correlations they were seeking.
Food questionnaires are notoriously unreliable. And even if people could accurately remember what they’ve eaten over a period of years, the correlations merely tell us that people who choose whole grains over white flour have better health outcomes.
Does that prove that whole grains are better than white flour? Not really. It could simply be that since whole grains have been declared health food, health-conscious people are more likely to consume them. Health-conscious people are different from I-don’t-give-a-@#$% people in all kinds of ways. Even the authors of the study acknowledged as much:
In our study cohort, both whole grains and cereal fiber were correlated with high levels of physical activity and better health status, as well as with low BMI, low levels of smoking, and low intakes of alcohol and red meat. However, our results were less likely due to the potential confounding of these factors because careful adjustment for these factors in our analyses did not significantly change the results. Nevertheless, we acknowledge that the positive associations may still be related to residual confounding of non-measured covariates.
Researchers can try to adjust for all the confounding variables, but it’s nearly impossible. Sure, you can try to balance out factors like smoking and alcohol consumption, but how do you know the I-don’t-give-a-@#$% people aren’t lying about how much they drink? Do the health-conscious people get more sleep, take more supplements, and generally have a better attitude on life that results in less stress? The researchers don’t know.
But let’s suppose for the sake of argument that the researchers really and truly teased out every possible confounding variable, and that people who eat whole-grains foods are really and truly healthier than people who eat white-flour foods. So what? That doesn’t in any way prove that whole grains prevent diseases.
To use my favorite analogy, if we compare people who smoke filtered cigarettes to people who smoke non-filtered cigarettes, the people who smoke filtered cigarettes will have lower rates of lung cancer. But only an idiot would look at those results and declare that filtered cigarettes prevent lung cancer, so people who don’t smoke at all are going to get lung cancer. That’s the logic of “whole grains prevent disease, so going grain-free will make you sick.”
Another Save The Grains Campaign article I didn’t mention last week was a hit piece on Pete Evans, the celebrity chef from Australia. (He visited the Fat Head farm in 2015.) The article was titled We Put Pete Evans’ Paleo Diet And Dairy Claims To A Clinical Dietitian. Here are some quotes:
“Pete Evans does an amazing job in his own field. But the concern is because he isn’t trained in any nutritional science, he doesn’t have the knowledge to be administering this kind of health advice. And a lot of it isn’t backed by evidence,” Accredited Practising Dietitian Melanie McGrice told The Huffington Post Australia.
Riiight. Because the standard-issue advice from dietitians is based on such rock-solid science, as we’ll see in a minute.
“I think there are some good aspects about the Paleo diet, for example its emphasis on fruits and vegetables, and cutting down on highly-processed and packaged foods. He supports these aspects,” McGrice said.
“But it falls down in its restriction of core food groups like grains and legumes. The latest research shows that grains and legumes are protective against conditions such as hypertension and other cardiovascular markers.”
Do dietitians ever ask themselves why grains are a “core food group”? Do they ever wonder how humans managed to thrive without the “core” food for 99% of our time on earth? Do they ever ask themselves if human health improved after we took up eating grains a mere 12,000 years ago? Apparently not.
As for the science, the quote from the Accredited Practising Dietitian had a link under the words latest research in the online article. So I followed the link. But before we go there, let’s review what the dietitian said:
“The latest research shows that grains and legumes are protective against conditions such as hypertension and other cardiovascular markers.”
So obviously the link will take us to a study demonstrating that grains and legumes – all of them – protect us against hypertension and cardiovascular markers. Now here are some quotes from the study:
Health claims regarding the cholesterol-lowering effect of soluble fiber from oat products, approved by food standards agencies worldwide, are based on a diet containing ≥3 g/d of oat β-glucan (OBG).
Yup, the study is about oat bran. That’s it. Not legumes, and certainly not all grains. Oat bran. And why is oat bran such wunnerful, wunnerful health food?
The objective was to quantify the effect of ≥3 g OBG/d on serum cholesterol concentrations in humans and investigate potential effect modifiers.
So it’s a study (actually a meta-analysis of studies) of oat bran’s effect on cholesterol levels. And by gosh, it turns out oat bran lowers cholesterol. The study lists the results in mml/l, but in terms of mg/dl (the units we use in the U.S.), oat bran lowers cholesterol by about 11 points.
Wowzers! If a food lowers cholesterol, it absolutely, positively MUST reduce heart disease, right?
Wrong. In the past couple of years, some embarrassing studies from the 1960s were “re-discovered.” In a study published in The Lancet, men who switched from animal fats to soybean oil experienced an average drop in cholesterol of 60 points. That’s a huge drop. And the result? Here it is:
The total number of men who had a major relapse at any time in the trial was 45 in the test group and 51 in the controls; of these major relapses 25 in each group were fatal. None of the differences found is significant.
A change in diet produces a big drop in cholesterol, but no reduction in heart attacks. So why the heck should we just assume a ten-point drop produced by oat bran will save us from heart attacks? Obviously we shouldn’t.
The “rediscovered” Sydney Diet Heart Study was even more embarrassing. The intervention group switched from animal fats to safflower oil. Their average cholesterol levels dropped by nearly 40 points. And here are the results:
The intervention group (n=221) had higher rates of death than controls (n=237) (all cause 17.6% v 11.8%, hazard ratio 1.62 (95% confidence interval 1.00 to 2.64), P=0.05; cardiovascular disease 17.2% v 11.0%, 1.70 (1.03 to 2.80), P=0.04; coronary heart disease 16.3% v 10.1%, 1.74 (1.04 to 2.92), P=0.04).
Big drop in cholesterol, but also a higher death rate – from all causes, including heart disease. Same thing happened in another “rediscovered” study that was conducted and then apparently buried by Ancel Keys.
So let’s follow the (ahem) “logic” of the hit piece on Pete Evans: he can’t be right because he tells people to avoid legumes and grains, and legumes and grains are good for you. We know this because of the latest research! … which consists of an analysis concluding that oat bran will lower your cholesterol. That means all legumes and grains must help to prevent heart disease, even though the effects of oats tell us nothing about the effects of other grains, and even though diets that produced a big drop in cholesterol in other studies also produced a higher death rate from heart disease.
Got that?
To summarize, the evidence presented by shills for the Save The Grains Campaign consists of 1) meaningless observational studies that compare the effects of whole grains to white flour (and therefore tell us nothing about the effects of ditching grains), and 2) one meta-analysis that tells us oats will reduce cholesterol, but in no way proves oats (much less other grains) will prevent heart attacks.
Now let’s look at an actual clinical trial – you know, the type of study that can tell us something useful. I like the opening of the abstract very much:
Recommendations for whole-grain (WG) intake are based on observational studies showing that higher WG consumption is associated with reduced CVD risk. No large-scale, randomised, controlled dietary intervention studies have investigated the effects on CVD risk markers of substituting WG in place of refined grains in the diets of non-WG consumers.
Perfect. They acknowledge that nearly all the studies purporting to demonstrate the wonders of whole grains are observational, then set up the central question: what if we have people who don’t normally consume whole grains start eating them? That eliminates the problem of comparing health-conscious to I-don’t-give-a-@#$% people.
The researchers divided the subjects into three groups: the control group continued their usual diet (i.e., a diet with almost no whole grains), a second group added 60 grams of whole grains for 16 weeks, and a third group switched to 60 grams of whole grains for eight weeks, then 120 grams of whole grains for another eight weeks. Then the researchers measured markers of cardiovascular risk, which they defined as:
BMI, percentage body fat, waist circumference; fasting plasma lipid profile, glucose and insulin; and indicators of inflammatory, coagulation, and endothelial function.
That’s a lot of markers. If whole grains are such wunnerful, wunnerful health foods, that third group must have rocked the house compared to the other groups. Here are the results:
Although reported WG intake was significantly increased among intervention groups, and demonstrated good participant compliance, there were no significant differences in any markers of CVD risk between groups.
Nothing. Epic fail. A big, fat zero. That’s after nearly four months of gobbling those heart-healthy whole grains. Perhaps to save their future funding, the researchers suggested that four months may not be long enough for whole grains to confer their magical health benefits.
Yeah, that’s one possible explanation. The other is that whole grains aren’t health food – no matter how hard the media shills for the Save The Grains Campaign want us to believe otherwise.
