It leaves us wondering where we can learn the truth or at least find a more clear way forward. The answer is to understand what a study means and how its results can be misinterpreted. In this article I’d like to share results of two studies that provide advice on opposite ends of the spectrum.
Study 1 – Carbohydrates are bad and are killing you
According to research published in 2010 in the American Journal of Clinical Nutrition, “Epidemiologic studies suggest that dietary glycemic index (GI) and dietary fiber are implicated in the development of type 2 diabetes, cardiovascular disease (CVD), and certain cancers.” That is a very strong, and compelling, conclusion.
The study looked at carbohydrate nutrition and inflammatory disease mortality in older adults by examining whether dietary glycemic index (GI), dietary fiber and carbohydrate-containing food groups were associated with the mortality attributable to non-cardiovascular, non-cancer inflammatory disease.
The analysis included almost 1,500 postmenopausal women and about 1,200 men aged 49 years. Over the following 13 years 170 participants died of inflammatory diseases. Women who consumed the most high glycemic foods, including fiber, sugar and starches, increased their risk of death by 2.9 times over those who consumed the least amount.
The results lead researchers to conclude, “In view of the effects of GI and fiber on inflammatory markers, it is logical to consider that carbohydrate nutrition is of particular relevance to diseases in which inflammation or oxidative stress is a predominant pathophysiologic contributor.”
Study 2 – Whole grains reduce disease, increase lifespan
According to research published in the Jan. 5, 2015 online journal, JAMA JAMA Internal Medicine, “higher whole grain consumption is associated with lower total and CVD [cardiovascular disease] mortality in US men and women, independent of other dietary and lifestyle factors.”
The researchers of this study looked at association between dietary whole grain (which is a carbohydrate) intake and risk of mortality. They investigated more than 74,000 women from the “Nurses’ Health Study” (1984–2010) and nearly 44,000 men from the “Health Professionals Follow-Up Study” (1986–2010). All patients were free of CVD and cancer at baseline.
During that time they documented a staggering almost 26,000 deaths. After adjusting for age, smoking, body mass index and other cofounders, they found that “every serving (28 g/d) of whole grain consumption was associated with a 5% lower total morality or a 9% lower CVD mortality.” This lead researchers to conclude that “higher whole grain consumption is associated with lower total and CVD mortality in US men and women, independent of other dietary and lifestyle factors.”
Why the results are different
When press releases from studies like these make their way into the mainstream news outlets and magazines, it is easy to see how they can be misinterpreted and thus confusing. While both studies sound similar enough, they are actually quite different.
The first talks about glycemic index and carbohydrates (which includes, but is not limited to, grains). And the grain forms that have the highest glycemic index are those that are refined, stripped of their outer bran coating and made into a powder (flour). This type of grain-based carbohydrate is quite popular and found in all breads that say “enriched” on their packages, as well as crackers, cakes, cookies and the like. Because of its processing it is devoid of its most important nutritional value and it also does not include its outer coating. This means it breaks down in the body rather quickly. And it is certain that carbohydrates that enter the bloodstream quickly do cause blood sugar spikes and inflammation because when glucose stays in the bloodstream it attaches to proteins causing a pro-inflammatory reaction called glycation. So the study is right to warn against eating high glycemic index fiber, starches and sugars.
The second study only talks about whole grain fiber. That is to say, breads, pasta and other products made using the whole grain that includes its bran coating. It is the fibrous bran coating that helps move stools through the bowels, pulls cholesterol from the blood, and stabilizes blood sugar because it takes longer to break down into sugars in the body. In fact, the study showed that bran intake alone was linked with up to 6 percent lower overall death risk and up to 20 percent lower cardiovascular disease-related risk. What’s more, whole grains naturally contain magnesium, fiber and other phytochemicals that help fight, and prevent, disease. So the study is right to advise consuming more whole grains.
The results of both studies show proof of their respective concepts. 1) If you eat high-glycemic index carbohydrates you will increase your risk of type 2 diabetes, cardiovascular disease and some cancers. 2) If you eat more whole grains, you will reduce your risk of type 2 diabetes and cardiovascular disease, while prolonging life by up to 9 percent.
But the fiber discussed in each study is not the same. The first is refined and the second is whole, and this is what makes all the difference in obesity and diseases like type 2 diabetes and heart disease. So when you read tidbits about studies proving this diet over that diet, please be sure to track down at least the abstract and see what it really means.
So by all means, heed the findings of both studies presented here, and 1) severely decrease your intake of simple carbohydrates and 2) consume more whole grains. Oh, and please stay off low-carb diets. Your brain needs the glucose from carbohydrates—just be sure they’re from whole grains.
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