You’d think that, with all the information at our fingertips today, nutrition myths would have become less pervasive than in our grandparents’ time.
Unfortunately, the internet is rife with misinformation, and it can be really difficult to tell what’s evidence-based without reading the original research yourself. Myths that were previously passed through word-of-mouth now spread like wildfire through social media, blogs, and even established media. Between a 24-hour news cycle, studies that are both long and difficult to read, and journalists scrambling for the latest viral hit, information often gets published without being verified. And once we’ve assimilated a piece of information, we seldom think to challenge it — we treat it as fact.
As an educational organization that looks only at the evidence, we’ve taken the time to identify 20 nutrition myths that just won’t die. At the end of each section, you’ll find a link to pages that further explore the section’s topic with extensive references.
Myth 1: Protein is bad for you
Carbs and fats often take the blame for various health issues, but the third macronutrient isn’t always spared by the media. Protein has often been accused of harming bones and kidneys.
Let’s tackle those two claims one at a time.
More protein in the diet has been linked to more calcium in the urine. Two reasons have been suggested to explain this phenomenon:
- Your body draws from its calcium stores (in bones) to buffer the acid load caused by dietary protein. This has led researchers to suggest that higher protein intake could cause greater bone loss.
- Most studies that looked at protein intake and calcium excretion list dairy products as a protein source, so higher urinary calcium could simply be the result of higher calcium intake (i.e., more calcium in, more calcium out).
Therefore, looking only at calcium excretion wasn’t enough. Subsequent studies showed that dietary protein promotes dietary-calcium absorption and that high protein intake “promotes bone growth and retards bone loss (whereas) low-protein diet is associated with higher risk of hip fractures.”
What happens is that when you ingest more protein, you absorb more of the calcium in your food, so less calcium ends up in your feces. Later, your body gets rid of the calcium it doesn’t need, so more calcium ends up in your urine, but not as much as would have otherwise ended in your feces. Therefore, an increase in protein intake leads to an overall decrease in calcium excretion, which points to an increase in calcium retention.
All in all, current evidence suggests that protein actually has a neutral or even protective effect on bones.
Other studies determined that high protein diets increased glomerular filtration rate (GFR), a marker for waste filtration in the kidneys. It was argued that increased GFR was a sign that undue stress was put on the kidneys,but later research has shown that kidney damage does not occur as a result of diets high in protein.
In conclusion, randomized trials thus far have not shown high-protein diets to harm the bones or kidneys of otherwise healthy adults.