19 popular nutrition claims (some are false!)

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19 popular nutrition claims (some are false!)

Collage of coffee & supplements

There are so many conflicting nutrition claims out there that it is nothing short of confusing!

  • The best diet is vegan/vegetarian
  • We need 10,000 steps per day for good health
  • We are 10x more microbe than human
  • Coffee is healthy/dehydrates you/causes cancer
  • Protein is good/bad for your bones
  • Multivitamins improve your health/do nothing/increase your risks
  • etc.

Which of these are true (and is the answer really that “black-and-white”)?


Are these nutrition claims true or false?


Our guts are closely linked to our brains and moods

Plate of spinach salad nutrition claims

Plant-based diets are better for your health and the Earth’s health

  • Short answer: Yep! (But you don’t have to go 100 percent vegan, just focus on having about 80-90 percent of what you eat from plants—not vegetarian junk food.)
  • Long answer: Eating mostly plants is highly recommended based on the majority of nutrition studies worldwide. This is also exemplified in Canada’s new industry-free science-based food guide. A recent systematic review of 18 studies found that diets that are higher in plants and lower in animals release fewer greenhouse gases and use less land and nitrogen (but they may use more water than animals). These “sustainable” plant-rich diets also reduce the risks of diabetes, cancer, and heart disease. And you don’t have to go fully vegan or vegetarian to realize these benefits. In fact, there is growing evidence that eating a diet similar to the “MIND diet” that focuses on whole grains, vegetables, fruit, nuts, and beans, with small amounts of poultry and seafood) is linked to reduced risks of Alzheimer’s symptoms. Also, a recent review of 153 studies showed that eating a nutrient-dense diet with a lot of plants can reduce your risk of premature death from any cause.
  • Note that we can’t claim these diets “prevent” these diseases because the research is based on correlations found in observational studies. That’s why we say “can reduce risk of.”
  • Oh, and one more thing. The more plants you eat the more fibre you get, so as this feeds your friendly gut microbes in a good way, there is one side-effect to prepare for: more farts.

Do happier people lead healthier lifestyles or do healthier lifestyles increase happiness?

  • Short answer: Healthier lifestyles can lead to more happiness.
  • Long answer: The first study of its kind tried to determine what comes first: healthier lifestyles or happiness? We already know there seems to be a correlation between the two, we really didn’t know which one comes first. While this is just the first study that tried to sort this out, and more research is most definitely needed, it’s pretty promising to think that eating more fruits and vegetables and participating in sports can lead to increases in happiness and life satisfaction.

You need to eat something to satisfy (and lower) your hunger hormone ghrelin

  • Short answer: Nope!
  • Long answer: A recent review of 10 studies found that once ghrelin levels shoot up from being in a stressful situation (yes, ghrelin is a stress hormone), they start to slowly come down over the following minutes and hours—even if nothing is eaten!

High-protein diets leach calcium from your bones

  • Short answer: Nope!
  • Long answer: We originally thought this—and for good reason—but new research has proven a different mechanism is at work. We’ve known for decades that after eating a high-protein meal there’s more calcium in the urine. The hypothesis (best guess) at the time was that the protein we just ate somehow “leached” calcium from our bones, hence we urinate it out. But, this never made much sense because people who eat more protein tend to have stronger bones. So more studies were done to find out where this extra urinary calcium comes from. In 2004 we learned that it comes from the meal itself—not your bones! This makes a ton of sense because when we absorb a lot more calcium from our food this not only can make our bones stronger, but also allows us to absorb a bit more than we need, so we excrete the excess in the urine.

Walking along cobblestone road nutrition claims

You need 10,000 steps each day for good health

  • Short answer: Nope!
  • Long answer: Don’t get me wrong: physical activity is amazing for your health! That’s not debated. It’s just the minimum number of steps required isn’t based on a ton of solid evidence. (That’s why I give “review” studies more weight because they look at several studies, instead of focusing too much on the results from just one or two studies.) Recent research shows that you can enjoy health benefits from fewer than 10,000 steps per day. There isn’t a universally agreed-to “magic” number, but at least some studies show that as few as 7,000 steps per day is just as good at reducing premature death as 10,000 steps per day.

It really is hard to “bounce back” into fitness after having a baby

We are 10x more microbe than human (i.e., for every ten microbial cells in our gut we have just one human cell in the rest of our body)

  • Short answer: Nope!
  • Long answer: Back in 1977, the first estimate of how many microbes lived in our guts was published, but there was some skepticism. In 2016 a much more accurate measurement was made and the best information we have now is that we’re about 50% microbe (not 90%). Basically, this means that for every human cell we have (e.g., skin cells, brain cells, muscle cells), we have about the same number of tiny microbes living in our digestive tract.

Probiotics reduce gut issues from antibiotics

  • Short answer: Most supplement companies have not spent the time or money to test this nutrition claim on their products . . . except for one.
  • Long answer: Stick with those supplements who have the evidence, like Bio-K+ (and no, I’m not an affiliate – they just really stand head and shoulders above all other probiotic companies as far as evidence is concerned). Here’s their approved label claim (that I’ve happily shared with pharmacists online).

Glass of water hydration nutrition claims

We should all drink eight glasses of water each day (plus an extra for each cup of coffee)

  • Short answer: Nope (and nope)!
  • Long answer about how much water to drink: If you’re healthy, your body can self-regulate its hydration and you only need to drink to thirst. Note that this doesn’t apply to children, older adults, athletes, or people prone to kidney stones or urinary tract infections—if this is you, you probably need to drink more than just to thirst.
  • Long answer about coffee: Coffee can count toward your fluid intake for most people. As long as you don’t have more than about 4 cups per day and you’re used to drinking that amount (because you drink it regularly), those 1-4 cups are considered to be hydrating.

Coffee increases your risk of cancer

  • Short answer: Nope!
  • Long answer: About 3-4 cups of coffee per day is healthy in most people. People who drink more coffee tend to have lower risks for or improvements in: heart disease, diabetes, depression, obesity, neurodegenerative diseases, and liver diseases including liver cancer. Coffee isn’t without its risks, though. Look out for high blood pressure, palpitations/arrhythmia, insomnia, and headaches. Plus, for women, coffee may increase your risks of fracture and, during pregnancy, low birth weight and preterm labour. When it comes to cancer risks, huge amounts of one substance found in many roasted foods/drinks (including coffee) can cause cancer in rodents.

Glass of beer alcohol nutrition claims

Alcohol increases your risk of cancer

  • Short answer: Yep!
  • Long answer: There is pretty convincing evidence that people who drink more alcohol tend to get more cancers of the: mouth, pharynx, larynx, esophagus, stomach, liver, colorectal, and breast. But, they do have lower risks of kidney cancer.

Beer is a good source of B-vitamins

  • Short answer: Nope!
  • Long answer: Beer has tiny amounts of some B-vitamins, but unlike eating the whole grains (beer ingredient) themselves, beer is a pretty bad source of any vitamins. Plus, it contains alcohol which is very strongly linked to some cancers (see nutrition claim above).

Supplement capsules nutrition claims

Melatonin supplements are safe and effective

  • Short answer: Sort of (but they’re not for everyone).
  • Long answer: Melatonin supplements have a lot of contraindications and work better at low doses than higher doses. But, there are other things you can do to increase your ability to produce melatonin naturally in your brain.

Multivitamins are simply “expensive pee” producers and have no health benefits whatsoever

  • Short answer: They have a few health benefits for a few people, but these aren’t as impressive as we’ve been led to believe.
  • Long answer: Multivitamins are safe (hence the “expensive pee” claims) and can help fill small nutrition gaps. People who take multivitamins tend to have a lower risk of age-related cataracts, and in some cases, enhanced “free recall memory” and cognitive performance (ability to think). Men who take multivitamins tend to have a small (8 percent) reduction in risk of cancers.

Turmeric is a miracle medicinal plant

There are no nutrient deficiencies in North America now

Canada has huge CAFO dairy farms and allows growth hormones

Hold off on getting multiple x-rays for potential broken bones

  • Short answer: Not if the benefits outweigh the risks.
  • Long answer: Exposure to lots of x-rays at a young age can increase the risk of some cancers, but it depends on a lot of factors. Plus, there are reasonable steps you can take to reduce overexposure, including insisting on ALARA (As Low As Reasonably Achievable) and tracking your exposures.


Why are there so many contradictory nutrition claims?


For one thing, hype sells. Having clickbaity headlines about novel studies that stoke fear, disgust, and surprise spread very, very easily online. The same thing goes when trying to sell courses, books, and documentaries. It’s a simple psychology trick that gets all of us at one time or another because we’ve evolved to survive and warn others about threats to our survival. It’s an innate gut reaction. Our emotions make us persuadable.

It’s also easy (and dare I say, lazy) to read a study or two (or a book/blog post/documentary or two) and present it to the world as though it’s the truth that explains everything. We know that the human body is infinitely complex, so that’s why we often hold off until there are many, many studies looking at the same thing in different ways before we can be confident how it’s going to help (or hurt) our physiology and biochemistry.

There are elements of truth almost everywhere. There are studies that support almost every position. The key thing is that without looking at the “big picture” (i.e., many studies done over time) on one topic and understanding the strength of each type of study, it’s so frustratingly confusing.

For me, I’m not “married” to any particular diet or lifestyle. I understand that our knowledge keeps getting deeper and broader as more and more research is done to understand our health and nutrition claims.

what is right

I’ll never say that I’m 100 percent objective, even though that’s what I strive for (everyone is human!). My university education taught me how to be objective and understand study design and results. And THIS IS EXACTLY WHY I am very careful to share how strong a study is when I talk about it or to cite several high-quality resources in every single pre-written done-for-you health article that you can purchase for your blog or program.

We can all update our knowledge with better, more recent or applicable studies (they’re published daily!) and reliable resources. I’ve changed my position before, based on new evidence, and that’s a great thing!




There are so many popular nutrition claims that are correct and so, so many that are false. As more and more high-quality studies are published, they continue to help us get closer to really understanding the complexity of the human body.


Signing off and toasting: To finding out which nutrition claims are true!


Over to you


Are you curious if other popular nutrition claims are BS? What kinds of claims motivate you to look them up yourself? How do you go about finding the credibility of these nutrition claims?

I’d love to know (in the comments below)!

Want a fairly constant flow of credible health information (and content marketing/blog strategy)? Follow me on Twitter or subscribe to the rEATsearch podcast: It’s like overhearing your nerdy health science friends chat and laugh over coffee.

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Originally published Jan 2020; updated with even more awesomeness Feb 2022.


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I’m Leesa Klich, MSc., R.H.N.
Health writer – Blogging expert – Research nerd.

I help health and wellness professionals build their authority with scientific health content. They want to stand out in the crowded, often unqualified, market of entrepreneurs. I help them establish trust with their audiences, add credibility to their services, and save them a ton of time so they don’t have to do the research or writing themselves. To work with me, click here.

19 popular nutrition claims (some are false!)


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