Let’s get one thing straight right off the bat: most of us don’t eat enough fruits or vegetables.
The recommended number of vegetables isn’t high – 7 to 10 servings a day, which I put in terms of handfuls – at least two large at both lunch and supper. Fruits, a piece or two a day.
Even easier is to ensure that half your plate is fruit and/or vegetables.
As a dietitian, it’s hard enough to parse out the reasons why people don’t get their produce. When these reasons include nutrition myths and outright misrepresentations of science, it’s even more aggravating.
I want you all to eat as many plants as possible, and to do it without fear.
This is why I’m here to debunk the 6 most common myths about fruits and vegetables.
Myth #1: Nightshades cause inflammation.
Nightshade vegetables are named for their preference for shady growing conditions and their ability to flower at night. Nightshade vegetables shouldn’t be confused with belladonna, aka deadly nightshade.
While they’re from the same family, belladonna can kill you. Bell peppers, not so much.
Nightshade vegetables include tomatoes, eggplant, white potatoes, and peppers. These foods contain an glycoalkaloids, which are a natural defence mechanism that’s produced by the plant.
Potatoes, in particular green potatoes, have the highest levels of the glycoalkaloid solanine, but you’d have to eat a lot of green potatoes – which are incredibly bitter – to ingest enough solanine to make you sick. Contrary to common belief, tomatoes, peppers, and eggplant don’t contain solanine.
Some people believe that nightshades cause inflammation which can exacerbate the symptoms of arthritis and autoimmune diseases. There is no credible research that backs up this claim, and the Arthritis Society of Canada does not recommend removing them from our diet.
That doesn’t stop many alternative providers from recommending that nobody consume nightshades. It’s always a red flag when you see a blanket recommendation like that one. Do some people have reactions to nightshades? Probably. Does this mean none of us can tolerate them? Absolutely not.
Nightshade vegetables are good sources of fibre, vitamins, and antioxidants, so unless you feel that you’re intolerant to them, please keep eating them.
Myth #2: Lectins are responsible for everything that’s wrong with us.
As if nightshades didn’t have enough bad press, they’re also often vilified for their lectins. Lectins are found in a lot of the foods we eat, including vegetables, grains, legumes, and even meat and eggs.
Lectins are proteins produced by plants as a defence mechanism, and are toxic in certain situations – like, if you eat raw kidney beans (which nobody does).
Lectins have been blamed for everything from leaky gut to weight gain to cancer, and have been the subject of a popular but discredited diet book by a certain discredited physician.
Not naming names, of course, but you can read my review of this book here.
Lectins are mostly destroyed by cooking, and humans have evolved to tolerate them. The healthiest populations in the world, known as the Blue Zones, eat more lectin-containing foods than anyone else. Interestingly, while lectin foods are being blamed for all sorts of horrible illnesses, the truth is that North Americans actually eat very few of these foods.
Countries like Italy, however, eat a lot of them. And strangely, they don’t have nearly the level of chronic disease that we have here.
Let’s put it this way: nobody is getting cancer or becoming overweight because they’re eating too many tomatoes and chickpeas. Actually, lectin foods like grains, lentils, and other legumes were some of the first crops to ever be farmed. We’re talking since 11,000 BC here.
Why should we fear lectins, again? Total nutrition myth.
Contrary to the belief that lectins are harmful, there is research showing that these compounds may actually be beneficial to health. Some clinical and preclinical studies show that lectins may be antimicrobial and antiviral, and may improve immune response.
Bottom line? Keep eating your lectin-containing foods, and don’t buy into the anti-lectin hype.
Myth #3: Carrots and beets have too much sugar, and so do fruits.
This myth is the bane of every dietitian’s existence.
One medium carrot contains 3 grams of natural sugars. 1 cup of raw beets has 9 grams of natural sugars.
As far as fruit goes, it’s sweet, because of course it is! Some fruits are higher in sugar than others, which is fine – you’re allowed to eat the fruits you enjoy!
Eliminating certain vegetables or fruits because they’re supposedly ‘too high’ in sugars is a bit counterproductive. The sugars in vegetables and fruits are packaged with fibre, vitamins, and antioxidants. Studies suggest that beets contain anti-inflammatory compounds that may reduce systemic inflammation. Carrots are a source of fibre, which is great for our gut, and polyphenols, which may help to prevent disease.
I see a lot of diets limiting ‘allowed’ fruit to berries and citrus, but this is 100% unnecessary.
Once again, most of us don’t eat enough vegetables and fruit to begin with. Conversely, we do eat far too many added sugars. Micromanaging which type of fruit you eat according to the grams of sugar it contains is unnecessary. You’d be better off trying to cut down the added sugars in your diet.
Also, comparing the sugars in produce to the added sugars in highly processed foods is confusing and misleading. It’s a huge red flag when someone does that.
Myth #4: We don’t need fibre.
There’s a lot of all-or-nothing thinking and blanket statements in these myths, isn’t there?
All-or-nothing thinking is the enemy of a good relationship with food.
It’s hard to believe that some people want to convince us that fibre – and plants – are unhealthy and unnecessary, but here we are.
What these individuals, who are usually following the Carnivore diet, are missing, is…pretty much every piece of evidence that shows that fibre and plants promote health.
Sure, you can live without them, but are you looking to thrive, or are you looking to just exist?
Most of us know that fibre helps keep us regular, and that it helps with satiety. Fibre’s superpower is that it’s the best food for our microbiome. Our good gut bugs break it down into short-chain fatty acids, which they consume as food.
Science on the gut is really in its infancy, but it points to the hypothesis that when our gut bugs are happy, we are at lower risk for chronic diseases.
So yes, we can live without fibre. But no, we shouldn’t.
Myth #5: Potatoes have no nutritional value.
I’m not sure where this myth started, but it’s very persistent. Maybe it came from the fact that potatoes are starchy and white, and white foods – especially starches – are supposedly unhealthy?
White potatoes are delicious. They make a meal satisfying, and just like other vegetables, they’re a good source of fibre, antioxidants, and vitamins. Cooked and cooled (and even after reheating!), white potatoes are a source of resistant starch, a gut-friendly fibre.
A 2019 study from the University of Michigan showed that resistant starch from white potatoes produced the most butyrate – a type of short-chain fatty acid – compared to other sources. Butyrate is thought to improve gut health and decrease inflammation, among other benefits.
Myth #6: Raw, fresh vegetables are better than cooked, canned, or frozen ones.
Any vegetables are better than none at all, and there is no reason to avoid cooked, canned, or frozen ones.
Many canned and frozen vegetables have been picked at the peak of ripeness and quickly processed to retain their nutrients. Allowing the vegetables to ripen on the plant often means their levels of antioxidants are higher than if they were picked prematurely.
Fresh vegetables that have travelled for days to get to their final destination may lose nutrients via oxidation, and may be picked before they’re ripe.
Canned and frozen vegetables may also be more cost-effective than their fresh counterparts.
Cooking vegetables may actually make their antioxidants more bioavailable to the body, as is the case with lycopene in tomatoes.
While overcooking may destroy the fat-soluble vitamins A, D, E, and K, and water soluble B and C vitamins, lightly cooking vegetables quickly does not have as much of an effect. Exposure to water and heat are the culprits in nutrient loss, so choosing a cooking method that minimizes both of these things may be your best bet.
Bottom line? Eat as many plants as you can, and question the nutrition myths out there.