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The anti-nutrient myth and why you shouldn’t be scared of your food

Jennifer Hanes MS, RDN, LD

Just when you think you’ve got the basics of nutrition down, you hear about something new. Right?!  The term anti-nutrients has been making its rounds on social media again, and I thought we should discuss the concept of antinutrients.

While the word antinutrient is actually a scientific term, its definition and implication have become a phrase used to invoke fear in the general public.  There is some merit to antinutrients. However, they are not nearly the terrible destroyers of health that some will lead you to believe!

Anti-nutrients have been cropping up in social media again.  Certain diets that get very popular this time of year claim you have to eliminate these foods to be healthy. But is that true. Should you really be scared of beans and vegetables?
Anti-nutrients have been cropping up in social media again.  Certain diets that get very popular this time of year claim you have to eliminate these foods to be healthy. But is that true. Should you really be scared of beans and vegetables?

What is an anti-nutrient?

So other than a potentially scary word, what are antinutrients? 

The technical definition of an antinutrient is a compound in food that reduces the absorption of the nutrients in your food.   Reading that definition makes you think you should avoid those, right? 

However, the theory and the actual result are different.   We should know by now that nothing that has to do with nutrition is this black and white.

What are the different types of anti-nutrients?

There are many antinutrients, some that are more prevalent in our food than others. And some that are given more grief in social media/fad diets/lousy science…

So what are the different types of antinutrients, and where are they?

  • Lectins – probably the most well-known and most often maligned of the antinutrients. They are found in legumes, cereal grains, nuts, seeds, fruits, and vegetables. Hopefully, you see why the recommendation to avoid lectins is a little silly…
  • Oxalates – probably the next most talked about antinutrient. Again these are found in greens (particularly spinach), nuts, legumes, cereal grains, sweet potatoes, and potatoes.
  • Phytates – legumes, cereal grains, nuts, and seeds.
  • Goitrogens – Cruciferous vegetables (cabbage, broccoli, kale, some greens), millets, cassava.
  • Phytoestrogen – soy and flaxseeds
  • Tannins – tea, cocoa, coffee, berries, stone fruits, nuts, beans, whole grains.

Should we really be concerned about anti-nutrients?

No, we shouldn’t.

In fact, many anti-nutrients have health properties all on their own!  

    • Glucosinolates can prevent iodine absorption, only of concern to those with thyroid problems, and only when raw.  They also seem to help prevent lung and gastrointestinal cancers.
    • Lectins – can decrease the absorption of some minerals, such as iron, calcium, magnesium, and zinc. Certain fad (read “bogus”) diet promoters also say that lectins are responsible for obesity, chronic inflammation, and autoimmune diseases, though this has no basis on any actual science.  However, we have lots of science that shows that lectins act as antioxidants  (anti-inflammatory) and prevent high blood glucose and insulin levels. Extensive population studies show that consuming lectin-containing foods is associated with lower rates of heart disease and type 2 diabetes and weight loss.  Newer research is looking at the possibility of using lectins to stimulate gut cell growth in patients with nonfunctional gastrointestinal tracts and as anticancer treatments as they appear to induce cancer cell death.
    • Oxalates – can bind calcium. This is particularly noticeable in spinach, which actually has a lot of calcium content, but it’s believed that this calcium is only about 5% bioavailable. They’ve also been indicated in the development of kidney stones in people that are prone to them. Some research suggests that our gut actually breaks down oxalate BEFORE it can bind with calcium.  In fact, a probiotic (Oxalobactor formingens) actually uses oxalates as their energy source, so oxalate containing foods may improve gut bacteria. Oxalates play various roles in our metabolism. And interestingly, but maybe predictably, high calcium foods bind oxalates, helping prevent a buildup of high oxalate levels in the body.
    • Phytates – can decrease the absorption of some minerals, such as iron and calcium. However, they are also well known to help reduce cholesterol levels, slow digestion (keeps you full, increase absorption time in the gut), and prevents spikes in blood glucose.
    • Saponins – can also interfere with nutrient absorptions.  However, they play an essential role in immune system functioning (particularly regarding removing cancerous cells). They also seem to regulate blood glucose and normalize cholesterol levels. High saponin diets can reduce the risk of dental cavities, abnormal blood clotting, and kidney stones. And most saponin containing foods are high in fiber.
    • Tannins – can reduce iron absorption. However, they are antioxidants and can lower blood pressure and cholesterol and modulate immune responses. Tea, which is high in tannins, is known to combat cancer cells. Just maybe don’t drink it with meals if you have problems with iron deficiency anemia.

Great News for Vegetarians

Some studies suggest that vegetarians actually adapt to their diet by INCREASING the absorption of nutrients from their food, despite a higher intake of anti-nutrients than their omnivorous buddies. 

What can we do about the anti-nutrients in our food?

If I didn’t convince you not to let this  “problem” stress you out, there are some things you can do to reduce the anti-nutrients in your food

  • Switching your grains for sprouted grains can drastically reduce the anti-nutrient content in your food.
  • Some cooking methods can reduce anti-nutrient content, particularly boiling them. (But yuck, right?)
  • Soaking beans and nuts and then disposing of the water will also reduce their anti-nutrient content.

The fact is we’ve discussed many of these anti-nutrients before by another name: phytochemicals. If you don’t remember that discussion, the conclusion was to always strive for variety in your diet to ensure you get the as many of these phytochemicals as you can.

Here, we can look at it from another angle but arrive at the same conclusion: Vary your diet, so you don’t have too much of any one plant chemical.

How do these “problems” become so blown up?!?

To put it simply, albeit a bit cynically, these things get exaggerated and explode on social media because of the need to sell fad diet books! Or drive viewers to a blog or YouTube channel. Or sell you some other product.  

It’s much easier to get you to click when scary headlines imply that they are the only ones that can fix you!

Fad diets that eschew antinutrients: Paleo, Whole30, Bulletproof Diet. Keto is very low in anti-nutrients as well, but this is more of a result of eliminating pretty much any carbohydrate source, not the anti-nutrients in particular. 

The bottom line is this. There is a reason that U.S. News and World Report consistently rank diets with the most vegetable content as the healthiest.  Mediterranean, DASH, Flexitarian, Mayo Clinic, TLC, Mind, and Volumetrics all include lots and lots of plants and rank consistently at the top end for overall and health.   Additionally, diets that purposely eliminate plant foods are ranked poorly. Keto is ranked very low for health, and the carnivore diet wasn’t even deemed worthy of evaluation.

An anti-nutrient never hurt anyone, when consumed in normal amounts.

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