5 Things All Dog Owners Should Know About Lectins

Lectins in Dog Foods

These days there’s a ton of talk about lectins and their health effects. And it’s quite a controversial topic. That’s because lectins can be harmful. But lectin foods can also be rich in important nutrients. That’s true for humans, anyway.

But what about dogs?

There are several questions that come up when you consider lectins for dogs

  • Are high-lectin foods toxic for dogs?
  • What health issues can lectins cause?
  • What’s the link between lectins, grain-free dog diets, taurine and heart disease?
  • What foods should your dog avoid?

I’ll answer all those questions and provide more detail about lectins below.

Top 5 Things To Know About Lectins

These are the most important points about lectins.

#1 What Are Lectins?

Lectins are plant proteins. And they can be toxic. In fact, they’re the plant’s defense mechanism. Since plants can’t escape predators, they have other ways of protecting themselves. Some have thorns. Some have poisonous berries. Others have lectins. If a plant contains lectins, the person, animal or bug who eats it can get sick. So next time, they’ll probably avoid it!

Lectins are sticky proteins that bind to carbohydrates. That sounds a bit science-y … but it means lectins make carbohydrates clump together. When your dog eats food with lectins, they look for the sugars and starches in his body and grab onto them.

And when that happens, they stop your dog’s body from working properly. That’s why lectins are considered “antinutrients.”

Antinutrients

Antinutrients can interfere with digestive enzymes. They block the absorption of other nutrients like vitamins and minerals. This is part of the plant’s defense mechanism I mentioned earlier. Antinutrients can deter predators from eating them.

Some of the nutrients blocked by lectins include calcium, iron, phosphorus and zinc,

Lectins can also survive digestion. So they can get into the digestive tract and cause problems there too. I’ll talk more about that later. But at the very least, they’ll cause digestive discomfort like gas, bloating, nausea or diarrhea.

And digestive issues aren’t the only problem lectins can cause.

Lectins can stop important cell communication. And your dog’s body responds with inflammation. Inflammation can make your dog more susceptible to disease and illness.

That’s not all. Remember lectins are “sticky” proteins? That means they can attach to harmful bacteria and viruses, helping them stick to cells in the body. So lectins could mean your dog is more likely to pick up infections.

Some lectins are truly poisonous. Ricin contained in castor beans is a deadly poison. There are news stories about public figures receiving packages containing ricin … to try to poison them.  

And red kidney beans contain high levels of a lectin called phytohemagglutinin. This means it’s very dangerous to eat red kidney beans raw or undercooked. Even cooking them in a slow cooker is risky, because the temperatures aren’t high enough.

But it’s not all bad …

Good Things Lectins Do

Despite all the negative press lectins get … they do have a good side!

There are several classes of lectins … and they’re not all harmful! Here are some of the good things about lectins.

  • Lectin antioxidants protect cells from damage caused by free radicals.
  • They slow digestion and absorption of carbohydrates. This helps prevent blood sugar spikes and diabetes.
  • They may reduce cardiovascular disease risk.
  • They can promote weight loss.
  • They’re rich in B vitamins, protein, and minerals.
  • They’re a good source of fiber. When undigested fiber reaches the colon, it’s fermented by bacteria. This converts it to short chain fatty acids (SCFAs). SCFAs build immune cells and help protect the gut lining. Fiber as prebiotic also feeds the good bacteria in the gut.
  • They may be anti-cancer. Research shows some lectins may cause cancer cell death.

So, lectins aren’t all bad. But lectins can be bad for your dog … so which foods contain high levels of lectins?

#2 Where Are Lectins?

Lectins are in all foods, but the main problems are in plant foods. The main culprits are legumes and grains …

Lectins In Legumes

  • Peanuts
  • Cashews
  • Lentils
  • Lima beans
  • Red kidney beans
  • Peas
  • Soybeans
  • Fava beans
  • Chickpeas
  • Pinto beans

Lectins In Grains

  • Wheat
  • Oats
  • Barley
  • Quinoa
  • Rye
  • Corn
  • Millet
  • Buckwheat

Other Foods With Lectins

Harmful lectins are also in some other surprising places.

  • Nightshade vegetables (potatoes, tomatoes, eggplant, peppers)
  • Cow’s milk, yogurts and cheeses made with A1 milk (meaning most commercial milk)

GMOs

Lectins are also in many genetically modified (GMO) foods. Remember lectins in plants can harm predators like insects? Well … GMO developers take advantage of that. They splice lectins into GMOs to increase their pest and fungus resistance.

There are already many reasons to avoid feeding your dog GMOs … and lectins are another one.

Safe Lectin Foods

Lectins are in many plant foods. But some contain low levels of lectins that are not harmful. I’ve listed some examples below. Lectins are not a concern in these foods. The nutritional benefits outweigh the risks of low lectin amounts.

  • Nut and seeds (chia, pumpkin, sunflower)
  • Squashes (pumpkin, butternut or acorn squash, zucchini)
  • Fruits (bananas, melons, goji berries)
  • Green veggies (broccoli, Brussels sprouts, leafy greens)

#3 How Lectins Harm Your Dog

In #1 above, I broadly described some of the ways lectins can damage your dog’s health. But let’s get into some specifics.

Lectins Damage Your Dog’s Gut

Digestive problems are one of the most common effects of eating lectins. That’s their defensive nature again. They discourage being eaten by causing digestive distress. That could just mean a bit of gassiness, nausea or loose stool for your dog. Or it could be much worse.

Because lectin survive digestion, they get into the gut. Research shows the damage they do there …

  • Interfering with nutrient digestion
  • Damaging the cells in the gut lining
  • Shifting bacterial flora, affecting your dog’s immune response
  • Disrupting metabolism of fats, proteins and carbs
  • Harming internal organs and tissues
  • Altering hormones

These effects on the gut are the biggest problems with lectins. They can cause widespread havoc in your dog’s body … with leaky gut syndrome.

The cells in your dog’s gut lining usually stick close together. These tight junctions stop toxins from getting into your dog’s blood stream. But the cells can get damaged. This opens up the junctions between the cells, letting particles to pass through. This lets toxins, allergens, bacteria and yeast into the blood stream. 

Leaky Gut Problems

Leaky gut can be at the root of many health issues for your dog, including …

As you can see, leaky gut is at the heart of a host of chronic health problems. So it’s really important to avoid it in your dog. Lectins in foods can be one of the biggest culprits.

And with lectins, it’s a bit of a vicious circle.  If your dog’s gut is damaged, it’ll be more sensitive to harm from any lectins he eats!

RELATED: Leaky gut in dogs: a growing epidemic

Grain-Free Foods And Taurine Deficiencies

You’ve likely read the stories about a possible link between grain-free foods and canine heart disease … specifically dilated cardiomyopathy (DCM).

This started with a 2018 FDA announcement that they were investigating these foods. As of a November 2020 announcement, the investigation continues, without any real conclusions.  The latest information was presented at a September 2020 forum hosted by Kansas State University. You can read some of the papers here.

So, what does this have to do with lectins? It’s quite a long explanation, but stay with me …

Grain-free foods started as a marketing ploy by the pet food industry. Consumers realized that dogs don’t need grains in their diets. So they wanted grain-free foods.

But you can’t make kibble without starch. That’s what holds it together. So the industry found an alternative starch … in the form of legumes and potatoes. (Yes, these are high lectin foods.) And they promoted these diets as grain-free.

RELATED: The truth abut grain-free foods and DCM.

DCM And Taurine

Grain-free foods are the main target of this FDA investigation. Taurine deficiency can be one cause of DCM. The FDA suspects these diets don’t provide sufficient taurine for dogs. But they do admit that there are many possible causes of DCM … so they haven’t pinpointed the reason for DCM cases. They’re not even shore it has anything to do with diet.

But let’s talk a bit about taurine, because lectins are an important factor! Here’s a bit of history about taurine in pet foods.

Taurine In Pet Foods

The link between DCM and taurine was first discovered in cats in the 1970s. Cats were developing heart disease. That’s because, unlike dogs, cats can’t manufacture taurine. So they need it in their diets. They weren’t getting enough taurine from their starchy commercial diets. So manufacturers started adding taurine to the diets. Taurine is considered an essential amino acid for cats. So supplementing with taurine solved the problem.

Fast forward to 2003-2005. Researchers found some dog breeds had DCM caused by taurine deficiency. Newfoundlands, Golden Retrievers and American Cocker Spaniels all had DCM and low blood taurine levels. The dogs recovered when they were given taurine supplements.

So that’s why the FDA and other researchers think grain-free diets could be part of the problem. There could be something to that theory.

How Taurine Works In Dogs

Taurine is an amino acid.

It’s considered non-essential for dogs … because they make taurine themselves. But to make taurine, your dog’s body needs two other amino acids: methionine and cysteine.

Methionine and cysteine are plentiful in many meats, as well as eggs and fish. So why would swapping grains for legumes and potatoes cause a taurine deficiency? There are lectins in grains too, aren’t there?

But here’s the difference.

Legumes Vs Grains In Dog Food

The grains in dog food do have lectins. But they’re low in protein. And legumes like lentils, peas or beans are much higher in protein than grains.

So … adding these foods instead of grains allowed manufacturers to use more plant proteins. That allowed them to cut back on more expensive animal proteins.

Using legumes isn’t just about marketing … it’s about bigger profits too!

So because there’s less meat … these foods have lower levels of methionine and cysteine. And that means dogs don’t get these building blocks to make taurine.

And it’s not just that there’s less methionine and cysteine in the food. The problem is compounded because …

  • Lectins also stop dogs absorbing methionine and cysteine. Again, dogs need these to make taurine.
  • AND … inflammation from lectins may stop dogs from producing taurine as well.

And there’s one more thing. You can deactivate lectins in foods by pressure cooking them. But pressure cooking also reduces taurine levels.

Do Lectins Cause DCM?

Well … the FDA is still investigating. So we don’t officially know. But there’s good reason to be suspicious of the effects of these lectin foods on your dog’s taurine production.

Poultry, beef, fish, eggs and organ meats are all rich in taurine.  Feed your dog a diet with plenty of animal proteins … and he won’t have a taurine deficiency. (Sadly I can’t promise he won’t get DCM, because there could be other reasons for that.)

RELATED: Taurine might not be behind heart disease from kibble.

Lectins Increase Glyphosate Exposure

This isn’t a direct health effect of lectins. But it’s impossible to talk about lectins without considering it. Many high lectin foods are contaminated with the pesticide glyphosate (Roundup).

I mentioned GMOs already. And you might notice there’s some overlap. Many high-lectin grains and legumes are foods that are often genetically modified (GMO) … like wheat, corn or soy.

And that means these crops are sprayed with the weedkiller glyphosate. But it’s not just GMOs. Other crops are sprayed with glyphosate as a dessicant, to dry them before harvesting. These include …

  • Oats
  • Wheat
  • Legumes
  • Barley
  • Millet
  • Potatoes

In fact, testing by researchers at HRI Labs shows the OWL foods are the very highest in glyphosate. OWL stands for oats, wheat and legumes. And those 3 categories include other grains like barley and rye … plus legumes like lentils, chickpeas and beans. They’re all high-lectin foods!

HRI Labs has also shown that dogs have 30 times more glyphosate in their bodies than the average human! And even more than horses and cats. That’s likely because kibble contains massive levels of glyphosate. Kibble has 200 to 600 parts per billion (ppb) of glyphosate. That’s compared to raw dog food at only 5 ppb.  So kibble-fed dogs are getting whopping amounts of glyphosate in their food.

Why Avoid Glyphosate

You don’t want your dog to eat glyphosate. The WHO has said that glyphosate is ….

  • A probable human carcinogen
  • known animal carcinogen

So glyphosate can increase your dog’s risk of cancer. Not to mention many other health risks:

  • Interferes with gut bacteria
  • Damages the gut lining, causing leaky gut
  • Harms kidney function, can cause kidney disease
  • By disrupting gut bacteria, weakens the immune system
  • Is linked to autoimmune disease and chronic inflammatory diseases

There are ways to deactivate or block lectins. But you can’t get glyphosate out of food. So glyphosate is another big reason to avoid giving your dog high-lectin foods. And raw dog foods have tiny amounts of glyphosate. So a raw diet is your best choice.

If you do feed kibble, try to find one that’s organic. Organic foods have 95% less glyphosate.

RELATED: Is Roundup safe for dogs?

So … what can you safely feed your dog to avoid lectins?

#4 What To Feed Your Dog

So by now you may be wondering what you should feed your dog. Even some meats could have lectins!  

But most meats are low in lectins. And they have plenty of taurine, as well as other nutrients that support your dog’s health.

If you’re already feeding a raw meat-based diet, your dog’s food will be low in lectins. Remember that pasture-raised meats are best if you can get (and afford) them. Animals fed a lot of grains could contain some lectins.

You can safely feed some fruits and veggies. They contain valuable nutrients that benefit your dog’s health.

Avoid These Foods

  • Legumes
  • Grains
  • Nightshade veggies
  • A1 dairy

Feed These Foods

  • Raw meats and organ meats – pasture raised if possible
  • Free range eggs
  • Wild caught fish
  • Berries
  • Dark leafy vegetables

It’s best to try to avoid high-lectin foods in your dog’s diet. If you do give your dog some grains or legumes, or you feed a grain-free kibble … you’ll want to read how to limit the damage in the next section.

#5 How To Limit Lectin Damage

There are several ways to limit any damage lectins may cause in your dog.

Pressure Cooking

Thoroughly pressure cook grains and legumes. Most lectins are deactivated by pressure cooking. Cooking this way also makes legumes and grains more easily digestible.

PRO TIP

Some people recommend slow cooking. But the lower temperatures usually won’t deactivate lectins. Skip your crockpot when. you cook legumes and grains.

Peel And Seed

If you feed any nightshade vegetables (like tomatoes and peppers), peeling and de-seeding them removes most of the lectins.

Feed Lectin Blocking Foods

Certain foods can help block lectins. And lots of them are good for dogs.

Glucosamine-Rich Foods

For dogs, it’s great news that foods that contain glucosamine help block lectins. Because that gives them tons of choice! Glucosamine is naturally in lots of foods with cartilage. Here are some things you may already be giving your dog.

  • Pigs feet
  • Chicken, duck or turkey feet
  • Green lipped mussels
  • Beef trachea
  • Beef knuckle bones
  • Pig tails or oxtails

Feed these raw … or you can make them into a lovely gelatinous bone broth,

Shellfish Shells

Shellfish shells are rich in glucosamine. Whenever I eat shrimp, my dogs line up at the table for the shells and tails. They can eat them raw or cooked.  If you eat other shellfish with harder shells, like crab or lobster … save the shells and grind them up. You can add some of the ground shells to your dog’s food.

Cranberries (D-Mannose)

Cranberries are another wonderful lectin-blocking option. They contain D-Mannose which binds to lectins, especially from legumes.  So give your dog some cranberries. They’re full of antioxidants and can even help prevent urinary tract infections.

Okra

Okra is a vegetable that’s rich in raw polysaccharide. It binds to lectins and stops them from harming your dog.

You can feed okra raw or cooked (sliced and roasted is a great crunchy option).  Just don’t give your dog fried okra. You might love this dish yourself, but it’s way too fatty for your dog. And of course it’s made with flour, meaning more lectins!

Bladderwrack

This is a seaweed that’s a powerful way to block lectins. If you live on the Atlantic or Pacific coasts, you can find it at the beach and add it to your dog’s food. Otherwise, you can buy it in supplement form.

And, speaking of supplements … there are a few that can help.

Supplements That Block Lectins

Here are a few supplements that can help protect your dog from lectin’s effects. 

N-Acetyl Glucosamine (NAG)

NAG is a glucosamine supplement made from shellfish. It binds to lectins and helps stop them attaching to the gut lining. It also builds connective tissue like other forms of glucosamine. You can buy NAG supplements at health stores.

Give your dog 250 to 1000 mg daily, depending on his size.

Bladderwrack

If you don’t live near a beach, you may not be able to find this seaweed in its fresh form. Luckily it’s available as a supplement at many health stores.

Bladderwrack also binds to heavy metals like mercury and helps remove them from the body. It’s rich in fiber and minerals too.

Dosing: If you’re giving the dried herb, you can feed sprinkle 25-250 mg per lb of your dog’s weight on his food. Or make a tea using 5-30g per cup of water. Give ¼ to ½ cup per 20 lbs weight. (Recommended dose from Veterinary Herbal Medicine by Susan G Wynn and Barbara J Fougere.)

Caution: Don’t use bladderwrack for pregnant or lactating females. Also, it contains natural iodine. So if your dog’s on any thyroid medication or supplements, consult your holistic vet about giving this herb.

Larch Arabinogalactan

Larch arabinogalactan is a prebiotic fiber that increases butyrate production in. your dog’s gut. Butyrate is a short chain fatty acid that’s anti-inflammatory and protect the gut lining. As a bonus, butyrate has also been shown to cause cancer cell death and slow cancer growth.

You can buy a probiotic supplement that contains larch. If it’s made for dogs, follow the dosing instructions. If it’s a human product, assume it’s for a 150 lb person and adjust for your dog’s weight.

Or you can buy larch and give a medium sized dog about ½ tsp a day. Don’t give this every day of your dog’s life. It’s a good idea to give it for a couple of months, then give a 2 week break before restarting.

In summary …

Lectins can be harmful to your dog if you feed a lot of legumes or grains. You can manage the risks as I’ve explained. But isn’t it better to feed your dog a fresh, whole food, meat-based diet and avoid the problem in the first place?

References

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Shana J Kim et al, Effects of dietary pulse consumption on body weight: a systematic review and meta-analysis of randomized controlled trialsThe American Journal of Clinical Nutrition, Volume 103, Issue 5, May 2016, Pages 1213–1223.

Berg JM, Tymoczko JL, Stryer L. Lectins Are Specific Carbohydrate-Binding Proteins. Biochemistry. 5th edition. New York: W H Freeman; 2002. Section 11.4,

de Punder, Karin, and Leo Pruimboom. The Dietary Intake of Wheat and Other Cereal Grains and Their Role in Inflammation. Nutrients, vol. 5, no. 3, 12 Mar. 2013, pp. 771–778., 

Ilka M Vasconcelos, José Tadeu A Oliveira, Antinutritional properties of plant lectinsToxicon, Volume 44, Issue 4, 2004, Pages 385-403, ISSN 0041-0101 https://doi.org/10.1016/j.toxicon.2004.05.005

Willy J.Peumans and EISJ.M. Van Damme. Lectins as PIant Defense ProteinsLaboratory for Phytopathology and Plant Protection, Katholieke Universiteit Leuven, Belgium.

Guinane CM, Cotter PD. Role of the gut microbiota in health and chronic gastrointestinal disease: understanding a hidden metabolic organTherap Adv Gastroenterol. 2013;6(4):295-308. doi:10.1177/1756283X13482996

Vojdani A, Afar D, Vojdani E. Reaction of Lectin-Specific Antibody with Human Tissue: Possible Contributions to AutoimmunityJ Immunol Res. 2020 Feb 11;2020:1438957. doi: 10.1155/2020/1438957. PMID: 32104714; PMCID: PMC7036108.

Vojdani A. Lectins, agglutinins, and their roles in autoimmune reactivitiesAltern Ther Health Med. 2015;21 Suppl 1:46-51. PMID: 25599185.

Lei-lei Fu, et al. Plant lectins: Targeting programmed cell death pathways as antitumor agentsInternational Journal of Biochemistry & Cell Biology, Volume 43, Issue 10, 2011, Pages 1442-1449.

Catarino, Marcelo D et al Phycochemical Constituents and Biological Activities of Fucus sppMarine drugs vol. 16,8 249. 27 Jul. 2018, doi:10.3390/md16080249

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