The Biggest Pitfalls Of A Vegan Diet + How To Fix Them

Myths About Vegan Diets Dr. Will Cole

I was a young student in college when I first decided not to eat any animal products. This impulse came from a well-intentioned place – I had educated myself on factory farming, CAFOS (or concentrated animal feeding operations, where animals live in deplorable conditions), and the damage that eating animals causes our health and environment.

Back then, I thought I knew it all. I was going to tell anyone who would listen about how being a vegan was better than what they were doing. I was enlightened. Or so I thought. Little did I know that my new diet was slowly chipping away at my youthful energy and taken-for-granted health.

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Now, if you are a vegetarian or a vegan, don’t worry – I am not here to convince you to eat one way or another, and this diet might work for you. But I look back on my youthful attitude now as egotistical and elitist. No matter how anyone eats, it’s an ugly look to turn up a nose at someone else and their beliefs. We are all on our own journeys and we should honor each other. But that doesn’t mean we can’t share what we have learned along the way, as long as we do it respectfully and with love.

The turning point in my life coincided with the beginning of my study of functional medicine. One of the first things I learned about getting to the root causes of illnesses was that there’s no “one size fits all” approach to wellness. I had to come to grips with the fact that I was eating healthfully but wasn’t feeling healthy. Something was missing. My diet wasn’t right….for me.

So, after 10 years as a vegan, I quit – and now I feel better than ever. Was veganism better for me than the Standard American Diet? Certainly! But just because something is an improvement doesn’t make it optimal. For me, a vegan diet was not optimal. Again, that doesn’t mean it’s not right for you.

I’m not here to convince you to eat one way or another. You can be a vegetarian or vegan and be in great health (like my friends Dr. Joel Kahn and Dr. Garth Davis). We all have different genetics, biochemistries, and microbiomes. We all have different requirements to thrive.

Why Being Vegan Wasn’t Right For Me

1. I wrecked my digestion

I believe that years of not eating healthy, organic meat and fat contributed to hypochlorhydria, or low stomach acid, and gallbladder issues. (I found this out by running functional medicine labs on myself.) This made it difficult for my body to digest foods. That, along with all the grains I was eating, contributed to my leaky gut syndrome.

2. I weakened my detox pathways

It’s estimated that around 40 percent of us have methylation dysfunctions, such as MTHFR mutations, and I am one of them. Methylation is a process that acts like a biochemical superhighway that helps with your detoxification system, brain, gut, and immune health. A mutation that weakens the effectiveness of this system could increase the risk of chronic brain, hormonal, digestive, and autoimmune conditions.

Choline and vitamins B9 (folate) and B12 are essential for healthy methylation pathways – and these three nutrients are found most abundantly in meat and animal products. Sure, I could have supplemented, but if I can’t get these nutrients naturally from the foods I’m eating, I don’t believe such a diet is optimal for me.

3. My skin was breaking out

My skin is prone to breaking out, and when I was vegan, in addition to my wrecked gut health, I also wasn’t getting enough beneficial vitamin A from the foods I was eating. Retinol, what’s sometimes called true vitamin A, or the bioavailable form, is only found in animal products like fish, shellfish, fermented cod liver oil, grass-fed liver, and butterfat from grass-fed cows.

Plant carotenes, a precursor to vitamin A, are found in sweet potatoes and carrots – but the conversion rate to the usable retinol is very weak. In fact, research suggests that just 3 percent of beta-carotene gets converted in a healthy adult. Once I started optimizing my diet with true vitamin A-rich foods like liver, and collagen-rich foods like bone broth, I noticed that my skin improved. That was all the proof I needed.

4. I had brain fog and fatigue

I believe that a lack of healthy fats in my vegan diet contributed to the brain fog I experienced. The omega fats found in fish make it a superfood for the brain. Sure, omega-3 fat ALA can be found in plant sources such as walnuts and flaxseed, but this form is not easily used by the human body. It must be converted into DHA or EPA, and that process is inefficient. My body wasn’t effective at this conversion, as evidenced by my energy crashes and fatigue. Once I started getting arachidonic and docosahexaenoic acids from fish and other animal sources, I felt immediately better, because these two forms of fat play an important role in brain health.

5. My immune system was weak

Back in my vegan days, it seemed like I caught every cold virus. I was often found tired and run down, and didn’t have much energy. I believe that this was in part due to a lack of healthy fats, as well as a lack of fat-soluble vitamins.

Vitamin K2: Often-overlooked, fat-soluble vitamin K2 is also crucial for healthy immune reactions. One study in the Journal of Neuroimmunology found that vitamin K2 was effective at inhibiting the pro-inflammatory iNOS in the spinal cord and the brain immune system in rats that had multiple sclerosis symptoms. Unfortunately, K2 is one of the most common nutrient deficiencies in the Western diet. Vitamin K2 is best paired with the other fat-soluble vitamins, A and D, in whole-food form like grass-fed butter oil (ghee). Natto, a Japanese superfood made from non-GMO fermented soybeans, also has high levels of K2, for those who still choose not to eat animal foods.

How I changed my philosophy

Changing my diet meant changing my philosophy, and this wasn’t easy. I had to rethink many of my beliefs and prioritize my health. I’m not the only one who has made such a conversion and had to admit I was wrong about the best diet for me. My dear friend and colleague Dr. Terry Wahls, who was a vegetarian for years herself, said poignantly:

I spent some time reflecting on life in the wild. We all consume one another in the end. Our atoms and molecules are continually recycled. Every living thing without the benefit of photosynthesis must consume other beings – plants, fungi, bacteria, and animals. And in the end, they will consume me. I prayed and meditated on these ideas. Humans have been eating all these things for thousands of generations, so I decided I was not committing a crime against nature if I ate meat. Perhaps I was getting even closer to nature.

As for me, I also realized that I was not separate from or above nature, but a part of it. And because of my MTHFR methylation impairments and digestive and skin issues – as well as a family history of autoimmune conditions – veganism was not right for my long-term health.

My Ketotarian Transformation

What’s a former vegan who knows the benefits of animal products but still leans towards a plant-centric diet to do? The answer to my own dietary dilemma turned out to be a protocol I developed that I call the Ketotarian Diet. This diet combines the best parts of a ketogenic diet with the best parts of a flexible plant-based eating plan. Here’s how I did it:

  1. First, I eliminated all of the foods I normally reached for on my conventional vegan diet: Gluten-free grains, loads of high-fructose fruits, and legumes
  2. I replaced these foods with antioxidant-rich low-fructose berries, plant-based fats like avocados and coconut, and mounds of nutrient-dense vegetables such as dark leafy greens.
  3. While I chose to be mainly plant-based, I knew I needed more omega-3s and vitamin A in my life that I couldn’t get as easily from plant foods, so I chose to incorporate wild-caught fish and cage-free organic eggs on occasion as well.

What happened after I changed my diet

Today, eating a variety of vegetables, fruits, meats, and fats, I feel better than ever. My energy is great, and my skin and digestion have improved dramatically. Now, I also coach people around the world who are struggling with the health problems I had. Consider a free webcam or phone evaluation, or check out my elimination diet course with mindbodygreen, to find out how to bring in healthy meats and fats into your diet. In addition, our new video course Heal Your Hormones, Brain, and Gut is available as well.

The Common Pitfalls of a Vegan Diet

Vegetarian and vegan diets sound like a great idea – you’ll be eating more greens and easing the load on the planet. But when it comes to the nutritional picture, both vegetarian and vegan diets have some cons as well as pros. When they go wrong, they can lack nutrients and fuel inflammation, harming your health more than helping it. Let’s put these diets under the proverbial microscope so we can take a closer look at some common plant-based pitfalls.

Too many carbs

If you don’t eat meat, you have to replace it with something, right? Sure, but the problem is that many plant-based diets default to carbs, believing that “healthy” whole-grain carbs are the best source for sustainable energy. This belief is one of the biggest misconceptions and leads to one of the primary nutritional problems with a conventional plant-based diet.

The reason why heavy carb consumption is so bad, is that our bodies simply aren’t designed for that kind of load. A report in the American Journal of Clinical Nutrition (1) explains why: The development of agriculture caused a rapid change in our world over a relatively short period of time. Our current food supply, soil depletion, and environmental toxins, all caused by agriculture happened long after most of our genes were in place. People have only been cultivating grains like wheat for around 10,000 years. That’s nothing, in evolutionary terms, and the result is essentially a diet that is mismatched to our genes. To make matters even more confusing, hybridization of grain species, the spraying of pesticides and fertilizers, and genetic modification of the grain supply have all further adulterated this supposedly natural food, to the point that our bodies may not respond well to these products that make up a large portion of our diets. Our ancient genes are living in a whole new world.

When it comes to plant-based eaters, the problem becomes a twofold one: First, grains (and a lot of other foods) are not what they once were. Because we live in a modernized and largely polluted, toxic world, we are already under assault and therefore have less wiggle room for unhealthy foods. In the generations before us, human bodies were better matched with the food supply and were more vigorous. Today, not so much. Add a genetic problem with grain digestion or intolerance (such as a gluten intolerance or a wheat allergy) and the situation gets even worse. All of these scenarios are potential triggers for chronic disease.

Second, we simply eat too many grains, and in the absence of meat, grain consumption is even higher than average. Even if the grains we were eating were of the more ancient, natural type, they are still filled with starch and natural sugars that can overwhelm the body’s blood sugar balance. Consuming too much can quickly raise blood sugar, which over time can get out of control. These blood sugar surges can cause insulin spikes and a hormonal hurricane of insulin resistance, high triglycerides, and inflammation—hallmarks of chronic disease with the end result often being diabetes.

Yet another potential problem with excess grain consumption is FODMAPs. This funny-sounding acronym stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols—in other words, fermentable sugars. These short-chain sugars are not fully digested in your small intestine. They travel undigested into your large intestine, to be fermented by your gut bacteria. But you don’t need much. If you overload your body with these FODMAPs, excessive fermentation releases hydrogen gas that causes distention of the intestines—which can cause major IBS and small intestinal bacterial overgrowth (SIBO), with uncomfortable symptoms like pain, gas, bloating, constipation, and diarrhea.

Gluten sensitivity

The sugars and starches in grains can cause a lot of problems, but there is another problem with many common and heavily consumed grains: the proteins. One of the primary proteins in wheat, barley, rye, spelt, and some other grains is gluten, and researchers estimate that around 18 million Americans have a “gluten sensitivity.” Some people are genetically predisposed to this problem, but in many cases, gluten sensitivity or intolerance may be related to overconsumption. Not only do these grains naturally contain gluten, but many processed grain products like bread contain extra isolated wheat gluten.

There is a growing awareness of gluten and its potential for harm, and that has spawned a seemingly endless vortex of gluten-free everything. While many people doubt the validity of gluten-intolerance, one trial published in Clinical Gastroenterology and Hepatology (2) studied people who thought gluten was causing them digestive problems to find out for sure. For one week, participants were given either a small amount of gluten or a placebo pill of rice starch. After only one week, those who were taking the gluten pills reported a significant increase in symptoms compared to those who took gluten-free placebo pills. Other randomized control trials have shared similar findings. (3) The more research results come in, the more it appears that gluten intolerance is all too real.

To understand gluten intolerance, we first need to understand autoimmune conditions. Many people think when we talk about gluten intolerance, we are referring to the autoimmune condition called celiac disease. Celiac disease is really the extreme end of a broader gluten-intolerance spectrum. The other end of that spectrum is nonceliac gluten sensitivity (NCGS). In other words, you may be a little sensitive to gluten, or extremely sensitive to gluten. In either case, if you aren’t eating meat, chances are you are consuming a lot of gluten, and that may be causing you some mild to serious health issues.

What are the symptoms of gluten intolerance? People in the study noticed the following:

  • Abdominal bloating
  • Ulcers
  • Intestinal pain

Because your gut is your “second brain” (due to the close connection of the brain and the gut via the gut-brain axis), people with gluten intolerance can also experience the following:

  • Brain fog
  • Depression
  • Anxiety
  • Fatigue

But gluten isn’t the only problem with wheat (the grain most responsible for gluten exposure in our modern world). There are more than 20 different properties in wheat that are potential allergens or that can cause intolerance and health problems. Most patients who ask to be tested for gluten intolerance get a simple alpha-gliadin lab test, which is a test for celiac disease. If the test comes back negative, they are told they are not gluten intolerant. You may want to then celebrate the good news by eating a basket of breadsticks, but not so fast. Alpha-gliadin and the common celiac lab test for transglutaminase 2 are just two pieces of about a 20-piece wheat puzzle. Only a doctor willing to explore more thoroughly will be able to give you a reliable answer to your questions about your own possible gluten intolerance.

Antinutrients: Lectins and phytates

Moving beyond starch, sugar, and gluten, grains also contain antinutrients. These are compounds that interfere with nutrient absorption. Two of the most common are lectins and phytates.

Lectins are another type of protein found in grains, including the gluten-free ones like rice and corn. Their purpose is to protect the grain plant from consumption, and these grain defense mechanisms are highly indigestible. That’s the point, from the grain plant’s perspective, but it’s not good for the human body. Lectins can damage your gut lining. They are a mild toxin and can cause inflammation. (4) Lectins can also bind to insulin and leptin receptor sites, causing hormonal resistance patterns such as weight-loss resistance, (5) and can block the absorption of some nutrients.

Blocking nutrient absorption is also a specialty of phytates, which are veritable nutrient leeches. Phytates bind to minerals in your body and make them unusable. Grains do contain some nutrients, but they are diminished by the phytates, (6) which make them unavailable for your body. It hardly matters how many nutrient-dense vegetables you are eating if you are also eating phytates that block all those benefits.

Pseudograins like quinoa, which is a popular staple for vegetarians and vegans, also contains saponins, which can damage your gut, leading to increased gut permeability. This can further contribute to inflammation and chronic conditions.

Grains aren’t the only food group full of these antinutrients. Another common staple in a plant-based diet is legumes. This category encompasses all types of beans, lentils, and peanuts. Because of their protein content, they have become a typical stand-in for meat in many vegetarian and vegan lifestyles, but they are also loaded with lectins and phytates, just like grains are.

But what about fiber? Isn’t fiber a good thing? This is a common argument for eating grains as well as legumes, but these are hardly the only fiber source. Vegetables offer ample amounts of fiber (not to mention a whole slew of other nutrients) without the  many offenses to your gut, brain, immune system, and hormones that grains and legumes commit.

Nutrient deficiencies

Over time, a diet heavy in grains and legumes rather than fresh vegetables is likely to result in some degree of health dysfunction. But even in those people who don’t rely heavily on those two food groups, there can be nutrient deficiencies that can compromise optimal health.

Many studies link vegetarian and vegan diets to deficiencies in key nutrients including vitamin D, magnesium, B vitamins, and iodine—all nutrients that, if lacking, can lead to hormonal, thyroid, and methylation impairments. Many of these nutrients are most bioavailable from animal sources. Plant sources often have some precursor to these nutrients that need to be converted to be available, and even then, do not provide nearly the amount one would get from the animal product version. For instance, plants have less available precursor versions of iron, vitamin A, and DHA, the omega fatty acid in fish. Also, even when the plant versions do have decent nutrient levels, the phytates they contain can block the absorption of those nutrients.

For the most part, while vegetarian and vegan diets can both lead to major nutrient deficiencies, this is more of a problem in vegan diets than in vegetarian diets. Vegetarians usually still eat some type of animal product, such as eggs. Either way, let’s take a deeper look at the most common deficiencies and why plant-based diets don’t always make the cut in this department.

1. DHA and EPA

Omega fatty acid deficiencies in the standard vegan diet are the subject of a long-standing argument. If you are feeling better not eating meat, is it that important to worry about getting these omega fatty acids? Vegan diets are typically much lower in fat than standard diets, but a well-balanced diet with natural sources of alphalinolenic acid (ALA) and the long-chain omega-3 fatty acids DHA and EPA is fundamental to maintaining a healthy omega fatty acid ratio. This helps to prevent inflammation and promotes long-term health by protecting against health problems like autoimmune and cardiovascular disease. Additionally, your brain is composed of about 60 percent fat, so depriving your body of fat can contribute to all kinds of unpleasant brain symptoms, from brain fog and fatigue to depression and anxiety. Bottom line: Healthy fat is essential for optimal brain health.

You must get these fats from food because your body can’t synthesize them. But what about omega fats from plant-based sources such as legumes, nuts, and seeds? This is where the bioavailability problem rears its ugly head.

The average American consumes most of their omega-3s in the form of ALA, which comes from plants. ALA is an energy source for our cells, and a small percentage of this is converted (7) into DHA and EPA. But this low conversion rate isn’t enough. In fact, only up to 10 percent of EPA and up to 5 percent of DHA actually end up being converted (8) in the body. The best sources of DHA and EPA are fatty, cold-water fish like salmon, trout,  herring, mackerel, and sardines; in shellfish such as shrimp, oysters, clams, and scallops; and in cod liver oil. These sources of omega-3 are the most bioavailable (9) to your body. Vegetarians have an estimated 30 percent deficiency in both EPA and DHA; vegans have a 50 percent deficiency in EPA and a 60 percent deficiency in DHA. (10) You just can’t get enough of these brain-critical fatty acids from plants. To get enough, you have to eat some fish, or at least algae like spirulina (which also contains bioavailable omegas) into your diet. Many people who don’t eat seafood don’t recognize that this is an option, so they become deficient.

2. Vitamins A and D

Fat-soluble vitamins, in particular, are some of the most severe deficiencies that we see in vegans and vegetarians. This is because these two vitamins are almost exclusively found in animal-based foods such as organ meats, eggs, dairy fats like ghee, and wild-caught seafood.

Let’s start with vitamin D, because no other vitamin can hold a candle to vitamin D when it comes to widespread influence on health. Since vitamin D is fat-soluble, it acts more like a hormone than a vitamin. It regulates thousands of vital pathways in your body. Besides your thyroid hormones, this vitamin is the only other thing every single cell of your body needs in order to function properly. Also known as the sunshine vitamin, vitamin D is synthesized by your body when your bare skin is exposed to sunlight. It is impossible to get enough vitamin D from food alone, and unless you live in a very sunny place and are outside frequently without sunscreen, you are probably deficient.

Since vitamin D deficiency is already a problem for most of the population, omnivores included, it is even greater for plant-based dieters. Typically, vegetarians and vegans, on average, are more severely vitamin D deficient (11) than meat eaters.

Vitamin A is essential for a strong immune system, and vitamin A deficiency has been linked (12) to autoimmune diseases, which are on the rise in a major way. Some researchers believe this has to do with our dendritic cells, which are the immune system’s alarm cells. They send out a “red alert” to stimulate immunity or a “calm down” message to keep immune reactions from damaging the body. The “calm down” message requires vitamin A.

Plant beta-carotenes, a precursor to vitamin A, are found in sweet potatoes and carrots, but again, the conversion rate to the usable form of vitamin A, retinol, is very weak. In fact, research suggests that just 3 percent of beta-carotene gets converted (13) in a healthy adult. Because of this, you can see how deficiency can be common among people who eat a vegan or vegetarian diet. You’d have to eat huge amounts of carrots and sweet potatoes to even attempt to reach adequate levels. By contrast, a single serving of beef or lamb liver will take care of your daily requirement for vitamin A.

3. B12

This is potentially the most common deficiency for all types of plant-based diets. B12 is absolutely necessary for methylation, a biochemical process that happens more than 1 billion times a second in your body to keep you alive and healthy. It is your DNA protection system; it controls how efficiently you detoxify, and every single cell of your body depends on this process. In short, if methylation is not working well, a lot can go wrong with your health.

True B12 is found only in animal products such as wild-caught fish, grass-fed beef, eggs, and dairy products. A common alternative for plant-based B12 comes from sea vegetables like seaweed and spirulina, and is also in fermented soy products like miso and tempeh. However, these don’t contain true B12. Instead, they are B12 analogues known as cobamides, and once again, these are not nearly as bioavailable (14) as B12 from animal sources.

For vegan and vegetarian dieters, this is one nutrient that no matter what or how much you choose to eat, you’ll never truly be able to reach optimal levels without supplementation. In fact, it’s estimated that 68 percent of vegetarians and 83 percent of vegans are deficient (15) in this vital vitamin.

And that’s not taking into account any possible genetic weaknesses. A mutation in your MTR/MTRR methylation gene, which regulates B12 production, can require higher intakes of B12 than normal since the body ends up using B12 faster than it can produce it. A diet that necessitates a vitamin supplement is certainly not an optimal diet.

4. Zinc

Your body has no significant way to store this important mineral, so it’s important to make sure you’re getting it through your diet or supplementation. Zinc’s main role is to help your body increase white blood cells and fight off infection, and it also assists with the release of antibodies. Deficiency has been linked to increased instances of illness, (16) so it’s no wonder you often find zinc as a common ingredient in the cold and flu aisle of your pharmacy. It’s especially important for pregnant women since it is required for proper fetal growth and development. (17)

This is a very easy nutrient to get through a plant-based diet. But what we often see is that typical plant foods that contain zinc still contain phytates, which block nutrient absorption. So if intake is not monitored, zinc deficiency can still happen and often requires more zinc-containing foods to reach necessary daily intake levels.

5. Iron

Iron helps get oxygen to your cells, and your cells can’t function properly and well if they are deprived of oxygen. In fact, not much else in your body does, either. Some typical symptoms I see with low iron are fatigue and low sex drive.

There are two ways to look at iron levels in your body. One is serum iron, which measures the levels of iron currently circulating in your blood. The other is ferritin, which measures long-term iron storage in the body. The serum levels of most vegetarians and vegans are similar to those of meat eaters, but measuring ferritin levels reveals the real difference.

While we definitely don’t want ferritin levels to be too high (this is correlated with increased inflammation), we don’t want them to be low either, which is a sign of iron deficiency.

There are also two different types of iron—heme and non-heme. Heme is the most bioavailable iron for your body and is found only in meat. Non-heme isn’t absorbed as easily and is found in dairy, eggs, and plant foods.

Many plant foods contain iron but only the non-heme variety. Dark leafy greens, mushrooms, nuts and seeds, and legumes all contain high amounts of iron, but if you are consuming too many legumes, you’ll run across problems with phytates decreasing your absorption. Additionally, iron absorption can be inhibited by other substances  like calcium, coffee, and tea. And again, plant sources just do not have the same level of bioavailability as animal sources. All of these factors contribute to an 85 percent lower (18) non-heme iron absorption rate in plant-based diets.

As our deficiencies continue to escalate, so does our need to supplement. For vegans and vegetarians, all of these deficiencies can be mitigated through regimented supplementation—but only if you’re aware of the problems in the first place.

For all these reasons, a vegetarian, and especially a vegan diet, is not something to practice lightly. It takes a lot of effort, awareness, careful calibration of nutrients, and supplementation. Or, just eat a wide variety of fresh vegetables and animal products including seafood and organ meat, and you can rest assured you are getting all the nutrients your body needs.

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Dr. Will Cole, IFMCP, DNM, DC, leading functional medicine expert, consults people around the world via webcam and locally in Pittsburgh. He received his doctorate from Southern California University of Health Sciences and post doctorate education and training in functional medicine and clinical nutrition. He specializes in clinically researching underlying factors of chronic disease and customizing a functional medicine approach for thyroid issues, autoimmune conditions, hormonal imbalances, digestive disorders, and brain problems. Dr. Cole was named one of the top 50 functional medicine and integrative doctors in the nation and is the best selling author of Ketotarian and The Inflammation Spectrum.