What Are the Drawbacks of A Plant-Based Diet?

If you want to start a fight, bring up plant-based diets. Everyone’s got an opinion, which makes this topic rife for misconceptions. For example, plant-based eaters commonly have to field questions like:

• How do you possibly get enough protein?
• Don’t you know plants contain anti-nutrients that can harm gut function?
• Aren’t you worried about nutrient deficiencies?

It’s true that each of these could be pitfalls, but plant-based eating done correctly can be a great option. On the other hand, plant-based diets can just as easily be designed around unhealthy, processed foods or lack essential nutrients that lead to compromised brain function, athletic performance, or higher rate of chronic disease.

This article will review the pitfalls of plant-based eating and provide a few guidelines for doing a plant-based diet the right way.

What Is A Plant-Based Diet?

The confusing thing about a plant-based diet is that there’s no clear definition. It is less a “diet” than a lifestyle. Plant-based diets vary widely depending on the extent to which a person includes animal products in their diet.

For example, the legendary quarterback Tom Brady says he eats a plant-based diet (1). He’s not a vegetarian, but much of his plate is covered in vegetables, fruits, and other plant-based foods. He includes meat, seafood, and dairy in reasonable quantities and strives for balance. Brady says that about 20 percent of his plate is a healthy protein (generally animal based) and the rest is vegetables. He also stresses that he avoids ultra-processed foods that make up much of the average westerner’s diet. These foods have at least three major drawbacks:

They are low in nutrients and won’t provide the body with the building blocks needed for optimal health or performance.

They contain refined grains and added sugar that elevate blood sugar and predispose you to diabetes and other metabolic problems.

They are designed to be irresistible, stimulating food intake and weight gain. The effect is huge: One recent study found that when volunteers ate a diet high in processed foods for 2 weeks they gained a little over a pound of fat due to consuming 508 extra calories, whereas a group that ate whole foods lost a pound of fat (2).

Avoiding ultra-processed foods is probably the number one most important thing you can do to improve your diet. Therefore, it’s important that if you go plant-based, you gravitate away from packaged foods in favor of whole foods in their most natural state. After all, cookies, chips, soda and other junk foods are all completely plant-based, but that doesn’t make them healthy.

Other possible pitfalls of plant-based eating include the following:

#1: Lack of Essential Nutrients: Vitamin B12 & The Omega-3 Fats

Depending on what you eat on a plant-based diet, it’s possible to be deficient in certain essential nutrients (3). Vitamin B12 and the omega-3 fatty acids EPA and DHA are only available in foods that come from animals. Vegans must supplement because a deficiency in either can be disastrous and lead to compromised nerve function and energy metabolism in the case of B12 and higher rates of inflammation and depression for EPA and DHA.

Vitamin B12 is available in eggs, so including them regularly can prevent a deficiency. Eggs can also provide choline, a crucial brain nutrient that influences liver function (4). Shortfalls in choline are linked to irregularities in blood fat metabolism as well as excess free radical cellular damage that leads to inflammation.

EPA and DHA are available in fatty fish and to a lesser degree, grass-fed beef. As long as you eat these foods frequently, even in small quantities, you can probably meet baseline needs, especially if you limit grains and refined oils that provide the opposing omega-6 fat that cancels out EPA and DHA. Another solution is to supplement with a vegetarian source of EPA and DHA from microalgae. This approach actually cuts out the middleman: Fish get their omega-3s from the algae they live off of.

#2: Poor Bioavailability of Iron & Zinc

If you’ve done any research on plant-based eating, you’ve probably heard about the dangers of anti-nutrients in plants. Now, anti-nutrients sound scary but they’re not that big of a deal as long as you do a few things to protect from their effects.

They work like this: Plants contain compounds called phytates that impair absorption of zinc and iron. Even if you are eating plenty of leafy greens, nuts, and seeds that are rich in iron and zinc, a deficiency is possible. Zinc deficiency is dangerous because this mineral is necessary for hormone release, it impacts thyroid function, and plays a key role in immunity. Iron is necessary for the body to transport oxygen to tissues, so it’s essential for energy and avoiding fatigue. Anemia is a fairly common condition that results from iron deficiency.

People who include meat in their plant-based diets have less reason to worry about deficiencies because meat provides highly bioavailable iron (known as heme iron) and zinc. For vegetarians, supplementation with zinc and iron is an option but you can also reduce the action of phytates by soaking beans, grains, and seeds prior to eating them. Vitamin C also reduces phytates so eating zinc-rich foods with a vitamin C supplement or other C-containing foods may help.

#3: Lack of Performance Nutrients: Creatine, Carnosine & Carnitine

Something rarely talked about in the plant-based world is the fact that there are certain animal-based nutrients that are essential for cognition and athletic performance. If you are a vegetarian or eat a low-meat diet, you may be missing out on reaching your potential.

Creatine is a short-term energy source found in animal flesh that powers exercise and benefits brain function. Studies show that when vegetarians supplement with creatine they increase work capacity, exercise training volume, working memory, and intelligence markers. (5, 6)

Carnosine is an amino acid found in animal foods that helps buffer acid from muscles to avoid the burning sensation from intense exercise. Supplementation can improve work capacity and delay fatigue in vegetarians (7).

Carnitine is a metabolic compound found only in animal flesh that allows the body to burn fat. It also affects hormones and neurotransmitters and studies show supplementation can improve cognition, motivation, and work capacity (8, 9).

Plant-based eaters who avoid meat have no dietary source of these three nutrients so it’s a no-brainer to supplement to achieve your potential and equalize the playing field with your meat-eating peers.

#4: Too Little Protein

It’s completely possible for plant-based eaters to get sufficient protein, however, it should be noted that you will likely need more total protein than omnivores because the body can’t use vegetable-derived protein sources as efficiently. Simply, you may need to bump up your daily total protein goal if you’re getting your protein from vegetarian sources.

In addition, you’ll be hard pressed to get optimal levels of the amino acid leucine, which appears to be the most powerful stimulator of protein synthesis (10). If you eat eggs or whey protein, you can easily meet your leucine needs, or supplemental leucine can be gotten from BCAAs or free form amino acid supplements.

Take Aways

Switching to a plant-based should not be an end in and of itself, but should be considered alongside additional dietary and lifestyle changes.

Macronutrients should be strategically planned to manage blood sugar and energy levels. Some people will benefit from balanced macros, whereas other may choose lower carb or lower fat options, depending on individual goals.

Eating whole foods in their most natural state and avoiding nutrient deficiencies will lead to more substantial benefits than simply avoiding meat.

Avoiding ultra-processed foods is probably the number one most important thing you can do to improve your diet. Focusing on excluding refined foods, like added sugar, flour, and processed oils should be the first change you make.