Do I Need to Eat Vegetables?

This is part 2 of a 5 part series on carnivore dieting. You can read this is a stand alone article if you are interested in the need for plants in a healthy diet or if you are interested in learning more about carnivore, check out part 1 of this series What is a Carnivore Diet?

The biggest fear with going full carnivore is the complete removal of plants from the diet.  Especially since we have been told our whole lives that vegetables are essential to health. When considering a particular nutrition recommendation, it is crucial to ensure that the basis of thinking behind that recommendation isn’t flawed.  We should not just accept recommendations at face value without digging in a little more.  

When it comes to plant recommendations, the thinking is a little flawed.  Most people assume that plants are what provide us with essential micronutrients and cutting them out will lead to micronutrient deficiencies.  However, that’s not the case when you consider the bioavailability of plant sources of food.

Nutrient Absorption 

Bioavailability is a term used to describe how much of a consumed substance actually is digested and enters the bloodstream where it can be used by the body.  If a food is highly bioavailable to humans, that means we can use most of the nutrients contained within that food. Conversely, if a food has a low bioavailability to humans then we cannot use most of the nutrients contained within that food.

While plant foods are rich in micronutrients, these micronutrients are poorly absorbed or have low bioavailability for humans.  However, the micronutrients found in animal meats is a different story. 

While research has demonstrated that only 10-15% of many micronutrients found in plants can be absorbed by humans, nearly 90% can be absorbed from animal meat (1).  For example, vitamin A has been shown to be 15-20x more bioavailable in meat compared to plant sources (2). Additionally, plant sources contain non-heme iron that has demonstrated 3x less bioavailability compared to heme iron found in meat sources (3).  Even more, many nutrients, such as vitamins D,E,K, and A are fat soluble meaning that they are best absorbed by the body when consumed in conjunction with dietary fat, which you also get from consuming animal meat.

Another concern regarding the uptake of plant nutrients is that there are compounds found within many plants that can interfere with the absorption of certain nutrients like folate, calcium, iodine, and zinc.

It is important to point out that there are some vitamins that plant sources are considered to be a better sources of, like vitamin C.  However, Dr. Stephen Phinney, co-author of The Art and Science of Low-Carbohydrate Living, has speculated that the ketone beta-hydroxybutyrate, produced by the body when carbohydrates are restricted, may replace the need for vitamin C.  Furthermore, one of vitamin C’s roles in the body is to form collagen, but Phinney also says that the amino acids you get from meat intake, can be used to form collagen without the need for vitamin C. 

Ruminants to The Rescue

Now you may be wondering what is it that makes the nutrients found in animal meat better absorbed compared to plants.  The answer is that humans are carnivores and cows are herbivores. The biggest difference between the two is not just their food choices but their digestive systems.  

Ruminant animals, which includes cattle, sheep, goats, buffalo, deel, elk, giraffes, and camels, are a classification of animals with digestive systems much different from ours.  

Ruminant animals have four chambers in their stomachs; reticulum, rumen, omasim, and abomasum.  When a ruminant animal eats plant material, it is only partly chewed before going into the rumen chamber of the stomach.  The rumen chamber is rich with microorganisms that can actually breakdown plant material. Here the partially chewed plant material is broken down into what is called “cud”.  Once an animal is full it will continue to chew this cud to further breakdown the material before passing it off into the next three compartments of their digestive system, the reticulum, omasum and their true stomach, the abomasum.  

Interestingly, while it appears that these ruminant animals are on a low fat, high carb/fiber diet, the unique digestive tract actually allows them to ferment almost all plant matter into short chain fatty acids, which go to the liver to form monounsaturated and saturated fats that get put to use in the body.  This means that the cows are keto too!

Outside of short chain fatty acids, monounsaturated fat, and saturated fat, ruminants can also create a superior source of the anti-inflammatory omega-3 fat.  ALA, a plant based omega-3 fatty acid must be converted to EPA/DHA for humans to be able to use. Unfortunately, there is only a 0-7% conversion of ALA to EPA/DHA in humans.  However, ruminants come to the rescue here again and take ALA from plants and convert it to EPA/DHA for us and store it in their muscle meat where we can have better access to a superior source of omega-3 fatty acids. 

It is these digestive processes that allows ruminants to breakdown plant food and acquire their nutrients where they are then stored within the flesh of these animals where humans, because we are carnivores, can have better access to them.

This process is important to understand because we as humans cannot complete this action.  We cannot breakdown plant material very well and we cannot ferment salads into fat. Which is why it is important for us to be consuming high quality meat sources.

The point of this breakdown of ruminant animals and their digestive systems is that for humans animal meat is a superior source of nutrients.  It is both more bioavailable, and in regards to some nutrients as displayed below in a graphic from Chris Kresser, actually contains more of certain micronutrients including vitamins B12, D, and K2 which are only found in meat and not plants. 

I also want to take a second to point out that it is the nutrient absorption process of ruminant animals that is why we must consider the diets of these animals. Ruminants breakdown plant material and store their nutrients in their meat. This is why we want out animals fed grass and plants that are rich in micronutrients, not corn, grain, or soy. Food quality matters!

Why is it Recommended That We Have Plants Then?

This is a great question.  If we cannot get the proper nutrients from plants that we need to survive and thrive, then why do so many people insist we eat plants?  A great explanation can be found in a quote from Dr. Georgia Ede:

“It may be that vegetables appear so healthy in all the epidemiological studies because of what they are not, and not because of what they are.”


The point here is that a lot of studies and anecdotal stories that demonstrate a diet high in vegetables improving health parameters are likely seeing these improvements because a plant based diet is much better for health than the diet subjects in these studies were following prior to the plant based diet. 

In most plant based diet studies, prior to the intervention, subjects are consuming a typical Standard American Diet, or SAD, consisting of refined carbohydrates and ultra-processed foods.  Of course switching to having more broccoli is going to lead to improvements in health compared to McDonalds. But just because a diet is better than the horrible diet most of us are consuming today, doesn’t mean that it is the most optimal diet for us to consume.

The truth is that most plant based diets demonstrate improvements in the short term, but in the long term demonstrate numerous side effects from nutrient deficiencies because we cannot get the nutrients we need to survive and thrive from plant sources alone. 

Are plants bad for you then?

Of course this is the next logical question and for many people who become passionate about carnivore dieting this is a general assumption.  Because we don’t need plants they must be bad for you.  This is not entirely true.  

For most people, there is nothing wrong with consuming plants as long as you understand this cannot be your only source of nutrition.

However, it is important to point out that there are some of the features of plants that can be harmful to our health.  This is not intended to promote fear towards plants but rather demonstrate a few things to take into consideration if you are eating a lot of plants.  

Oxalates:

Oxalates are compounds that occur naturally in many plant foods like nuts, kale, spinach, beans, chocolate, and many others.  Oxalates are often referred to as “anti-nutrients” because they interfere with absorption of other vitamins and minerals and are often thought to be toxic to prevent animals or insects from eating them.  

Interestingly, oxalates are not just found in food.  They can also be produced in the liver when we consume too much vitamin C, yeast, and fructose.  All compounds that come from plants.  

Oxalates can have some negative health consequences since they can bind to minerals and form compounds like calcium oxalate and iron oxalate. While most people can get rid of these compounds through stool and urine some individuals have a sensitivity to these compounds and when consumed in large amount can cause health complications (4).  One of the main complications associated with oxalates is kidney stones if the compounds clump together and form crystals but can also form stones in the bladder and gut wall (5). 

If you notice that you feel bloated or inflamed after eating a lot of plants, you may be sensitive to oxalates.  Sensitivities can be due to a genetic alteration in the oxalate breaking down gene called SLC26A1 or it can be due to impaired gut function, or nutritional deficiencies.  

Sugar in Fruit:

Fruits contains a lot of sugar which is not only harmful to a state of ketosis, but can also promote insulin resistance when consumed overtime.  

I know what you are thinking, “the sugar in fruit is healthy sugar.”  This is a common misconception. In fact, research looking at the acute consumption of fructose, the main sugar found in fruit, has found that the compound can actually promote inflammation (6).  This study had subjects consume 50g of either glucose, fructose, or sucrose and found that those consuming fructose had a greater increase in c-reative protein, a common marker of inflammation. 

Certain fruits that are lower in sugar content like berries may be better alternatives for fruit but the moral of the story is that we should not be consuming ample amounts of fruit thinking that we are being healthy.

Pesticides:

Besides some of the harmful compounds that can be found inside plants, there are also all of the toxins that are found outside plants due to poor agricultural techniques like spraying pesticides.  These chemicals can be very harmful to your health and further render these plants useless for contributing to health improvements.

In 2018, the 12 MOST pesticide contaminated produce items were:

  • Strawberries

  • Spinach

  • Nectarines

  • Apples

  • Grapes

  • Peaches

  • Cherries

  • Pears

  • Tomatoes

  • Celery

  • White Potatoes

  • Sweet Bell Peppers

Over Consuming Fiber

Just like studies demonstrating plant based diets being good for health are flawed, so are studies demonstrating the importance of fiber in a very similar sense. In fact, for those suffering from impaired digestion, more fiber can actually be counterproductive. Check out this study below which actually found that removing fiber from the diets of those suffering from constipation actually led to improvements in symptoms (7). This may seem counterintuitive but this is because the overconsumption of fiber can be disruptive to our digestive tract.

Do we need fiber?.jpg

As mentioned previously, this is not meant to scare you from consuming plants but rather educate you that there are certain compounds found within plants that can be harmful and another reason why they should not be the primary component of a healthy diet.

What’s Good About Plants?

While we have spent some time talking about the negatives of plants, I do want to take a brief moment to point out some big wins for plants.

Herbs, spices, and essential oils, which all come from plant sources, can provide health benefits to humans.  These herbs, spices, and oils can act as adaptogens in the body and alter our state of mind by promoting calming and relaxation.

Speaking of altering the mind, psychedelic plants like cannabis and psilocybin containing mushrooms can provide powerful therapeutic effects and is something that we are seeing more research evidence of everyday.

Plants aren’t all bad!

Conclusion

To reiterate, the purpose of this article is not to tell you that plants are dangerous and that you should not be eating them. The point is to show you that you do not need to consume them and that a diet based primarily of plants is not ideal for optimal health.

In regards to carnivore dieting, now you should be able to see that it’s not so crazy to think you can consume a diet of just meat with no vegetables. In fact, you may find that is is much healthier this way.

This concludes part 2 of this 5 part series on the carnivore diet. Check out part 3 to this series to get the question answered that you might be most curious about, Is the Carnivore Diet Safe?

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References:

  1. Sauberlich, H. E. (1985). Bioavailability of vitamins. Progress in food & nutrition science, 9(1-2), 1-33.

  2. Haskell, M. J. (2012). The challenge to reach nutritional adequacy for vitamin A: β-carotene bioavailability and conversion—evidence in humans. The American journal of clinical nutrition, 96(5), 1193S-1203S.

  3. Yang, L., Zhang, Y., Wang, J., Huang, Z., Gou, L., Wang, Z., ... & Yang, X. (2016). Non-Heme Iron absorption and utilization from typical whole Chinese diets in young Chinese urban men measured by a double-labeled stable isotope technique. PloS one, 11(4), e0153885.

  4. Bsc, S. N., & Bsc, G. S. (1999). Oxalate content of foods and its effect on humans. Asia Pacific journal of clinical nutrition, 8(1), 64-74.

  5. Peck, A. B., Canales, B. K., & Nguyen, C. Q. (2016). Oxalate-degrading microorganisms or oxalate-degrading enzymes: which is the future therapy for enzymatic dissolution of calcium-oxalate uroliths in recurrent stone disease?. Urolithiasis, 44(1), 45-50.

  6. Jameel, F., Phang, M., Wood, L. G., & Garg, M. L. (2014). Acute effects of feeding fructose, glucose and sucrose on blood lipid levels and systemic inflammation. Lipids in health and disease, 13(1), 195.

  7. Ho, K. S., Tan, C. Y. M., Daud, M. A. M., & Seow-Choen, F. (2012). Stopping or reducing dietary fiber intake reduces constipation and its associated symptoms. World Journal of Gastroenterology: WJG, 18(33), 4593.

Christopher Irvin