By May 1, 2015 May 12th, 2015 Lifestyle & Stress, Nutrition

Some individuals choose to not eat animal products, including meat and fish, for various reasons. Most people claim ethical, health, religious, political, cultural, or emotional reasons for being vegetarian. Ovo-vegetarians consume eggs but no meat, fish or dairy. Lacto-vegetarians consume dairy but no eggs, meat or fish. Lacto-ovo-vegetarians consume both eggs and dairy but no meat or fish. Vegans don’t eat any eggs, dairy, meat or fish, and also avoid honey. A strict vegan avoids all forms of exploitation of, and cruelty to, animals for food, clothing or any other purpose. Vegans say they avoid honey because it exploits the bees that produce it.

About three percent of the U.S. population is vegetarian, with only 0.5 percent being vegan.

Those who avoid meat, fish, eggs and dairy can obtain adequate protein, especially if needs are not high, by carefully planning each meal. At one time it was thought that certain combinations of plant foods had to be eaten at the same meal to ensure sufficient essential amino acids for protein needs. But this type of protein combining is not necessary, as long as a variety of unprocessed plant foods are eaten each day and include legumes, whole grains, nuts and seeds, soy and other beans, and vegetables.

Unfortunately, after evaluating the diets of hundreds of vegetarians throughout my career, this is usually not accomplished even after providing these individuals with proper dietary guidelines.

While the various forms of vegetarianism have shown health benefits, there are many studies that demonstrate ill-effects due to malnutrition. I was an ovo-vegetarian for several years in my early twenties, thinking it would improve my health. Initially, I felt better overall. In part, this was due to the required care of shopping for food and creating meals, which resulted in healthier food intake. It was a very difficult—actually impossible—task considering the nutrients not available in a strict vegetarian diet. These included vitamins A, B12 and a number of key amino acids such as cysteine, glutamine and creatine. These could be obtained from dietary supplements. I attempted to obtain sufficient protein by consuming several whole eggs a day, in addition to nuts and seeds, whole grains, and protein supplements.

Eventually, my energy was not sufficient enough to maintain a busy practice and workout schedule everyday, and my muscle mass was declining. I also did not like relying on dietary supplements. In addition, I began craving meat—and when I finally began eating it felt much better.

I also had many patients throughout my career who followed various forms of vegetarianism. While some were careful about their diets, most were not. The majority consumed too much junk food, including a lot of processed carbohydrates and sweets, and very little vegetables. Most of the vegetarians I saw were extremely unhealthy.

For many years, a variety of published studies showed why. Vitamin B12 is usually abnormally low in vegetarians, particularly vegans, because this nutrient can only be obtained in sufficient levels from animal foods such as all meats with some in egg yolks and dairy. The result of low levels of vitamin B12 is the rise in a chemical called homocysteine, which significantly increases the risk cardiovascular disease, including heart attack and stroke.

While mushrooms, tempeh, miso and sea vegetables are often reported to provide some vitamin B12, they will not prevent deficiency. These foods contain an inactive form of B12, and which can interferes with the normal absorption and metabolism of the active form of B12.

Another nutrient that tends to be low in vegetarians is iron. Vegetable sources of iron (called nonhaem iron) are not well absorbed by the body while haem forms from meat are well absorbed. In addition, certain foods can impair the absorption of both forms of iron. These include tea and coffee (which contain tannins), and phytates found in whole grains and legumes. (Zinc absorption is also impaired by phytates.)

Studies have shown that bone density is lower in those adhering to a vegetarian diet, especially in vegans, compared to meat-eaters. However, this has not shown that fractures are more common in vegetarians.

To be a healthy and fit vegetarian, an individual will require a high level of care to obtain high quality food, and carefully preparing daily meals. Unprocessed protein supplements along with other dietary supplements, are usually required.


  • Fenix says:

    Hi Ivan,

    Just like to add to this from my recent observations. I began MAF training nearly a year ago now and followed a strict low carb high fat diet. I ate plenty of greens and most the fats came from avo, nuts, eggs etc. Anyhow i noticed this way of eating after several months caused a minor few issues. I also didnt see any major improvements in my maf pace despite seeing good results in my %body fat etc. After some research i decided that HFLC probably isnt the best way of eating whether for health or fat adaption and decided to follow a whole foods plant based diet and currently the outcome is brilliant. I feel excellent health wise, my recovery is super fast, doing 100km is a breeze and my MAF pace has improved significantly in the past 2 months. I have gone from 5’30min/km when on HFLC and now at 4’45min/km. Protein hasnt been an issue so far but i do agree that one must take B12 supplements when following such diets. I can honestly say that i gave HFLC a good go (+6months) whilst following strict MAF runs and the progress was nowhere near anything great. For those who follow a veterinarian or vegan way of eating this training method still works, and in my experience works even better than on a HFLC diet. For one you will be getting WAY more antioxidants and minerals which are key to optimal health and obviously you will be shocked at how fast you can recover from workouts! Finally, i think there is a misconception out there today about HFLC diets…people need to be careful.

  • Wanausha Campbell says:

    Really disappointing to see this article hasn’t been updated with recent and relevant research. is a good place to go for evidence-based nutritional information. Nowadays people are much better informed about what to eat on a vegan diet and there are so many plant-based and natural options available. If you feel this isn’t the case, this is probably more a reflection of your diet and your lack of knowledge than ours. From a clearly malnourished vegan and her malnourished family.

  • Dominic says:

    Interesting looking at the comments 2 years on. I am a pescetarian. I suffered some lung damage and went back to eating fish from having been a pure vegetarian for the previous 14 years.
    What I think Phil Maffetone is saying is that eating some meat is the ideal diet, because we get certain things we need in a higher quality.
    However, those that choose to be either vegan or vegetarian for whatever reasons get an adequate diet, but not quite of the same quality.
    I have the highest regard for Dr P.M. and I think his theories about a holistic (or in his words Wholistic) approach are something we should all take on and consider living by. But , when we look at world and the problems of feeding everyone, we ought to consider whether meat production is the best and healthiest way to feed millions. This goes beyond wasteful use of land for raising meat rather than growing crops, but to intense farming of fish. Global action needs to be taken to produce high quality food for everyone. It should not be seen as profit making machine, but a need and a service. It has a major impact , ultimately, on the healthcare of a country.
    Big business, including farming and those connected with mass food production, are able to influence governmental decisions, which means it will be difficult to change what is produced and sold. Look at the variety of sweets and candy available in a shop and then consider how the tobacco industry ..“Increasing the addictive potential of cigarettes with additives increases the likelihood
    that new smokers will become addicted and that current smokers will have more difficulty
    quitting.” — Rabinoff, M, et al., “Pharmacological and Chemical Effects of Cigarette
    Additives,” American Journal of Publich Health, Nov. 2007.
    What we eat is personal. We choose for many reasons. Neither side should be attacking the other about the details, instead we should be helping each other to a healthier lifestyle, whatever our choices, or whatever foods are available to us.
    PM, you have re-awakened my interest in proper sports nutrition.

    • Hi Dominic,

      Thanks for your comment! I agree in principle with much of what you’re saying but I also suggest that you look at polyculture farming e.g. PolyFace farms. You’ll find that they leverage animal use to potentiate the plant systems, and increase the amount of biomass they can cultivate from the same amount of soil, while making the land even healthier for it!

  • Mircea Andrei Ghinea says:


    well.. this is a tough subject. a really tough one.. and we should all be aware of that.

    i’ve been vegan for two years, now mostly vegetarian for about five.

    yup, there are many top athletes out there that are vegans or vegetarians. for instance now comes to my mind:
    Carl Lewis, who had his last part of his career as a vegan, and in those times he made all those world records..
    Dave Scott, the first six-time Ironman Triathlon Hawaii Champion, was vegetarian too at that time.
    Ruth Heidrich, vegan, first woman (or human i think, but not sure) who did four Ironman in the same year. and after switching to vegan diet her bone density increased a lot (she said). less acidity in the body and more alkalinity keeps the bones healthy and strong.
    and.. just have a look on internet-videos with vegan Frank Medrano.. yup, crazy calisthenics!!

    anyway, what i want to point out is that for us, normal people, not doctors, it’s really really really crazy the information out there.. you read one thing, then the next is that’s not really like that, then like this, then like that, pure CRAZY.. it’s really hard for us (normal people) to understand what’s going on.. because “everybody’s right”.. i feel bad many times because of that but, i know, there’s nothing you can do.. just keep informing and do what makes sense..


  • Avi says:

    A huge number of Indian families have been vegetarian for generations. Traditionally, our meals would include a variety of vegetables, legumes, pulses, grain, fruits, milk , milk products (including ghee), nuts etc. A meal would comprise a variety of taste like spicy, sweat, sour and also bitter (example bitter gourd vegetable). Jaggery is ideally used as sweetener instead of sugar. The variety of vegetables consumed is huge, typically we cant find many of these vegetables in Western super markets. Herbs like tulsi, neem, coriander leaves also form part of the diet. Usage of processed food is still quite low in India, though this is changing.
    The food habits were based on the caste system which also determined the occupation. The caste whose profession consisted on studying (doctors, priests, astrologers etc) were mostly vegetarian, the warrior(ruler) caste meat eating, business caste depending on region and worker/labor caste varied depending on region. Even now, most vegetarian families are so because of the caste they belonged to, though it doesn’t define the occupation anymore.
    I am not sure if there are any studies pointing to the impact of introducing meat/fist/egg etc in diet of a person whose whole lineage has been vegetarian for generation. I have read that digestion of food we eat and absorption of nutrients also depends on various gut bacteria which are in turn passed on genetically or “in the family”. Any thoughts on this aspect ?

    • Avi:

      It’s an interesting problem. However, most of the adaptations that disallow the consumption of a particular food (lactose, starch, gluten) are typically genetic in nature. In that sense, it’s more likely that, if people from these families can’t find a way to add animal protein to their diet, that they’ve moved genetically away from it, rather than not having the right bacteria. (If they don’t have the right bacteria, then it’s mostly just a matter of getting it).

      However, I wouldn’t rule out the possibility that moving away genetically from the possibility of eating meat means that they’ve also become genetically incompatible (through their immune system) with bacteria that help digesting meat.

      Take this with a grain of salt—it’s speculation. But it would make an interesting avenue of research.

  • Horton says:


    Maybe “slightly misinformed” was a poor choice of words. He is however slightly misinforming others. To be a healthy and fit vegetarian, vegan, carnivore or omnivore requires a high level of care to obtain high quality food, and carefully preparing daily meals. My point is if you want to be healthy and fit it doesn’t matter what diet you choose it requires effort. It could be argued, due to the processing, antibiotics, GM hormones, and other aspects of meat consumption that even more care is required with an omnivores diet.

    As to protein, yes athletes require more than the typical person but with a varied diet, something people with any diet should have, protein is not the issue that anti plant based diet people make it out to be.

    As to supplements, exercise, especially extreme exercise like ultra running or anything competitive act for that matter, causes oxidation. This over the long term can lead to health issues. I’m not denying that moderate exercise is great for everyone but without supplements (anti oxidants) excessive exercise may be bad for your health, especially if you’re consuming foods (or beverages) that are loaded with free radicals on top of it all. How many people do you know that exercise so that they look good and can still eat whatever they want? Does that mean they’re healthy? Absolutely not. I think, it could be argued, that those that exercise a great deal would be better served to use supplements (anti oxidants) than protein supplements, depending on their diet.

    Let’s not pretend that there aren’t vegan athletes at the elite level. Scott jurek the first and most prominent that comes to mind. If you haven’t heard of him you should look into his resume.

    As I said in my original post I respect the majority of Dr. Maffetone’s advice and, even a good deal of his dietary information is fantastic, but the fact that a healthy plant based diet requires thought and care is no reason not to subscribe to one. Every healthy diet requires thought and care, especially in this day and age!

    • I’m not sure what to make of your comments that Dr. Maffetone is misinforming people on nutrition. There are drawbacks to all diets. In this particular post, he’s being candid on the drawbacks of vegan diets.

  • horton says:

    Dr. Gary null is a long time vegan and competitive athlete and seems to be doing ok. I appreciate your method and even your nutrition advice is better than 99.9% of what is out there but I think you may be slightly misinformed on vegetarian and vegan nutrition.

    • Horton:

      I don’t see how Dr. Maffetone is “misinformed,” given this caveat:

      “To be a healthy and fit vegetarian, an individual will require a high level of care to obtain high quality food, and carefully preparing daily meals. Unprocessed protein supplements along with other dietary supplements, are usually required.”

      Would you elaborate?

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