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Do You Have to Combine Plant Proteins at a Meal?

All nutrients come from the sun or the soil. Vitamin D, the “sunshine vitamin,” is created when skin is exposed to sunlight. Everything else comes from the ground. Minerals originate from the earth, and vitamins from the plants and micro-organisms that grow from it.

The calcium in a cow’s milk (and in her 200-pound skeleton) came from all the plants she ate, which drew it up from the soil. We can cut out the middle-moo, though, and get calcium directly from the plants.

Where do you get your protein? Protein contains essential amino acids, meaning our bodies can’t make them so they’re essential to get from our diet. But, other animals don’t make them either. All essential amino acids originate from plants and microbes, and all plant proteins have all of the essential amino acids. The only truly “incomplete” protein in the food supply is gelatin, which is missing the amino acid tryptophan, so the only protein source you couldn’t live on is Jell-O.

Those eating plant‑based diets average about twice the estimated average daily protein requirement. Those who don’t know where to get protein on a plant-based diet don’t know beans… (Get it? :) That’s protein quantity, though—what about protein quality?

The concept that plant protein was inferior to animal protein arose from studies performed on rodents more than a century ago. Scientists found that infant rats don’t grow as well on plants. However, infant rats don’t grow as well on human breast milk either. Does that mean we shouldn’t breastfeed our babies? Ridiculous! They’re rats. Rat milk has ten times more protein than human milk because rats grow about ten times faster than human infants.

It is true that some plant proteins are relatively low in certain essential amino acids. So, about 40 years ago, the myth of “protein combining” came into vogue—literally, in the February ’75 issue of Vogue magazine, as I discuss in my video The Protein Combining Myth. The concept was that we needed to eat so-called complementary proteins together (for example, rice and beans) to make up for their relative shortfalls. However, this fallacy was refuted decades ago. The myths that plant proteins are incomplete, aren’t as good as animal proteins, or need to be combined with other proteins at meals have all been dismissed by the nutrition community decades ago, but many in medicine evidently didn’t get the memo. Dr. John McDougall called out the American Heart Association for a 2001 publication that questioned the completeness of plant proteins. Thankfully, they’ve changed and now that “[p]lant proteins can provide enough of the essential and non-essential amino acids” and that we “don’t need to consciously combine…complementary proteins…”

It turns out our body is not stupid.

Our body maintains pools of free amino acids that can be used to do all of the complementing for us, not to mention our body’s massive protein recycling program. Some 90 grams of protein are dumped into the digestive tract every day from our own body to get broken back down and reassembled, so our body can mix and match amino acids to whatever proportions we need, regardless of what we eat, making it practically impossible to even design a diet of whole plant foods that’s sufficient in calories but deficient in protein. Thus, plant-based “consumers do not need to be at all concerned about amino acid imbalances…from the plant-food proteins that make up our usual diets.”

How did all of these myths surrounding protein come to be? Learn about The Great Protein Fiasco.

I cover protein quantity in my Do Vegetarians Get Enough Protein? video.

For more detail on the benefits of protein from plants, see:

Plant protein also doesn’t have the same effect on the cancer-promoting growth hormone IGF-1 that I discuss in the cancer section of my Food as Medicine presentation. Meat-heavy maternal diets may even affect the obesity rates and stress responses of their children, as I explore in my videos Animal Protein, Pregnancy, & Childhood Obesity and Maternal Diet May Affect Stress Responses in Children.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

53 responses to “Do You Have to Combine Plant Proteins at a Meal?

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  1. Who are the sources for these quotes?

    “[p]lant proteins can provide enough of the essential and non-essential amino acids” and that we “don’t need to consciously combine…complementary proteins…”

    “consumers do not need to be at all concerned about amino acid imbalances…from the plant-food proteins that make up our usual diets.”

    1. If you click on the video link in the above article, The Protein Combining Myth, in the sixth paragraph and watch that you will see it. Around the three minute mark is when that specific quote is said. You can see the sources under the videos as well.


    2. SarahTorres, if you click on the green words in the text (in this case the words “called” and “concerned”), it will take you straight to the article he’s quoting.

  2. I remember from my preclinical course in nutrition, almost three decades ago, something like “20% of our daily protein we get from dead bacteria in our gut.”

    The doctor suggested that this recycling provides a buffer of essential amino acids over a few days.

  3. This article (and the associated video) seems to say that a varied diet is not necessary for getting adequate amounts of all essential amino acids. The need for combining at the same meal has been disproven for decades, refuted by its own author. But even if all plants contain all essential amino acids (I hadn’t known that), do they contain them all in adequate amounts such that a varied diet is not required to get adequate amounts of all essential amino acids? Is the complimentary legumes and grains, methionine and lysine guidance (over the course of a day) not relevant?

    1. Hi I’m a RN health support volunteer. Thanks for your great question. We definitely want a varied, healthy, plant based diet- like Dr. Greger’s daily dozen for a variety of reasons- fiber, vitamins, antioxidants and all the different health benefits different plant based foods offer. We aren’t suggesting you live on sweet potatoes or rice alone.

      The point is, there is no complex mathematical formula needed for the perfect antioxidant combination. If you are eating a healthy plant based diet, you will get all your essential amino acids and your body is able to absorb what it needs and combine them appropriately to build tissue.

      The complete protein myth was based on microscopic evaluation of our tissues and a faulty assumption that we should be eating foods with the same amio acid makeup of our tissues. Well, the only way to get a true protein in the ratio of amio acids of our tissues would be to practice cannibalism. Animal products are closer to our amino makeup because they are genetically closer to us than plants. But how did they get those amino acids? Mostly from eating plants and their bodies rearranging and absorbing the needed amino acids to build their tissue. Most of the animals humans eat are vegetarians. They got all those amino acids from plants.

      If you are eating a healthy diet, you will give your body the amino acids it needs over the course of the day and your body will know what to do with it. It doesn’t need to be all packaged up in the right ratio. The healthiest cultures throughout history have eaten a mostly plant based diet and not given any thought to combining amino acids and have had the lowest disease rates and longest longevity to show for it. Like in Okinawa for example

      All best to you.

  4. This is wonderful, thank you! I’m wondering however the amino acid levels that our body needs for tissue repair and muscle building? I work out with a friend each day for a 1/2hr at our home gym. Would you say it is a good move to eat a pumkin/watermelon seed protein bar as a post recovery snack?

    1. Look up Rich Roll and other vegan athletes who understand how to get enough calories you need. Try having a green smoothie instead of hard to digest processed protein bars, the fresher the better. Less fat consumption is better, you need glucose for energy.

    2. Hi I’m a health support volunteer and a marathon runner and triathlete myself. After a strenuous workout, your body needs carbs more than protein. That is your muscles’ primary fuel source. After strenuous activity, if you don’t replenish the carbs and your glycogen stores, that is when you can experience muscle breakdown because your muscles are starving for energy, carbs being its preferred source. They say you want roughly a 3:1 carbohydrate to protein recovery source. For endurance training like I do, chocolate milk is being promoted like the magic recovery food. There is nothing magic about it. It just has about that ratio of carbs to protein. I don’t think you need to do a complex math formula after a workout, but just make sure to have something with carbs and protein. I like to have some whole grain bread with peanut butter after a long workout. Dr. Garth Davis, plant based advocate and triathlete himself, prefers rice and beans. Plant based diets are getting very popular among elite athletes and no one is suffering muscle breakdown and damage. Some plant based athletes you could look up are Rip Esselstyn, Dr. Garth Davis, Rich Roll, Scott Jurek.

      Keep up the exercising and healthy diet!

  5. As always, I appreciate the nuances of the writing.

    Love the history lesson and the little science details and the little jokes.

    “came into vogue—literally” made me smile and I laughed that you wrote (Get it?)


  6. John McDougall, MD is a national treasure, he deserves more recognition. I live in his adopted home town of Santa Rosa, and amazing how few people here have even heard of him.

      1. Mims & Nancy

        I agree with both of you.

        Saving lives deserves so much more recognition than some of the people who do get recognition.

        1. I thought about it with Dr. Swank.

          He stopped the progression in 95% of his MS patients for decades and my friend who has MS lives in an apartment complex made for people with MS and none of them have heard of him.

          I had a friend from church die of MS and she didn’t have to die.

          She didn’t have to die.

          1. I am trying to get the word out.

            It has taken a year, but my relatives are no longer making fun of me and they aren’t defended against the message.

            Keeping my dog alive and having so many people around me be sick has taken a lot of my focus, but, next year, maybe I will start going to places with people with MS and Diabetes. Those seem easiest to start with.

            1. A child died of Cancer this week. I think he was 7. Possibly 8. His wake is interrupting our Christmas gathering. Then, my brother should be finding out something on Christmas Eve and my friend after that. On the better news end, my cousin is home from the hospital just in time for Christmas.

              I think I am going to be putting copies of How Not To Die in the hospital waiting rooms.

              1. Wondering about childhood cancer.

                Cancer is up 27% in children since the 1970’s even though Adult Cancer has fallen some.

                Per Web MD

                The rise seems to be driven, in large part, by an increase in leukemia, which is up almost 35% since 1975. Leukemia is the most common cancer in kids. Soft tissue cancers, like those that develop in bones or muscles, are up nearly 42%. Non-Hodgkin’s lymphoma is up 34%.

                Do we know if it is diet or environmental or genetic?

                  1. I watched a video on immunotherapy being combined with radiation doubling the survival rate for kidney Cancer by showing the immune system the cancer.

                    That is what water fasting does.

                    Wondering if water fasting would double survival rates, too.

          2. The problems with the Swank diet trial included the fact that there was no control group, there was a high drop-out rate and the inclusion criteria were not especially rigorous.

            Its results have not been replicted and it’s also worth remembering that Dr McDougall, an admirer of Swank, recently did a more rigorous study of a completely vegetarian version of the Swank diet for ms patients. After 12 months the diet was seen to have no effect on brain MRI outcomes, number of MS relapses or disability.

            1. As an MS patient, I’m also disappointed that my MRI shows new and worse disease activity after 5+ years of following low fat and low sodium WFPB strictly. I’m still resisting the push to start using drugs because of the side effects.

              I know my MS might have been even worse without this diet and I don’t regret going on it at all. I won’t go back to SAD no matter what!

              1. Hi Olga

                Sorry to hear about your MRI results. However, the best available evidence seems to suggest that your diet is appropriate although you might want to consider upping your nut and vitamin D consumption a little?

                There may also be a benefit to following a disciplined exercise regime as well

                1. Hi Mr. Fumblefingers,
                  Thank you for the links and suggestions. Indeed, I’m taking D3 at the higher end of recommended dose but should probably eat more nuts and get even more exercise. I’m not doing much currently as I’m recovering from a kneecap fracture. It’s slow going but getting there.

                  Otherwise, I have been without MS symptoms so far, just the worrying MRIs and push for medication from the doctor.


  7. The same people that created the false classification system of proteins in quality vs non-quality are the same that ate a diet based on quality proteins. That is like an ethno diet, which is that whatever I eat, it must be the best from a design point of view. If you lived isolated and with nothing else to eat, then walking seals would look like the best ethno diet. But ethno diets are based on lack of choice not on superiority. If Europeans decide what is the best diet and their survival depend on animals, then they would assume that animals are essential or high protein. Thus, the protein classification they made was based on lack of knowledge and an ethno centric diets base assumption.

  8. True, but most indigenous cultures do combine grains or starches and legumes.
    Rice and beans, barley and beans, etc. both tasty and filling.
    Dr. Gregor’s daily dozen does include both. Really like the DD. Can just give people the list as a great guideline.

  9. Before my vegan adventures I frequently used Whey protein. Believe most who use Whey will testify to increased strength and energy compared to vegan proteins. There are also proteins such as L-Tryonsine when combined in appropriate does with DHEA and Phosphatidyl Choline(plant based) will bump up IQ about 15%. How do I know this? Internet chess rating improves usually 100 to 150 points when taking this supplement.

    1. It is possible to achieve improved performance from various substances including caffeine, coca leaves and steroids for example. However the key question, for me at least, is what are the long term health effects? The long term effects of whey protein supplementation haven’t been well studied to y knowledge.

      However high protein diets in general do appear to increase mortality rates eg

      To my mind, Dr Mirkin’s views are always worth considering This is his take on dietary protein

    2. Frank,

      My grandmother used to say “you are sweet enough already” when I would drink coffee without sweetener.

      It may be true that whey protein raises the IQ that much, but vegetarian males test a full ten-points higher than meat eaters on IQ tests, so it might be that vegans already are smarter and the fact that they are also going to live longer tells me that they aren’t all that bad at strategic decisions either.

  10. Hello Dr. Greger! I am an ardent fan and follower, and also a 58 yr old athlete on a plant based diet pursuing a Half Ironman in June. I’ve read a book by a female Ph.D (I won’t name her here), who strongly suggests women athletes, and especially ones who are in menopause need lots of protein, at least 100gr (non-workout) a day all the way up to 130gr (vigorous workout) a day. I do want to build muscle. How do you respond to this? Thank you.

    1. Hi Nadine, The best way to build muscle is to lift heavy weights. I’m a 54 yr old WFPB female (avid runner and cyclist) and have been able to add significant muscle / strength in the past year by lifting weights 3x a week. It doesn’t take much to see results… just consistency and proper form. I highly recommend dead lifts, lunges, bench press, and squats. I don’t pay any attention to the amount of protein I get. I just make sure to eat enough calories and follow Dr. G’s daily dozen as a guide. Good luck!

      1. Hi Phyllis,

        Do you use any plant-based protein powder? I do some weigh lifting as well, and I’m trying to completely switch from animal-based protein.

        It would be really helpful if Dr. Greger could cover what kind of plant-based protein powder is healthiest (hemp, rice, pea, or any other).

        Dmitriy P,
        Shilajit Secret

    2. Nadine, while you already received some comments which you can judge as helpful or not, as one of the volunteers for this website, I wanted to give you some research-based ideals to answer to your question. First of all there is general agreement that you do not need that much protein. Here is what two respected academic institutions have to say:

      The Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine recommend 1.2 to 2.0 grams of protein per kilogram of body weight per day for athletes, depending on training. Protein intake should be spaced throughout the day and after workouts.Jul 17, 2017
      In addition you may want to review this article Recommendations for Healthy Nutrition in Female Endurance Runners: An Update
      “The usual recommended amount of 1.2–1.4 g protein/kg/day has recently been questioned by new findings suggesting that 1.6 g/kg/day would be more appropriate for female athletes”
      “…The only situation where dietary protein requirements exceed those for relatively sedentary individuals is in top sport athletes where the maximal requirement is approximately 1.6 gPRO/kg/d. Although most endurance athletes get enough protein to support any increased requirements, those with low energy or carbohydrate intakes may require nutritional advice to optimize dietary protein intake.”
      I hope you find this helpful.

  11. This is some of the junkiest junk science I’ve ever seen! I’m embarrassed for the medical profession that this was written by a physician! This site should be called “”

    Justin Hamlin, DO
    Board Certified Family Medicine
    Board Certified Obesity Medicine
    Board candidate Clinical Lipidology
    Assistant Clinical Professor of Family Medicine and Obesity Medicine
    Master’s candidate in Biology and Applied Statistics

    1. That’s a bit rich coming from an osteopath

      What does an osteopath know about science based or evidence based medicine in the first place?

      ‘Osteopathy is a pseudoscientific belief system developed in 1874 by the physician Andrew Still. The fundamental premise of osteopathy is the inter-relatedness of mind, body, and spirit. Still believed that this tripartite system had intrinsic, self-healing and self-correcting capabilities. He believed that disease states were caused by misalignments or obstructions of various structural elements of the body (bones, muscles, fascia, nerves, blood vessels, lymphatics), and that specific corrective manipulations could facilitate the body’s innate ability to heal. Like many wacky medical belief systems of this era, osteopathy was not any worse than much of the prevailing thought and practice of the day. Today, the practice of osteopathy varies considerably within the profession, as does the degree of adherence to the fundamentals of the original dogma preached by Dr. Still.’

  12. Do I believe the body recycles 90 grams of protein a day? Considering that amounts to 3/4 of a pound of muscle tissue I’d say no chance of this happening. Where is your source for this information?

  13. Good catch. Greger gives a link to the source for his statement in his blog post. The relevant journal article states:

    ‘Estimates of the amounts of the various materials entering the human gut are highly variable, but it would appear that some 90 grams of endogenous protein per day flows through the digestive tract from the mouth to the terminal ileum in the adult human(8)’ [accessed Dec 25 2018].

    That may well be a type for ‘exogenous’ in the source article. Perhaps one of the support staff can check/confirm?

  14. Here is my prospective when it comes to protein. In order to form muslce and organ tissue the body needs to put together the right balance of amino acids. If your daily intake of protein is adequate it doesn’t mean that the balance is correct. When I was following the McDougall diet where you were only allowed a maximum of one cup of bean per day my total protein was roughly 55 grams which was prefectly fine. However, critical aminos like Lysine and some of the Banch Chain aminos rarely made it past 50% of requirements. That would mean that roughly only 27 gram of protein could be used to rebuild organs and muscles. The balance were burned up as energy. What finally woke me up to these facts was something that happened to Dr. McDougall. At the age of 67 he fainted in his bedroom on the way to the bathroom. In the process he fractured two vertabrae in his lower back, his hip and finally ended with a sprial fracture of his upper leg bone. This speaks to terrible bone health after following his own diet for over forty years. The only time I’ve seen this kind of damage was falling down a long flight of stairs or a motorcycle accident, never from fainting. Protein is critical for bone health since all bones are made of a protein matrix from which the calcium holds to. If you lose the matrix there is nothing for the calcium to cling to. It like the siding of a house. If the frame is damaged the siding falls away. It was at this point that I upped my bean consumption so that my Cron-0-meter indicated I had made the minimum for all my critical amino acids. If you want to confirm what happend to doctor McDougall visit his web site and check out the May 2016 issue of his newsletter to read about this event in his own words.

  15. The fault in your logic is that your body is not constantly falling apart to the point that you need so much protein and “balanced” amino acids to rebuild yourself. Physiologically your body is quite stable, conserves amino acids and proteins very efficiently so that very little protein is needed to maintain health. The only significant protein requirements arise from loss of skin, nails and hair. No one eating a calorically adequate, varied plant based diet has ever been shown to suffer from lack of protein intake.

    And the rumor of one elderly physician losing his balance at home does not make for a diagnosis of low protein intake or invalidate the thousands of clinical studies in support of an unprocessed plant based diet resulting in reduced disease and premature death.

    Dr. Ben

  16. The concept of amino acid utilization promoted by Dr. Minkoff suggests that there is a ‘perfect balance’ among the 8 essential amino acids to develop muscle: (L-Leucine, L-Valine, L-lsoleucine, L-Lysine HCI, L-Phenylalanine, L-Threonine, L-Methionine, L-Tryptophan).

    What do you think of the concept of amino acid utilization for maximum muscle development?

  17. Muscle development? How much muscle are you developing? Are you “maxing” heavy weights every day in your workout? Most of us are just trying to keep what we have and not get fatter as we get older. Unprocessed plants provide all the essential amino acids we need.

    Dr. Ben

  18. I don’t know how to respond when people say that we cannot absorb plant protein, iron, calcium, etc. like we can with meat. Is this true? Does it mean we just need to eat more plant foods? Or is the differences in the bioavailability of these nutrients a myth?

  19. It is a myth. As with many myths, there is a grain of truth at its base. In this case, while certain factors make plant nutrients more or less available to our bodies, if one eats a diversity of whole fruits, vegetables, greens, and legumes/beans, the amounts of useful nutrients are more than enough. In fact, plant based eaters have far fewer nutrient deficits that those who eat predominantly meats. Protein is obtained wonderfully by beans/legumes and all other plant foods, calcium comes from beans and greens (with spinach not providing available calcium: another grain of truth in the overall myth), iron comes from legumes, whole grains, nuts, seeds, greens (including spinach). Here are two videos of many that Dr Greger has made. One addresses plant iron: and the other is on nutrient deficiencies in plant based eaters compared with omnivores:

    When people ask me, “Where do you get your protein?” I say, “Beans. Now, are you getting enough fiber?” Here’s a third video on this topic by Dr G:

  20. What do you think about the protein of lupin flour. I never saw that mentioned by Dr.Greger but rather red a lot about the more known soy protein. What are the pros and cons of lupin flour versus beans as a source of protein? Would you recommend lupin flour?
    Thank you for your answers!

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