I am currently training for my second marathon in my adult life, and while the aches and pains feel the same as last year, and as the mileage starts to creep up it feels like deja vu- one minor detail has changed: this year I am running the marathon as a vegetarian.
Vegetarian endurance athletes have become quite a trend in the last couple of years. Some noteworthy endurance athletes include Brendon Brazier (vegan ironman), Rich Roll (vegan ultra ironman), Robert Cheeke (vegan body builder), and Michael Arnstein (fruitarian ultra runner); just to name a few.
Giving up meat during this marathon training means I will be missing out on complete proteins and key amino acids from my diet. These amino acids are also called limiting amino acids and they are: lysine, threonine, methionine, and tryptophan. Limiting amino acids are found in the shortest supply from incomplete proteins. Incomplete proteins are those found in plant food sources and geletin.
The most frequently asked question I get asked when becoming a vegetarian involved getting enough protein. While I do not eat meat, fish, or dairy (except for yogurt) I get plenty of protein in my diet by using protein complementation.
Protein complementation is the most efficient way to get all 9 amino acids into a vegetarian’s diet. Protein complementation is when you combine two vegetable proteins (legumes and grains for an example) to get all 9 amino acids that are essential for your body. The breakdown of protein complementation goes like this:
| Food | Limited Amino Acid | Complement |
| Beans | Methionie | Grains, nuts, seeds |
| Grains | Lysine, threonine | Legumes |
| Nuts/seeds | Lysine | Legumes |
| Vegetables | Methionine | Grains, nuts, seeds |
| Corn | Tryptophan, lysine | Legumes |
By combining vegetarian protein sources you can ensure that you are getting all 9 amino acids. Protein complementation does not have to be done at the same meal. If you ate beans for lunch and then had some raw almonds for a snack later, you would be adding the methionine that you had missed out on during lunch.
A vegetarian diet, if planned correctly, can provide you with all of the vitamins, minerals, and amino acids the body needs.
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Protein is protein, right? Well, what if that protein is complete — or incomplete?
To understand the difference between complete and incomplete proteins, you first need to get to know amino acids. These are the molecular building blocks that combine to form every gram of protein you eat. When you eat protein-rich foods, your body breaks those proteins back down into amino acids, explains Marie Spano, RD, CSCS, the Atlanta-based lead author of Nutrition for Sport, Exercise, and Health. Your body then uses those amino acids to build muscle, repair tissues, support metabolism, and help along other processes in the body.
Of the roughly 20 amino acids, 9 are essential, meaning the body can’t make them. They include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine, according to the National Institutes of Health (NIH).
The only way to get these amino acids is through food. Foods that contain all of them, and in amounts similar to those required by the body, are called complete proteins or complete protein sources, Spano explains. Meanwhile, those that do not contain enough of one or more essential amino acids is incomplete.
RELATED: 15 Best Sources of Lean Protein
Complete vs. Incomplete Protein Foods
According to Harvard Health Publishing, all animal-based foods, including meat, dairy, and eggs, contain complete protein. The majority of plant-based protein sources, such as whole grains, legumes, seeds and nuts, spinach, broccoli, and mushrooms, are incomplete. However, some plant-based foods, such as soy, quinoa, buckwheat, and algae, are complete.
While it’s commonly believed that incomplete protein sources have zero of at least one of the nine essential amino acids, that’s not actually the case, explains Abbie Smith-Ryan, PhD, CSCS, director of the University of North Carolina in Chapel Hill’s Applied Physiology Laboratory.
Many incomplete protein sources have some of every single essential amino acid, just not in levels high enough for that protein to accomplish everything you want, she says. Leucine, which is a main driver of muscle building, tends to be relatively low in most incomplete sources of protein, says Constance Brown-Riggs, RD, CDCES, who’s based in Massapequa Park, New York.
RELATED: What to Eat Before and After You Exercise
How to Get All of the Amino Acids You Need
If you regularly consume meat or a lot of animal products, you’re getting enough of all of the essential amino acids you need. (Most Americans are, according to Harvard University.) The current recommended daily allowance for protein is 0.8 gram (g) per kilogram of body mass. However, many recent studies, including an article published in July 2015 in Applied Physiology, Nutrition, and Metabolism, suggest more, up to double that amount, is necessary for optimal muscle health, especially in older adults and those trying to lose weight or build muscle.
But what if you don't eat meats or animal products or are trying to cut down on how much of them you eat to focus on a more plant-based diet? After all, filling up on plant-based protein sources is associated with better overall health and longevity, according to an August 2016 study published in JAMA Internal Medicine. (Researchers explain this may be due to the fact that high-protein plants also tend to be brimming with fiber, vitamins, minerals, and antioxidants.)
The good news: Experts all agree that by eating a wide variety of plant-based protein sources you can get all of the amino acids you need on a vegetarian or vegan diet. That said, how complicated this is is up for debate.
RELATED: 9 Scientific Benefits of Following a Plant-Based Diet
For example, a February 2017 study published in The American Journal of Clinical Nutrition found that there’s no significant differences in muscle mass or strength in the general population based on what foods people eat to get their protein. But other studies, including a March 2017 article in Nutrition in Clinical Practice, suggest that vegetarians and vegans, especially older ones, may need slightly more total daily protein compared with omnivores to enjoy the same protein benefits. This may be due to the body being able more easily to digest, absorb, and use incomplete proteins, according to the March 2017 article.
Meanwhile, some experts say that to make incomplete proteins complete, you need to consume multiple and specific complementary proteins within the same meal. But as you can imagine, memorizing which plant-based foods have which essential amino acids and in what quantities — and then using that intel to craft every meal for the rest of your life — may not be realistic, Brown-Riggs says.
“Will this make a difference in the end? It may depend on several factors,” Spano says. “I think the only true way to know is to do a crossover longitudinal trial with all meals provided. That’s one expensive study!” It’s likely that for adults eating a plant-based diet, getting protein from multiple sources throughout the day is sufficient, but it might not be ideal. “For someone who wants the most muscle and to maximally build structures in their body, I would try to combine proteins in each meal,” she says.
Fortunately, whether you try to pair protein at each meal or do so throughout the day, you don’t have to worry about memorizing each amino acid. Just focus on variety, Smith-Ryan urges. Check off whole grains, legumes or protein-rich vegetables, and then a seed or nut, and you’ll be in a pretty good place with protein.
RELATED: Why Are Healthy Eating Habits Important?
See also: protein (nutrient), protein quality, and complete protein Protein combining or protein complementing is a dietary theory for protein nutrition that purports to optimize the biological value of protein intake. According to the theory, vegetarian and vegan diets may provide an insufficient amount of some essential amino acids, making protein combining with multiple foods necessary to obtain a complete protein food. The terms complete and incomplete are outdated in relation to plant protein. The position of the Academy of Nutrition and Dietetics is that protein from a variety of plant foods eaten during the course of a day supplies enough of all essential amino acids when caloric requirements are met.[1] Though it is undisputed that diverse foods can be combined to make up for their respective limiting amino acids, a general consensus has emerged among nutrition scientists and writers contrary to the original vegetarian nutrition dogmas of the 1970s. First, such foods do not need to be combined within a single meal. Second, though historically protein combining was promoted as a method of compensating for supposed deficiencies in vegetables as foods, studies on essential amino acid contents in plant proteins have shown that vegetarians and vegans typically do not actually need to complement plant proteins in each meal to reach the desired level of essential amino acids as long as their diets are varied and caloric requirements are met.[2] The American Dietetic Association and Dietitians of Canada support this position.[3] In fact, the American Dietetic Association states that complementary proteins do not need to be consumed at the same meal and plant proteins can meet all requirements.[4] It is however indeed possible for one to develop an amino acid deficiency if they, for example, ate solely rice and in quantities limited to that necessary to meet caloric intake needs. To avoid such a deficiency, either a complementary food high in the limiting amino acid (such as legumes which are high in lysine, in the case of rice) or quantities of rice greater than that necessary to meet caloric intake needs would be required. This is not an issue when eating a varied diet. Amino acids are not stored and may be excreted sooner than complemented, under limiting conditions.[citation needed]
Protein nutrition is complex because any proteinogenic amino acid may be the limiting factor in metabolism. Mixing livestock feeds can optimize for growth, or minimize cost while maintaining adequate growth. Similarly, human nutrition is subject to Liebig's law of the minimum: The lowest level of one of the essential amino acids will be the limiting factor in metabolism.
If the content of a single indispensable amino acid in the diet is less than the individual’s requirement, then it will limit the utilization of other amino acids and thus prevent the normal rates of synthesis even when the total nitrogen intake level is adequate. Thus the "limiting amino acid" will determine the nutritional value of the total nitrogen or protein in the diet.[5]Plants are thus rated as protein sources by their limiting amino acids.[6]
Examples of "limiting" amino acids in plant protein
According to WHO, human need for proteins is 0.66 g per kg of bodyweight per day.[7] For a 70 kg person has an estimated protein requirement of 46.2g (70 kg x 0,66 g/kg).
In addition, there is a specific need of essential amino acids quantities. See Essential amino acid#Recommended daily intake for a table of the values; the tables below use a percentage of the requirement.
| 1236 | 176% | 1274 | 182% |
| 2056 | 146% | 1984 | 141% |
| 4021 | 144% | 3294 | 118% |
| 1854 | 88% | 3095 | 147% |
| 1095 | 156% | 606 | 87% |
| 2509 | 143% | 2479 | 141% |
| 1781 | 169% | 1717 | 163% |
| 618 | 220% | 444 | 158% |
| 2852 | 156% | 1942 | 106% |
In the above examples, neither whole rice nor canned chickpeas have sufficient amounts of all required amino acids when used as the only source of 46.2 g of daily protein. The insufficient amino acid is called the "limiting" amino acid: for rice it's lysine and for chickpeas it's methionine. Consuming the specific quantity for long periods of time might result in deficiency of the amino acid.
| 618 | 637 | 1255 | 700 | 179% |
| 1028 | 992 | 2020 | 1400 | 144% |
| 2011 | 1647 | 3658 | 2790 | 131% |
| 927 | 1548 | 2475 | 2100 | 118% |
| 548 | 303 | 851 | 700 | 122% |
| 1254 | 1240 | 2494 | 1750 | 143% |
| 891 | 858 | 1749 | 1050 | 167% |
| 309 | 222 | 531 | 280 | 190% |
| 1426 | 971 | 2397 | 1820 | 132% |
In the above example, the combination of both whole rice and canned chickpeas has no limiting amino acids, that means that only consuming rice and chickpeas, in these specific quantities of 306g/day and 261g/day respectively, for long periods of time, would not result in any of the essential amino acid deficiency, at least to the extent they are metabolized at the time.
As the data of the example show, all essential amino acids are found in a specific plant, however one of them may or may not be limiting, that is, present in quantities below the WHO daily recommendation. For this reasons vegan and vegetarian diets need to be varied in terms of plants consumed.
The first biochemist to enter the field was Karl Heinrich Ritthausen, a student of Justus von Liebig. Thomas Burr Osborne continued what Ritthausen started and published The Vegetable Proteins in 1909. Thus Yale University was the early center of protein nutrition, where William Cumming Rose was a student. Osborne also worked to determine the essentials, and later led the Biochemistry Department at the University of Chicago.
When Ritthausen died in 1912, Osborne praised his efforts in biochemistry:
As a result of his later work he proved that wide differences exist between different food proteins; and he was the first to direct attention to this fact, and to discuss its probable bearing on their relative value in nutrition.[10]Osborne then joined forces with Lafayette Mendel at the Connecticut Agricultural Experiment Station to determine the essential amino acids.
In the 1950s and 1960s, Nevin S. Scrimshaw took this knowledge to India and Guatemala. He designed meals using local vegetables to fight against the scourge of kwashiorkor. In Guatemala he used the combination of cottonseed flour with maize, while in India he combined peanut flour with wheat.[11]
In 1954, Adelle Davis published Let's Eat Right to Keep Fit, which described the importance of combining "incomplete" proteins to make "complete" proteins, and advised that any incomplete proteins not complemented within one hour could not be used by the body.[12]
In 1971, Frances Moore Lappé published Diet for a Small Planet, which explained how essential amino acids might be obtained from complementary sources in vegetarian nutrition. The book became a bestseller :
An extension of a one-page handout that Lappé had circulated among her fellow improvisors in Berkeley, Diet for a Small Planet (1971) soon became the vegetarian text of the ecology movement, selling in the next ten years almost two million copies in three editions and six languages.[13]Lappé wrote:
Complementary protein combinations make for delicious recipes – they are combinations that formed the basis of the world’s traditional cuisines. We use them naturally in our cooking without even being aware of it. The three most common complementary protein combinations are:- Grains (rice, corn, wheat, barley, etc.) + legumes (peas, beans, lentils)
- Grains and milk products
- Seeds (Sesame or sunflower) +legumes[14]: 238
In 1975, both Vogue and American Journal of Nursing carried articles describing the principles and practice of protein combining.[15][16] For a time, The American National Research Council and the American Dietetic Association (ADA) cautioned vegetarians to be sure to combine their proteins.[17]
In 1985, the principle of protein combining was explained by J. Rigó:
The biological value of proteins in general, hence also of grain-proteins, is fundamentally determined by the ratio between the essential amino acids to be found in cereals and the requirement of essential amino acids of the living creature, consuming protein...the most important way of raising the biological value ... [is] given by the technique of complementing.[18]In 2011 PLOS ONE published an article investigating the specifics of protein combining for 1251 plant-based foods. The bases of reference are the amino acids indispensable to human nutrition, and the ideal proportioning of these amino acids in a meal. They explain, "complementation involves consuming two or more foods together to yield an amino acid pattern that is better than the sum of the two foods alone."[19] In contrast to pairings based on food groups, such as pairing a grain with a bean, the investigators reported that pairing by food group was not supported by their work: "Examining the top 100 pairings for each food, we found no consistent pattern of food group-food group pairings."[19]
Protein combining has drawn criticism as an unnecessary complicating factor in nutrition.
In 1981, Frances Moore Lappé changed her position on protein combining from a decade prior in a revised edition of Diet for a Small Planet in which she wrote:
"In 1971 I stressed protein complementarity because I assumed that the only way to get enough protein ... was to create a protein as usable by the body as animal protein. In combating the myth that meat is the only way to get high-quality protein, I reinforced another myth. I gave the impression that in order to get enough protein without meat, considerable care was needed in choosing foods. Actually, it is much easier than I thought."With three important exceptions, there is little danger of protein deficiency in a plant food diet. The exceptions are diets very heavily dependent on [1] fruit or on [2] some tubers, such as sweet potatoes or cassava, or on [3] junk food (refined flours, sugars, and fat). Fortunately, relatively few people in the world try to survive on diets in which these foods are virtually the sole source of calories. In all other diets, if people are getting enough calories, they are virtually certain of getting enough protein."[14]: 162Necessity of protein combining was not asserted. Rather, the increased biological value of meals where proteins are combined was noted. In a concession, Lappé removed from the second edition "charts that indicate exact proportions of complementary proteins".[14]: 239
The American Dietetic Association reversed itself in its 1988 position paper on vegetarianism. Suzanne Havala, the primary author of the paper, recalls the research process:
There was no basis for [protein combining] that I could see.... I began calling around and talking to people and asking them what the justification was for saying that you had to complement proteins, and there was none. And what I got instead was some interesting insight from people who were knowledgeable and actually felt that there was probably no need to complement proteins. So we went ahead and made that change in the paper. [Note: The paper was approved by peer review and by a delegation vote before becoming official.]In 1994, Vernon Young and Peter Pellett published their paper that became the definitive contemporary guide to protein metabolism in humans. It also confirmed that complementing proteins at meals was totally unnecessary. Thus, people who avoid consuming animal protein do not need to be at all concerned about amino acid imbalances from the plant proteins that make up their usual diets.[20]
While many plant proteins are lower in one or more essential amino acids than animal proteins, especially lysine, and to a lesser extent methionine and threonine, eating a variety of plants can serve as a well-balanced and complete source of amino acids.[20]
Pediatrician Charles R. Attwood wrote, "The old ideas about the necessity of carefully combining vegetables at every meal to ensure the supply of essential amino acids has been totally refuted."[21]
In 2002, Dr. John McDougall wrote a correction to the American Heart Association for a 2001 publication that questioned the completeness of plant proteins, and further asserted that "it is impossible to design an amino acid–deficient diet based on the amounts of unprocessed starches and vegetables sufficient to meet the calorie needs of humans."[22]
Later that year, Dr. Andrew Weil wrote that "you don’t have to worry that you won’t get enough usable protein if you don’t put together some magical combination of foods at each meal."[23]
In Healthy Times Jeff Novick wrote that the necessity of protein combining is a "myth that won’t go away".[24]
In 2005, Dr. Joel Fuhrman wrote:
...plant foods have plenty of protein and you do not have to be a nutritional scientist or dietitian to figure out what to eat and you don’t need to mix and match foods to achieve protein completeness. Any combination of natural foods will supply you with adequate protein, including all eight essential amino acids as well as unessential amino acids.[25]Dr. T. Colin Campbell wrote in 2006:
We now know that through enormously complex metabolic systems, the human body can derive all the essential amino acids from the natural variety of plant proteins that we encounter every day. It doesn’t require eating higher quantities of plant protein or meticulously planning every meal.[26]In 2009, the American Dietetic Association wrote:
Plant protein can meet protein requirements when a variety of plant foods is consumed and energy needs are met. Research indicates that an assortment of plant foods eaten over the course of a day can provide all essential amino acids and ensure adequate nitrogen retention and use in healthy adults, thus, complementary proteins do not need to be consumed at the same meal.[27]The American Heart Association now states:
You don’t need to eat foods from animals to have enough protein in your diet. Plant proteins alone can provide enough of the essential and non-essential amino acids, as long as sources of dietary protein are varied and caloric intake is high enough to meet energy needs. Whole grains, legumes, vegetables, seeds and nuts all contain both essential and non-essential amino acids. You don’t need to consciously combine these foods (“complementary proteins”) within a given meal.[28]Some institutions use the Protein Digestibility Corrected Amino Acid Score to assess diets without consideration of protein combining and hence find the use of combinations to be a challenge to their methodology.[citation needed]
On the other hand, the site 2000KCAL.CZ asserts that any regular-sized protein source can be converted into a high-quality protein if combined with a small quantity of whey protein supplement. Without making a direct case for or against the practice of protein combining, the site challenges the notion that protein combining has to be complicated.[29]
- ^ Melina, Vesanto; Craig, Winston; Levin, Susan (2016-12-01). "Position of the Academy of Nutrition and Dietetics: Vegetarian Diets". Journal of the Academy of Nutrition and Dietetics. 116 (12): 1971. doi:10.1016/j.jand.2016.09.025. ISSN 2212-2672. PMID 27886704 – via //www.eatrightpro.org/~/media/eatrightpro%20files/practice/position%20and%20practice%20papers/position%20papers/vegetarian-diet.ashx. {{cite journal}}: External link in |via= (help)
- ^ Young, V. R.; Pellett, P. L. (1994-05-01) [1994]. ABSTRACT. "Plant proteins in relation to human protein and amino acid nutrition". The American Journal of Clinical Nutrition. 59 (5 Suppl): 1203S–1212S. doi:10.1093/ajcn/59.5.1203s. ISSN 0002-9165. PMID 8172124.Young, V. R.; Pellett, P. L. (1994-05-01) [1994]. FULL ARTICLE - TABLE 11. "Plant proteins in relation to human protein and amino acid nutrition" (PDF). The American Journal of Clinical Nutrition. 59 (5 Suppl): 1203S–1212S. doi:10.1093/ajcn/59.5.1203s. ISSN 0002-9165. PMID 8172124. Archived from the original (PDF) on 2017-10-13. Retrieved 2017-05-22.
- ^ Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets, vol. 103, Journal of the American Dietetic Association, 2003, pp. 748–765, retrieved 2017-07-12
- ^ "American Dietetic Association" (PDF).
- ^ Food and Nutrition Board of Institute of Medicine (2005) Dietary Reference Intakes for Protein and Amino Acids, page 685, from National Academies Press
- ^ Young VR, Pellett PL (1994). "Plant proteins in relation to human protein and amino acid nutrition" (PDF). American Journal of Clinical Nutrition. 59 (5 Suppl): 1203S–1212S. doi:10.1093/ajcn/59.5.1203s. PMID 8172124.
- ^ Joint WHO/FAO/UNU Expert Consultation (2007). "Protein and amino acid requirements in human nutrition" (PDF). World Health Organization Technical Report Series (935): pag 88 – table 4. ISSN 0512-3054. PMID 18330140.
- ^ a b "Show Foods". Archived from the original on 2014-03-05.
- ^ a b //ndb.nal.usda.gov/ndb/foods/show/303677[dead link]
- ^ Osborne, Thomas Burr (1913) "In Memoriam: Heinrich Ritthausen", Biochemical Bulletin 2:338, published by the Columbia University Biochemical Association
- ^ Scrimshaw obituary from Massachusetts Institute of Technology
- ^ Davis, Adelle (1954). Let's Eat Right to Keep Fit. Harcourt, Brace. ISBN 4-87187-961-5.
- ^ Warren Belasco (1989) Appetite for Change: how the counterculture took on the food industry 1966 — 1988, page 56, Pantheon Books ISBN 0394543998
- ^ a b c Lappé, Frances Moore (1981) Diet for a Small Planet, ISBN 0-345-32120-0
- ^ Judith S. Stern (1975) "How to stay well on a vegetarian diet and save money too!", Vogue 165(2):150,1
- ^ Eleanor R. Williams (1975) Making Vegetarian Diets Nutritious, American Journal of Nursing 75(12):2168–73 from JSTOR
- ^ Maurer, Donna. (2002). Vegetarianism: Movement or Moment? Philadelphia: Temple University Press. ISBN 1-56639-936-X. p. 37
- ^ Rigó, J. (1985) "Nutritional Functions of Cereals", in Amino Acid Composition and Biological Value of Cereal, Radomir Lásztity & Máté Hidvégi editors, International Association for Cereal Chemistry
- ^ a b Woolf, P. J.; Fu, L. L.; Basu, A. (2011). Haslam, Niall James (ed.). "VProtein: Identifying Optimal Amino Acid Complements from Plant-Based Foods". PLOS ONE. 6 (4): e18836. Bibcode:2011PLoSO...618836W. doi:10.1371/journal.pone.0018836. PMC 3081312. PMID 21526128.
- ^ a b Young VR, Pellett PL (1994). "Plant proteins in relation to human protein and amino acid nutrition". The American Journal of Clinical Nutrition. 59 (5 Suppl): 1203S–1212S. doi:10.1093/ajcn/59.5.1203s. PMID 8172124.
- ^ Attwood, Charles R. "Complete" Proteins?, VegSource.com
- ^ McDougall, J (25 Jun 2002). "Plant foods have a complete amino acid composition". Circulation. 105 (25): e197. doi:10.1161/01.CIR.0000018905.97677.1F. PMID 12082008.
- ^ Vegetarians: Pondering Protein? Archived 2016-04-19 at the Wayback Machine, DrWeil.com, Dec. 11, 2002
- ^ Complementary Protein Myth Won't Go Away! Archived 2016-05-12 at the Wayback Machine, Jeff Novick, M.S., R.D., Healthy Times (May 2003)
- ^ Fuhrman, Joel (2005). Eat to Live. Little Brown. p. 137. ISBN 9780316735506.
- ^ Campbell, T. Colin; Campbell, Thomas M. (2006). The China Study. BenBella Books. p. 31. ISBN 1935251007.
- ^ Craig, WJ; Mangels, AR (July 2009). "Position of the American Dietetic Association: Vegetarian Diets" (PDF). Journal of the American Dietetic Association. 109 (7): 1267–1268. doi:10.1016/j.jada.2009.05.027. PMID 19562864. Retrieved 13 January 2017.
- ^ Vegetarian Diets American Heart Association, Sep 26, 2016
- ^ Protein Quality and Protein Combining: Visual tools for the PDCAAS method, 2000kcal.cz
- When Your Friends Ask: "Where Do You Get Your Protein", McDougall Newsletter
- The Protein-Combining Myth, NutritionFacts.org
- The Myth of Complementary Protein, Forks Over Knives
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