Is Protein Intake an Issue for Vegans?

This article was written by Dietetically Speaking’s intern Zachary Wenger. Zack is a Student Dietitian and a Vegan himself.

Protein might just be the biggest ‘talking point’ of concern for those on a vegan diet. Vegans roll their eyes every time protein is brought up.

Proteins form the building blocks of skin, hair, blood, and muscle. Protein also plays a role in proper immune function.

Many fear that by going vegan, they won’t be able to get enough protein. This article will explore whether most vegans need to worry about their protein intake. 

How Much Protein Do We Need?

The recommended daily intake (RDA) in the US is set at 0.8 grams per kilogram of bodyweight a day for adults over 18. To apply this, someone who weighs 72.5 kg (160 pounds) is advised to consume roughly 58 grams of protein per day. In the UK, the reference nutrient intake (RNI) for protein is 0.75 grams per kilogram of bodyweight. 

However, the RDA (and RNI) are set to maintain “minimum” nitrogen balance.

Nitrogen balance is simply a reflection of protein intake versus protein losses in the body. The RDA does not account for physical activity, which would require more protein. The RDA also doesn’t account for muscle wasting as we age, which would require even more protein. In other words, the RDA set for protein, should be the bare minimum that we should be consuming. 

The International Society of Sports Nutrition (ISSN) set their recommendations at 1.4 to 2.0 grams per kilogram of body weight for building and maintaining muscle mass and 1.2 to 2.0 grams per kilogram of bodyweight for elderly adults (1, 7). As a reference, the 72.5kg (160 pound) individual that we used as the earlier example would need to consume 101 to 145 grams of protein per day to meet this guideline. 

Summary: The minimum protein requirement for healthy adults is 0.75g per kg of body weight per day. However, older adults and those working on building muscle mass require between 1.2 – 2.0g and 1.4 – 2.0g of protein per kg of bodyweight per day (respectively).

How Much Protein Do Vegans Usually Consume?

Determining the average protein intakes among vegans is tricky.

While there are a handful of studies that have tried to investigate this, they almost all have the unfortunate commonality of diet switchers (study participants switching their diet mid-study).

This all comes down to how the researchers determine that one is vegan. To be considered vegan in one of these studies, generally speaking, you would’ve had to self-report that you have been vegan for at least a year prior to the study. That’s all. Looking closely at the Nutrinet-Santé paper, the ‘vegans’ on average consumed 5.8 grams of processed meat, 5.4 grams of eggs, 6.1 grams of poultry, and 45 grams of dairy products per day (2)! Why did this occur? Those that claimed to have been vegan in the beginning of the study, aren’t anymore, and the researchers didn’t exclude them. 

What we can confidently gather from this data, is that the further one restricts animal products, on a population level, the less protein one consumes (1).

The EPIC-Oxford study demonstrated similar results. While the “vegan” group on average consumed 35 mg of dietary cholesterol (due to diet switchers), they restricted animal products more than any other diet group within the study (2). As a result, the vegan group consumed 4% less kilocalories from protein than the omnivorous group (13.1% vs 17.2%). 

Summary: While the jury is still out on how much protein vegans consume, we can confidently conclude that according to the data, restricting animal products, generally speaking, decreases protein intakes. This may be especially problematic for athletes that need extra protein or older adults that also need extra protein. 

Which Vegan Foods Are High in Protein?

If one chooses to eliminate animal products from their diet, it is important to consume vegan replacements that are similar in terms of protein content. 

Seitan is first on the list by a long shot.

Seitan is made out of wheat gluten and is ridiculously high in protein.

Per serving, it contains 21 grams of protein, which is roughly 100 kilocalories. 

Other good sources of plant protein include:

• Tempeh – 14 grams of protein per 65g serving
• Tofu – 10 grams of protein per 70g serving of firm tofu or per 120g of regular tofu
• Beans – roughly 10 grams of protein per cup i.e. 150g
• Hemp seeds – 10 grams of protein per 3 tbsp
• Soy milk – 10 grams of protein per 300ml
• Plant protein powder – 20 to 30 grams of protein per scoop

Do Vegans Need to Worry About Consuming ‘Complete Proteins’?

Animal-based sources of protein are considered ‘complete’ as they contain all nine essential amino acids which we need to consume in our diet for good health. 

As most plant-based sources of protein are low in one or more essential amino acids, it was previously thought that vegans and vegetarians needed to combine different protein sources at each meal. But it isn’t necessarily true that plants are incomplete sources of protein. All plant foods contain all 20 dietary amino acids (6).

More accurately, plants contain less essential amino acids than animal products. For example, lysine is found in much lower quantities in the plant kingdom, especially in grains. However, this is only problematic for one exclusively eating grains. Good sources of lysine on a vegan diet include legumes, seitan, wheat germ, soy milk, nutritional yeast, tofu, and much more! 

We also now know more about the amino acid pool in our body. Quite simply, the amino acid pool is a collection of amino acids in the body that is able to create proteins in the body throughout the day, whenever it is required (4). The pool isn’t large, though it takes place in many metabolic reactions in the body (5).

For instance, if dinner is lacking in one of the essential amino acids, our body is able to pull amino acids stored from past meals, like breakfast and lunch, to carry out protein synthesis and/or other processes in the body.

Summary: Protein combining per meal isn’t necessary but vegans do need to consume a variety of protein sources over the course of the day to make sure that the amino acid pool is replenished.

Conclusion:

Overall, the further one restricts animal products, on average, the lower protein consumption tends to be. Nonetheless, getting enough protein on a vegan diet is more than manageable and can be easily achieved on a well-balanced diet which includes a variety of plant-based proteins every day! 

References: 

1. Jäger, R., Kerksick, C.M., Campbell, B.I. et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr 14, 20 (2017). https://doi.org/10.1186/s12970-017-0177-8
2. Allès, Benjamin et al. “Comparison of Sociodemographic and Nutritional Characteristics between Self-Reported Vegetarians, Vegans, and Meat-Eaters from the NutriNet-Santé Study.” Nutrients vol. 9,9 1023. 15 Sep. 2017, doi:10.3390/nu9091023
3. Sobiecki, Jakub G et al. “High compliance with dietary recommendations in a cohort of meat eaters, fish eaters, vegetarians, and vegans: results from the European Prospective Investigation into Cancer and Nutrition-Oxford study.” Nutrition research (New York, N.Y.) vol. 36,5 (2016): 464-77. doi:10.1016/j.nutres.2015.12.016
4. V R Young, P L Pellett, Plant proteins in relation to human protein and amino acid nutrition, The American Journal of Clinical Nutrition, Volume 59, Issue 5, May 1994, Pages 1203S–1212S, https://doi.org/10.1093/ajcn/59.5.1203S
5. Pitkanen, Hannu T et al. “Free amino acid pool and muscle protein balance after resistance exercise.” Medicine and science in sports and exercise vol. 35,5 (2003): 784-92. doi:10.1249/01.MSS.0000064934.51751.F9
6. Gardner, Christopher D et al. “Maximizing the intersection of human health and the health of the environment with regard to the amount and type of protein produced and consumed in the United States.” Nutrition reviews vol. 77,4 (2019): 197-215. doi:10.1093/nutrit/nuy073
7. Baum, Jamie I et al. “Protein Consumption and the Elderly: What Is the Optimal Level of Intake?.” Nutrients vol. 8,6 359. 8 Jun. 2016, doi:10.3390/nu8060359