Are You Getting Enough Protein on a Veg~n Diet?

Protein has become increasingly popular in recent years due to diet trends, fitness culture, and growing awareness of its health benefits. During this time, we have seen shifts in the consumer market, with a rapid expansion of protein supplements and plant-based meat alternatives that offer various sources of protein beyond conventional animal products. When it comes to protein, it has often been believed that animal products are the gold standard and that protein from plant sources is insufficient or incomplete, therefore people on a veg~n diet don’t get enough protein. So how much protein do we really need, and does it matter whether we get it from animal or plant foods? 

Protein is an essential nutrient that has many functions that keep the body running smoothly. It is vital for building and maintaining lean muscle, repairing the body, supporting immune function, enzyme production and for providing an energy source, among other things.

Protein is made of 20 building blocks called amino acids. To function optimally, our bodies need all 20 amino acids. Our bodies naturally make 11 of these, and they are referred to as nonessential amino acids. The remaining nine amino acids are called essential amino acids as they can only be obtained from food.

Protein foods can be either complete or incomplete. A complete protein source contains all nine of the essential amino acids in sufficient quantities. Most animal proteins are considered complete proteins. Examples include meat, poultry, fish, eggs, and most dairy products. An incomplete protein source lacks one or more of the nine essential amino acids.

Incomplete proteins are still an essential part of a balanced diet as they contribute to overall protein intake and can be combined with other foods to create a complete profile. For example, combining legumes with grains will provide the full range of essential amino acids (1). It is not necessary to combine proteins for every meal, but eating a variety of protein foods throughout the day will provide all the complete protein you need. Most plant-based proteins from legumes, nuts and seeds, grains and vegetables, are considered incomplete. Some plant sources contain all nine essential amino acids. Examples of complete plant proteins include quinoa, soy (tofu, tempeh, edamame), chia seeds, hemp seeds, buckwheat, nutritional yeast and spirulina.

Plant proteins have lower bioavailability compared to animal proteins, meaning they are generally less digestible or absorbable. This is due to the presence of anti-nutrients in some plant foods (e.g., phytates, lectins) and the fibre content in legumes and grains. However, cooking methods such as soaking, fermenting, and cooking can reduce these anti-nutrients and increase the digestibility and bioavailability of plant proteins (2).

The recommended daily intake of protein for New Zealand adults aged 19-64 years is around 0.8 g of protein per kilogram of body weight per day. For example, for a person weighing 70 kg, this would be 56 g of protein per day (3).

Some population groups will require additional protein, depending on their lifestyle, health conditions or specific goals. This includes the following:

• Some studies suggest that vegetarians and vegans require additional protein to account for the decreased bioavailability of protein from plant sources. However, recommended protein intakes for people on a veg~n diet have not been formalised in official guidance and studies differ slightly in the amount of protein recommended. Aiming for 1.0 g of protein per kilogram of body weight is generally a safe target for vegetarians or vegans (1).

• For adults aged 70 years and older, the recommendation is 1.0 g of protein per kilogram of body weight (3) to help preserve lean muscle mass that naturally degenerates with age. Perimenopausal women may also benefit from additional protein.

• Women who are pregnant require 1.0 g of protein per kilogram of body weight to support fetal growth, and lactating women require 1.1 g per kilogram of body weight for milk production (3).

• Athletes or people who are very physically active require increased amounts of protein to build and repair muscle tissue – the amount of protein required will depend on the type and amount of activity, and vegan or vegetarian athletes may need additional protein (3,4).

• People recovering from injury or surgery need more protein to support recovery and regeneration of healthy tissue.

There is no official upper limit of protein for New Zealanders, though your body can only use so much protein. Consistently high intakes of protein are sometimes reported to be damaging to the kidneys or bone health, though recent studies have reported this is not the case for people who are otherwise healthy (4). For people with kidney or liver disease, too much protein can be harmful and individual needs should be discussed with a doctor.

Some researchers believe that official protein requirements are outdated and the values are too low, particularly for older adults, perimenopausal women, athletes and pregnant or lactating women (4–6). Although there have been no updates to the official recommendations yet, this is potentially an emerging area to watch.

Studies of protein intake in vegetarians and vegans have generally reported that people eating a range of plant proteins are able to meet their protein needs, although vegans are at greater risk of not meeting the requirements (7,8). A recent review of 13 studies assessed the protein intake of vegans, vegetarians, flexitarians and pescatarians in the United States, Korea and Europe. It concluded that all veg~n diets met the dietary recommendations for protein intake overall, however people on a vegan diet tended to have the lowest protein intake. Cereal-based foods (bread, rolls, crackers, grains) were the main source of protein in the diets assessed (9).

Protein supplements (such as protein powder or bars) are a convenient way to supplement your diet, especially for people with higher protein needs. If taking protein supplements, keep in mind that most people can meet their protein needs without further supplementation, and that supplements may lack the additional nutritional benefits (such as vitamins, minerals and fibre) obtained from eating whole foods (11).

• Although not included in the official guidance, studies suggest that vegans and vegetarians may require slightly more protein to compensate for the decreased bioavailability in protein from plant sources.

• With careful planning, people on a veg~n diet typically have no problem meeting the recommended intakes of protein. Vegans are more likely to have lower protein intakes than vegetarians.

• Athletes, older adults, pregnant or breastfeeding women, and people recovering from injury or surgery will require additional protein.

• Eating a variety of plant-based foods throughout the day is key. This ensures you can get the full spectrum of essential amino acids plus other health benefits, such as fibre, antioxidants, and healthy fats.

• Read the nutrition information of food labels to check the protein content of foods. For example, plain Greek yoghurt can contain almost twice the protein of plain natural yoghurt. Non-dairy milks, yoghurts and cheese (with the exception of soy or fortified products) contain very little protein.

By Catherine Lofthouse

Catherine Lofthouse is a passionate plant-based foodie who loves to explore all things related to veg~n living. She is also a registered
dietitian.

For more articles like this, check out our quarterly magazine Vegetarian Living NZ.

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3. National Health and Medical Research Council, Australian Government Department of Health and Ageing, New Zealand Ministry of Health. Nutrient Reference Values for Australia and New Zealand Including Recommended Dietary Intakes. Canberra: National Health and Medical Research Council; 2006.

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