Plant Protein vs. Animal Protein: Which is Better?

Emmie Satrazemis, RD, CSSD
     
Emmie Satrazemis, RD, CSSD
Emmie Satrazemis, RD, CSSD

Let the official showdown begin! Whether you call it vegan, flexitarian or just plant-based eating, opting for non-animal sources of protein continues to be trendy. And numerous health advocates claim that plant-based proteins may be better for your health and the environment. But are plants better than animals when it comes to quality protein sources? 

While ultimately it boils down to personal choice and food preference, we put these two protein sources head to head to see who comes out on top when looking at key health and fitness factors like:

What is Plant Protein?

Plants include anything that grows out of the ground and anything that isn't an animal or fish or hasn't come from an animal or fish. This includes all fruits, vegetables, grains, legumes, nuts, seeds, and any food product produced from these ingredients. 

Not all plants are high in protein though. In fact, most aren't even considered a good source. The best plant-based proteins include those offering at least 5 grams of protein per standard serving (1). Beans, lentils, soy, green peas, and many nuts and seeds, are all considered "good sources" of protein. And food manufacturers have developed additional meat-like alternatives, like pea protein burgers, tofu, and tempeh, with even more protein per serving - sometimes as high as 20 grams! Outside of these key sources, plant-based eaters can also get adequate protein intake with a well planned vegan diet, and strategically combining options to offer more protein per meal. 

What is Animal Protein?

Essentially any animal or fish we consume, as well as their by-products, like milk and eggs counts as an animal-based protein. 

Which Protein is Best for... Nutrition

Most plants just can't compete with animals when it comes to the amount of protein they provide. This is because most vegan protein sources are also a source of fat or carbohydrates, making them less protein dense.

For example, a meal with beans and quinoa can provide 30 grams of protein, but also has over 600 calories and 100 grams of carbs. And to get 30 grams of protein from peanuts, you also get 650 calories and 58 grams of fat. Compare this to 30 grams of protein from grass-fed steak which is less than 200 calories, 8 grams of fat and 0 grams of carbs.

However, when you are eating only plants or high amounts of the most protein-rich plants, your protein adds up quickly. And some meat alternatives, like pea protein burgers, are helping to bridge the gap in protein density. 

Food Macro Comparison
Beans + Quinoa 30g protein 100g carbs  5g fat
Peanuts 30g protein 14g carbs 58g fat
Pea Protein Burger 30g protein 7.5g carbs 30g fat
Steak 30g protein 0g carbs 8g fat


On the flip side, plants are loaded with good nutrition like fiber, vitamins, minerals, and healthy fats - making them a well-rounded source of good nutrition, outside of just protein. Vitamins C, A, and E, folate, and magnesium can be hard to come by in animal proteins but are abundant in many plant sources (2). Also, most plants contain no cholesterol or saturated fat.

However, they lack vitamin B12, which is only found in animal sources (3). And animal-based proteins contain more zinc, vitamin D and the important omega-3s, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Zinc plays an important role in wound healing and is thought to be more easily absorbed from animal sources (4). Vitamin D is not naturally found in most foods; it is synthesized by the body from sunlight. Animals synthesize vitamin D in a similar way and thus can be a good source of it. Mushrooms can also contain some vitamin D, but significantly less than animal sources like salmon, eggs and beef liver. 

And while plants can contain large amounts of beneficial omega-3s, they are not a significant source of EPA and DHA omegas. EPA is a power anti-inflammatory, and DHA is the type of fat that 80% of our brains are made of and is thought to be important for brain health (5).

Heme vs. Non- Heme Iron

Animal proteins also provide heme-iron, which comes from a protein (hemoglobin) in red blood cells, and is absorbed more efficiently than non-heme iron (6,7). Both plants and animals are a source of non-heme iron, but heme-iron is unique to meat and seafood, especially red meat.

Iron absorption could be an important consideration for individuals with higher needs or those at risk for anemia. 

Superfoods

Plants may offer an edge with unique plant-based compounds called phytochemicals - the term "phyto" means from plants. In addition to their high amounts of vitamins and minerals. phytochemicals are part of the reason why most plants are considered superfoods. 

Phytochemicals are thought to provide color, flavor, and smell to the plant, but they also have a protective component. When you consume these phytochemicals, they are thought to provide protective health benefits, although more research is needed to clearly understand their role in health and disease prevention (8). 

Cutting out meat means even more room for plants in your diet. And with a well-planned approach, you may be able to get a significant amount of good nutrition and adequate protein all at once. 

Complete vs. Incomplete Proteins

A common argument against plant proteins is that not all of them are considered "complete". This is in regards to their amino acid profile. 

There are nine essential amino acids your body needs to synthesize new proteins and thrive. These amino acids are considered essential because your body cannot make them and has to get them from food. Some foods, like meat and dairy, contain all nine essential amino acids in adequate proportions and are considered complete proteins. An incomplete protein, like many plant-based sources, contain only some of the amino acids or all of them in less desirable amounts. 

But this does not mean you can't get all of your essential amino acids from plants. Some plant proteins are complete - like soy, quinoa, pea, and buckwheat. Tofu, seitan, and many processed vegan meat alternatives would also be considered complete. 

Some plant proteins are considered complimentary to each other - meaning when combined they provide adequate amounts of all essential amino acids. The most popular complementary pairings are rice and beans, lentils and nuts/seeds, beans and corn, and whole grains with nuts/seeds. 

According to the research, you probably don't have to consume all of your amino acids at once to get the benefits, as long as you are eating a balanced diet each day. Not to mention, no evidence has shown that vegans become deficient in specific amino acids (9,10,11). 

The Verdict: 

Both plants and animals can both supply many key nutrients to the diet - some of which are unique to either pant or animal sources. When it comes to protein density, animal proteins are supreme, but plants can offer much more than just protein to your diet.

There is no clear winner on this one. Including a variety of plant and animal protein sources in your diet is probably going to give you the most well-rounded approach to nutrition. 

Health Benefits    

In addition to potential phytochemical benefits, a diet high in plant-based foods has been linked to a number of positive health benefits, including increased energy, better mood, heart health (12,13,14,15).

Some research also suggests that plant-based diets may have protective benefits against cancer (16,17). However, the associated risks are only slightly lower with vegetarian diets compared to animal-based, and the science is much stronger with fruits and vegetable intake overall (18,19). In other words, eating more plant-based can also mean eating more fruits and veggies, which can lead to protective health benefits. 

Research has also suggested some positive health benefits associated with seafood intake, including heart health, brain health, mood, and eye health (20,21,22). And some dairy intake has been linked to heart health, gut health and bone health (23,24,25). 

With the exception of seafood and dairy, there isn’t an abundance of research looking at the health benefits of meat itself. But many experts agree that the protein contribution of animal-based foods as well as key nutrients can benefit overall health when included as part of a healthy diet (26,27). 

Unlike plant-based diets, there is a decent amount of science linking meat consumption, especially processed meat and red meat, to an increased risk of certain diseases like heart disease and cancer (28,29). But these studies aren't able to show a direct cause of red meat consumption to disease and some studies still contradict these findings (30,31,32). Some also argue that choosing lean, grass-fed red meats over conventional red meat and processed meat options may offer better nutrition. 

The Verdict: 

Its worth noting that while both animal proteins and plant proteins have been associated with positive health benefits, there isn't any research suggesting that plant-based proteins have a negative health impact, while there is for certain animal proteins. 

If looking at this factor broadly, plant proteins appear to be a clear winner. But when looking at specific animal proteins like fatty fish and certain dairy options, animal proteins can have significant and unique benefits. The solution? Focus on the quality of your protein choices, and when eating a balanced, nutrient-rich diet, both plant and animal foods can provide many health advantages. 

Weight Loss 

Protein is thought to have positive weight loss effects through appetite suppression and its impact on preserving lean mass. But as far as we know, there isn't any research showing that plant-based or animal-based proteins in specific are more beneficial for weight loss than calorie control alone.

There is also a growing body of research looking at high protein, low carb diets is showing promising results for weight loss (33,34,35,36). And animal proteins offer the most nutrient dense protein sources for this type of diet - since most plant-based options can be lower in protein and higher in carbs comparatively. 

Some research suggests that vegan eaters tend to be leaner than omnivores (37,38). And numerous studies have associated vegan diets with improved weight loss capabilities (39,40,41,42). 

However, this doesn't mean that plant protein will automatically help you lose more weight. Weight loss still boils down to calorie control. Vegan diets may offer an edge because they restrict entire food groups - all meat and dairy, which can, in turn, help someone cut a significant amount of calories, especially if they were previously eating a lot of extra ingredients like cheese, mayonnaise, cream based sauces, etc.

Also, eating more nutrient-dense foods, like fruits and veggies, may help with appetite control and overall energy levels, making cutting calories a little easier (43).

The Verdict: 

This one is a draw! Weight loss ultimately comes down to calorie control. And while both plant and animal-based proteins may have additional weight loss benefits, it is not clear that one type of diet or certain foods promote weight loss more than others. 

Muscle Gain

When it comes to building muscle, there are two critical dietary factors you need more of: calories and protein. And research suggests that plant-based eaters tend to get less of both (44,45). 

In addition, animal sources of protein, especially dairy, rank higher in terms of bio availability and digestibility - meaning you absorb this type of protein more efficiently, which is why some studies suggest that milk protein is better than soy-based options in promoting muscle growth (46,47,48). The hormones present in dairy may also play an important role. Insulin growth factor one, or IGF-1, in milk is associated with more lean muscle growth (49,50). 

Moreover, because many plant proteins are incomplete, they may be lacking in certain amino acids (specifically the branch chain amino acid (BCAA) lysine) that play a key role in muscle building (51). This is likely most crucial during workout recovery since a plant-based diet, in general, has not been associated with amino acid deficiencies. And consuming more complete proteins and adequate protein in the hours following a strength training workout can improve the amount of available protein for muscle building (52). 

The Verdict:

Animal proteins may offer a clear advantage in getting high amounts of quality protein in the diet. However, it is key to remember that muscle building is generally a complex and slow process, and highly dependent on individual factors. Thus it is difficult to say whether or not plant-based proteins can really hold you back from gaining lean muscle mass, especially when calories and overall protein intake is adequate. 

If you are looking to gain muscle mass on a plant-based diet, you may want to consider supplementing with dairy or whey protein. Or increase your plant protein intake overall (53).

The amount of protein you need is most closely related to your muscle mass and fitness needs. The more muscle you have, and the more you use your muscles, the more protein you need to maintain it.

Sustainability

There is just no sugar coating this one, raising animals for meat and dairy requires a significant amount of resources, much more than crops alone - land, feed, and water, as well as the amount of labor involved in slaughtering, processing and distributing these foods. Ranching also generates air pollution, since livestock release gas into the atmosphere through waste (54,55). And according to a report by the United Nations Food and Agriculture Organization, animal agriculture accounts for more greenhouse gas emissions than transportation systems (56).

However, including some animal livestock in our agricultural system could be key for biodiversity and contribute to better soil quality and land use if done responsibly (57,58). 

The issue of seafood sustainability gets even more complex, with concerns of over-fishing depleting the ocean's natural ecosystem and farm-raised fish offering a controversial alternative. 

Food Waste

A majority of the food we produce doesn't even go towards food - in the US, only one-third of crop production is for eating, the remaining is used for animal feed and bio-fuel (59,60,61,62). To make matters worse, one-third of food produced is wasted. In other words, we only eat 27% of all crop calories we grow. 

Theoretically, increasing our consumption of these crops through a plant-based diet can help make our agricultural system more efficient, especially as our population continues to increase and food becomes more scarce worldwide. It would make sense that the calories we grow are consumed rather than used to feed other animals for a lower overall calorie return - it is estimated to take about 100 calories of grain to produce three calories of beef. 

Animal Welfare

A common reason for many to choose vegan proteins is the guilt associated with slaughtering animals for food. And this topic, in particular, is part of why the protein debate can get so emotional and heated. It has also fueled an emerging focus on animal welfare and humanely raised products in the food industry - allowing some to opt for meat but feel a little better about it. 

Humanely raised animals are those raised in an environment and fed a diet that more closely resembles their natural state and supports the overall well-being of the animal. However this term is loosely defined and not well regulated - not to mention standards can differ from one farm to the next. Thus many outside organizations have created third-party labeling standards to help bring more clarity and control to this area of agriculture. One of the highest labeling standards is through the 5-step animal welfare program. 

Outside of the ethical component to eating animals, some research suggests that humanely raised and well taken care of livestock might produce more nutritious meat and positively impact sustainability efforts (63,64,65). 

Grass-fed beef is typically leaner and may have a more favorable fatty acid composition, as well as slightly more vitamin A due to their diet (66). Relying on more grass also helps cut down on crop production for grain fed cattle. Pasture-raised poultry and eggs have also been associated with better nutrition (67). 

The Verdict:

At first glance, plant proteins are better for the environment than animal-based options. However, experts still seem to disagree on this one for some reason. Some argue that eating locally and farming more varieties of foods, has a potentially greater positive impact than just cutting out meat and dairy (68). 

The reality is that our food system is fairly complex and there may not be a single solution to making our food supply more sustainable for all - it likely requires a multifaceted approach. And decreasing the overall consumption of meat could be part of the solution.

What is the Best Source of Protein?

Like most things, it depends on the person and personal preference. The human body is incredibly adaptive, and as omnivores, we can adapt to a variety of eating styles - from cutting carbs to eliminating meat and dairy. We have the choice and can thrive on more than one type of diet. 

You can't just decide to weigh one area more heavily than the other - is our nutrition, health, or the environment most important? When in reality they are all important and the solution to the best type of protein probably involves a combination approach. 

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