- Both plants and meats can be sources of protein.
- Each has its own benefits and drawbacks.
- You might want to modify your protein intake depending on your health goals.
In the United States, meat has been so central and essential to the traditional diet that we coined the phrase “meat and potatoes” to represent anything fundamental.
But in recent decades, that collective mindset has begun to shift.
Meatless diets have existed since time immemorial, but now there’s a new and unprecedented focus on reducing or eliminating meat consumption for both health and environmental reasons.
But how exactly does this impact the human body? And how do you know what protein sources are right for your own health goals? Let’s take a look.
There are three macronutrients that provide your body with the energy and raw materials to continue functioning: carbohydrates, fats, and protein.
Carbohydrates (carbs) include fiber, sugar, and starch and serve many functions in your body.
Likewise, there are several types of fats, from omega-3 fatty acids to triglycerides, that have a number of effects on your body, both good and bad.
The third type of macronutrient — protein — is no different, in that it’s essential for your body. Proteins are responsible for many things like growing new tissue and serving as messengers called hormones.
Proteins are made from chains of molecules called amino acids. Amino acids are like the letters of the alphabet and proteins are like words. Your body can string them together into complex sentences that say things like “make new cells” and “destroy this virus.”
There are hundreds of amino acids that exist in nature, but you need just 20 of these to make all of the different types of protein in your body.
When you consume protein, either from plants or from meat, you’re really consuming amino acids that your body can then rearrange into whatever proteins you need at that time.
So how do the different sources of protein compare to each other?
Garrett Swisher, registered dietitian at IU Health in Indianapolis, IN, told Healthline, “Animal protein is considered complete, meaning that it contains all 20 of the amino acids, whereas plant proteins do not always contain all amino acids needed for protein synthesis.”
This doesn’t mean that you have to eat meat, though.
While no single plant source contains all 20 amino acids (for the most part), all 20 can be found in plants. You just have to consume more than one type of plant to get them all.
“Typically plant foods are less protein-dense than animal foods, meaning that individuals need to eat a larger quantity of plant-based foods in comparison to animal protein,” said Swisher.
Of course, whether you’re eating meat or plants, you’re taking in more than just the protein. Each can contain different amounts of fats and carbs which also affect their overall health profile.
“Animal protein is a very efficient delivery system and is more easily digested and absorbed than plant protein and often in a smaller caloric package, plus it’s the best source of omega 3 fats, vitamin B12, calcium, and vitamin D,” said Kate Cohen.
Cohen is a registered dietitian at the Ellison Clinic at Saint John’s, part of the Ellison Institute for Transformative Medicine and Providence Saint John’s Health Center in Santa Monica, CA.
“On the con side, red meat and processed meats are often higher in saturated fat and may also increase the risk of several cancers, including colorectal cancer,” Cohen added.
It’s easy to overgeneralize, too. There are many different types of plants and of meats. Each has its own unique attributes and makeup.
“For example,” said Swisher, “most Americans overconsume processed meats (high in saturated fat and sodium) and under-consume the recommended intake of seafood (good source of omega-3 fatty acids) and nuts/seeds and legumes (high in fiber).”
Protein is often associated with exercise, athleticism, and muscle gain, and not without reason.
Your muscle fibers are made up of smaller components called myofibrils. The myofibrils are long tubelike structures that can contract to make your muscles tighten. Having more myofibrils makes your muscle both stronger and physically bigger.
And myofibrils are made of (you guessed it) protein chains.
So if your goal is to increase your muscle mass, will one type of protein be more beneficial?
“Animal protein is likely better at building muscle given its complete amino acid profile and better digestibility. Animal protein is higher in the amino acid leucine which helps stimulate new muscle growth and with muscle recovery after exercise,” said Cohen.
“Plant-based protein is generally wrapped in a fiber package which means you don’t absorb as much since your body doesn’t break down fiber easily,” said Cohen.
That doesn’t mean that consuming plant proteins won’t allow for muscle gain, though.
A 2023 study compared muscle growth in young adults consuming either a vegan or omnivorous (mixed plant and animal) diet, and a 2020 study reviewed similar criteria in older adults.
Both studies found that vegan diets led to equal muscle gains as omnivorous diets. It should be noted, however, that both studies were small (57 participants between them). Both studies also studied resistance training, and all participants specifically consumed high-protein diets.
You may also be wondering how protein powders fit into this mix. These powders can be made from either plants or meats, though whey is most commonly used.
“Protein powders do not replace a well-balanced diet and should be considered a supplement, not a replacement. Protein powders, however, can be very useful for those with higher protein needs,” said Swisher.
This could include not only people who are trying to gain muscle but people with cancer or those who have had bariatric surgery, he explained.
“Protein powders are a processed food, so you’re always better getting your protein from a whole food source because it’s never a good idea to overdo it with a chemically created food,” Cohen agreed.
“That said, high-quality protein powders can be included as part of a healthy diet to fill in gaps. Look for products with as few ingredients as possible and limit the added sugar or chemicals,” said Cohen.
If your goal is not to gain muscle but instead to lose weight, you might take a different approach to your protein consumption.
“Relying on plant-based (i.e. carbohydrate-based) protein sources makes it harder for vegetarians to lose weight,” said Cohen.
This is because you need to eat more of the more carb-heavy plants to get the same amount of protein as from meat, and those carbs contain calories.
“People switching to this diet are often surprised when they start to gain weight,” said Cohen.
But some plant-based proteins will help you achieve your weight loss goals better than others.
“If your goal is weight loss, be mindful of portion sizes for starchier or high-calorie plant proteins like beans and nuts and seeds,” Cohen said.
“Lentils have the highest amount of protein compared to other legumes so they are a very efficient protein source in a reasonable serving size, as is edamame, and you get lots of fiber to boot,” she advised.
You’re also better served consuming whole food for your protein needs as opposed to processed foods to avoid ingredients that wouldn’t align with your goals.
“Both animal and plant proteins are healthy and can be incorporated into a healthy diet. The diet as a whole is much more important than the individual foods,” said Swisher.
“It is recommended to vary types of protein (especially if choosing plant proteins) to ensure nutritional adequacy and take into account the other nutrients consumed with protein foods,” he added.
“Aim to include less frequently processed protein types such as sausage, bacon, deli meat, and processed plant-based meat alternatives. Consume more fresh seafood proteins and avoid frying and breading them. Eat more nuts, seeds, and beans/legumes,” Swisher recommended.
“Eating plants is objectively healthier than eating animals, but research shows that the Mediterranean diet — which has plants as its foundation and also includes lean protein sources and seafood — reigns supreme,” said Cohen, adding, “Diversity is best.”
The Mediterranean diet emphasizes whole fruits, vegetables, and grains, and includes a moderate amount of seafood while limiting dairy products and red meats.
There are also other benefits to switching some of your protein intake from processed foods or meats to plants.
“Increasing plants in the diet improves the diversity of your microbiome which has tons of benefits we know about already, including improving your immune system and keeping your GI system humming,” said Cohen.
“Environmentally, animal protein is also responsible for twice as much of the greenhouse gas emissions as plant foods, not to mention the questionable quality of meat coming out of commercial feed-lots,” Cohen added.
At the end of the day, proteins are all the same. They’re made up of amino acids, and your body can’t make them all on its own, so you’ll have to consume something in order to get them.
You can get all of the amino acids you need from either plants or meat. The main differentiating factor is what else is included in those foods besides the proteins.
Meats will have all of the amino acids you need, but they’re more likely to contain unhealthy fats, and they don’t have any fiber.
Eating a variety of plants will get you all 20 amino acids, but you’ll have to consume more plants pound-for-pound in order to get the same amount of protein. This can involve taking in more carbohydrates.
On the whole, eating a wide variety of foods — and especially whole, unprocessed foods — seems to achieve the healthiest balance.
