Protein is found in most foods. Your body uses it for building and repairing, communication, defence and many other jobs.
Proteins are large molecules made from different amino acids hooked together. Amino acids (AAs) are like interlocking blocks who connect together to order to build different proteins. For more on protein see All About Protein.
You need more protein than you think. According to the latest research: for optimal health adults need between 1.1 and 2.0 g protein per kg of body weight (bw) a day (or 0.5-0.9 g protein/lb/bw). This is more than the current DRI. (discussion Weiler et al. 2020).
Current research also indicates if you are older, sick, inflamed or under stress you need more protein. See Why You Need Protein for more information.
Eating normal amounts of animal and/or plant protein does not cause higher risks of dying from all-causes, cardiovascular disease, or cancer. In fact, a large study (15,937 women and men) showed that eating animal protein may be mildly protective against cancer mortality (Papanikolaou et al. 2025).
Choose unprocessed red meat (fatty or lean). Research suggests that unprocessed red meat does not increase inflammation or increase risk of metabolic disease (O'Connor et al. 2021, Wang et al. 2022).
Stay away from processed meats like hot dogs. Consuming processed meats was associated with an 11-19% average increase in the risk of type 2 diabetes (T2D) risk, a 7% increase in the risk of colon cancer and a 42% increase in risk of cardiovascular disease (Micha et al. 2010, Haile et al. 2025). Processed meats were defined as meats preserved by smoking, curing or salting, or adding chemical preservatives, like bacon,hot dogs, salami, sausages, or processed deli or luncheon meats.
Nitrites and nitrates added to preserved meat can form harmful nitrosamines, especially when meat is cooked at higher temperatures. If you can't resist the nitrites and nitrates used to preserve cured meats (ummm bacon) take some vitamin C with it. Vitamin C, ascorbic acid, blocks the formation of carcinogenic substances (Tannenbaum et al. 1991).
☆ Fatty fish like salmon, mackerel, tuna, herring, anchovies and sardines contain omega-3 fatty acids.
☆ Fish such as sardines, anchovies, salmon, herring, Atlantic mackerel, cod, tilapia, haddock, pollock, flounder, catfish, perch, rainbow trout and bass are low in mercury.
☆ Other seafood and fish are also healthy sources of protein.
Eggs are rich in B vitamins and a nutrient called choline.
Whey and dairy proteins are excellent protein sources for people who are not allergic to dairy.
Meat: beef, pork, lamb, goat, bison, chicken, turkey, fish, or other meat
Fish: salmon, tuna, sardines, halibut, cod, or other fish
Eggs: egg white protein
Dairy: whey protein, greek yogurt, milk, cottage cheese, hard cheeses, casein protein; and other dairy
Grains: wheat, rice, spelt, rye, barley, oats, amaranth, corn, millet, quinoa, wild rice and others
Legumes: beans, chickpeas, peas, lentils, peanuts and others
Quinoa
Seeds: hemp seed, chia seed, sunflower, pumpkin
Nuts: walnuts, pecans, pistachios, hazel nuts, almond and others
Naturally fermented bean products: tofu, tempeh
Vegetable protein powders
Protein quality depends on essential amino acid content and digestibility. These factors are influenced by:
1) The food matrix, sadly not starring Keanu Reeves, describes the complicated structure of food including nutrient and non-nutrient component interactions (Forde and Bolhuis 2022).
2) Processing and food form (solids, semi-solids, or liquids); this includes food texture. Processing and cooking influences the microstructure of foods. Cell wall integrity influences nutrient absorption, energy and metabolism. Crushing, grinding and/or heating foods also changes nutrient availability.
When you eat whole foods; such as nuts, legumes, and cereal grains; you absorb less calories than reported by current calorie estimations based on the food's protein, fat and carbohydrate composition. This is because food with intact food matrix structures are harder for your body to digest. The cell walls and natural food structure locks up the energy in food making it harder to access (Forde and Bolhuis 2022).
For example, when almonds were chewed by healthy young people most of the almond cells remained whole. The lipid (fat) was trapped within the cell walls. Since the fat was trapped, it was unaccessible in the early stages of digestion. This means almonds had less available calories than previously calculated. It is estimated that the actual energy content (calories) of almonds may only 2/3 of what was previously thought (Novotny et al. 2012, Grundy et al. 2015).
Likewise, whole grains have factors that work together synergistically to reduce starch digestion. This includes physical barriers, such as an intact cell wall; starch structural features, such as a partial ordered crystalline structure; and the the soluble/insoluble proteinaceous materials in cells (Li et al. 2020).
In contrast, processed and highly processed foods are much easier to digest.
3) Mechanical digestion includes chewing and stomach churning. It is the physical process of breaking down food into smaller pieces without changing its chemical structure.
4) Bioavailability can be influenced by protein source, cooking, processing and food preparation methods. Animal-based proteins are easier to digest. Plant-based proteins often contain anti-nutritional factors and have more complex fibrous cell structures that often reduce their digestibility. Some legumes and cereals seed proteins have tight globular form and/or a hydrophobic core which makes them more resistant to digestion (discussion Ajomiwe et al. 2024). Cooking and/or processing can change protein structures and either improve or reduce digestibility.
5) The capacity to stimulate protein synthesis is highest in animal-based proteins although all proteins have this effect to some degree. What does this mean? For most people it will be easier to gain muscle using animal-based protein products. I'm not saying you can't gain muscle using plant-based protein, there are vegan strongmen and strongwomen, just that it will be harder.
Discussion of these concepts in Matthews et al. 2025.
Proteins from animals are normally complete proteins. This means they contain enough essential amino acids relative to people's daily essential amino acid requirements.
Proteins from plants are often incomplete protein sources. They lack enough of one or more essential amino acids. See more about plant proteins here.
☆ Cereals, grains, and seeds are usually proportionally low in the amino acid lysine
☆ Legumes and vegetables are usually proportionally low in the amino acid methionine
☆ Most plant proteins also contain limited amounts of the amino acids isoleucine and valine
Proteins with higher amounts of essential amino acids increase muscle protein synthesis rate more than proteins with lower amounts of essential amino acids (see discussion Berrazaga et al. 2019).
In one small cross-over study, women and men (16 adults, 65-85 years old) who ate a beef meal (lean ground beef, potatoes, string beans, apple sauce, herb butter) had 47% higher postprandial muscle protein synthesis rates when compared with when they ate an isonitrogenous and isocaloric vegan meal (quinoa, soy beans, chickpeas, and broad beans). Consuming a single meal with meat raised plasma essential amino acid concentrations more than the vegan meal (Pinckaers et al. 2024).
*Names and some minor identifying details in all stories in this website are changed to protect people's privacy.
This information in this website is for informational purposes only and does not constitute medical advice, diagnosis, or treatment.
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