Most people think they don’t get enough protein. Debbie Fetter, an associate professor in nutrition at the University of California, Davis, says that when she asks her lecture hall of more than 500 students this same question, “almost every hand shoots up”. Yet the evidence suggests the reverse is true for most of the population. In the UK, the Reference Nutrient Intake (RNI) is 0.75g of protein per kilogram of body weight per day — roughly 45g for women and 56g for men based on average weights. Official data shows that British adults typically eat well above that: men average around 85g daily, women about 67g. The perception of deficiency is widespread, but for the vast majority, it is not backed by the numbers.
Why protein matters
Protein is essential for building and repairing tissues, and for producing enzymes, hormones and disease-fighting antibodies. It is made from smaller units called amino acids. The human body uses 20 amino acids to function; it can make 11, but the other nine must come from food. In the US, new dietary guidelines recommend adults consume 1.2–1.6g per kilogram per day, up from 0.8g, though some experts say the change is unnecessary and could lead to less balanced diets. The UK does not specify a numerical upper limit for protein, but regularly consuming more than 2g per kilogram per day could strain the kidneys, particularly for those with pre-existing kidney issues, says Nicole Stob, an assistant teaching professor of integrative physiology at the University of Colorado, Boulder. Insufficient protein can cause muscle mass loss, anaemia and a slower metabolism. To use protein effectively, the body benefits from an even distribution across meals: 20–40g per meal is advised for optimal muscle protein synthesis. For older adults, consuming 25–30g of protein three times a day is recommended to preserve lean mass and function.
Which sources are best?
The idea that one protein source is universally superior is misleading. “There’s a time and place for all proteins,” says Fetter. What matters is the individual’s dietary needs, preferences and overall nutritional balance. “Protein is important, but it’s not the only thing that’s important for health,” adds Andrea Glenn, an assistant professor of nutrition at New York University. Protein sources also deliver fibre, vitamins and minerals — and the environmental impact varies dramatically. A 2024 study found that eating red meat twice a week compared with four times a week can shrink your carbon footprint and increase longevity. Plant proteins generally have a lower carbon footprint, use less water and land, and produce fewer emissions than animal proteins, with beef and lamb being the most damaging.
Beef is a nutrient-dense, complete protein, meaning it supplies all nine essential amino acids. According to the USDA, 3oz (85g) of ground beef contains about 22.2g of protein, while beef shank cross-cuts have about 28.6g. It provides omega-3 fatty acids, vitamin B12, niacin, zinc and iron. Some research suggests moderate portions of lean beef as part of a healthy diet may not increase heart disease risk. However, concerns centre on cholesterol and saturated fat. The American Heart Association advises choosing “lean” or “extra lean” cuts. “Prime” cuts contain more fat. The Cleveland Clinic notes that sticking with smaller portions is probably best.
Pork provides about 7g of protein per ounce. Ham contains 19g per 100g, while pork chops contain 26.6g per 100g, according to the USDA. Nutritionists describe fresh pork as a high-quality, low-cost protein rich in B-complex vitamins, zinc and iron. A 2025 study on intense exercise found that lean pork protein after training helped with muscle soreness and inflammation compared with plant protein, likely because pork contains more creatine and amino acids. The major caveat involves processed varieties: bacon and ham are linked to increased risk of cardiovascular disease, cancer and type 2 diabetes. The World Health Organization describes processed meat as “probably carcinogenic to humans”. In the UK, advice is to limit red and processed meat to no more than 70g per day. Heart UK recommends avoiding processed meats altogether and preferring fish and plant proteins.
Chicken offers 23–31g of protein per 100g depending on the cut. It is comparable to other animal meats: 100g of sockeye salmon has 26.5g, skinless chicken breast 29.5g, and tenderloin steak 21g. A 2023 Purdue University study suggests lean, unprocessed chicken is a healthy source of potassium, iron and B-group vitamins. There is no clear link between eating poultry and an increased risk of coronary heart disease. However, processed chicken can be high in sodium, and chicken skin is a source of saturated fat. Large-scale poultry production also raises environmental and animal welfare concerns.
Fish contains approximately 7g of protein per ounce, with small differences between species. A fillet of raw tilapia has about 23.3g, while raw cod has 17.7g, according to the USDA. Fish is a good source of omega-3 fatty acids, vitamin D, B12, iodine, selenium and potassium, and tends to have less saturated fat than other animal meats. The FDA and the American Heart Association recommend two to three servings per week. The UK’s Eatwell Guide suggests two portions a week, one of which should be oily. The main drawback, says Stob, is expense; canned fish can be a cheaper alternative.
Eggs are nutrient-dense: one large whole egg contains about 6.2g of protein, with the yolk providing 2.7g and the white 3.6g. Egg protein supports skeletal muscle health and can decrease appetite. It is considered a high-quality protein because of its digestibility and low fat, cholesterol and calorie content in the white, says Fetter. A large egg yolk has about 186mg of cholesterol, but recent research indicates egg cholesterol does not raise the risk of heart attack, stroke or other cardiovascular diseases. The Mayo Clinic says most people can eat up to seven eggs a week without affecting heart health.
Beans are incomplete proteins — they lack or are low in one or more of the essential amino acids. However, combining them with grains creates a complete protein, says Stob. A half-cup of kidney beans contains about 8g of protein, while the same amount of refried beans has 6g. Pulses such as beans, lentils and peas reduce the risk of heart disease, diabetes and some cancers. Beans are rich in minerals, B vitamins, carbohydrates and fibre. Fibre helps lower cholesterol and blood sugar, prevents constipation and aids weight management. “Compared to some animal sources, beans may contain a little bit less protein,” says Glenn, “but at the same time, you’re also getting fibre, which most Americans are not getting enough of.” Glenn’s research suggests substituting red and processed meat with plant proteins yields cardiovascular benefits. A 2021 study found that a plant-centred, high-quality diet starting in young adulthood is associated with lower cardiovascular disease risk by middle age. “People who opt to make most of their protein sources come from plants have improved health outcomes and body composition,” says Fetter. For those unused to fibre-rich foods, beans may cause bloating and gas; adding fibre gradually helps.
Lentils provide about 9g of protein per half-cup. They are a source of manganese, potassium, iron, fibre and folate, and contain polyphenols linked to reduced blood pressure. They are lower in calories than animal proteins and contain no saturated fat. Scientists have found a link between lentil consumption and reduced incidence of diabetes, obesity, certain tumours and cardiovascular diseases. Some research suggests lentils increase fullness and support weight management. Glenn recommends using lentils in dishes such as meatloaf and spaghetti bolognese. Cooking methods can alter some nutrient content — boiling can cause vitamin loss — but proteins typically stay intact. Because lentils are incomplete proteins, Stob recommends alternating them with other protein sources such as tofu. Affordability and long shelf life are additional advantages. Digestive issues can occur with high fibre intake.
Tofu stands out among plant proteins because soy protein is a complete protein. On average, a half-cup of firm tofu contains roughly 21.8g of protein — more per serving than most cooked beans. For comparison, one cup of boiled black beans has about 15.2g. Soy-based foods are rich in B vitamins, fibre, potassium and magnesium. When calcium sulfate is used as a coagulant, tofu becomes a good source of calcium. It also contains isoflavones, which are structurally similar to oestrogen. A 2020 study found that higher intake of isoflavones and tofu was associated with a moderately lower risk of coronary heart disease. Other research suggests tofu consumption is linked to a lower risk of osteoporosis and breast cancer. Tofu is higher in fat than other plant proteins like lentils or beans, but the fat is heart-healthy polyunsaturated fat. Softer tofu has less fat. People with soy allergies should avoid tofu.
The distinction between complete and incomplete proteins is central to understanding plant-based eating. Animal proteins — meat, fish, eggs, dairy — and soy are complete, supplying all nine essential amino acids. Plant proteins such as beans, lentils, nuts and seeds are often incomplete, lacking sufficient amounts of one or more essential amino acids. The body can assemble a complete profile by pairing complementary sources, such as beans with grains or lentils with rice. Stob notes that combining them creates a complete protein. Leucine, an amino acid particularly important for muscle protein synthesis, is abundant in meat, fish, dairy and some pulses. Increasing protein quality through a better amino acid profile, especially combined with exercise, can enhance anabolic signalling for muscle growth.
The protein powder question
Protein powders, derived from sources such as whey, egg and pea, typically contain 20–25g of protein per serving, according to the Mayo Clinic. They are primarily intended to supplement, not replace, whole foods. “I encourage people to get some whole food sources in there, and not just rely on protein powders or shakes,” says Glenn. The FDA does not regulate dietary supplements, so the ingredients listed on labels may not match what is in the product. Fetter recommends choosing products that have undergone third-party testing. For plant-based powders, Stob advises choosing varieties that combine multiple sources to ensure all essential amino acids are present.
Protein powders may include added vitamins and minerals, but researchers caution that labels can be inaccurate. Excess protein does not automatically translate into more muscle and can contribute excess calories. Some powders are high in sugar and calories because of flavours and fillers. Glenn recommends avoiding those with high levels of additives, which dilute the protein content. There is also a risk of lead exposure with some powders, though the levels are probably not immediately harmful. In the UK, “high protein” claims on food labels are regulated: at least 20% of the energy value must come from protein. Mandatory back-of-pack nutrition labels include protein content per 100g or 100ml, offering consumers some transparency.
