Protein is an essential macronutrient vital for growth, development, and tissue repair. It plays a crucial role in various bodily functions, making it a fundamental component of a healthy diet. While adequate protein intake is necessary to prevent malnutrition and maintain muscle mass, the increasing popularity of high-protein diets raises concerns about their potential side effects. This article explores the benefits and risks associated with high-protein diets, providing a comprehensive overview of their impact on health.
Understanding Protein and Its Role in the Body
Protein is a building block of every human cell. It’s involved in the vital biochemical functions of the human body. Foods rich in animal protein are meat, fish, eggs, poultry, and dairy products, while plant foods high in protein are mainly legumes, nuts, and grains. It is particularly important in growth, development, and tissue repair. So, consuming enough protein is required to stave off malnutrition; it may also be important to preserve muscle mass and strength as we age.
The Recommended Dietary Allowance (RDA) for protein is 0.8 grams of protein per kilogram (g/kg) of body weight - roughly 0.36 grams of protein per pound of body weight. The current recommended dietary allowance (RDA) for protein is 0.8 g protein/kg body weight/day for adults (for children 1.5 g protein/kg body weight/day, and for adolescents 1.0 g protein/kg body weight/day). “The benchmark is around 60 grams per day, which is not a whole lot, but it’s been proven over and over again to be sufficient for the vast majority of people,” says Dr. Bettina Mittendorfer.
However, protein requirements can vary depending on age, activity levels, body weight, and other factors. For physically active adults, the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Medicine jointly recommend 1.2 to 2.0 g/kg of body weight. The Dietary Guidelines for Americans 2020-2050 recommends adults get between 10% and 35% of their daily energy intake from protein.
The Appeal of High-Protein Diets
High-protein diets are often promoted for their potential to aid in weight loss, weight management, and muscle gain. These diets often encourage consumers to reduce carbohydrates and fats in favor of protein to lose weight and gain lean muscle.
Read also: High-Fiber Diet for Better Health
Weight Loss and Management
Higher protein diets may assist with weight loss and weight management. Consuming a high-protein diet helps you burn more calories than eating a diet high in carbs. High protein diets can likely promote weight loss because high protein foods tend to promote a feeling of fullness, helping reduce hunger cravings and overeating.
Several clinical trials have found that consuming more protein than the recommended dietary allowance not only reduces body weight (BW), but also enhances body composition by decreasing fat mass while preserving fat-free mass (FFM) in both low-calorie and standard-calorie diets. Fairly long-term clinical trials of 6-12 months reported that a high-protein diet (HPD) provides weight-loss effects and can prevent weight regain after weight loss.
Muscle Building
Protein is essential to your body’s function. It can also help you gain and retain muscle. Research shows that when you eat protein - up to the recommended daily intake - there’s a direct relationship between the protein you consume and the protein your body uses to repair cells, maintain bones and build muscle.
Potential Side Effects and Risks of High-Protein Diets
While high-protein diets offer certain benefits, it's crucial to be aware of the potential side effects and health risks associated with excessive protein consumption.
Digestive Issues
Consuming too much protein can lead to problems with the digestive system, including indigestion, digestive discomfort, nausea, diarrhea, and fatigue.
Read also: Delicious High-Fiber Smoothie Recipes
Kidney Problems
Consuming too much protein can lead to problems with the kidneys. Protein ingestion increases renal acid excretion, and acid loads, in turn, may be buffered in part by bone, which releases calcium to be excreted by the kidney. This protein-induced hypercalciuria could lead to the formation of calcium kidney stones. People with chronic kidney disease and other health conditions may need to limit their protein intake.
High total protein intake, particularly high intake of nondairy animal protein, may accelerate renal function decline in women with mild renal insufficiency.
Bone Health Concerns
Diet which is high in protein generates a large amount of acid in body fluids. The kidneys respond to this dietary acid challenge with net acid excretion, and, concurrently, the skeleton supplies buffer by active resorption of bone resulting in excessive calcium loss. Moreover, acid loading directly inhibits renal calcium reabsorption leading to hypercalciuria in combination with the exorbitant bone loss.
In a prospective study, protein was associated with an increased risk of forearm fracture for women who consumed more than 95 g per day compared with those who consumed less than 68 g per day. Women who consumed five or more servings of red meat per week also had a significantly increased risk of forearm fracture compared with women who ate red meat less than once per week.
It has been shown that the consumption of high calcium diets is unlikely to prevent the negative calcium balance and probable bone loss induced by the consumption of high protein diets (protein-induced hypercalciuria).
Read also: Explore the pros and cons of a high metabolism diet
A high ratio of dietary animal to vegetable protein increases the rate of bone loss and the risk of fracture in postmenopausal women. Animal foods provide predominantly acid precursors, whereas protein in vegetable foods is accompanied by base precursors not found in animal foods. Imbalance between dietary acid and base precursors leads to a chronic net dietary acid load that may have adverse consequences on bone.
Increased Cancer Risk
Up to 80% of breast, bowel, and prostate cancers are attributed to dietary practices, and international comparisons show positive associations with high meat diet. The association, however, seems to have been more consistently found for red meat or processed meat and colorectal cancer. Possible mechanisms include the formation of heterocyclic amines in meat when it is cooked. These heterocyclic amines require acetylation by P450 enzymes, and individuals with the fast-acetylating genotype who eat high amounts of meat may be at increased risk of large-bowel cancer.
Red meat is the main dietary source of saturated fat, which has been associated with breast and colorectal cancers. Moreover, NH3 and N-nitroso compounds (NOC) formed from residues by bacteria in the large bowel are probably also important. NH3 is a promotor of large-bowel tumours chemically induced by NOC, and some of the chromosomal mutations found in human colorectal cancer are consistent with effects of NOC and heterocyclic amines.
An elevated risk of colon cancer was associated with red meat intake. Men who ate beef, pork, or lamb as a main dish five or more times per week had an elevated relative risk compared to men eating these foods less than once per month. The association with red meat was not confounded appreciably by other dietary factors, physical activity, body mass, alcohol intake, cigarette smoking, or aspirin use.
The multivariate odds ratios (ORs) for the highest tertile of red meat intake (≥7 times/week) compared with the lowest (≤3 times/week) were 1.6 for stomach, 1.9 for colon, 1.7 for rectal, 1.6 for pancreatic, 1.6 for bladder, 1.2 for breast, 1.5 for endometrial, and 1.3 for ovarian cancers. Thus, reducing red meat intake might lower the risk for several common neoplasms.
Other Potential Risks
Efforts to eat a high-protein diet may have you grabbing protein wherever you can find it. But the source of your protein matters. “The composition of each protein is different,” Dr. Mittendorfer says. She recommends you look at the other risks and benefits of protein sources. Plant-based proteins provide phytochemicals, which can help with immune and brain function and cancer prevention.
An amino acid found in animal-protein foods, such as beef, eggs and milk, was found to be responsible for signaling activity in macrophage cells that typically clear away debris in blood vessels. As consumption of dietary protein increases, so does the consumption of leucine, the specific amino acid responsible for triggering this macrophage cellular activity in the blood. When functioning normally these macrophage cells work to keep blood vessels free from plaque buildup. When their production becomes overactive the resulting accumulation of spent cells in the vascular system can cause the plaque buildup and blockages they are supposed to prevent. The researchers found that consuming more than 22 percent of daily calories from protein carries more downside risk than dietary benefit.
Finding a Balance
While protein is essential, moderation is key. Experts have long known that eating too much red meat - and its saturated fat - is bad for your health. But Dr. Mittendorfer says that newer studies show a strong relationship between all types of protein and chronic health conditions, even protein without saturated fat. “There’s a trade-off with protein,” she says. “You gain all the benefits from protein up to a certain point.
Eating more than the RDA or eating more than 25 grams of protein per meal (assuming three meals a day) doesn’t offer any further benefit,” Dr. Mittendorfer says. “You can only build so much lean muscle mass with protein. Your body can store endless amounts of fat. “When you eat more protein than your body can process, it lingers until it’s ultimately turned into fat,” Dr. Mittendorfer says. Eating a high-protein diet helps you burn more calories than eating a diet high in carbs. But if you eat so much protein that you’re getting more calories than you need, you’ll gain weight.
“The idea that we need to enrich a balanced, Western diet with protein is not supported by data,” Dr. Mittendorfer says. Supplements and enriched foods certainly have benefits - adding vitamin D to milk reduces rickets (weak bones in children) and decreases vitamin deficiencies for example. The problem, says Dr. Mittendorfer, is that we are now adding protein to foods that don’t naturally contain it, such as water, chips and cereal.
Balance in your diet will bring you the best benefit. A good way to figure out personal nutritional goals includes identifying objectives that benefit health, including: managing weight, increasing cardiovascular health, increasing energy, improving gut health and digestion.
Recommendations and Guidelines
Most people should consume no more than 2 grams of protein per kilogram (2.2 pounds) of body weight per day. The amount of protein a person should aim for each day can vary. The recommended daily intake for adult females is around 46 g, while adult males can consume around 56 g per day. It depends on your body weight. Most people should not exceed 2 g/kg per day. Generally, healthy people can consume up to 2 g of protein per kg of body weight daily, but athletes may require more.
If someone has concerns about the possible side effects of consuming too much protein, they should contact their doctor. If a person worries about consuming too much protein, a dietitian can help them monitor their protein intake and create a suitable eating plan where necessary. If a person has concerns about their protein intake, they can contact their doctor for advice.