Jillian Kubala, MS, RD on February 1, 2021

https://www.healthline.com/nutrition/too-much-protein

Protein functions

Muscle and other tissue growth and repair.

Immune system function.

Nerve impulse transmission

Oxygen transport

Reduced blood sugar levels via a high protein + low carbohydrate diet.

Protein requirements

Dependents: body weight, age, body composition goals, physical activity level, and overall health.

The RDA for protein is 0.36 grams per pound of body weight (0.8 grams per kg) AT MINIMUM to prevent muscle loss, meet amino acid requirements, and maintain nitrogen balance.

Physically active individuals need much higher amounts than the RDA. Many recommend 0.54–0.9 grams per pound (1.2–2 grams per kg) per day.

For athletes, needs may be even higher. Additionally, pregnant and breastfeeding women, older adults, and those with certain medical conditions have higher protein needs than the general population.

Are there benefits to high protein diets?

High protein diets have been associated with a number of health benefits.

For example, higher protein diets increase feelings of fullness, reduce hunger, and boost resting energy expenditure, all of which may encourage weight loss.

Studies show that high protein diets promote weight loss and improve body composition in many populations.

Study: 54 overweight or obese women perform exercise and consume either a high protein diet or a low calorie, high carb diet for 14 weeks.

· The higher protein diet lost significantly more weight and body fat than the low calorie, high carb

  diet.

· High protein diets can also help improve body composition by increasing muscle mass.

· High protein diets may increase blood sugar control, reduce blood fat levels, and increase bone 

  density in older adults.

Are high protein diets harmful?

In the past there have been concerns over the safety of high protein diets and their effects on kidney, heart, and bone health, but most of the concerns are not supported by scientific research.

Kidney health

The kidneys filter and remove waste products of protein metabolism from the body. Research has shown that even though high protein diets increase the workload of the kidneys, they don’t negatively affect people with healthy kidney function.

Study: Protein intake and kidney function among 48 trained men and women.

· Consuming a diet containing 1.5 grams of protein per pound (3.4 grams per kg) for 8 weeks in

   combination with resistance training did not lead to any adverse health effects.

· No effect on kidney function markers like glomerular filtration rate (GFR), blood urea nitrogen 

  (BUN), and creatinine.

· However, people with decreased kidney function should avoid high protein because it may 

  accelerate the decline of that function.

Heart disease

Research shows that higher protein diets don’t typically harm heart health.

Studies:

· No association between animal or plant protein intake and increased heart disease risk in 12,066 

  adults.

· A high protein diet did not harm heart health or blood vessel function after a 34-month intervention, 

  compared with a moderate protein diet, in 38 overweight adults.

· Higher protein diets may help reduce blood pressure levels, decrease belly fat, and increase HDL 

  (good) cholesterol, which may help reduce the risk of heart disease.

· No association between higher total protein intake and the risk of death from heart disease.

· However, higher plant protein intake may have a protective effect against death from heart disease, 

  while higher animal proteinintake may be associated with an increased risk.

Cancer

Studies:

· Total protein intake is not significantly linked to the risk of breast, esophageal, colorectal, ovarian, or 

  prostate cancer.

· No association between higher total protein intake and risk of death from cancer.

· Higher protein intake was associated with better survival rates in women with breast cancer.

· However, processed meat products may cause an increased risk of colorectal, breast, and gastric 

  cancer.

Bone health

Protein is essential for bone health, along with other nutrients, including calcium and vitamin D. In fact, over one-third of bone mass is made of protein.

Studies:

· High protein diets may lead to low bone mineral density, but more recent studies have shown that it 

  may be beneficial for bone health including bone mineral density of the lumbar spine as compared 

  with lower protein intake.

· High protein intake above the current RDA was significantly associated with a reduced risk of hip 

  fracture along with the increased bone mineral density.

· Organizations like the European Society for Clinical and Economic Aspects of Osteoporosis and 

  Osteoarthritis (ESCEO) recommend higher protein intakes of 0.45–0.54 grams per pound (1–1.2 

  grams per kg) per day.

SUMMARY

High protein intake is not associated with certain major health conditions in most populations and healthy people. However, particular protein sources, such as processed meat, are associated with health concerns.