From the Guidelines
Inadequate protein intake can lead to several harmful effects on the body, including muscle wasting, impaired immune function, and decreased quality of life, emphasizing the importance of consuming sufficient protein daily, approximately 0.8 grams per kilogram of body weight, as recommended by the most recent and highest quality studies 1.
Effects of Inadequate Protein Intake
Inadequate protein intake can cause:
- Muscle wasting as the body breaks down muscle tissue to access amino acids
- Impaired immune function, making individuals more susceptible to infections and slower to recover from illness
- Deterioration of hair, skin, and nail health, with symptoms including brittle nails, hair loss, and skin rashes
- Delayed wound healing due to insufficient building blocks for tissue repair
- Disrupted fluid balance, potentially causing edema (swelling) in the extremities or abdomen
- Hormonal imbalances, as many hormones require protein components for synthesis
- Decline in cognitive function, with symptoms like confusion, irritability, and difficulty concentrating
- Stunted growth and development in children, potentially causing permanent effects
Recommended Protein Intake
To prevent these issues, adults should consume approximately 0.8 grams of protein per kilogram of body weight daily, with higher requirements for athletes, pregnant women, and older adults, focusing on complete protein sources like lean meats, dairy, eggs, legumes, and certain plant combinations, as supported by recent studies 1.
Importance of Protein Quality
The quality of protein consumed is also crucial, with plant-based sources, such as nuts and legumes, promoting favorable health outcomes, while excess intake of red and processed meats may have negative effects on health, highlighting the need for a modernized definition of protein quality that considers health outcomes and environmental impact 1.
From the Research
Effects of Inadequate Protein Intake on the Body
Inadequate protein intake can have several negative effects on the body, including:
- Stunting and growth impairment 2
- Anemia and physical weakness 2
- Edema and vascular dysfunction 2
- Impaired immunity and increased risk of infections 2
- Loss of muscle mass and strength 3, 4
- Decreased bone density and increased risk of osteoporosis 3
Protein Requirements for Different Populations
The recommended daily protein intake varies depending on factors such as age, sex, weight, and activity level. For example:
- Healthy adults with minimal physical activity: 0.8 g protein per kg body weight per day 2
- Older adults: 1.0-1.2 g protein per kg body weight per day 3
- Athletes and individuals with high physical activity: 1.2-1.6 g protein per kg body weight per day 4
- Individuals with certain medical conditions, such as kidney disease: may require lower protein intake 3
Consequences of Excessive Protein Intake
Excessive protein intake can also have negative effects on the body, including:
- Digestive problems, such as nausea and diarrhea 5
- Renal strain and potential kidney damage 2, 5
- Increased risk of dehydration and electrolyte imbalances 5
- Potential for hyperaminoacidemia, hyperammonemia, and hyperinsulinemia 5
Importance of Protein Quality
The quality of protein is also an important consideration, as it can affect the body's ability to utilize the protein. Factors that influence protein quality include: