Does an infection increase protein requirements? The vital link between immunity and nutrition

January 3, 2026 •

2 min read

During an infection, the body's metabolic demands increase significantly, often leading to a catabolic state where muscle tissue is broken down for energy. This metabolic stress directly impacts your nutritional requirements, with a particular emphasis on protein, which is crucial for fighting off illness and repairing tissues.

Quick Summary

Infection raises the body's protein needs to fuel the immune response and repair tissues. Consuming extra protein is crucial for preserving muscle mass and ensuring a swift recovery.

Key Points

Infections increase protein needs: The body enters a catabolic state during an infection, increasing protein breakdown to fuel the immune response.
Protein supports immune function: Amino acids are essential for producing antibodies, cytokines, and immune cells that fight pathogens.
Severity dictates requirements: The amount of additional protein needed depends on the severity of the infection, with critical illness requiring significantly higher intake.
Deficiency hinders recovery: Inadequate protein intake can lead to muscle wasting, weakened immunity, and delayed healing.
High-quality sources aid recovery: Focusing on high-quality protein from both animal and plant sources, and considering supplements, can help meet increased needs, even with a reduced appetite.

The Body's Catabolic Response to Infection

When an infection occurs, the body enters a catabolic state to fuel the immune response, breaking down tissues for energy and resources. This leads to a negative nitrogen balance, as nitrogen from muscle protein is used to support immune functions. The body's increased metabolic rate, including fever, further accelerates protein and energy demands, potentially causing muscle wasting.

The Role of Protein in Immune Function

Protein is vital for a strong immune system. It is essential for producing antibodies to fight invaders, cytokines to regulate immune responses, and immune cells like T-cells and macrophages. Insufficient protein can weaken these functions, making the body more vulnerable.

How Much More Protein Do You Need?

Increased protein needs during illness depend on the infection's severity. Mild infections may require only a slight increase, while severe or critical illnesses can double or more.

Protein Recommendations During Illness

Health organizations recommend higher protein intake during illness. For mild to moderate conditions, 0.8 to 1.2 g/kg/day is often suggested. Critically ill patients may need 1.2 to 2.0 g/kg/day, and specific cases like dialysis patients might require up to 2.5 g/kg/day.

Comparison Table: Protein Needs (g/kg/day)


Condition	Typical Daily Recommendation	Recommended During Illness
Healthy Adult	0.8 g/kg/day	-
Mild to Moderate Infection	-	0.8 to 1.2 g/kg/day
Severe or Chronic Illness	-	1.2 to 2.0 g/kg/day
Dialysis Patient	-	Up to 2.5 g/kg/day

The Dangers of Protein Deficiency During Infection

Not meeting increased protein needs during an infection can lead to several complications:

Impaired Immune Function: Reduced ability to produce antibodies and immune cells prolongs illness.
Muscle Atrophy and Weakness: The body breaks down muscle, causing wasting and weakness.
Delayed Wound Healing: Protein deficiency slows tissue repair.

Practical Tips for Boosting Protein Intake When Sick

Increasing protein intake can be challenging with a suppressed appetite. Focus on nutrient-dense, high-quality protein sources like meat, poultry, fish, eggs, and dairy, or plant-based options like legumes and soy. Incorporate protein-rich snacks and consider protein supplements if needed. Soft foods like soups and smoothies are easier to consume with a sore throat. Ensure adequate calorie intake from other macronutrients so protein is used for recovery, not just energy.

High-Protein Food Sources for Recovery

Animal-Based: Eggs, lean meats, fish, and dairy.
Plant-Based: Legumes, soy products, quinoa, nuts, and seeds.
Easy-to-Eat Options: Smoothies, fortified soups, and mashed foods.

Conclusion: A Proactive Approach to Nutrition

An infection definitively increases protein requirements. The immune response demands resources, and sufficient protein is crucial for fighting pathogens, repairing tissue, and recovering strength. Adjusting your diet to include more high-quality protein during and after illness is a vital part of recovery, supporting overall health and potentially shortening the duration of convalescence. Cleveland Clinic on Low Protein in Blood

Frequently Asked Questions

An infection increases protein needs because the body shifts into a catabolic state, breaking down muscle tissue to provide amino acids. These amino acids are then used to create immune cells, antibodies, and other proteins essential for fighting the infection and repairing damaged tissue.

For mild to moderate illness, intake may be 0.8 to 1.2 g/kg of body weight per day. For critically ill patients, it can be higher, ranging from 1.2 to 2.0 g/kg per day, depending on the severity.

A protein deficiency during illness can impair immune function, leading to a weaker immune response. It also causes muscle wasting, weakness, and can delay recovery and wound healing.

For a low appetite, easy-to-consume options include protein shakes, smoothies, soft scrambled eggs, Greek yogurt, and protein-fortified soups. These are nutrient-dense and easier to digest.

While all infections increase metabolic demand, the protein increase is most significant for severe or chronic infections. Minor illnesses like a common cold typically don't require a drastic increase beyond the normal recommended intake.

Yes, consuming adequate calories from carbohydrates is also essential. Without sufficient overall energy, your body may use protein for fuel instead of its crucial roles in immune function and tissue repair.

Yes, protein supplements like powders or shakes can be a beneficial way to meet increased protein needs, especially when appetite is poor or dietary intake is insufficient.