How Common is Protein Deficiency in the US?

December 20, 2025 •

3 min read

According to data from the Centers for Disease Control and Prevention (CDC), the average American adult's protein intake has increased over time, and severe protein deficiency is considered rare in the US. This broad trend, however, can obscure the fact that inadequate protein intake remains a concern for specific segments of the population, particularly older adults and adolescents.

Quick Summary

Most healthy American adults consume sufficient protein, but vulnerable populations like older adults, adolescents, and those with chronic diseases face a higher risk of inadequate intake.

Key Points

Prevalence is Low Overall: For the general, healthy US population, consuming sufficient protein is not a common problem.
High-Risk Groups Exist: Protein intake is a concern for older adults, adolescents, individuals with chronic illness, and those with certain dietary restrictions.
Symptoms are Varied: Signs of inadequate intake include fatigue, swelling (edema), muscle loss, weakened immunity, and issues with hair and nails.
Needs Differ by Age: While the RDA is a baseline, older adults and athletes may require significantly more protein to maintain muscle and support activity.
Plant-Based is Feasible: A well-planned plant-based diet can easily meet protein needs without the myth of combining specific foods at every meal.
Diet Quality Matters: Focusing on the quality and source of protein, not just the quantity, is an important health consideration.

Is Protein Deficiency a Widespread Problem in the US?

For the average, healthy adult in the United States, consuming enough protein is typically not a challenge. Statistics show that most Americans consume well over the Recommended Dietary Allowance (RDA) of 0.8 grams per kilogram of body weight. The abundance of protein-rich foods, both animal- and plant-based, makes meeting basic needs relatively straightforward for those with consistent access to food. Severe protein-energy malnutrition, like kwashiorkor, is extremely rare in developed nations and primarily occurs in contexts of severe food scarcity.

At-Risk Groups for Inadequate Protein Intake

Despite the reassuring national average, several demographic and health-related factors can increase an individual's risk of having a protein intake below optimal levels.

Older Adults: Studies indicate that a significant portion of older adults (age 55+) have a protein intake below the RDA, with one meta-analysis finding prevalences between 14-30%. For adults over 70, this is a particular concern due to age-related muscle loss (sarcopenia), which can be exacerbated by low protein intake and requires a higher daily amount for maintenance.
Adolescents: A 2018 study found that a notable percentage of adolescent girls (14-18 years old) and boys consumed less than the RDA for protein. This may be linked to changing eating patterns, increased independence in food choices, and dieting tendencies in this age group.
Individuals with Chronic Illnesses: Certain health conditions, such as cancer, chronic kidney or liver disease, and digestive disorders like celiac or Crohn's disease, can impair nutrient absorption or increase the body's protein needs.
Vegans and Vegetarians: While it is entirely possible to meet protein needs on a plant-based diet, it requires mindful planning. Some studies, like one in the UK, have noted a higher proportion of vegans and vegetarians with inadequate protein intake compared to meat-eaters, though it's easily preventable.
Those with Eating Disorders or Malnutrition: Individuals with conditions like anorexia nervosa or those with a generally inadequate overall food intake are at a high risk for protein deficiency.

Symptoms of Protein Deficiency

When protein intake is inadequate, the body starts to show signs as it cannibalizes muscle stores and fails to perform critical functions. Symptoms can include:

Edema: Swelling in the abdomen, ankles, and feet caused by a lack of albumin, a protein that regulates fluid balance in the blood.
Muscle Loss and Weakness: Your body will break down muscle tissue to get the amino acids it needs, leading to reduced strength and fatigue.
Hair, Nail, and Skin Issues: Hair can become brittle or thin, nails can develop ridges, and skin may appear dry and flaky.
Weakened Immune System: Antibodies, which fight infection, are made of proteins. Low intake can lead to frequent illness and slow recovery.
Mood Changes: The amino acids from protein are used to produce key neurotransmitters like serotonin and dopamine. A deficiency can cause irritability and brain fog.

Optimal Protein Intake for Different Groups

Protein requirements are not one-size-fits-all. While the RDA serves as a minimum guideline, specific needs vary significantly based on factors like age and activity level. This is why it's important to consider personal circumstances, not just national averages. For a deeper dive into personalized nutrition, resources like Harvard's nutrition guidelines can be helpful.

Protein Intake Recommendations by Group


Group	Recommended Intake (per kg body weight)	Notes
Healthy Adult (RDA)	0.8g	Minimum amount to meet basic nutritional needs and prevent deficiency.
Older Adult (70+)	1.0 - 1.2g	Suggested for maintaining muscle mass and function to counteract sarcopenia.
Athlete	1.2 - 2.0g	Varies based on type and intensity of training. Higher ranges for strength athletes.
Vegan/Vegetarian	0.8+g	Needs are met through a variety of plant sources; no need to combine specific foods at each meal.

Conclusion: Looking Beyond the Average

In summary, overt protein deficiency is not a significant public health issue for the majority of the healthy US population. However, an adequate protein intake is not universal, and vulnerable groups require specific attention to avoid negative health outcomes. Being aware of the symptoms and tailoring your intake to your specific needs, particularly for older adults and athletes, is crucial for long-term health. Focusing on the quality and source of protein, with an emphasis on incorporating more plant-based options, can further improve overall dietary health. For those with concerns or symptoms, consulting a healthcare professional or a registered dietitian is the best course of action. For more information, visit The Nutrition Source from Harvard T.H. Chan School of Public Health.

Frequently Asked Questions

No, it is considered rare. Most healthy Americans consume enough protein, with national averages exceeding the basic Recommended Dietary Allowance (RDA).

Older adults (especially those over 70), adolescents (particularly girls aged 14-18), individuals with chronic diseases, and people with poor overall food intake are at a higher risk.

Symptoms can include fatigue, loss of muscle mass, edema (swelling), brittle hair and nails, weakened immune response, and mood changes.

If you are a healthy adult eating a varied and calorie-sufficient diet, you are likely consuming enough. However, observing for symptoms like persistent fatigue, swelling, or muscle loss can be indicators.

Yes, a well-planned plant-based diet can provide sufficient protein. Variety is key, and the idea that specific foods must be combined at every meal is a myth.

Due to age-related muscle loss (sarcopenia), older adults, especially those over 70, may benefit from a higher intake of 1.0 to 1.2 grams per kg of body weight, exceeding the standard RDA.

If you experience symptoms or are concerned about your intake, consult a healthcare provider or a registered dietitian. They can provide a proper assessment and guidance.