Can nutrition cause disease? The definitive link between diet and illness

October 20, 2025 •

4 min read

According to the World Health Organization, malnutrition—which includes both undernutrition and overnutrition—can lead to a range of noncommunicable diseases such as heart disease, stroke, and diabetes. This fact underscores the critical reality that nutrition can cause disease, impacting health through both deficiency and excess.

Quick Summary

Malnutrition, stemming from nutrient deficiencies, excesses, or imbalances, is a primary driver of disease. It is linked to chronic illnesses, obesity, developmental issues, and can impact nearly every organ system.

Key Points

Malnutrition is a Dual Threat: Malnutrition includes both undernutrition (deficient intake) and overnutrition (excessive intake), both of which can cause disease.
Deficiency Diseases are Widespread: Conditions like iron deficiency anemia, rickets, scurvy, and goiter are caused by insufficient intake of specific micronutrients.
Excess Leads to Chronic Conditions: Overnutrition, especially excessive intake of calories, sugar, and unhealthy fats, is a major risk factor for chronic noncommunicable diseases (NCDs) like obesity, type 2 diabetes, and cardiovascular disease.
Ultra-Processed Foods are a Key Driver: The high palatability and poor nutrient content of ultra-processed foods promote overeating and contribute to chronic disease risk.
Early Nutrition is Crucial: Optimizing nutrition early in life, including during pregnancy and childhood, provides long-term health benefits and helps prevent malnutrition's lasting effects.
Balanced Diet is Preventive Medicine: A well-balanced diet focused on whole foods can significantly reduce the risk of diet-related illnesses and promote lifelong health.

The Dual Threat of Malnutrition: Deficiency and Excess

Malnutrition is not solely a problem of starvation; rather, it encompasses any imbalance in a person's intake of energy or nutrients. This includes both getting too few nutrients (undernutrition) and too many (overnutrition). Both extremes can trigger the development of various diseases, from acute deficiency syndromes to chronic noncommunicable diseases (NCDs). Understanding this dual threat is crucial for appreciating the profound impact of diet on overall health.

Undernutrition: The Consequences of Nutritional Deficiencies

Undernutrition, the most commonly recognized form of malnutrition, occurs when the body does not receive enough of the necessary nutrients. This can happen due to inadequate food intake, malabsorption issues, or increased nutritional requirements.

Protein-energy malnutrition (PEM): This severe condition is caused by a deficient intake of protein and/or energy. It can lead to two major syndromes: kwashiorkor and marasmus. Kwashiorkor is characterized by severe protein deficiency, often resulting in fluid retention and a swollen belly, while marasmus is caused by an extremely low intake of calories, leading to severe wasting of fat and muscle.
Micronutrient deficiencies: Even a lack of small amounts of essential vitamins and minerals can have serious health consequences. Some of the most significant micronutrient deficiencies include:
- Iron deficiency: A common global deficiency, it can cause microcytic hypochromic anemia, leading to fatigue, weakness, and impaired cognitive function.
- Iodine deficiency: A lack of iodine can cause hypothyroidism and goiter, and during pregnancy, it can lead to permanent neurological damage in the offspring.
- Vitamin A deficiency: The leading cause of preventable blindness in children, it also impairs immune function and can lead to severe eye infections.
- Vitamin D deficiency: Insufficient vitamin D causes rickets in children, characterized by weakened bones and skeletal deformities, and osteomalacia in adults.
- Vitamin C deficiency: A prolonged lack of vitamin C leads to scurvy, which causes symptoms like bleeding gums, delayed wound healing, and internal bleeding.

Overnutrition: The Dangers of Excess

While undernutrition is often associated with developing nations, overnutrition is a major health crisis in developed countries. It arises from consuming more energy and nutrients than the body requires, and the health effects can be equally devastating.

Obesity: Excessive energy intake from fats and sugars is the primary cause of obesity, which is a major risk factor for numerous chronic diseases. The World Health Organization has recognized overweight and obesity as a form of malnutrition.
Chronic diseases: Diets high in saturated and trans fats, refined carbohydrates, and sodium contribute significantly to NCDs. These conditions include:
- Type 2 Diabetes: High intake of refined carbs and sugary foods can lead to insulin resistance and a higher likelihood of developing diabetes.
- Cardiovascular Disease: A diet rich in processed foods containing high levels of saturated fats, cholesterol, and sodium elevates blood pressure and promotes heart disease.
Micronutrient toxicity: While rare from food alone, excessive intake of certain vitamin and mineral supplements can have toxic effects. This is particularly dangerous for fat-soluble vitamins like A and D, which can accumulate in the body.

The Role of Ultra-Processed Foods

The rise of ultra-processed foods has significantly contributed to the problem of overnutrition. These products, which often contain little to no whole food, are made from inexpensive ingredients like refined grains, sugar, salt, and unhealthful fats. They are also laden with artificial additives to improve taste and prolong shelf life.

High Palatability: Ultra-processed foods are designed to be exceptionally tasty, which encourages overeating and weight gain.
Nutrient-Poor: Despite being energy-dense, these foods provide very little nutritional value, leaving the body simultaneously over-fed and undernourished.
Increased Risk of NCDs: Regular consumption of ultra-processed foods is linked to a higher risk of heart disease, cancer, obesity, and type 2 diabetes.

Comparison: Undernutrition vs. Overnutrition


Aspect	Undernutrition	Overnutrition
Underlying Cause	Insufficient caloric or nutrient intake, malabsorption, increased needs.	Excessive caloric or nutrient intake, often from a poor-quality diet.
Key Conditions	Kwashiorkor, marasmus, anemia, rickets, scurvy, goiter.	Obesity, type 2 diabetes, cardiovascular disease, hypertension.
Key Mechanisms	The body lacks building blocks for repair, growth, and function.	Excess energy stored as fat, leading to chronic inflammation and metabolic issues.
Risk Factors	Poverty, food insecurity, eating disorders, chronic illness, restricted diets.	Sedentary lifestyle, high intake of ultra-processed foods, poor dietary patterns.
Physical Symptoms	Wasting, stunted growth, weakness, compromised immunity.	Excessive body fat, high blood pressure, insulin resistance.

Conclusion

Can nutrition cause disease? The overwhelming evidence shows that it is not merely a possibility but a powerful driver of both acute and chronic health issues. From severe deficiency diseases like scurvy and rickets to the widespread problems of obesity and type 2 diabetes caused by excess, dietary imbalances are a leading global risk to health. Achieving and maintaining optimal health requires a balanced approach that avoids both the pitfalls of undernutrition and overnutrition. By focusing on a diverse diet rich in whole foods, individuals can significantly lower their risk of diet-related illness and promote long-term well-being.

For more information on the role of nutrition in health and disease, the World Health Organization (WHO) is an excellent resource, providing evidence-based guidance on healthy dietary practices.

Frequently Asked Questions

Undernutrition is a deficiency of nutrients, caused by insufficient food intake or poor absorption. Overnutrition is the excessive intake of energy and nutrients, often leading to obesity and related health problems.

Yes, poor nutrition during childhood can have long-lasting effects on growth and development. Undernutrition can cause stunting and wasting, while overnutrition can lead to childhood obesity, increasing the risk for NCDs later in life.

Some common deficiency diseases include rickets (from a lack of vitamin D), scurvy (from a lack of vitamin C), goiter (from a lack of iodine), and anemia (from a lack of iron or B vitamins).

Excess intake of certain nutrients can be harmful. For example, too many calories from fats and sugars contribute to obesity and chronic diseases. Overdosing on certain vitamin or mineral supplements can also have toxic effects.

Ultra-processed foods often contain excessive amounts of sugar, fat, and salt, while lacking in essential nutrients. Their high palatability encourages overconsumption, which promotes weight gain and increases the risk of chronic diseases like diabetes and heart disease.

Yes, this is possible. Some people consume high-calorie, low-nutrient diets (often filled with ultra-processed foods), leading to overnutrition in terms of calories but undernutrition in terms of essential vitamins and minerals.

Healthy dietary patterns, such as those rich in fruits, vegetables, whole grains, and lean proteins, are associated with a reduced risk of chronic diseases like cancer and cardiovascular disease. Conversely, unhealthy dietary patterns are a major risk factor.