What Happens if You are Deficient in Flavonoids? The Surprising Health Consequences

November 16, 2025 •

4 min read

Based on a 2013 review from the National Institutes of Health, while no specific deficiency disease exists for flavonoids, their presence in the diet is considered "life span essential" for reducing chronic disease risk. So, what happens if you are deficient in flavonoids, and how might this affect your long-term health?

Quick Summary

A diet low in flavonoids can increase the risk of chronic diseases related to inflammation and oxidative stress, weaken blood vessels leading to easy bruising, and impair immune function.

Key Points

Compromised Immunity: Inadequate flavonoid intake can weaken the immune system, leading to more frequent colds and infections.
Vascular Weakness: Low flavonoid levels are associated with increased capillary permeability, which can cause easy bruising, swelling, and nosebleeds.
Increased Chronic Disease Risk: A lack of flavonoids, which have antioxidant properties, can increase your long-term risk of heart disease, diabetes, and certain cancers.
Physical and Mental Fatigue: Chronically low intake can contribute to fatigue, poor circulation, and reduced cognitive function, including "brain fog".
Dietary Habits are Key: A diet high in processed foods and low in whole plant-based foods is the primary cause of low flavonoid intake, as processing removes these compounds.
Easy Fix with Whole Foods: The simplest and most effective way to prevent flavonoid-related issues is by consuming a variety of colorful fruits, vegetables, and teas daily.

Flavonoids are a broad group of phytochemicals, or plant compounds, that are naturally present in a wide variety of fruits, vegetables, grains, bark, roots, stems, flowers, tea, and wine. Though they are not classified as essential nutrients like vitamins, they are crucial for optimal health and are considered by many to be "life span essential" due to their protective effects against chronic diseases. A diet lacking in these powerful antioxidants can have several noticeable and systemic consequences, particularly relating to immune function, vascular health, and long-term disease risk.

The Multifaceted Role of Flavonoids in the Body

Flavonoids act as powerful antioxidants, scavenging free radicals that can damage cells and contribute to chronic disease. They also possess potent anti-inflammatory properties, regulating cellular activity and helping to modulate the body's inflammatory response. This dual action is fundamental to their protective effects across multiple physiological systems. By fighting oxidative stress and inflammation, flavonoids help the body function more efficiently and defend itself against everyday stressors.

Protecting Cardiovascular Health

Flavonoids promote better cardiovascular health by aiding in vasodilation (the relaxation of blood vessels), which helps manage high blood pressure. They also help prevent blood clots and can lower the risk of heart attack or stroke by reducing the oxidation of bad cholesterol (LDL). In contrast, a low intake of flavonoids has been associated with a higher risk of cardiovascular mortality.

Supporting Immune Function

Flavonoids are known to support the immune system by acting as immunomodulatory compounds, helping to reduce the inflammatory response triggered by allergens, toxins, and germs. A sustained deficiency can therefore compromise immune function and leave the body more vulnerable to frequent infections.

Signs and Symptoms of Low Flavonoid Intake

While a true flavonoid deficiency is not a formally recognized diagnosis like a vitamin deficiency, chronically low intake can lead to a number of physiological issues that manifest as visible symptoms. These are often related to increased oxidative stress and poor microvascular integrity.

Easy Bruising and Swelling: A common sign of low flavonoid status is an increase in capillary permeability, the 'leakiness' of small blood vessels. This can result in easy bruising, excessive swelling after a minor injury, and frequent nosebleeds.
Weakened Immune Response: Individuals may experience frequent colds or recurring infections due to a compromised immune system.
Fatigue and Poor Circulation: Low intake of certain flavonoids, like flavanols, can contribute to poor blood flow and circulation, leading to symptoms such as fatigue, cold hands and feet, and tingling sensations in the limbs.
Pain in Extremities: Some studies, specifically on the bioflavonoid hesperidin, have linked inadequate intake to weakness, aches, and night leg cramps.
Cognitive Issues: Flavonoids have been linked to improved cognitive function and brain health. A low intake has been associated with brain fog and may increase the risk of age-related cognitive decline.

High vs. Low Flavonoid Diets: A Comparison


Characteristic	High Flavonoid Diet	Low Flavonoid Diet
Immune Response	Stronger, well-regulated immunity.	Compromised immune function, more frequent illnesses.
Vascular Health	Improved blood flow, lower blood pressure, less risk of clotting.	Weaker capillaries, increased risk of bruising and swelling.
Chronic Disease Risk	Lower risk of cardiovascular disease, diabetes, and certain cancers.	Higher risk of chronic, inflammation-related diseases.
Energy & Vitality	Better overall vitality, less fatigue and brain fog.	Increased fatigue, poor circulation, and cognitive issues.

Why Processed Foods Contribute to Deficiency

One of the main culprits behind low flavonoid intake is a diet that is high in processed foods and low in whole, plant-based options. The extensive processing of fruits and vegetables, including repeated heating and stripping away fibrous parts through juicing, significantly reduces their flavonoid content. This means that even if a diet includes some fruits and vegetables, if they are primarily processed, the beneficial flavonoid content can be severely diminished.

How to Ensure Adequate Flavonoid Intake

The best approach to preventing the consequences of low flavonoid intake is to adopt a diet rich in a variety of colorful whole foods. Focus on incorporating a wide range of plant-based options to ensure you're getting different types of flavonoids, as each subgroup has unique benefits.

To boost your flavonoid intake, consider including:

Berries: Anthocyanin-rich berries like blueberries, strawberries, and blackberries.
Citrus Fruits: Flavanone-rich fruits such as oranges, lemons, and grapefruit.
Teas and Cocoa: Flavanol-containing drinks like green tea, black tea, and dark chocolate.
Leafy Greens and Onions: Flavonol sources like kale, spinach, and onions, particularly the skin.
Herbs: Flavone-rich options including parsley, celery, and thyme.
Legumes: Isoflavones found in soy products like edamame and tofu.

While supplements are available, nutrition experts generally recommend obtaining flavonoids from whole food sources to maximize health benefits.

Conclusion

While a specific deficiency disease for flavonoids does not exist in the same way as for essential vitamins, inadequate intake can lead to noticeable health issues, from compromised immunity to easy bruising. The long-term consequences are even more significant, contributing to the risk of chronic diseases linked to oxidative stress and inflammation, including cardiovascular disease and certain cancers. The solution is fortunately straightforward and delicious: embracing a diverse, plant-rich diet full of colorful fruits, vegetables, and other whole foods. Making these simple dietary adjustments can help ensure you receive the broad-spectrum protection that flavonoids provide. For further reading on flavonoids, refer to this comprehensive review from the National Institutes of Health Important Flavonoids and Their Role as a Therapeutic Agent.

Frequently Asked Questions

Flavonoids are plant-based compounds with antioxidant and anti-inflammatory properties. They regulate cellular activity, fight free radicals, support cardiovascular health, and help manage inflammation, contributing to overall long-term wellness.

Common signs include easy bruising, frequent infections, fatigue, poor circulation (cold hands and feet), and difficulty concentrating. Some people may also experience leg cramps and swelling after injury.

No, flavonoids are not considered essential nutrients like vitamins because the body can survive without them. However, they are highly beneficial and considered 'life span essential' for reducing the risk of chronic diseases.

While supplements are available, the best way to get flavonoids is through a diverse diet of whole foods. Food-based flavonoids are more readily utilized by the body, and a balanced diet provides a wider array of different flavonoid subclasses.

Great sources include berries, citrus fruits, onions, kale, tea, dark chocolate, and soy products. The key is to eat a variety of colorful plant foods, as different colors indicate different flavonoid types.

Yes, food processing, including cooking and juicing, can significantly reduce the flavonoid content in fruits and vegetables. For example, heating can destroy these nutrients, and juicing removes the fiber and pulp where many are concentrated.

Since flavonoids have anti-inflammatory and antioxidant effects, low intake is associated with higher levels of oxidative stress and inflammation. This can increase the risk of developing chronic conditions like heart disease, diabetes, and certain cancers over time.