All You Need to Know About Flavonoid Supplements: Health Benefits, Sources, And Buyer's Guide

Quick Reference

What Are Flavonoids?
Health Benefits
Food Sources
Helpful Products

What Are Flavonoids?
Flavonoids are a type of polyphenolic molecule. They are found in plant-based foods, and they are believed to play a role in health and disease prevention.

Flavonoids can be divided into six main subgroups:
- Anthocyanidins
- Flavanones
- Flavones
- Flavanols
- Proanthocyanidins
- Isoflavones

Quercetin Supplementation
Quercetin is a flavonoid in the pigments of various fruits, flowers, and vegetables. It belongs to the class of flavonoids with antioxidant properties.

Flavonol Quercetin Supplements
Typical daily dosages are between 500 and 1,000 mg. However, it isn't advisable to consume quercetin exclusively due to its limited bioavailability. You may also include vitamin C and digestive enzymes

Side Effects Of Quercetin
- Headaches
- Nausea
- Tingling feelings in the hands and feet

Precautionary Measures of Quercetin
- Pregnant and lactating women may safely consume quercetin in food.
- Pregnant and lactating women should avoid taking quercetin supplements if there's a lack of research on the supplement's safety.
- Check with your doctor before taking quercetin, as the supplement can interfere with several drugs, including antibiotics and blood pressure medications.

Dietary supplements are becoming increasingly popular globally. In alternative medicine, flavonoids, a widely used joint supplement, are utilized for various purposes.

Flavonoid supplements possess numerous health benefits and act with several dietary factors. Some dietary flavonoids can improve brain function and enhance mental health by increasing dopamine production, making it easier to learn, process information, and solve problems.

Accordingly, we've compiled an extensive guide on flavonoids and a list of the best dietary flavonoid supplements and their health benefits. It's important to note that these dietary supplements are closely regulated by the FDA and aren't intended to treat or prevent any disease or condition.

They're primarily used to support the healthy function of the brain, heart, skin, eyesight, kidneys, bones, and joints.

What are flavonoids? (biochemical makeup of flavonoids)

Biochemical structure of flavonoids in post about Flavonoid Supplements

Flavonoids are polyphenolic molecules soluble in water, such as tea polyphenols. They have 15 carbon atoms and are made up of phenolic groups. Furthermore, they consist of two benzene rings linked together by a benzene chain that's only three carbons long.

One of the carbons in this chain is directly or indirectly connected to the carbon in one of the benzene rings, forming a third middle ring. This connection can take the form of an oxygen bridge.

Six major subtypes of flavonoids can be distinguished from one another. These subtypes are;

  • Flavonols
  • Flavones
  • Isoflavonoids
  • Flavanones
  • Anthoxanthins
  • Anthocyanins

Some of these molecules, particularly anthoxanthins, are responsible for the yellow color of some petals. In contrast, the red color of buds and the purple-red color of fall leaves is typically attributable to anthocyanins. Flavonoid supplements are found in high concentrations in plants, where they serve a variety of purposes.

They are necessary pigments for producing colors required to attract insects for pollination. Dietary flavonoids are essential for protecting higher-order plants from ultraviolet radiation (UV), nitrogen fixation, the suppression of the cell cycle, and their role as chemical messengers.

Peas, clover, and beans are examples of vegetables that benefit from a symbiotic interaction with rhizobia.

This interaction is facilitated by flavonoids exuded by plants' roots as per nutritional science. The presence of flavonoids triggers the production of Nod factors by the rhizobia found in the soil.

Plants can recognize these Nod components, which leads to the induction of specific responses such as ion fluxes and the creation of root nodules. In addition, some flavonoids prevent particular spores, which helps protect plants from various illnesses.

Away from plants, let's see how they affect animals and humans.

Since flavonoids are abundant, and their toxicity is minimal compared to other plant chemicals, animals, including humans, can consume vast quantities without experiencing adverse effects.

Onions, parsley, blueberries, bananas, dark chocolate, and red wine are all excellent examples of foods that contain a high concentration of flavonoids. Flavonoids can only be obtained from plant sources since plants contain a diverse array of secondary plant metabolites and flavonoids.

It's practically impossible to replace this complicated mixture of secondary plant metabolites with single purified compounds that can be taken as dietary supplements. You need to consider the concerns about the toxicity and interactions between nutrients and drugs if you take flavonoids as dietary supplements.

High amounts of purified flavonoids used as dietary supplements have the potential to alter the body's levels of trace elements, folate, and vitamin C (citrus flavonoids).

Health benefits of flavonoid vitamin supplements

Flavonoid supplements have several positive impacts on health and thus may be useful in relieving various health conditions. However, their greatest accolade involves their effective role in cancer prevention and treating cardiovascular diseases (heart and coronary artery diseases).

Here are some potential health benefits of flavonoid supplements:

Antioxidant effects

Flavonoid supplements have been shown to have antioxidant effects and vital chemical structure.

Thus, they're beneficial to your body since they protect the DNA from damage and cells from being destroyed by reactive oxygen species. In addition, flavonoids restrict the accumulation of fatty acids by binding to these acids and preventing their release. This effect contributes to the maintenance of your physical health and fitness.

Flavonoids can protect the cardiovascular health

Dietary flavonoids help protect the cardiovascular system of the body. They accomplish this function by protecting against the effects of aging, which in turn stave off heart diseases and chronic diseases.

The progression of heart disease can be slowed down by taking these supplements, and the risk of developing dementia can be reduced. There's significant evidence that the polyphenols and tea flavonoids found in many plant foods, including fruits and vegetables, can help treat cardiovascular diseases and high blood pressure.

Flavonoids can help improve lipid profiles by lowering oxidation in low-density lipoprotein (LDL, also known as "bad" cholesterol).

This role is made possible by the antioxidant properties of flavonoids. Consequently, one's likelihood of developing cardiovascular disorders may decrease. Furthermore, they can facilitate vascular function and vasodilation (the widening of blood vessels) and control the process of programmed cell death in the endothelium (the inner lining of blood vessels).

Studies have revealed that the antioxidant properties of dietary flavonoids are responsible for these effects.

However, more recent research has shown that various signaling pathways are related to flavonoids, suggesting that other processes are involved in the actions of flavonoids.

They reduce the risk of diabetes

According to a study conducted in the United Kingdom, consuming foods high in flavonoids may also help reduce the likelihood of a person acquiring type 2 diabetes.

Nutrition researchers at the Norwich Medical School of the University of East Anglia discovered that women whose diets had a significant quantity of flavonoids had a reduced risk of inflammation and insulin resistance.

Recall that inflammation and insulin resistance are considered to be the precursors to diabetes.

Tea was the primary source of total flavonoids for the nearly 2,000 people who took part in the study. Other sources of flavonoids included grapes, pears, wine, berries, oranges, and peppers.

Meanwhile, the average daily intake of total flavonoids was 1.2 grams.

The result established that women who consumed anthocyanins and flavones had the lowest levels of inflammation and the least insulin resistance than any other group.

Furthermore, the presence of diabetes mellitus can be determined by measuring elevated levels of blood glucose or a rise in insulin resistance.

Carbohydrate digestion, insulin signaling and secretion, glucose uptake, and fat deposition are all regulated by consuming diet-rich flavonoids.

Flavonoids can target molecules that improve beta-cell proliferation (the process by which insulin-producing cells in the pancreas reproduce).

They can also promote insulin secretion and reduce apoptosis (the process by which cells undergo programmed death).

Again, using flavonoids may improve hyperglycemia by regulating glucose metabolism in the liver.

The association between dietary consumption of flavonoids and their subclasses and type 2 diabetes was investigated by a study that included 200,000 participants.

It was found that increasing one's consumption of the anthocyanins found in pears, apples, and blueberries reduced one's chance of developing diabetes.

Flavonoid supplements may boost the immune system

Flavonoid vitamin supplements may help to strengthen the general immunity capacity of the cells in your body, which can be a crucial benefit.

According to many research findings, some vitamins may shield the body from the effects of free radicals and the development of lesions. Taking a daily dosage of either vitamin C or vitamin E can be beneficial in lowering the risk of developing heart disease. You can find out our idea on how to boost your immune system on What Does It Mean to Be Healthy?

They may protect against cognitive diseases

Some researchers believe flavonoids found in cocoa and green tea can enhance the brain by combatting free radicals and reducing inflammation. Additionally, flavonoids are thought to protect brain cells from damage.

Several animal studies have shown that flavonoids prevent the buildup of beta-amyloid plaque in the brain, a marker of Alzheimer's disease. In addition, flavonoids may improve blood flow to the brain, which benefits the cardiovascular system and the brain.

This windfall presents a win-win situation for both systems. Although human studies are still in their infancy, the findings appear promising.

High consumption of flavonoids has been associated with a lower risk of Alzheimer's disease and dementia.

Some researchers examined the eating patterns of almost 3,000 people without any signs of dementia using data from a study called the Framingham Heart Study. The average age of these participants was 59.

Individuals with the highest flavonoid intake (about 297 milligrams) for 20 years had a lower risk of developing Alzheimer's disease or dementia than those who ate approximately 123 milligrams. These statistics were determined by comparing the two groups' flavonoid intakes.

Flavonoids enhance bone health and blood pressure

Flavonoids are known to have multiple cell-signaling pathways leading to vascular smooth muscle cells. These actions have the potential to contribute to the differentiation of osteoblasts and osteoclasts.

The growth of osteoblasts may in turn stimulate bone production. Adults and people of old age can benefit greatly from this benefit. In addition, a piece of research conducted in 2016 and published in the Journal of Investigative Medicine (JIM) looked into tea flavonoids' effects on the bone health of animals and humans.

The scientists observed that even moderate tea consumption could be beneficial for supporting bone strength. They propose more research on the combination of flavonoids in conjunction with elements that promote bone health, such as calcium and vitamin D.

Furthermore, oranges and other citrus fruits are one of the most common sources of hesperidin, a form of flavonoids. Supplementation with roughly 300 mg of hesperidin per day for four weeks resulted in a substantial reduction in diastolic blood pressure of an average of 3.2 mm Hg.

This experiment was carried out on healthy, overweight men who were given a placebo. Still, the systolic blood pressure wasn't affected in any way by hesperidin.

Role of flavonoids in cancer prevention

A published analysis of all studies and scientific evidence conducted on flavonoids over 11 years concluded that eating foods high in flavonoids reduces the risk of developing multiple types of cancer.

According to the findings of these studies, the antioxidant properties of flavonoids protect against breast, prostate, and colorectal cancers. It's essential to note that these surveys suggest various flavonoids may offer some degree of protection against specific kinds of cancer.

For example, taking anthocyanidins results in reduced risk of developing lung cancer, and flavonols lessen the chances of developing prostate cancer. Therefore, the best means to receive a wide variety of flavonoid subtypes is to obtain them by consuming various plant foods.

Effect of flavonoids on smoking-related cancers

The total flavonoid intake and consumption of specific flavonoid subclasses is inversely correlated with smokers' risk of smoking-sensitive cancers of the aerodigestive tract.

The particular flavonoid subclasses include flavonols, flavones, and flavanones. Meanwhile, the aerodigestive tract consists of the mouth, pharynx, larynx, esophagus, and stomach.

The above information is derived from a meta-analysis that included 19 case-control studies and 15 cohort studies.

An earlier meta-analysis of eight prospective randomized controlled trials (with substantial heterogeneity) revealed a preventive function of flavonoids against lung cancer in smokers exclusively. Yet, this study didn't substantially link the tumor risk with high flavonoid intakes.

Cancer prevention in women

Further research from the Multiethnic Cohort Study indicated that women who consumed the highest amounts of total isoflavones, daidzein, and genistein had a lower chance of developing endometrial cancer than those who consumed the lowest amounts of these compounds.

Besides, there's no link between total flavonoid consumption and the risk of developing ovarian cancer, according to the scant evidence from observational studies.

There's currently scant evidence to suggest that flavonoid-rich diets could protect against various malignancies; nevertheless, bigger prospective cohort studies are required to investigate this association.

In addition, postmenopausal women only demonstrated inverse relationships between breast cancer and intakes of flavonols, flavones, or flavan-3-ols in a pooled analysis of four case-control studies stratified by menopausal status.

Role in pain and inflammation management for patients with chronic conditions

The anti-inflammatory and pain-relieving qualities of most flavonoids have been established in extensive analyses. According to research, flavonoids can dampen the cellular reaction to pain.

Researchers have hypothesized that flavonoids might be useful in the medical treatment of inflammatory illnesses and the management of chronic diseases.

Effect on detoxification pathways

 Flavonoids can substantially change the liver and intestinal mucosa since cells recognize them as xenobiotics.

Thus, phase II enzymes can rapidly turn flavonoids into methylated, glucuronidated, and sulfated metabolites depending on their structural features.

Treatment of bacterial and viral infections

Flavonoid-rich foods have been shown to have beneficial effects against both bacteria and viruses.

Studies conducted in various laboratories have demonstrated that some flavonoids inhibit the ability of viruses like H1N1, HIV, SARS, and RSV to replicate inside the cells. Yet, it's necessary to perform additional studies to learn how flavonoids combat viruses within the body and whether or not they are a viable option for preventative care.

Bioavailability of flavonoids

The metabolism and bioavailability of flavonoids found in food can be influenced by the make-up of your gut microbiota— the community and balance of bacteria inhabiting your digestive tract.

In general, the bioavailability of flavonoids varies significantly with the various groups of flavonoids. For instance, the rate of absorption of flavones isn't as good as the rate of absorption of other forms of flavonoids.

Still, this characteristic doesn't negate that they're advantageous to your health, even if they're not entirely bioavailable. It's generally believed that your body uses what it needs and expels the residue.

Flavonoids can be absorbed and utilized by your body, but other substances might hinder the process. Several studies have shown that adding dairy milk to tea may reduce the flavonoid's natural antioxidant capacity. Dairy milk contains lactose, a type of sugar that may offset antioxidants. 

Again, casein, a protein found in milk, appears to bind with the antioxidants, which makes the antioxidants 11–27% less effective. Another survey suggests that consuming dairy milk with blueberries leads to a decreased rate of polyphenol absorption and inhibits the antioxidant activity of blueberries. Adding cow's milk to coffee can produce a similar effect.

The presence of particular carbohydrates may enhance the ability of your small intestine to absorb flavonoids. In a study conducted in 2011, steamed rice was given to mice, and it was discovered that the absorption of catechins from green tea was significantly increased by rice addition.

Additionally, combining foods may aid in the body's capacity to absorb flavonoids. For instance, bromelain, an enzyme derived from pineapples that aid in the digestion of protein, and vitamin C contribute to an increased rate of quercetin absorption.

Types of flavonoids and their dietary sources

Flavonoids are found in numerous plant-based foods and beverages. Below is a list of the six subtypes of flavonoids and their food sources:


These particular kinds of flavonoids are well-known for their antioxidant properties. They could help in the management of symptoms associated with cardiovascular problems.

Diets rich in these flavonoids include kale, onions, black tea extracts, green tea extracts, broccoli, and tomatoes.


Flavonoids are plant phenolics that include the most prevalent and extensively dispersed compounds—flavones, flavonols, flavan-3-ols, anthocyanins, flavanones, and isoflavones. In terms of structure, flavan-3-ols are the most diverse subclass of flavonoids. 

This class of flavonoids ranges from simple monomers like (+) catechin and its isomers (-) epicatechin, which can be hydroxylated to form gallocatechin and epigallocatechin, and complex mixtures like oligomeric and polymeric proanthocyanidins, which are also known as condensed tannins.

Numerous vascular functions are associated with the flavan-3-ol class of phenolic chemicals found in green tea extracts, cocoa beans, grapes, and their seeds. Non-gallate and gallate flavan-3-ol diets may protect against cancer, cardiovascular disease, diabetes, osteoporosis, and neurological illnesses when consumed for lengthy periods.

Food sources of flavan-3-ols include white tea, green tea, oolong tea, black tea apples, purple, red grapes, blueberries, strawberries, cocoa, and chocolate products.


Flavones are the main pigment in yellowish-white (cream-colored) flowers and contribute to the colors of blue flowers.

They protect plants from intense ultraviolet rays. Dietary sources of flavones include thyme, celery, parsley, green olives, and hot peppers.


Flavones are notable for their ability to reduce inflammation in the body. They may also assist you in maintaining a healthy weight and lowering cholesterol levels.

Fruits that contain flavones include lemons, limes, orange, and grapefruit juice.


Isoflavones may play a role in maintaining a healthy hormonal balance in the body. Isoflavonoids are most commonly found in soy, items made from soy isoflavones, and some other legumes like fava beans.


Anthocyanins are pigments created naturally and responsible for the red, purple, and blue colors of flowers.

Most of them are found in the outer skin of berries and products made from berries, such as grapes in red and purple tones, crimson wine, cranberries, blueberries, strawberries, and blackberries.

Quercetin supplementation

Quercetin is a flavonoid in the pigments of various fruits, flowers, and vegetables. It belongs to the class of flavonoids with antioxidant properties.

Antioxidants seek and destroy particles in the body known as free radicals, which can be destructive to cell membranes, interfere with irreversible DNA, damage, and even trigger the death of cells.

Thus, quercetin neutralizes free radicals and helps prevent some damages caused by free radicals. Strong antioxidant activity can be observed when quercetin is examined in a test tube.

However, it's uncertain whether ingesting quercetin (or several other antioxidants) has the same effects on the body. In test tubes, animals, and other preliminary investigations, certain natural substances, such as citrus flavonoids, especially quercetin, have shown antihistamine properties.

Still, no studies have examined whether these compounds help lessen allergic reactions in humans. Some data indicate that quercetin can prevent cardiovascular problems and cancer.

Quercetin helps to stabilize the body cells responsible for histamine release due to its anti-inflammatory and antihistamine effects.

Flavonol quercetin supplements

The dietary supplement quercetin is available online and in health food stores. It comes in capsules and powders, among other forms.

The typical daily dosages are between 500 and 1,000 mg. However, it isn't advisable to consume quercetin exclusively due to its limited bioavailability. You may also include vitamin C and digestive enzymes, such as bromelain, in the supplementation since they aid in absorption.

Furthermore, quercetin may enhance the effects of other flavonoid supplements, including resveratrol, genistein, and catechins, according to some studies.

Side effects and precautionary measures of quercetin

Various fruits and vegetables contain the antioxidant quercetin, which is perfectly healthy to eat. There are no known adverse effects when it's taken as a supplement.

Still, overdosing on quercetin can induce moderate side effects, such as headaches, nausea, or tingling feelings in the hands and feet. Take the following precautionary measures when ingesting quercetin: 

  • Pregnant and lactating women may safely consume quercetin in food.
  • Pregnant and lactating women should avoid taking quercetin supplements if there's a lack of research on the supplement's safety.
  • Check with your doctor before taking quercetin, as the supplement can interfere with several drugs, including antibiotics and blood pressure medications.

Best functional food sources of flavonoids

Some food sources contain considerably high amounts of flavonoid.

Here are some functional foods rich in flavonoids:


If you're a fan of berries, you can consider yourself lucky, as these fruits are flavonoid-rich. You can find these powerful nutrients in every variety of berries, which is great news for anyone who enjoys eating berries.

Cherries, blueberries, blackberries, strawberries, and raspberries are among the fruits packed full of flavonoids. Which variety of berry holds the most significant concentration of flavonoids?

When it comes to berries, blackberries are particularly remarkable because they possess all six subclasses of flavonoids and elevated levels of anthocyanins, which are both beneficial to the health of blood vessels and the cardiovascular system.

Mixed berry extracts are also an excellent food choice. It has been discovered that this particular food source may provide possible protection against cancer. Similarly, blueberries are ideal dietary flavonoid sources since they have a high concentration of anthocyanins and flavan-3-ols.


Kale is one of the best food sources of flavonoids. It shouldn't come off as much of a surprise, given that kale is a nutritious vegetable. It's difficult to find a dark leafy green that delivers as many benefits to one's health as kale does, and you can add flavonoids to its already extensive list of health benefits.

The subclass of flavanols with potent antioxidant abilities is abundant in kale. Hence, this vegetable may be good for preventing cardiovascular disorders and improving general heart health.

Red cabbage

Red cabbage is another vegetable rich in anthocyanins, a subclass of flavonoids shown to have potential anticancer properties and is also beneficial to cardiovascular health.

A single serving of this vegetable contains an astounding 72.98 milligrams of total anthocyanins per one hundred grams of weight. Red cabbage may not be as popular as green cabbage, its famous relative. Yet, it offers many health benefits, including high levels of vitamin K and fibers.  

Dark chocolate

If you're a fan of chocolate, you should know that every time you ingest something chocolaty or cocoa-based, you're giving your body a healthy dose of flavonoids. Flavonoids can be found in high cocoa, chocolate, and cocoa powder concentrations. Still, dark chocolate has a significantly higher flavonoid content.

A 100 grams serving of dark chocolate has more than 100 milligrams of flavan-3-ols, a type of flavanol that you may be more familiar with under catechins.

Catechins are nutrient-dense and beneficial for various health concerns, including inflammation, metabolic syndrome, and cancer prevention. Catechins are also abundant in green tea, a good source of these nutrients.

Similarly, cocoa is rich in flavan-3-ols, and several studies suggest that it may be effective in conditions such as metabolic syndrome, fatty liver disease, brain health, and even bone strength. However, you need to choose unsweetened chocolate to enjoy the health benefits of cocoa and its flavonoid content.


You've probably learned the wonderful advantages of drinking green tea in previous sections of this blog. However, the health benefits of tea aren't limited to this particular variety; almost every type of tea can provide you with a substantial quantity of flavonoids.

Flavan-3-ols can be found in high concentrations in black, green, and oolong teas. These types of tea are particularly abundant in this subclass of flavonoids due to the high catechin concentration of green, white, and oolong tea.

Meanwhile, black tea provides flavonols and some flavan-3-ols (theaflavins and thearubigins) that aren't found in green, white, or oolong teas. You may gain more rare variants of flavonoids from sipping black tea than you would get from drinking green, white, or oolong tea.

Regardless, you'll get an appreciable quantity of flavonoids from any type of tea, as all warm beverages contain flavonoids. We would recommend trying The Best Reviewed Lychee Tea Powder.

Citrus fruits

Citrus fruits may be best recognized for their high levels of vitamin C. Still; these fruits also contain a high concentration of flavanones, a subclass of flavonoids beneficial for reducing inflammation. Surprisingly large concentrations of flavanones are found in citrus fruits, and if you juice your citrus fruits, the flavanones in the juice will have an even higher concentration.

For instance, when compared to eating raw grapefruit slices, drinking grapefruit juice (which can contain anywhere from 19 to 31 milligrams of flavonoids per 100-gram serving) will provide you with a greater overall amount of flavonoids. 

Do you prefer the taste of fresh fruit to fruit juice?

Oranges give a remarkably good value for the money, as one serving has 42.57 milligrams of flavonoids, whereas one serving of fresh orange juice only contains 29.48 milligrams of flavonoids.


Soybeans are the best source of a specific type of flavonoid known as isoflavones, irrespective of their obtained form. They have a high concentration of isoflavones, which contribute to regulating hormones throughout the body.

Although isoflavones aren't essentially found in other foods (black beans offer a small amount), you'll get a good dose of them in every form of soybeans, from edamame to tofu to tempeh soy milk.

Other foods, like black beans, offer fewer amounts of isoflavones. It's best to stick with organic options because genetically modified organisms (GMOs) can be found in some soy crops.


Parsley may not play other roles in your dining room apart from garnishing or spicing your meals. However, this food source deserves more attention than it gets. This easy-to-grow green herb isn't only flexible;  it's also one of the foods with the highest concentration of flavonoids. 

It's rich in flavones, a subclass of flavonoids excellent for reducing inflammation. The flavone content of fresh parsley is around 227 milligrams per 100 grams, whereas the flavone content of dried parsley is an even more remarkable 13,525 milligrams per 100 grams.

Effects of flavonoid supplements on drugs

It's best to consult your health care provider or other qualified medical experts before using dietary supplements, including flavonoid supplements. These compounds can interact with various medications, both those that require a prescription and those that do not.

Consequently, they may downplay or amplify the effect of drugs. Some flavonoids can impede P-glycoprotein and other ATP-binding cassettes (ABC) from functioning properly. This action may increase the toxicity of medications that are substrates of P-glycoprotein after consuming supplements.

Some drugs that fall within this category are calcium channel blockers, cyclosporin, digoxin, and erythromycin. Again, several anthocyanins and anthocyanins have been identified as inhibitors of BRCP-mediated transport.

Certain flavones, isoflavones, flavonols, and flavanones, have also been implicated in this event. They may negatively interact with medications, such as anticancer drugs, antibiotics, beta-blockers, and antiarthritics.

Meanwhile, some flavonols, flavanones, and isoflavones have been reported to inhibit multidrug resistance proteins. This interaction may affect the MRP-mediated transport of numerous anticancer drugs.

Possible side effects of flavonoid supplements

Like other supplements, you need to follow the recommendations printed on the bottle before taking a flavonoid supplement. If you consume an excess dose of flavonoid supplements,  you risk experiencing adverse consequences.

For instance, taking extremely high doses of quercetin, such as 51.3 mg/kg of body weight, has been linked to kidney toxicity. On the other hand, research conducted with doses ranging from 3 mg to 1,000 mg per day for up to three months hasn't shown any negative signs or antagonistic effects. 

Green tea extracts can cause several gastrointestinal side effects when taken in doses of six grams per day. These side effects include;

  • nausea
  • vomiting
  • abdominal pain
  • diarrhea

Side effects may also occur when the extracts are taken in three to six divided doses. In addition, flavonoid supplements may affect how certain prescription drugs work in the body. They may make it more likely for the drugs to be harmful or increase the odds of overdosing on some particular substances.

How to choose the best flavonoids supplements (buyer's guide)

Finding the best flavonoid supplements can be challenging initially. Yet,  it's not always easy for longtime customers to determine which product best suits their needs.

Therefore, we've identified some elements to consider when selecting the best flavonoid vitamin supplements. These factors include:


It would help to examine the prices of various flavonoid products before purchase. If you aren't in a particularly urgent situation, such as an emergency, it's a good idea to wait for a sale.


It's best to compare flavonoid supplement brands before making a purchase, even if the brand doesn't matter to one product as much as it does to another.


When a supplement has high functionality, its specifications will be more in-depth. Therefore, you must understand how a flavonoid supplement works before ordering it.

Ensure you check the details of your preferred flavonoid vitamin supplement and confirm if you can use them. 

Customer reviews from other users

Most astute purchasers look up reviews from previous customers about their experiences using flavonoid vitamin supplement capsules and tablets.

This step enables potential customers to determine whether the product can be trusted or not.

Best flavonoid supplements

We've studied and outlined the most effective flavonoid supplements on Amazon according to the following criteria:

  • Substantial amounts of active substances
  • The product's success in various clinical trials
  • Numerous favorable reviews, ratings, and testimonials from past users or customers
  • Minimum potential risks and side effects
  • Adherence to Food and Drug Administration (FDA) guidelines and good manufacturing practice (GMP)
  • The supplement should be easy to consume
  • It must have proper packaging and in-depth labeling
  • It should be gluten-free, non-GMO, and vegan-friendly

According to our survey, here are the top 3 flavonoid supplements on Amazon:

  1. Nature's Best High Potency Quercetin
Nature's Best High Potency Quercetin
  • Brand: Nature's Best
  • Dosage Form: Tablet
  • Dose: 1 tablet per day, preferably with a meal
  • Servings Per Container: 60 servings
  • Concentration Per Serving: 500mg of Quercetin Dihydrate per tablet.
  • Count: 60 capsules
  • Suitable For: Adults, vegetarians
  • Other Ingredients: Cellulose, calcium carbonate, stearic acid, silicon dioxide
  • Additional Features: Non-GMO, gluten-free, vegan-friendly

Nature's Best opines that quercetin is the bioflavonoid that has been subjected to the most research, and the potential health advantages of this flavonoid have impressed scientists.

They assert that their brand's efficacy in supporting cardiovascular health was established in a recent study and urge the users to learn more about the nutrient on the internet. 

Each packet of Nature's Best High Potency Quercetin contains 60 easily absorbed tablets of 500 milligrams of quercetin. The product is gluten-free and suitable for adults and vegetarians.

According to the manufacturers, the product has antioxidant characteristics and helps to prevent the body's synthesis and release of histamines.

This supplement is significantly more potent than apples since an apple typically comprises between 5 and 10 milligrams of quercetin.

Nature's Best shows off a pure quercetin product in a form that's readily absorbed.


  • Oral consumption of quercetin before exercise reduces fatigue and improves one's capacity to exercise.
  • It has anticancer and antiinflammatory properties.


  • Extremely high doses of quercetin can harm the kidneys.
  1. Life Extension Vitamin C & Bio-Quercetin Phytosome
Life Extension Vitamin C & Bio-Quercetin Phytosome in post about Flavonoid Supplements
  • Brand: Life Extension
  • Dosage Form: Tablet
  • Dose: 1 capsule per day, preferably with a meal
  • Servings Per Container: 250 servings
  • Concentration Per Serving: Vitamin C (ascorbic acid) 1000 mg powder per Capsule.
  • Count: 250 tablets
  • Suitable For: Adults, at least 18 years old.
  • Other Ingredients: Microcrystalline cellulose, stearic acid, croscarmellose sodium, vegetable stearate, silica, coating (hydroxypropyl methylcellulose, glycerin).
  • Additional Features: Non-GMO, gluten-free

According to Life Extension, consuming vitamin C through food or taking it as a supplement to meet your body's requirements is vital. This guideline exists because the body can't manufacture vitamin C alone.

To solve the problem of vitamin C deficiency, Life Extension Vitamin C & Bio-Quercetin Phytosome exerts the biological action of vitamin C through flavonoid quercetin.

Thus, it may possess numerous positive vascular health effects. 

Each supplement pack holds 250 vegetarian tablets containing 1000 mg of vitamin C and 15 mg of bio-quercetin phytosome.

The product's manufacturers claim to source vitamin C and bioflavonoids from fruits (particularly citrus fruits) and vegetables to support the cardiovascular system.

Furthermore, Life Extension Vitamin C & Bio-Quercetin Phytosome comprises ultra-absorbable quercetin, which enhances the immune system and provides other benefits.

A randomized controlled trial demonstrated that the supplement helped athletes to reduce stress and inflammation.

Similarly, double-blind clinical trials showed that its quercetin constituent effectively reduced oxidative stress, promoted a healthy inflammatory response, and maintained overall health.


  • It supports immune health.
  • It helps in collagen production, a healthy cardiovascular system and more.


It may cause some serious side effects if overused.

  1. Dulàc Nutrition Quercetina Complex
Dulác Nutrition Quercetina Complex in post about Flavonoid Supplements
  • Brand: Dulàc Nutrition
  • Dosage Form: Tablet
  • Dose: 1 capsule per day, preferably with a meal.
  • Servings Per Container: 60 servings
  • Concentration Per Serving: Each tablet contains 200 mg of quercetin, antioxidant and anti-inflammatory flavonoid.
  • Count: 60 Tablets
  • Suitable For: Adults at least 18 years old
  • Other Ingredients: Magnesium salts of fatty acids, rutin, lemon, and orange bioflavonoids.
  • Additional Features: Non-GMO, gluten-free.

Dulàc Nutrition Quercetina Complex is an Italian flavonoid supplement brand. The product possesses a relatively high concentration of active antioxidant and anti-inflammatory flavonoids.

Using decent materials and cutting-edge technology, its manufacturers cooked up high-quality dietary supplements that could form a part of nutritious meals.

Each 700 mg tablet of Dulàc Nutrition Quercetina Complex contains quercetin (200 mg), rutin, vitamin C, and bioflavonoids. 

The product's manufacturers reportedly adhere to strict guidelines to ensure that their brand is of utmost quality and designed to improve the user's health. 


  • It may strengthen the immune system.
  • Its antioxidant effects protect the cells from the degenerative action of free radicals.


  • It could cause some serious adverse effects when taken in excess.


Flavonoids are found in high concentrations in meals derived entirely from plants, including but not limited to colorful fruits and vegetables, tea, red wine, herbs, and legumes.

Their antioxidant and anti-inflammatory activities may help to protect you from a wide range of diseases, including cardiovascular diseases, cancer, and neurodegenerative diseases. They may also have other positive effects on your health that are still being studied.

Although supplementation could benefit those with specific health conditions, it isn't required for most people. Flavonoid supplements may pose more potential risks than benefits. The most effective way to gain the countless health benefits of flavonoids is to consume a wide range of foods rich in flavonoids.


Are Flavonoid Supplements Worth Using?

Taking flavonoid supplements may benefit individuals with certain health issues. However, independent research has demonstrated that many supplements, including flavonoids, don't contain what they claim to contain.

How Much Flavonoid Supplements Should You Take Daily?

According to the findings of the National Health and Nutrition Examination Survey (NHANES), adults' daily consumption of flavonoids ranges from 200 to 250 milligrams on average.


What Are Flavonoids?
Science Direct: The biochemistry and medical significance of the flavonoids
Health Benefits of Flavonoid Vitamin Supplements
National Institute of Health: The Effects of Flavonoids on Cardiovascular Health
Verywell Fit: Benefits and Risks of Flavonoid Supplements
Antioxidant Effects
ResearchGate: Antioxidant properties of flavonoids
Flavonoids Can Protect the Cardiovascular Health
ScienceDirect: The beneficial health effects of flavonoids on the cardiovascular system
They Reduce the Risk of Diabetes
NCBI: Flavonoids and Their Anti-Diabetic Effects
Flavonoid Supplements May Boost the Immune System
NCBI: Flavonoids, Inflammation and Immune System
They May Protect Against Cognitive Diseases
American Journal of Clinical Nutrition: Can dietary flavonoids play a role in Alzheimer's disease risk prevention?
Flavonoids Enhance Bone Health and Blood Pressure
JIM: Tea flavonoids for bone health: from animals to humans
Pubmed: Effects of hesperidin in orange juice on blood and pulse pressures in mildly hypertensive individuals
Effect of Flavonoids on Smoking-Related Cancers
PubMed: Dietary Flavonoid Intake and Smoking-Related Cancer Risk
Cancer Prevention in Women
Journal of the National Cancer Institute: Cancer Risk in Postmenopausal Women
Role in Pain and Inflammation Management for Patients With Chronic Conditions
NCBI; Therapeutic Potential of Flavonoids in Pain and Inflammation
Effect on Detoxification Pathways
ScienceDirect: Dietary flavonoids: Effects on xenobiotic and carcinogen metabolism
Treatment of Bacterial and Viral Infections
NCBI: Antimicrobial activity of flavonoids
Bioavailability of Flavonoids
Increased Plasma Concentration of Epigallocatechin in Mice after Orally Administering a Green Tea ( Camellia sinensis L.) Extract Supplemented by Steamed Rice
Quercetin Supplementation
NCBI: Therapeutic Potential of Quercetin: New Insights and Perspectives for Human Health
Best Functional Food Sources of Flavonoids
NCBI: Food & Nutrition Research article
Effects of Flavonoid Supplements on Drugs
PubMed: Effect of dietary flavonoids on pathways involved in drug metabolism
Possible Side Effects of Flavonoid Supplements
PubMed: Potential health impacts of excessive flavonoid intake

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