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Vitamin C and Dihydroquercetin

December 2006

By Mark J. Neveu, PhD

Free radicals (black stream, bottom left to center right) damaging cellular DNA (white, center right). The DNA has originated from the cell nucleus (purple, lower right) and a sectioned cell membrane surrounds it. Vitamin C (blue particles) reduces this damage. LDL particles (orange) are oxidized by free radicals, and protected by vitamin E (yellow hexagons). Oxidized LDL is removed by white blood cells (pink/grey, upper center). These LDL-filled cells form atherosclerotic plaque (brown, upper right).

Every day, our bodies are under continual assault by damaging agents known as free radicals. Generally, both internal and dietary antioxidants do an excellent job of keeping free radicals in check. However, once this balance is disrupted, lethal diseases such as cancer, heart disease, lung disease, diabetes, Parkinson’s disease, arthritis, Alzheimer’s disease, and stroke can be initiated.1-3

A wealth of scientific evidence has repeatedly demonstrated that specialized compounds in fresh fruits and vegetables exert critical protection against free-radical assault.4 Of these, vitamin C and plant substances known as flavonoids may be among nature’s most potent natural antioxidants.1-6

Exciting new studies suggest that a flavonoid called dihydroquercetin, in combination with vitamin C, provides even more powerful, synergistic protection against oxidative stress than either substance alone.

Flavonoids: Nature’s “Biological Response Modifiers”

Scientists have recently begun to attribute many of the beneficial effects of fruits, vegetables, tea, and even red wine to the flavonoid compounds they contain.5,6

Flavonoids perform two important functions in the body. First, they strengthen the body’s immune response to attacks from allergens, viruses, and carcinogens. Second, they act as powerful antioxidants, protecting the body against the oxidative stress and free-radical damage that underlie many cardiovascular, neurological, and diabetic diseases. Studies have shown that those who have increased flavonoid intake clearly demonstrate a decreased incidence and mortality of heart disease.7-10

One of the most important attributes of these flavonoids is their ability to enhance the effects of vitamin C. Vitamin C’s main function in humans is to reduce the dangerous effects of oxidative reactions throughout the body. Unfortunately, because vitamin C is water soluble, it stays in the body for only a very brief time before being excreted. This time frame limits vitamin C’s efficacy.10 Until now, it has been recommended that vitamin C be taken in several doses to maintain optimal benefits. However, flavonoids have been shown to improve the concentration and efficacy of vitamin C throughout the body. This important finding means that you can take less vitamin C while it lasts longer and works harder.11


One flavonoid, dihydroquercetin, has been found to be extremely beneficial in helping vitamin C re-circulate throughout the body. Additionally, it limits the inactivation or oxidation of vitamin C, which enables vitamin C to last longer in the body.12,13

The addition of this unique flavonoid creates an entirely new way to deliver vitamin C to cells in need of its protection. Now, supplement users can maximize their benefits from longer-lasting and more effective vitamin C.

Dihydroquercetin Fights Cardiovascular Disease

Dihydroquercetin acts in several ways to help avert cardiovascular disease.

Scientists have demonstrated that dihydroquercetin inhibits lipid peroxidation, a process that often leads to atherosclerosis.14,24,32 In an animal study, dihydroquercetin inhibited the peroxidation of serum and liver lipids following exposure to toxic ionizing radiation.33 Dihydroquercetin’s inhibitory effects on lipid peroxidation are enhanced by both vitamin C and vitamin E.34 By inhibiting the oxidation of harmful low-density lipoprotein (LDL), dihydroquercetin may help prevent atherosclerosis.35

Lowering high levels of low-density lipoprotein (LDL) is one the the major goals of anti-cholesterol or statin therapy as used by mainstream physicians. Studies suggest that dihydroquercetin may be helpful in therapeutic efforts to lower LDL by inhibiting the formation of apolipoprotein B, one of the primary components of LDL.36

Other studies have shown that dihydroquercetin lowers serum and liver lipid and cholesterol concentrations in rats.37 A conjugated form of dihydroquercetin known as astilbin inhibits the same enzyme targeted by popular cholesterol-lowering statin drugs such as Lipitor®, Zocor®, and Pravachol®.38

Attacking heart disease from another angle, animal studies showed that dihydroquercetin lowers high blood pressure and normalizes an electrical measure associated with activation of the heart’s pumping chambers (ventricles).39

Synergistic Effects of Vitamin C and Dihydroquercetin

Unlike plants and most animals, humans cannot manufacture vitamin C within the body and therefore must obtain it from external sources. This has led some scientists, including the late Nobel Prize-winning chemist Linus Pauling, to propose that humans would enjoy better health if they supplemented their diets with an amount of the nutrient proportional to the amount produced in animal species that manufacture their own vitamin C. Moreover, aging adults experience a decrease in vitamin C levels, which may contribute to the development of several degenerative diseases, such as cardiovascular disease, cancer, neurodegenerative conditions, and eye disorders.14-16

The combination of vitamin C and dihydroquercetin offers such tremendous promise in preserving and restoring health that it has been approved as a prescription drug in some parts of the world.

Vitamin C and Dihydroquercetin: What You Need to Know
  • A novel bioflavonoid, dihydroquercetin, offers exceptional benefits by enhancing the health-promoting benefits of vitamin C. Dihydroquercetin enhances the effectiveness of vitamin C by extending its period of bioactivity, enhancing its regeneration, and slowing its elimination from the body.
  • Dihydroquercetin offers protection against cardiovascular disease by inhibiting several steps in the disease process. Additionally, dihydroquercetin helps guard nervous system health, prevents the complications of dia-betes, protects the liver against hepatitis-inducing agents, fights infection, and quells inflammation that can lead to dermatitis, arthritis, and pain.
  • Some of vitamin C’s best-known applications are preventing viral infection, enhancing cancer protection, and averting cardiovascular disease and stroke.
  • In some parts of the world, a combination of vitamin C and dihydroquercetin is available as a prescription drug known as Ascovertin. Physicians utilize Ascovertin to manage health conditions that share oxidative stress as an underlying mechanism. Ascovertin has demonstrated efficacy in protecting against stroke, heart attack, and light-induced damage to the eye.
  • Consumers in the United States can use the benefits of a dietary supplement combining dihydroquercetin and vitamin C without a prescription.

In Russia, a drug known as Ascovertin (a complex of dihydroquercetin and vitamin C) is a popular treatment for many health conditions that share oxidative stress as an underlying mechanism. Since oxidative stress characterizes many of the degenerative conditions associated with aging,1-3 Ascovertin’s potential applications are quite broad.

For example, Ascovertin may have applications in the management of stroke, a crippling, often fatal condition marked by a diminished supply of blood and oxygen to the brain. Studies of the effects of oxygen deprivation in rat brains demonstrated that Ascovertin decreased the damage caused by lack of blood flow. Additionally, Ascovertin restored normal structure and electrochemical activity to nerve synapses, the junctions that allow nerve cells to transmit information.17,18

The Russian Academy of Medical Sciences recently conducted two clinical studies of Ascovertin in 52 patients with impaired blood flow to the brain. Ascovertin was administered for 21 days. The resulting decrease in blood viscosity and blood-clotting tendency improved attention, memory, and mental performance, relieved vertigo, normalized sleep, relieved headaches, and decreased fatigue.19,20 No such changes were observed in the age-matched control patients.

Common Applications of Vitamin C

Long considered essential to optimal health, vitamin C may offer targeted protection against viral infections, cancer, cardiovascular disease, and stroke.

  • Viruses. Vitamin C is widely used to support the immune system’s protection against colds and flus. In adults and children, the preventive use of vitamin C reduced the duration of colds by up to 14%.64 In athletes and soldiers, daily vitamin C intake reduced the incidence of colds by 50%. A recent study found mice that were deficient in vitamin C experienced increased lung tissue damage following infection with the influenza virus. Vitamin C-deficient mice also demonstrated increased expression of pro-inflammatory cytokines. These findings suggest that vitamin C is required for an effective immune response to infection with the influenza virus.65
  • Cancer. Vitamin C may offer essential aid in fighting cancer. Higher intakes of vitamin C are associated with a decreased incidence of cancers of the mouth, throat, esophagus, stomach, colon, and lung.64 In 2005, research by the National Institutes of Health found that vitamin C administered intravenously helped kill several strains of cancer cells. This led scientists to note that intravenous vitamin C may be an important tool in fighting cancer, which supports similar findings by Linus Pauling.66 Furthermore, a recent clinical trial documented the safety of high-dose vitamin C in advanced cancer patients.67 Several recent studies indicate that the combination of lysine and proline with vitamin C more effectively inhibits cancer cells than vitamin C alone.68-79
  • Cardiovascular Disease and Stroke. Studies indicate that low or deficient intake of vitamin C is associated with an increased risk of cardiovascular disease. Similarly, the risk of death from cardiovacular diseases was found to be 25-42% lower in adults who consumed plentiful amounts of vitamin C through diet and supplements compared to adults who were deficient in vitamin C. Some research suggests that vitamin C supplements are more protective than dietary vitamin C in protecting against heart disease. Higher serum levels of vitamin C have been found to diminish the risk of suffering a stroke by up to 29%. Daily supplementation with vitamin C reduces high blood pressure, a contributor to cardiovascular and stroke risk.64

Ascovertin may also protect against some of the damaging consequences of heart attack. Studies in rats showed that Ascovertin inhibits the blood clotting and brain damage that can occur following a heart attack.21,22

The tissues of the eye may benefit from Ascovertin as well. Studies in rats found that Ascovertin inhibits damage to the eye’s retina induced by high-intensity light.23

Dihydroquercetin Supports Nervous System Health

The brain and nervous system are particularly sensitive to the damaging effects of free radicals. As we age, free-radical damage can accumulate in the brain, leading to cognitive decline and other illnesses such as dementia and Alzheimer’s. Maintaining optimal mental function is one of the leading goals of aging baby boomers. Fortunately, dihydroquercetin offers essential protection to critical brain and nerve cells.

To examine methods to protect the brain against injury, scientists used an animal model of stroke. Dihydroquercetin inhibited the expression of enzymes that lead to inflammation. Additionally, dihydroquercetin helped prevent inflammatory white blood cells from attacking and adhering to vulnerable areas of the brain. These actions help provide essential neuroprotection against the free-radical-induced oxidative damage that often occurs when the brain does not receive enough blood and oxygen.27,28,40

In addition to the cognitive decline that often accompanies aging, critical functions such perception, thinking, language, and consciousness can be adversely affected. Protecting the areas of the brain that oversee these functions is another important benefit of dihydroquercetin. In one study, researchers found dihydroquercetin prevented free radicals from causing oxidative damage to crucial nerve cells that oversee these functions.41

By protecting the cells of the brain and central nervous system, dihydroquercetin may help avert some of the most devastating changes associated with aging.