The Health Benefits of Quercetin

By Leigh Matthews, BA Hons, H.Dip. NT for Natural Factors. She is a health and wellness writer specializing in plant-based nutrition. A long-time vegan, Leigh is interested in diet as preventative medicine, as well as the politics of food justice. She also enjoys baking (and eating) delicious cupcakes.

Quercetin is a lipid-soluble, natural antioxidant. It is classed as a bioflavonoid, which is a type of plant pigment largely responsible for the bright colours of many fruits and vegetables. These bioflavonoids were once referred to as vitamin P because of their presence in paprika, and due to the fact that they have vitamin-like properties. Indeed, quercetin works especially well alongside vitamin C and other nutrients to support good health.

Quercetin is, as noted, particularly abundant in apples and onions, but it is also found in other fruits, vegetables, herbs and grains. As a lipid-soluble nutrient, though, it can be hard to absorb without the presence of dietary fat (more on this below).

Quercetin is an antioxidant that supports cardiovascular health

Like other bioflavonoids, quercetin possesses strong antioxidant activity, helping to fight oxidative damage and the negative symptoms of aging. This antioxidant activity also helps support cardiovascular health as quercetin is used in herbal medicine as a capillary protectant, meaning it helps to look after small blood vessels.

Quercetin has been associated with a range of activities that may support the health of arteries, including:

·      Inhibiting the oxidation of low-density lipoprotein (LDL) cholesterol

·      Reducing adhesion molecules and inflammatory markers

·      Protecting nitric oxide and endothelial function during oxidative stress

·      Supporting normal platelet activity.

Together, these activities help the body’s blood vessels stay flexible and responsive, dilating and contracting as needed to maintain healthy blood flow.

Quercetin has antiviral activities

Quercetin’s potential antiviral properties have been investigated in numerous studies and preliminary research suggests that the bioflavonoid might inhibit the ability of some influenza viruses to enter cells, which would help to prevent infection. Quercetin’s possible antiviral effects appear to be related to an ability to help prevent a virus from replicating itself and to cause infection. It does this by inhibiting polymerases, proteases, and reverse transcriptase, suppressing DNA gyrase, and binding viral capsid proteins.

There is also evidence that vitamin C and quercetin have a synergistic antiviral action because of their overlapping immunomodulatory properties and because vitamin C can ‘recycle’ quercetin, increasing its efficacy.[5] In return, quercetin and other bioflavonoids help vitamin C to be used effectively by the body and increase the effectiveness of vitamin C by slowing down its breakdown.[4] And, because quercetin is fat-soluble, it helps provide benefits in lipid membranes where vitamin C, which is water-soluble, can’t reach.

Quercetin for allergy control

Quercetin is also well-regarded for its ability to help control allergy symptoms. When my spring dogwood allergies kick in, quercetin is the first thing I reach for. And, if I remember, I start taking quercetin a few weeks in advance of the first dogwood flowers, so my body is ready to keep those histamine levels in check.

A 2016 review of quercetin noted:

“Quercetin is known for its antioxidant activity in [free] radical scavenging and anti-allergic properties characterized by stimulation of immune system, inhibition of histamine release, [and] decrease in pro-inflammatory cytokines.”

Quercetin can also support the balance of T-helper cells and antigen-specific antibodies, inhibits the production and release of histamine and appears to stabilize the cell membranes of mast cells (influential immune cells involved in the development of allergic responses). These immune modulating and anti-inflammatory actions contribute to quercetin’s usefulness against allergic rhinitis, seasonal allergies, and other allergic responses.

Why quercetin absorption matters

The bad news is that quercetin is pretty poorly absorbed in the standard form used in most supplements, largely because it is fat-soluble. This means that the clinical efficacy of quercetin is quite limited, unless care is taken to provide quercetin in an absorbable form.

EMIQ or Enzymatically Modified Isoquercitrin is a highly bioavailable soluble quercetin compound created using a natural enzyme process for superior bioavailability. Natural Factors Bioactive Quercetin EMIQ® reaches peak level in the bloodstream in just 15 minutes for almost instantaneous antioxidant support!

Natural Factors Quercetin LipoMicel Matrix is another great option for absorbable quercetin as it provides an advanced form of the antioxidant with 10 times higher absorption than standard forms. The unique patent-pending LipoMicel technology helps overcome low bioavailability by creating a liquid micelle matrix that disperses quercetin into tiny micro-droplets that enhance absorption. This supplement provides 250 mg of quercetin in each easy-to-swallow liquid softgel and is a great choice for anyone suffering from conditions related to constricted blood vessels or looking for additional immune and antioxidant support.

Natural Factors Quercetin 500 mg provides an even greater dose of concentrated quercetin and is suitable for vegetarians and vegans. And Natural Factors C Extra + Quercetin offers 500 mg of vitamin C and 250 mg of quercetin bioflavonoids in every softgel to provide antioxidant protection against free radicals, help with collagen formation to maintain healthy bones, teeth, gums, cartilage, and skin, and to help protect capillaries while supporting the body’s immune system to keep allergies in check and to fight off viruses. Whether prevention is on your mind, or you are looking for extra antioxidant and immune support, Natural Factors has a form of quercetin sure to meet your needs!

Masley reports that most doctors rely on lowering blood cholesterol and blood pressure to prevent heart disease. He says this is a boon for Big Pharma, but not necessarily for patients. He admits that, although statin drugs are needed in some instances, they increase the risk of diabetes. Unfortunately, statins also result in weight gain and, by lowering testosterone, reduce sexual pleasure. 

His 30-day tune-up is directed at shrinking coronary plaque, improving circulation and strengthening the heart. However, his primary message is that 30 to 50% of baby boomers now suffer from prediabetes. This, he says, can kill by a coronary or stroke even before they develop diabetes. It does this by changing the cholesterol profile and increasing inflammation. Yet at this point cardiologists would say, “So what’s new?” 

Dr. Masley, due to his training in nutrition, believes vitamin and mineral supplements hold the key to cardiac health, as much processed food is deficient in them. He adds that other critical elements are fiber, fish oil, magnesium and potassium. And, we should all take a daily multivitamin pill. 

He also believes we need mixed carotenoids, a pill that contains fruit and vegetable extracts. A further suggestion is that we need at least 100 micrograms (mcg) of B12 daily if we’re over 50 years of age, and 500 mcg if taking a stomach acid blocker. Then, we should check to see if the multivitamin pill contains 75 to 150 mcg of iodine for optimum thyroid function. 

According to Dr. Masley, it’s critical for overall health to take vitamin D as every cell in the body has vitamin D receptors. He explains studies show that people with high levels of D have less risk of heart attack, stroke, hypertension and obesity. If blood level of D is low, we need to take 5,000 IU of D for a couple of months, then 1,500 to 3,000 IU daily. Other authorities claim 5,000 IU is ideal. 

Other critical vitamins are vitamin K1 and K2. Most people get enough K1 in food, but lack K2 which directs calcium into bone and keeps it out of arteries where it can cause trouble. Masley recommends 100 mcg daily, but some experts stress that up to 1,000 mcg is required. 

Vitamin E has been associated with decreased risk of cardiovascular health for years, but comes in various forms. Masley recommends a supplement that contains mixed forms of E. 

For the elderly it’s a good time to add supplements that provide longevity to the heart’s muscles. A good combination is coenzyme Q10 (CoQ10) 100 mg twice daily, ribose 5 grams twice daily, and carnitine 2,000 to 3,000 mg. daily. 

Masley has two other suggestions. I was pleased to read that one I take in moderation is resveratrol, present in red wine. The other, curcumin, he reports, is an outstanding ant-inflammatory and he often prescribes it for patients with arthritis, dementia, and cancer prevention.

 Like other authorities, Masley claims many North Americans lack magnesium and suggests 300 to 500 mg daily. This mineral is responsible for at least 300 metabolic actions, one being to regulate the heart’s normal rhythm. 

His final remark was the need for nitric oxide (NO) that dilates arteries. It’s produced by the innermost lining of arteries, but decreases as we age. A deficiency can cause hypertension, angina and erectile dysfunction. A natural remedy, NEO40 produces NO and like other minerals and vitamins mentioned is available in Health Food Stores. 

So what more could I do to ensure a healthy heart? I should add iodine and curcumin. I’ll also be sure not to forget a relaxing glass of red wine with dinner. And to remember that it’s always prudent to maintain a healthy diet and daily exercise.