Studies Show The Anti-Carcinogenic Properties of Antioxidants
"Diets rich in antioxidants would diminish cancer-promoting action"
The key to antioxidants ability to "diminish cancer-promoting action" is due to their free radical scavenging activity. Although antioxidant rich foods and teas may have beneficial anti-carcinogenic effects...it's important to consider that while they may help, they're not a cure.
Flavonoids are phytonutrients produced by plants to fight off infections, inflammation, stress, bacteria and diseases. They're commonly found in vegetables, fruits, plants, bark, flowers, wine and teas. Thousands of studies have shown that flavonoids are anti-oxidant, anti-inflammatory, anti-diabetic, anti-aging, anti-hypertensive, anti-bacterial, anti-mutagenic, anti-viral and anti-carcinogenic.
A 2021 study actually found several phytochemicals in palo azul such as “flavones, isoflavones, flavanones, phenolic compounds, chalcones and dihydrochalcones” which have been linked to its health benefits, highlighting “diuretic, antidiabetic, antiglycation, antioxidant, anti-inflammatory, antimicrobial potential.”
1. Free radical scavenging activity
According to the findings of two medical reviews (1) (2) that analyzed 327 studies conducted on flavonoids, it is well established that oxidative stress can lead to cancer, diabetes, cardiovascular disease, and aging. They mention that "fruits and vegetables that have flavonoids have been reported as cancer chemopreventive agents and are inversely associated with cancer incidence."
What is oxidative stress?
Oxidative stress is an imbalance between free radicals and antioxidants in the body. This medical review explains that "oxidative stress may lead to cellular damage which is related to various health ailments such as diabetes, cancer, CVD, neurodegenerative disorders and ageing.”
A 2021 study actually found that palo azul tea "can reduce the oxidative stress caused by the imbalance between reactive oxygen species (ROS) because of its free radical scavenging activity."
Another medical review also concluded that "diets rich in antioxidants would diminish the cancer-promoting action of free radicals and oxidative stress."
What are free radicals?
Free radicals are atoms with a single valence electron that cause damage to the body associated with diabetes, cancer, aging, atherosclerosis, Parkinson's, Alzheimer's and many other diseases.
This happens because electrons like to be in pairs... and for this reason, free radicals look for "free" electrons in the body. This causes damage to cells, proteins, DNA and these damaged molecules can mutate, grow tumors, and damage the DNA code. Eventually, this cellular damage causes new cells to grow with defects and it will lead to aging and degenerative diseases.
A 2022 study which supports the previous 2021 study, explains that oxidative stress "leads to the formation of advanced glycation end products (AGEs) which facilitate further disease progression.
A 2018 study found that palo azul "showed antidiabetic and anti-hyperlipidemic activities, an ability to reduce the formation of advanced glycation end products, and an antioxidant capacity."
What is glycation and AGEs?
Glycation is the covalent attachment of a sugar to a protein or lipid. This process is responsible for many complications in diabetes mellitus, some diseases and in aging.
Advanced glycation end products (AGEs) are proteins or lipids that become glycated as a result of exposure to sugars.
A 2014 study which supports to previous study, found that "Eysenhardtia polystachya (palo azul) possesses considerable antioxidant activity with reactive oxygen species (ROS) scavenging activity and demonstrated an anti-AGEs and inhibits oxidative stress."
What are reactive oxygen species (ROS)?
Reactive oxygen species are a type of unstable molecule that contains oxygen and that easily reacts with other molecules in a cell. A build up of reactive oxygen species in cells may cause damage to DNA, RNA, and proteins, and may cause cell death. Reactive oxygen species are free radicals.
Another 2017 study mentions that there are "empirical studies exhibiting an association between AGEs and a variety of conditions such as decline in memory with age, cardiovascular complications, bone health, periodontitis, erectile dysfunction, peripheral artery disease, obstructive sleep apnea, cancer, elevated cellular oxidative and inflammatory state, Alzheimer’s disease, and risk for metabolic syndrome."
Hence, this is why one of the medical reviews points out that “potent antioxidants show potential to combat progression of carcinogenesis."
2. Gene regulation
Not that Gene! Nobody can regulate Gene Simmons! 😉 We're talking about genes as in the physical units of heredity which are made up of DNA.
This medical review explains the biological mechanisms of flavonoids' cancer-inhibiting effects:
“Flavonoids have complementary and overlapping mechanisms of action including antioxidant activity and scavenging free radicals, modulation of carcinogen metabolism, regulation of gene expression on oncogenes and tumour-suppressor genes in cell proliferation and differentiation, induction of cell cycle arrest and apoptosis, modulation of enzyme activities in detoxification, oxidation and reduction, anti-inflammatory properties and action on other possible targets.”
What are oncogenes and tumor-suppressor genes?
Oncogenes are a mutated genes that contribute to the development of a cancer. According to the American Cancer Society, an oncogene is a proto-oncogene that mutates and becomes a "bad gene that can become permanently turned on or activated when it is not supposed to be. When this happens, the cell grows out of control, which can lead to cancer. An oncogene could be compared with a gas pedal that is stuck down, which causes the cell to divide out of control."
They also explain that "tumor suppressor genes are normal genes that slow down cell division, repair DNA mistakes, or tell cells when to die (a process known as apoptosis or programmed cell death). When tumor suppressor genes don't work properly, cells can grow out of control, which can lead to cancer."
In other words...flavonoids showed the ability to suppress bad genes that lead to cancer because of their antioxidant and anti-inflammatory properties.
A 2005 study supports these findings, as they explain similar mechanisms for flavonoids' cancer modulating properties:
“Dietary flavonoids critically influence several cellular and immune processes associated with the development and progression of cancer. It is clear that these food components possess the propensity to modulate a variety of biological events associated with cancer progression and development, such as cell proliferation, apoptosis, cell differentiation and neovascularization."
What is cell proliferation and neovascularization?
The American Cancer Society explains that cell proliferation is how quickly a cancer cell copies its DNA and divides into 2 cells. If the cancer cells are dividing more rapidly, it means the cancer is faster growing or more aggressive.
Neovascularization refers to the growth of new blood vessels. Neo means new, and vascular refers to vessels. Neovascularization is associated with the growth of blood vessels that are part of abnormal tissue, such as tumors.
This essentially means that flavonoids showed the critical ability to control cell division and blood vessel growth that can lead to tumors.
3. Epidemiological studies
In addition to these mechanistic and biological plausibility studies, there's also been many epidemiological studies which show an inverse correlation between flavonoids and cancer.
A 2009 study mentions that "epidemiological, clinical and animal studies reveal that “flavonoids may exert protective effects against various disease conditions including cardiovascular disease and cancer.”
The authors of this medical review found that the “consumption of onions and/or apples, two major sources of the flavonol quercetin, is inversely associated with the incidence of cancer of the prostate, lung, stomach, and breast.”
* Here’s a very interesting fact for wine drinkers: “Moderate wine drinkers also seem to have a lower risk to develop cancer of the lung, endometrium, esophagus, stomach, and colon.”
The researchers even mentioned that “fruits and vegetables are the main dietary sources of flavonoids for humans, along with tea and wine."
Thank you flavonoids!
A 2019 study that looked at 1522 breast cancer cases and 1547 frequency control subjects from June 2007 to July 2018 in Guangdong, China. The results of this study indicated that consumption of “flavonoids and most flavonoid subclasses intakes were inversely associated with breast cancer risk.”
A 2012 study mentions that "epidemiological studies suggest dietary intake of flavonoids may reduce the risk of tumors of the breast, colon, lung, prostate, and pancreas.”
Finally, the authors of a medical review conclude that “the critical relationship of fruit and vegetable intake and cancer prevention has been thoroughly documented. It has been suggested that major public health benefits could be achieved by substantially increasing consumption of these foods.”
Oxidative stress and free radicals lead to cancer and other diseases, therefore we should consume lots of antioxidants to scavenge those free radicals and inhibit oxidative stress in order to stay healthy. This is why it's so important to eat vegetables, fruit and drink tea everyday... or wine occasionally! 😉
Flavonoid-rich foods: apples, pears, onions, strawberries, blueberries, celery, peppers, and teas such as palo azul
* Palo azul is commonly referred to by its scientific name: Eysenhardtia polystachya / E. polystachya / E.P - Cyclolepis genistoides / C. genistoides - kidney wood - palo dulce