Joint Venture: Purple Corn and Osteoarthritis
According to the CDC, 23% of adults – more than 54 million people – in the United States have some form of arthritis. There are several forms of arthritis – the most common being osteoarthritis – as well as rheumatoid, lupus, and gout. General arthritis symptoms include pain, aching, stiffness, and swelling in or around the joints. Arthritis often occurs with other chronic diseases, like diabetes, heart disease, and obesity (1).
Osteoarthritis (OA) – also known as "wear and tear" disease – affects roughly 32.5 million adults in the US (2). It occurs when the cartilage that protects the ends of our bones breaks down. It is classified as a degenerative disease that worsens over time. For many sufferers, it results in chronic pain that makes even the simplest of daily tasks very difficult. Symptoms of osteoarthritis can range from pain, swelling, and tenderness, to stiffness, bone spurs, and a loss of flexibility (3).
There is no cure for osteoarthritis, but there are a variety of treatment options currently available. Doctors will typically treat symptoms with a combination of therapies like medications (over the counter pain relievers and prescription drugs), physical therapy, occupational therapy, supportive devices (canes, crutches, and braces), and surgery, if other treatment options have not worked. Another treatment option for OA symptoms involves making lifestyle changes, like exercising more, losing weight (if overweight), movement therapies, heat and cold, capsaicin, and transcutaneous electrical nerve stimulation (TENS) therapy. Finally, there are several complementary and alternative medicine treatments that have been shown effective for some OA symptoms. These include acupuncture and nutritional supplements (glucosamine and chondroitin, avocado-soybean unsaponifiables (ASU), and omega-3 fatty acids) (3).
While anyone can develop OA, it seems that women are more likely to develop it than men. Especially after the age of 50. Obesity is another risk factor for OA, since carrying extra weight puts more stress on our joints. Furthermore, the metabolic effects of obesity may also increase OA risk (2). Previous studies have shown that people with diabetes have a higher prevalence and increased severity of OA, as well as an increased risk of requiring joint replacement surgeries as opposed to people without diabetes (4).
Diabetes is a disease that affects how our bodies turn food into energy. With diabetes, the body either does not make enough insulin or is unable to use insulin properly (5). A lack in insulin can cause hyperglycemia (high blood sugar), which some evidence has shown is one of the main causes of diabetes-mediated OA. This is potentially due to the long-term accumulation of irreversible advanced glycation end products (AGEs) (4), also known as glycotoxins (6). Some research has found high levels of these AGEs in plasma, synovial fluid, and cartilage (4). While the formation of some AGEs is part of normal metabolism, excessive levels can be damaging, promoting oxidative stress and inflammation (6). A recent research study explored the role diabetes plays in OA and the potentially chondroprotective effects of anthocyanins from purple corn (4).
Anthocyanins, a member of the flavonoid group, have long been studied for their anti-inflammatory properties and are well-known antioxidants (7). They are also known to have anti-diabetic properties (4). Purple corn (Zea mays L.) contains six major anthocyanins – cyanidin‐3‐glucoside, pelargonidin‐3‐glucoside, peonidin‐3‐glucoside, cyanidin‐3‐(6”-malonylglucoside), pelargonidin‐3‐(6”-malonylglucoside), peonidin‐3‐(6”-malonylglucoside); the major anthocyanin is cyanidin‐3‐glucoside (4, 8). Purple corn also has less starch and a lower glycemic index than other, lighter-colored varieties of corn making it more suitable for diabetes patients (4).
According to a recent study, published in Scientific Reports journal, purple corn anthocyanins were found to be beneficial in the reduction of diabetes-associated inflammation, suggesting they may have a positive effect on the inflammation of cartilage caused by diabetes (4). They used a method to freeze-dry the extract they obtained from the purple corn kernels. They then obtained articular cartilage from the metacarpophalangeal joints of pigs. Additionally, they obtained non-OA joint material from patients at Maharaj Nakorn Chiang Mai Hospital (4).
The study yielded several results that support the chondroprotective potential of purple corn extract.
(1) There was a reduction in glycosaminoglycans (GAGs) released from AGEs-induced cartilage explants, corresponding with diminishing of uronic acid loss of the cartilage matrix (4). Evidence suggests that glycosaminoglycans (GAGs) play a key role in cell signaling, regulating many biochemical processes in the body (9).
(2) With the addition of the purple corn extract, AGEs-induced cartilage degradation was significantly diminished (in a dose dependent manner) (4).
(3) Purple corn anthocyanins, and their metabolite protocatechuic acid (PCA), had anti-inflammatory effects on AGEs-induced human articular chondrocytes via the inactivation of the NFκb and MAPK signaling pathways (4).
(4) Their study showed that among purple corn anthocyanins, C3G exhibits the highest inhibitory potency on AGEs induced MMPs expression and inflammatory response (4).
Based on their findings they suggested that purple corn anthocyanins and PCA may help improve inflammation from AGEs and diabetes-mediated cartilage degradation (4).
(1) Arthritis. (n.d.). Centers for Disease Control and Prevention. Retrieved May 5, 2021 from https://www.cdc.gov/chronicdisease/resources/publications/factsheets/arthritis.htm
(2) Osteoarthritis (OA). (n.d.) Centers for Disease Control and Prevention. Retrieved May 5, 2021 from https://www.cdc.gov/arthritis/basics/osteoarthritis.htm
(3) Osteoarthritis. (n.d.). Mayo Clinic. Retrieved May 5, 2021 from https://www.mayoclinic.org/diseases-conditions/osteoarthritis/symptoms-causes/syc-20351925
(4) Chuntakaruk, H., Kongtawelert, P. & Pothacharoen, P. (2021). Chondroprotective effects of purple corn anthocyanins on advanced glycation end products induction through suppression of NF-κB and MAPK signaling. Scientific Reports, 11(1): 1895. https://doi.org/10.1038/s41598-021-81384-4
(5) What is Diabetes? (n.d.). Centers for Disease Control and Prevention. Retrieved May 6, 2021 from https://www.cdc.gov/diabetes/basics/diabetes.html
(6) Uribarri, J., Woodruff, S., Goodman, S., Cai, W., Chen, X., Pyzik, R., Yong, A., Striker, G. E., & Vlassara, H. (2010). Advanced glycation end products in foods and a practical guide to their reduction in the diet. Journal of the American Dietetic Association, 110(6), 911–16.e12. https://doi.org/10.1016/j.jada.2010.03.018
(7) Lee, Y. M., Yoon, Y., Yoon, H., Park, H. M., Song, S., & Yeum, K. J. (2017). Dietary Anthocyanins against Obesity and Inflammation. Nutrients, 9(10), 1089. https://doi.org/10.3390/nu9101089
(8) Lao, F., Sigurdson, G. & Giusti, M. (2017). Health Benefits of Purple Corn (Zea mays L.) Phenolic Compounds. Comprehensive Reviews in Food Science and Food Safety, (16)2, 234-246. https://doi.org/10.1111/1541-4337.12249
(9) Casale, J. & Crane, J.S. Biochemistry, Glycosaminoglycans. [Updated 2020 Jul 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK544295/
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