Flavonoids are a diverse group of health-promoting plant compounds. Over 5,000 family members have already been identified, and researchers keep discovering more. These wellness molecules play a crucial role in plant function and are responsible for many plant characteristics. For instance, flavonoids are responsible for plant color, aroma, anti-viral protection, anti-bacterial protection, and resistance to frost, drought, and UV damage.
Humans do not naturally produce flavonoids; they are only synthesized in an appreciable amount in plants. Thus, if you want the health benefits, you have to weave plant food into your diet. In humans, flavonoids have been found to exert a dramatic influence on antimicrobial, antiviral, anticancer, anti-inflammatory, and antioxidant activity.
Flavonoids are divided into six major subclasses, each with unique yet overlapping benefits. The classification scheme is as follows:
- Anthocyanidins: Blue, purple, and red berries
- Flavan-3-ols: Tea, chocolate, apples, peaches, pears
- Flavonols: Red onions, kale, broccoli, almonds, garbanzo beans
- Flavanones: Oranges, grapefruits, lemon
- Flavones: Parsley, thyme, celery, bell pepper
- Isoflavones: Soybeans, soy products, legumes
How do flavonoids promote musculoskeletal health?
Flavonoids provide multi-pronged protection against the ills of musculoskeletal injury. Research indicates flavonoids demonstrate the following attributes:
Anti-inflammatory – Chronic low-grade inflammation is a driving force behind chronic joint, bone, tendon, and muscle injury. Flavonoids inhibit the same inflammatory pathway targeted by commonly prescribed NSAIDs. Research suggests flavonoids reduce:
- The synthesis of inflammation-inducing signaling molecules, like cytokines and interleukins.
- The activity of pro-inflammatory enzymes, like COX-2.
- The production of pain-inducing substances, such as prostaglandins.
Antioxidant – Oxidative damage is a key mechanism that causes premature aging of joint, muscle, bone, and tendon tissue. Flavonoids are potent antioxidants, counteracting oxidative damage through multiple pathways. Flavonoids disarm high-energy free radicals that injure cell proteins, healthy fats, and DNA.
Anti-catabolic – Chronic inflammation and oxidative stress catalyze the cellular breakdown of muscle, bone, cartilage, and tendon. Flavonoids have been shown to reduce the production of enzymes, such as matrix metalloproteinases and collagenase, that target vital cellular components. These enzymes act like corrosive acid, melting away key tissue components and hastening dysfunction and injury.
Anabolic – Flavonoids stimulate the production of many crucial substances that promote cell vitality and health. Flavonoids have been shown to boost collagen, proteoglycan, and glycosaminoglycan levels. These substances compose the core framework that provides musculoskeletal tissue with optimal amounts of strength, shock absorption, and elasticity.
Anti-apoptotic – Apoptosis is a process referred to as “programmed cell death.” If a cell is so injured it can no longer function properly, then the cell undergoes a series of steps to cause its own demise. Overall, this is a beneficial event when appropriate. However, in the setting of excessive pro-inflammatory substances and free radicals, a cell can trigger “programmed cell death” even in the absence of significant injury. Flavonoids help disrupt this signal and prevent a healthy cell from inadvertently killing itself.
1. Flavonoids Boost Bone Health
Australian researchers examined the association of black tea and flavonoid intake with fracture risk. The investigators found that three cups of black tea per day were associated with a 30% lower risk of any osteoporotic fracture. Statistically significant reductions in fracture risk were observed for higher intake of flavonols, as well as flavones for hip fracture (Meyers et al., 2015).
2. Flavonoids Enhance Muscle Health
Investigators at the University of California, San Diego examined the effect of epicatechin on markers of muscle strength and growth. The results suggested epicatechin can improve strength (hand strength) and was able to improve the ratio of pro-growth to pro-breakdown muscle markers (Salmean et al., 2014).
3. Flavonoids Support Joint Health
Researchers from Arizona evaluated two groups of participants with knee arthritis. Groups were given either a concentrated form of a flavonoid mixture or naproxen, a potent prescription anti-inflammatory. After 12 weeks of treatment, both groups showed similar improvement in symptoms, suggesting that high flavonoid exposure is similarly effective to a leading prescription medication in managing osteoarthritis symptoms (Levy et al., 2010).
Precautions
No adverse effects have been correlated with high dietary intakes of flavonoids from plant-based foods. Increased intake of naturally occurring flavonoids is usually accompanied by a concomitant increase in fiber intake that mitigates toxicity risk. The more that goes in, the more that goes out.
Theoretically, high intakes of flavonoids, especially in supplemental form, might increase the risk of bleeding when taken with anticoagulant medication. When considering supplementation, potential side effects should be discussed with a qualified medical professional. Furthermore, high consumption of grapefruit may reduce absorption of a multitude of prescription medications and should be discussed with the prescribing physician.
References
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