Zinc: Boosts Muscle & Bone Health
Zinc is an essential trace element. Of all the trace elements in our body, zinc is second only to iron in its concentration. A metal, zinc is critical to the structure and function of approximately 2800 molecules and over 300 enzymes. Incredibly, zinc is a component of about 10% of human proteins. The majority of zinc (85%) is localized in muscles and bones, with 11% in the skin and liver.
Zinc is essential for the body’s immune system to function properly. It also plays a role in the breakdown of carbohydrates, protein synthesis, DNA synthesis, wound healing, cell division, and cell growth.
4 Musculoskeletal Benefits of Zinc
1. Zinc Boosts Joint Health
Oxidative stress and chronic inflammation are known risk factors for chronic joint disease. Free radical damage initiates a chain reaction that results in irreparable changes to the normal architecture of cartilage and the layer of bone just beneath cartilage, called subchondral bone. Zinc is a necessary co-factor for an important antioxidant called superoxide dismutase. Superoxide dismutase neutralizes super dangerous oxygen free radicals and breaks them down to regular oxygen and peroxide. Interestingly, peroxide instructs special immune cells called neutrophils to self-destruct. This is a crucial protective mechanism to curb unhealthy inflammation. Neutrophils release many substances that are like potent acid, melting away tissue. This is a good thing if the target is foreign bacteria that cause illness, but it’s a really bad thing if the target is healthy joint tissue. Zinc, via its interaction with superoxide dismutase, helps ensure optimal amounts of peroxide are generated to neutralize excessive immune cell activity and promote balanced inflammation.
2. Zinc Supports Bone Health
Chronic free radical damage and unhealthy inflammation are driving forces behind osteoporosis. Certain metals tend to associate with fat in cell walls and cause free radical damage. An example would be iron. Iron bound to cell wall fat can create a dangerous scenario if it reacts with peroxide. The chemical interaction between the bound iron and peroxide generates a free radical that then can attack nearby fat and initiate a chain reaction that can cause significant damage and even result in cell death. This process is referred to as lipid peroxidation. Zinc, since it has a similar structure to iron, can dislodge iron and bind to the cell wall fat instead of iron. Zinc exhibits less attraction to peroxide, and free radical generation is less likely to occur. Zinc helps avoid the chain reaction that leads to unwanted cellular injury and chronic inflammation.
Moreover, heavy metal toxicity induces oxidative stress. Excessive oxidative stress causes bone-resorbing cells, called osteoclasts, to produce more free radicals and to resorb more bone. Bone loss is the hallmark of osteoporosis.
Additionally, zinc is essential for the production of special metal-binding proteins called metallothioneins. Metallothioneins capture heavy metals, such as arsenic and mercury, and detoxify them before they can cause damage. Metallothioneins are also able to disarm a wide range of oxygen free radicals. Research has demonstrated that the ability of metallothionein to scavenge hydroxyl radicals is 300 times greater than that of glutathione. Glutathione is one of the body’s most abundant natural antioxidants. Iranian researchers assessed the relationship between zinc intake and bone mineral density. The scientists identified an association between low zinc intake and lower bone mineral density. (Mahdavi-Roshan M, Ebrahimi M, Ebrahimi A. Copper, magnesium, zinc, and calcium status in osteopenic and osteoporotic post-menopausal women. Clinical Cases in Mineral and Bone Metabolism, 2015; 12(1), 18-21. doi:10.11138/ccmbm/2015.12.1.018.)
3. Zinc Promotes Muscle Health
Sarcopenia is defined as a progressive loss of muscle mass and commonly occurs as we age. Chronic inflammation and free radical injury are thought to play a central role in sarcopenia’s manifestation and progression. Zinc increases the activity of a specialized protein, referred to as a transcription factor, that selectively turns on genes. The protein (Nrf2) activates genes that code for antioxidant enzymes. The more these genes are activated, the more enzymes they produce. An abundance of antioxidants boosts the body’s defenses against oxidative stress. Additionally, research has demonstrated that zinc stymies the function of a pro-inflammatory transcription protein called nuclear factor kappa beta (NF-kB). Nuclear factor kappa beta is involved in the activation of inflammation-promoting genes. Reduced NF-kB activity leads to decreased expression of pro-inflammatory proteins and less unhealthy inflammation.
Dutch researchers investigated the relationship between zinc intake and physical performance in older adults. The authors of the study concluded that healthy zinc intake improved physical performance in older adults. (van Dronkelaar C et al. Minerals and Sarcopenia; The Role of Calcium, Iron, Magnesium, Phosphorus, Potassium, Selenium, Sodium, and Zinc on Muscle Mass, Muscle Strength, and Physical Performance in Older Adults: A Systematic Review. J Am Med Dir Assoc., 2017 Jul 12. pii: S15258610(17)303055. doi: 10.1016/j.jamda.2017.05.026.)
4. Zinc Enhances Tendon Health
Healthy tendons need collagen to function properly. In fact, tendons are 90% collagen by dry weight. Collagen confers on tendons the proper amount of strength that is needed to transfer the force generated by muscle to bones. Zinc deficiency hinders collagen biosynthesis and promotes collagen degradation.
Precautions
Zinc from natural foods is generally well tolerated. RDA amounts can usually be obtained from a balanced, healthful diet. An upper limit for zinc consumption for adults has been set at 40 mg/day. Common adverse side effects include nausea, vomiting, and other GI symptoms. Chronic excessive consumption can cause low copper status, iron dysfunction, and reduced immune function. Any consideration of supplementation should be discussed with a qualified health professional familiar with your unique medical history.
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