How’s Your Zinc?
Zinc is another metallic element that, like magnesium, is an essential nutrient. We can’t make it in the body; it has to come from the diet. Like magnesium, zinc is crucial for numerous biochemical reactions. And like the trace metallic element, selenium, we need adequate amounts of zinc primarily to keep the immune system humming along at peak efficiency. That’s because zinc and selenium are among the few metals that are indispensable components of certain important immune system proteins.
Scientists have known for some time that certain forms of serious disease, including prostate, ovarian and lung cancers, and autism, are characterized by notable zinc deficiency. Although the reasons have been unclear, the implication has been that too little zinc in the body is associated with illness.
Now scientists think they know why, exactly. It has to do with a biomolecular pathway in the body called the Hedgehog signaling pathway. This pathway is intimately involved in regulating cell growth, so it’s especially important during early growth and development. After we’re fully grown, Hedgehog is supposed to fall more or less silent. But now scientists think that dietary zinc deficiency may somehow reactivate the pathway.
"Hedgehog is critical to normal development, but in adults the pathway, if reactivated, may lead to uncontrolled cell growth and proliferation in cancer," said Chunyu Wang, associate professor in biological sciences at Rensselaer, and co-author of the research. "Our paper suggests a link between zinc deficiency and activation of the Hedgehog pathway in many diseases where zinc deficiency and Hedgehog activation co-exist.”
In essence, zinc inhibits a protein that reactivates the otherwise obsolete pathway. If there’s too little zinc in the diet, the Hedgehog pathway machinery may start up again. And that can have disastrous consequences in a healthy adult body, evidently. Rapid cell division, growth, and reorganization are all important functions to a young growing body. But when it happens in adults, cancer can result.
"Normally, in adults, zinc will inhibit the production of the Hedgehog ligand, and therefore inhibit the Hedgehog pathway," said Wang. "But if there is a zinc deficiency, the pathway can be activated due to enhanced production of Hedgehog ligand. We show that zinc inhibits this autoprocessing reaction from the precursor to the ligand, providing an additional mechanism of how zinc deficiency may promote cancer development. This is something that nobody else has shown before. Zinc and Hedgehog are essential and extremely versatile biomolecules; linking these two will have profound implications for normal physiology and disease.”
So how to ensure you’re getting enough dietary zinc? If you happen to like oysters, you’re in good shape. These shellfish have the highest concentration of any food source. Other good sources include beef, crab, fortified cereal, lobster, and baked beans. Or take a multivitamin with minerals if you’re in doubt.
Jian Xie, Timothy Owen, Ke Xia, Ajay Vikram Singh, Emiley Tou, Lingyun Li, Brigitte Arduini, Hongmin Li, Leo Q. Wan, Brian Callahan, Chunyu Wang. Zinc Inhibits Hedgehog Autoprocessing: Linking Zinc Deficiency with Hedgehog Activation. Journal of Biological Chemistry, 2015; jbc.M114.623264 DOI: 10.1074/jbc.M114.623264