Zinc is an essential trace mineral, but to list all of its functions in the body would take up several pages! It is also found throughout the body tissues, but it is its role in tissue repair and renewal that's especially important for cyclists.
During an endurance ride or hard training session, your muscles are working flat out, while your heart, lungs and circulation system work together to bring in oxygen and take away waste gasses and the products of metabolism. Enzymes within your muscles promote energy production and minerals are pumped in and out of nerves to allow them to send signals to muscles to contract and work well.
While you are out cycling, this incredible system is hard at work but, as with any machine, there is wear and tear. So by the end of a ride your muscle fibres will have suffered some damage - which is normal, even if it is not as obvious as the cuts and grazes suffered from a tumble. Regardless of how the damage has occurred though, zinc will perform an essential function in promoting tissue repair and renewal. While you are soaking in a hot bath or recovering before your next ride, new proteins will be formed and muscle fibres repaired. The surface of your skin is constantly being renewed anyway, and zinc is involved with this process too.
Zinc is also important for your immune system to work well too. A group of white blood cells called the T-lymphocytes are designed to attack microbes and abnormal cells. The lymphocytes are released from your thymus gland (located in your neck area) but it is important that the right balance of cells is discharged to cope with different infections. Zinc is needed to produce this balance.
Running low
Not surprisingly the symptoms of a deficiency include tiredness and a lack of power in your muscles due to poor recovery. This is a difficult symptom to pick up in athletes because there are so many other factors that can affect recovery - you may simply not be eating enough carbohydrate, or replacing enough fluid in between training sessions. However, another sign of zinc deficiency might be that those cuts and grazes are also taking longer to heal. A dry, flaky skin and horizontal white marks on your nails also point to a lack of the mineral.
An ineffective immune system means that you're likely to suffer regularly from coughs, colds and sore throats. Again, this may be due to other factors rather than a lack of zinc.
For example, too much exercise is known to have a negative effect on your immune system. If you do suffer from too many sore throats, it may be time to look at your training schedule and zinc intake. Choose a throat lozenge which contains added zinc. Some research has shown that zinc in this form can coat throat viruses and help to stop infection. It may be useful to take a couple of packets with you on a long ride. The half teaspoon or so of sugar in each sweet will also provide a small amount of carbohydrate, but at least your zinc requirement for the day will be covered. Adults need about 15mg of zinc each day, but there aren't many foods that are particularly good sources.
Oysters are by far the richest source of zinc, but aren't a food most cyclists eat regularly. Sardines, eggs, milk and beef are more every day sources. For vegetarians, cheese and nuts are the only significant sources. The refining of wheat into flour and processing brown rice into white, strips away a significant amount of zinc. If these form the basis of your carbohydrate intake, you may need to think about taking a zinc supplement too. If you're deficient in zinc, it is likely you are lacking in other minerals too. A daily supplement which contains other minerals (such as chromium and copper) would be useful. Be careful though, if your zinc levels are too high you can upset the balance of other minerals in the body.
Are you getting enough zinc?
(Adult RDA 15mg)
Oysters, 3 large raw - 45 - 70mg
Liver, 2 pieces grilled - 10mg
Shrimps, 1 cupful - 8mg
Sardines, 4 small - 7mg
Brazil nuts, 10 large nuts - 5mg
Beef, small grilled steak - 4mg
Wholemeal bread, 2 slices - 2mg
Eggs, 2 boiled - 2mg
Chicken, casserole large portion - 2mg
Peanuts, 1 small packet roasted - 1mg
Cow's milk, half pint - 1mg