Nancy S. Harrison Contributing Columnist
November 11, 2013
The immune system protects the body against infections by bacteria, viruses and other parasites. There are two parts to the immune system: built-in immunity and acquired immunity. A person’s built-in immunity is the first line of defense.
• The skin outside the body and other tissues lining the respiratory and gastrointestinal tracts which form a barrier.
• Mucus lining of the gut and lungs which traps invading bacteria.
• Hairs which move mucus and trapped bacteria out of the lungs.
• Stomach acid which kills bacteria that have been swallowed.
• Helpful bacteria growing in the bowels which prevent other bacteria from taking over.
• Urine flow which flushes bacteria out of the bladder and urethra.
• White blood cells called neutrophils which can find and kill bacteria and other infectious agents.
Acquired immunity is the second line of defense and provides protection differently than the built-in immunity. After the body is exposed to a disease, it learns to recognize each different kind of bacteria and virus it meets. The next time that the bacteria or virus tries to invade the body the immune system is ready to fight it off. This is the reason why you usually only get some infectious diseases once, for example, measles or chicken pox.
To keep these two parts of the immune system in tip top shape it is very important to maintain good health. Good health includes things such as staying physically active, maintaining an appropriate weight for your size and lifestyle, reducing stress, and eating nutritious/well-balanced meals throughout the day.
Good nutrition includes a diet that is rich in nutrient dense foods, such as fruits and vegetables. Nutrient dense foods contain more vitamins, minerals and phytochemicals, which are necessary for optimal health. Three or more meals and snacks each day, depending on an individual’s energy needs, can provide adequate nutrients needed for a strong immune system. Supplements are not necessary if you are eating a balance and variety of nutrient dense foods. However there may be certain instances where multivitamins and/or mineral supplements should be taken, such as an older adult with a poor dietary intake.
Some important nutrients to enhance and maintain immunity include:
• The B-complex vitamins are a group of eight inter-related vitamins, which occur together in natural plant and animal sources. These vitamins are water soluble, so they cannot be stored to a large degree in the body and therefore must be consumed daily. Rich sources of B vitamins are green vegetables, potatoes, whole grain cereals and grains, fresh and dried fruit, peas, beans, lentils, nuts, seeds, liver and lean meat.
• Vitamin C is a water-soluble vitamin that also cannot be stored by the body and has to be included in the daily diet. This vitamin is needed to help the body to resist infection, maintain tissues, and heal wounds. Vitamin C can be found in fruits, especially citrus fruits and fruit juices, and vegetables.
• Vitamin A is a fat-soluble vitamin that helps in promoting vision, maintains the health of epithelial tissue and skin, and supports cell reproduction and growth. Rich sources of vitamin A include liver, fish liver oils, milk and milk products, butter and eggs. Some plant foods that contain vitamin A activity are dark leafy greens and rich yellow or deep orange fruits and vegetables.
• Zinc is required for its role in resistance to infection and wound healing. It is the highest in protein-rich foods such as meats, poultry, and liver. If eaten in large quantities, legumes and whole grains are also good sources of zinc. Seafood, especially oysters, contains very high amounts of zinc.
• Magnesium is a mineral essential for activating chemical reactions, transporting glucose to the cells and boosting your immune system. At times of high psychological stress, magnesium requirements are even higher. This mineral can be found in oysters, shellfish, herring, liver, legumes and milk.
So next time you are deciding on what to eat, think about including foods that contain B vitamins, vitamin C, Vitamin A, zinc, and magnesium. It is very important to remember that while the body cannot always fight off every virus or bacteria it comes in contact with, we can help optimize the function of our immune system by consuming a nutrient rich diet.
A canning workshop is Nov. 18 at the State Farmer’s Market Phillips Market Center, 3501 Charleston Highway, West Columbia from 10 a.m. - 2 p.m. The cost is $30 and payments can be made to Clemson Extension. Registration deadline is Nov. 14. Participants will be provided canning material, bring your own lunch, class limited to 25, contact info: Nancy S. Harrison, P.O. Box 161, St. Matthews, S.C. 29135, email to firstname.lastname@example.org, 803-874-2354 ext. 113
Nancy S. Harrison is retired Food Safety and Nutrition Educator with the Clemson University Cooperative Extension Service.