http://www.wikihow.com/Strengthen-Your-Immune-System
 
Three Parts:Eating the Right FoodsTaking Vitamins and Other SupplementsAdopt a Healthy Lifestyle
White blood cells, also known as leukocytes, are the body's natural  defense against infections, and are a major part of the function of the  immune system. They eat away foreign bacteria and other organisms that  invade the body, and they are therefore responsible for immunity (the  ability of the body to fight infections). Some people may have weaker  immune systems genetically; others may have weaker immune systems  because of viral or bacterial infections.
ating the Right Foods    -         1 Get enough protein. Eating a balanced diet ensures  that the right nutrients reach the bone marrow, where white blood cells  are produced. Start by making sure to eat plenty of protein, which is  the most important component of white blood cells. [1] You can get protein from meats, fish, poultry, cheese, eggs, and milk. 
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-         2 Choose the right fats. Avoid saturated fats, but eat  plenty of unsaturated fats. Saturated fats increase the risk of heart  disease, but unsaturated fats aid absorption of fat-soluble vitamins in  the body.  [2] These "good fats" are found in corn, sesame, safflower, soybean, and cottonseed oils. 
 
-         3 Eat limited amounts of carbohydrates. Consuming  appropriate amounts of wheat, corn, and cereals helps to create the  energy required for the body to produce white blood cells. However,  consuming excessive amounts of these foods will result in lower levels  of T-lymphocytes (and thus lead to lower immune responses)  [3]
 
-     4 Incorporate other immunity-boosting foods into your diet. There are a number of particular foods that can help. These include:     
 
-         5 Eat antioxidants. Antioxidants are vitamins, minerals, and other nutrients that help repair damaged cells in the body. [14]  Examples of antioxidants are Beta Carotene, Vitamins C and E, Zinc, and  Selenium. These nutrients can be found in certain fruits or vegetables,  or can be taken with a supplement.             - Beta Carotene is found in apricots, broccoli, beets, spinach, green peppers, tomatoes, corn, and carrots. [15]
- Vitamin C is found in berries, broccoli, nectarines, oranges, strawberries, bell peppers, tomatoes, and cauliflower. [16]
- Vitamin E is found in broccoli, carrots, nuts, papaya, spinach, and sunflower seeds. [17]
- Zinc is found in oysters, red meat, beans, nuts, and seafood.
 
 
    -     Be skeptical of "immune-boosting" products. There is  no scientific evidence that has proven that increasing the number of  immune-fighting cells is a good thing. In fact, in some cases,  increasing the number of certain "good" cells in your body can increase  the risk of stroke. [18]Medically  speaking, the best thing you can do for your immune system is to live a  healthy daily lifestyle and get proper and timely medical treatment for  illnesses and infections. 
 
-         2 Increase your intake of Zinc. Zinc is one of the most  important components of enzymes present in white blood cells, and a  deficiency of this mineral can result in a weaker immune system. [19] You can get zinc from meat, fish, and milk.             - Supplements are also available, but you should consult your doctor before taking them regularly.
 
 
-     3 Make sure you are getting enough copper. You only  need a very small amount of copper to be healthy (the total amount of  copper in a healthy human body is only around 75-100 milligrams  [20]),  but it does play a very important role in metabolic and immune  function, neutralizing free radicals and possibly even reducing some of  their harmful effects  [21] You can get copper from organ meats, leafy green vegetables, and cereals.             - That being said, too much copper can cause it to act as a  pro-oxidant in your body, and in larger quantities it may contribute to  the development of Alzheimer's disease.[22] As such, you should exercise caution and be sure to check with your doctor before increasing your copper intake.
 
 
-     4 Get enough vitamin C. Vitamin C increases your white blood cell count and enhances the cells' effectiveness. [23]  It is also an antioxidant, which means that it prevents the destruction  of existing white blood cells. In addition to supplements, you can get  vitamin C from oranges, berries, and most citrus fruits.             - For adults, tolerable upper intake levels of vitamin C are about 2,000 mg [24].
 
 
-         5 Be mindful of your vitamin A levels. Vitamin A is also an antioxidant, and helps your immune system to function more efficiently. [25] In addition to supplements, you can get vitamin A from carrots, tomatoes, chilis, and squash. 
 
-         6 Take vitamin E. Vitamin E, like vitamins C and A, is an antioxidant, and is also beneficial for your skin and eyesight. [26] In addition to supplements, you can find vitamin E in olive oil, nuts, and some fruits and vegetables. 
 
-         7 Try other natural remedies. Echinacea, [27] ginseng, [28] aloe vera, [29] and green tea [30] are all said to boost your white blood cell count.  [31]        - Selenium is found in tuna, beef, and Brazil nuts. [32]
 
 
-     8 Consider colostrum supplementation. If you have a weak immune system, you may need supplementation. Colostrum powder containing immunoglobulins [33]  is a convenient option since it is available over the counter (without a  prescription) in the form capsules for oral consumption. For most  people, a month of consumption is adequate every five years. 
 
-     9 Talk to your doctor about immunoglobulin injections.  If you have an especially weak immune system, you may need intravenous  injections of immunoglobulins (polyvalent IgG antibodies) extracted from  donor human blood. This is always by a doctor's advice and only if you  have primary immune deficiencies, autoimmune diseases, severe  inflammatory diseases, or acute infections. 
Part 3 of 3: Adopt a Healthy Lifestyle
    -         1 Eat a healthy diet. Many people only think about  their health when it is in danger; don't wait until you are sick or  injured to care for your body. Making healthy food choices on a daily  basis is one of the best ways to maintain your cardiovascular health,  improve your energy levels, and keep your muscles and bones strong. A  healthy diet should be high in fruits, vegetables, and lean proteins,  and low in excess sugar, fat, and alcohol.             - Citrusy fruits like oranges, tangerines, and tomatoes contain Vitamin C, which helps protect the immune system.[34]
- Eat chicken, turkey, salmon, tofu, and other lean meats. These foods  are rich in protein without the extra fat that is found in red meats  and shrimp. Other protein sources included quinoa, kidney beans, and  black beans.
 
 
-     2 Exercise regularly. Getting enough exercise improves  your cardiovascular health, and greatly reduces the likelihood of  certain chronic diseases.. Exercise increases the flow of blood through  different parts of the body, and it increases the body's excretion of  harmful metabolites, helping your immune system function properly, and  may even decrease your chances of developing heart disease,  osteoporosis, and cancer. [35] So run, bike, swim, walk -- whatever gets you moving!             - Children and adolescents aged 6-17 should get 60 minutes of exercise  per day. Most of this time should be spent doing aerobic activities,  while the rest of the time should be spent doing muscle-toning  activities. [36]
- Adults aged 18-64 need at least 150 minutes (2 hours and 30 minutes) of aerobic exercise each week and at least two days per week of muscle strengthening activities like lifting weights. [37]
- Older adults aged 65 or older with no existing medical conditions  should do at least 150 minutes (2 hours and 30 minutes) of moderate  exercise like brisk walking, and two or more days of muscle strengthening exercises. [38]
 
 
-         3 Stop smoking. Smoking harms nearly every organ in the body, damages your immune system and increases the likelihood for stroke [39],  heart attack, and lung cancer. Nicotine binds to hemoglobin in the  blood in preference to oxygen reducing its capacity to deliver oxygen to  each cell of the body. [40]In  addition, smoking exposes the body to carcinogenic chemicals and tar,  which results in an increase in infections by putting your immune system  into overdrive. [41]
 
-     4 Drink enough water. Water helps energize your muscles, improve bowel function, and balance your body's fluid levels. [42] You should drink 8 glasses of water every day.             - Avoid quenching your thirst with soda, alcohol, tea, or coffee, as these drinks actually dehydrate you.
 
 
-         5 Limit alcohol consumption.  When it is metabolized in the body, alcohol results in the formation of  harmful chemicals, which can destroy white blood cells. Alcohol also  decreases the absorption of many vitamins and minerals, adversely  affecting white blood cell count. [43]
 
-         6 Sleep for at least six to eight hours a night. Getting adequate sleep not only improves your mood and energy levels, it prevents strokes and helps you manage your weight. [44]Sufficient  deep sleep also helps the cells replenish and regenerate and is  therefore necessary if you want to maintain a healthy immune system. [45]
 
-         7 Get regular medical screening tests.[46]This will help catch illnesses early on so that you can get the most effective treatment. 
 
-     8 Be hygienic. Hygiene goes beyond looking and smelling  your best. Taking the proper precautions can help prevent the onset and  spread of infections or other illnesses.             - Wash your hands regularly with soap and water. This is help get rid  of any dirt, germs, or bacteria you may have picked up throughout the  day. You should wash your hands after using the restroom, before, after,  and while cooking food, after handling animals or animal waste, and  before eating.
- Shower daily. If you don't want to wash your hair every day, then  invest in a shower cap and rinse your body with soap and water. Use a  loofah or body sponge to remove excess dirt and dead skin cells.
- Brush your teeth twice a day, and floss every night. This will help prevent the gum disease Gingivitis.
 
 
-         9 Manage stress. Stress isn't just an emotion; it has  physical repercussions, and chronic stress can negatively affect your  immune system.Stress strains the body's resources, which can decrease  the function of your immune system. [47]        - Overcoming stress can be done in two ways, and will ideally involve a  little of both. Avoid the activities and people that cause you extreme  stress, if possible. While this will help, you must also learn how to  cope with the inevitable ups and downs of life in a healthy way. Spend  time doing relaxing activities like meditating, dancing, or having sex.
- If you think you have chronic stress, consider seeing a therapist or other professional to help you manage your condition.