There are a number of things you can do to strengthen your immune system. One of these things which may seem basic, is getting enough vitamin C in your diet. I remember as a kid, my mother giving me the constant reminder to drink my orange juice or I could get sick.
After reading several chapters in the book "The Disease Delusion" by Dr. Jeffery Bland (great book, I'd highly recommend it), my mother's reminders again came to mind as he discussed the immune system and vitamin C.
How much vitamin C the body requires for optimal health and what the daily recommended intake of vitamin C is are two very different questions.
Many people believe that meeting the daily recommended intake for different micro- and macro-nutrients is appropriate. The issue here is that the recommended daily doses are typically based on what a person with an average height, weight and age would require. Unfortunately most people do not fall into this category and utilizing this method to determine a "recommended daily dose" for a given nutrient becomes extremely flawed.
Additionally, the recommended daily intake as Dr. Bland puts it, is "how much vitamin C one should consume regularly to avoid developing the nutritional deficiency disease called scurvy". It does not take into account how much vitamin C should be consumed to have optimal health - just "average" health. The thing is, you don't go from being symptom-free one day to having scurvy the next. People experience symptoms of varying degrees of severity and frequency based off their nutritional intake. Regularly catching the common cold is good sign your immune system may not be effectively doing its job. A lack of vitamin C in your diet may be contributing to your weakened immune state.
Currently the recommended daily intake for vitamin C if 90 milligrams for the "average" 19 year old man and is 75 milligrams for the "average" 19 year old woman. Dr. Mark Levine has done much research on vitamin C intake at the National Institutes of Health. His findings have shown that most healthy people can increase their intake of vitamin C to 1,000 milligrams daily. At that point, the body's stores of vitamin C would then become saturated and additional vitamin C intake would then be excreted from the body. When you are sick your turnover of vitamin C is increased so you're able to take even more vitamin C than previously mentioned without saturating your system.
So how can you increase your daily vitamin C intake? Although there are vitamin C supplements out there, vitamin C can be found in many common fruits and vegetables. The veggies that pack the biggest punch of vitamin C are peppers, broccoli, cabbage, brussels sprouts, and snow peas. The highest vitamin C content in fruit are found in guava, papaya, kiwi, oranges, lychee, strawberries and pineapple.
Strengthen that immune system!