This is Dr. David
there is a lot of controversy about how to best improve the immune system. there are no good research trials to study what are the best ways to improve the immune system
really the best way to improve the immune system is to exercise regularly, eat plenty of fruits and vegetables, drink plenty of water, avoid smoking and drinking alcohol, and getting regular and plenty of sleep.
Astragalus is considered safe for most adults although its side effects are not known. the NMCD review concluded that doses greater than 28 grams might limit the activity of the immune system. I would not take more than 28 grams a day.
you need about 1 gram of L-lysine (amino acid) per day, according to NYU Langone Medical Center, but people who eat protein-rich diets tend to get enough without supplementation. you can get L-lysine through fish or egg whites.
Zinc has two standard dosages. The low dosage is 5-10mg, while the high dosage is 25-45mg. The low dose works well as a daily preventative, while the high dosage should be taken by anyone at risk for a zinc deficiency. I would take the low dose daily.
Vitamin C is best obtained through natural fruits and vegetables, like eating an orange a day.
men more than 18 years old should take about 90 milligrams of vitamin C daily. many vitamins and regimens recommend more which is not harmful. the body excretes excessive vitamin C out in your urine what you don't need.
To improve exercise performance and boost immune syste, five of the 400 milligram doses of echinacea have been taken by mouth four times daily for 28 days. that is 8000mg a day.
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