Can a gym going boy of 17.6 old, take protein powder ?

Can or should? If you have a well-balanced diet, I find the use of such supplements a waste of money. A smoothie made of egg whites is a simple home-made supplement that has as much value as most expensive powders. You can take it at that age if you wish. Much of the content that is not needed is converted to stored carbs or fat.

Agree with Dr. Ferguson. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV vaccine. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines