Dietary supplements are considered as an adding anything to a person regular diet which is mainly improving persons health.

Here's some dietary supplements example:

Glucosamine 

• Green tea 

• Vitamin C 

• Vitamin D

• Zinc

• Iron 

• Turmeric

•  Fish oil 

• Omega 3 fatty acid

• Testosterone Boosters 

• Branched chain amino acids 

• Ginkgo 

• Ginseng