There are various causes for dandruff;
1. Improper/ Poor diet.
2. Chemicals in products.
3. Stress.
4. Extreme weather conditions.
5. Health problems.
Remedies to treat dandruff;
1. Coconut oil has antibacterial properties and is great for hair.
2. Olive oil promotes healthy scalp if used regularly.
3. Apple Cider Vinegar helps clearing the dandruff effectively. Dilute apple cider vinegar with water and spray on scalp generously. Let it sit for an hour and wash with mild shampoo. It truly works like a charm; I use it all the time.
4. Lemon juice is great too. Use lemon juice on scalp every other day for good results. Wash hair after half an hour.
Hope this helps.