This will only yield a tiny speed boost, but every little helps. If you declare a field as having an Age field of type INT, this query is in fact valid:
UPDATE table SET Age = "1"
The query states that Age should be set to the string value "1", not the number 1. However, MySQL will recognise that Age should be an integer, and automatically convert the string "1" to the integer 1 before updating the table. This type conversion is indeed very helpful, but, as we already knew that Age was going to be an integer, we could have saved MySQL some pointless work and not used the quotes.