Nutritional needs can best be described as what through life

Nutritional needs can be described as Changing, through life
for Example :
When we are young, we could basically have no problem with our digestive system even if we do not fulfill our daily fiber need
But as we got older, we could no longer digest food as well as we're young, so we need to change our daily diet into somethings that have more fiber.

From the example above, we can see how our nutritional needs are changing throughout our life

It hurts for them at first then they get used to it