[cypher]

If they can still eat their dry mix I also only give any soft foods like baby food or porridge about once a week as a treat.
They don't really need any extras but variety is always good so fresh veg each day varying it as much as you can will give a bit of a boost & I find they seem to enjoy their veg even more as they get older. That will help give more micronutrients without giving too much fat or protein, I tend to cut back on protein too as they get older.
If your hams fur begins to lose condition some extra flax seeds can make quite a difference.
I haven't really noticed any real problems with a weaker immune system but if you're concerned you could give a probiotic.