A question about breastmilk

[mummalish]

I would like your opinion on this... Which is better - formula, or breastmilk from a woman who has a poor diet?

Do you think that breastmilk is still the best drink for a baby if the mum does not eat or drink well?

Breastmilk is always advised to be the best for your baby, but was just wondering how a poor diet can affect the quality of milk, and would formula sometimes be the better option?

Would really value your opinion on this.