M&S Remarksable White Pittas A natural source of Vitamin D and fibre, these pittas are best served warm with your favourite filling or dip. Toast or grill for one to two minutes. Suitable for vegans. Six per pack. All of our breads are a natural source of Vitamin D and Fibre, two nutrients that are naturally low in our diets. We use a natural source of Vitamin D that is produced by yeast, which is why you will find ‘yeast’ on our list of ingredients, not because we use it as part of the dough making process.