Bear in mind that nutritionalists aren't necessarily qualified, while dieticians are.
I think fresh, local produce is your best best.
That Fawlty Towers quote reminds me of a pizza chain. They used to advertise that they used tomatoes straight from the can. If you work out who they are, don't ever order from them, BTW. In fact, I don't recommend eating from any of the pizza chains, including the one you can dine in with and buy their pizzas now from the supermarket. For hygiene reasons. Trust me. They are sick b*stards, you don't know what they've done to your food. As for that chain, I'm not the only one who has experienced unhygienic objects that should not be in their food...
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I've left WP.