Is fresh always best?

Read the labels

Tinned tuna Be aware that there may be added sugar or salt in canned foods, and canned fish in brine contains far more salt than fish canned in oil. (The oil can also be drained off more easily than the salt.) You will also find that meat in cans is rarely British, which puts me off a little.

Considering the environment

Most canned food doesn't need costly airfreighting and, because it's not perishable, there's no wastage for the shopkeeper. The cans can also be recycled. Exotic fruits will probably be canned in the country they're grown in, providing local jobs, but the steel to make the cans may have been imported. Though the carbon picture is complicated, air-freighted fresh produce probably creates more carbon emissions overall than canned.

Best frozen

Alaskan pollack - Marine Stewardship Council-certified, it's a sustainable alternative to cod.
Black Forest or summer fruits have the health benefits of fresh, and out of season they're cheaper, too.
Broad beans are undervalued compared to peas. They're delicious and packed with nutrients. Spinach is great for a curry or quiche.
Cornish sardines from MSC-certified fisheries are British and very healthy.
Sea bass - posh fish at a reasonable price.

Best in cans

Artichoke hearts for risotto, pizza and salads.
Borlotti beans are hard to find fresh, and a handful makes a minestrone authentic. Cannellini beans for a cassoulet or salad. Chickpeas for a healthy dip or couscous.
Mandarin segments in mandarin orange juice. A bargain and perfect for quick puds. Mangoes for smoothies and lassi.
Sardines in olive oil - better value and healthier than canned tuna. Wild Alaskan pink salmon - look for MSC-approved. Good for super-quick fishcakes - just mix with mashed potato and spring onion.
Tomatoes are an essential storecupboard staple.