Children, pregnancy and older adults
Growing children can be vegetarian with planning - protein, iron, calcium and energy density need attention. GP or dietitian advice is sensible if you are excluding whole food groups.
Pregnancy needs folic acid, iron, iodine and B12 planning - start supplements as your midwife or GP advises, not when you remember at month five.
Older vegetarians may need more protein to protect muscle - do not let appetite shrink to toast and tea alone.
Iron, B12, iodine and omega-3
Plant iron (beans, lentils, spinach, fortified cereal) is less easily absorbed than meat iron. Pair with vitamin C in the same meal - tomato sauce on lentils, pepper in a bean salad, citrus with fortified cereal.
Vitamin B12 is not reliable from plants alone. If you eat dairy and eggs regularly you may get enough; vegans need fortified foods or supplements - discuss blood tests with your GP if tired or tingling.
Iodine comes mainly from dairy and fish in UK diets; vegetarians who avoid dairy should consider iodised salt or fortified plant milks. Algae-based omega-3 supplements may suit people who do not eat oily fish - ask your GP if pregnant or on anticoagulants.