A high protein, low carbohydrate diet is generally indicated for people with O+ blood group.
People with this blood group tend to have an under active thyroid. Foods like corn, potatoes, Brussels sprouts, cabbage, cauliflower, eggplant, mushrooms, soybeans, avocados, coconut, kidney beans can further lower the thyroid functioning.
O+ blood group types tend to suffer from hyper acidity, hence fruits which have alkaline property should be consumed more. This includes berries, plums, pears, bananas, carrots, cucumbers and celery. Fresh fruit juices containing these elements can be especially beneficial to the type O diet.
Their metabolism can often be slow, hence dairy products should be used moderately. Cashews and peanuts should also be used sparingly. However walnuts and pumpkin seeds can be taken.