Nutritionist: kiwi isn't just vitamin C - the enzyme actinidin helps the body break down protein

We usually remember kiwi for its vitamin C. Dietitian-nutritionist Salena Sainz points out that this is only the beginning. One kiwi contains fibre, vitamin C, folate, potassium, vitamin K, carotenoids, polyphenols and other antioxidants - quite a workload for one small fruit in a fuzzy skin.

Actinidin - the enzyme few have heard of. Kiwi contains a proteolytic enzyme that helps break down proteins and can make digestion easier. If you feel heavy after a pastrmajlija, the meat-topped Macedonian flatbread, or a big Sunday lunch, this is the fruit that, on paper at least, has a job to do.

Digestion. Insoluble fibre adds bulk to stool, while soluble fibre holds water and softens it. Clinical studies, the expert notes, link eating kiwi regularly with more frequent bowel movements and partial relief from constipation. But it is not a miracle in a skin: water, exercise and a diet with other fruit, vegetables, legumes, nuts and whole grains matter just as much.

Immunity and heart. Vitamin C contributes to normal immune function, and potassium, fibre and antioxidants fit into a heart-friendly diet. Sainz chooses the word "contributes" carefully - she does not claim kiwi cures anything. That distinction is one many supplement ads skip right over.

Diabetes. Kiwi has a moderate amount of carbohydrates and a relatively low glycaemic load per normal portion, so it can fit into a diabetic diet - with attention to portion size and to how each individual's blood sugar responds.

When and for whom. There is no ideal time - at breakfast, as a snack or as dessert. It does not have to be every day either; it can be swapped with other fruit. People allergic to kiwi should avoid it, and those allergic to latex should be careful because of a possible cross-reaction. In some people kiwi also causes stomach upset, so tolerance is individual.

The message at the end is the opposite of the one "superfoods" sell: one kiwi a day is an easy way to get fruit, fibre and micronutrients in, but it is not mandatory, and the effect depends on everything else you have been eating for months.