Two kiwis give you more than a full day of vitamin C.
Actinidin breaks down protein, so it helps a meat-heavy meal settle.
It is the fruit most likely to cause mouth itching in people with latex allergy.
Kiwi reached Iranian orchards in the 1980s and took to Gilan and Māzandarān so well that Iran is now one of the larger producers in the world. It is a winter fruit here, picked in autumn and stored through the cold months. Two of them carry more vitamin C than an orange, and they hold an enzyme called actinidin that breaks down protein, which is why the fruit is eaten after a heavy meal rather than before it.
Known to botanists as Actinidia deliciosa.
Chapter 2 of 12
Why It Matters
Constipation is one of the most common complaints after 60 and most answers to it come in a sachet. Two kiwis a day worked as well as psyllium in a proper trial, and people stayed on it because it's fruit.
Two kiwis a day is one of the few dietary habits with a proper randomised trial behind it for constipation, and constipation is the complaint that quietly shapes an older person's whole day. The vitamin C also helps iron absorption at an age when iron often runs low.
The vitamin C content is among the highest of any common fruit, which matters for immunity and for collagen.
It was used: the fibre softens stool and speeds up a slow bowel. It supplies vitamin K and folate at an ordinary portion.
Chapter 3 of 12
Traditional Persian Perspective
Persian temperament: Cool & Moist (1st degree). Cooling and softening. Iranian practice pairs it with cinnamon or cardamom for people who run cold in winter.
It was used: introduced to Gilan and Māzandarān orchards in the 1980s from New Zealand stock. Adopted quickly by Iranian herbalists as a cooling, bowel-softening winter fruit. Now one of Iran's significant fruit exports, sold mostly to the Gulf and Central Asia.
Kiwi is on the Gilani fruit plate and in the Tehran winter fruit bowl, sliced beside orange and pomegranate. It has become one of the country's export crops, which is a short journey for a fruit nobody grew here forty years ago.
Chapter 4 of 12
What It Contains
Primary compounds
Actinidin is a protein-digesting enzyme, the same class of thing as the papain in papaya.
Vitamin C sits around 70 mg per fruit, higher per gram than orange.
Lutein (a yellow pigment linked to eye health) and zeaxanthin are the pigments that collect in the retina.
Soluble and insoluble fibre together hold water in the stool, which is what the constipation trials measured.
Other notable constituents
Minerals: Potassium, Copper · Antioxidants: Polyphenols (protective plant compounds) · Fiber: About 2 g per kiwi, in the flesh and the edible seeds
Chapter 5 of 12
In the Laboratory
From laboratory work, not from people taking it
Kiwifruit eaten with a meal increased protein digestion in the stomach in a laboratory model. Rated: early research.
Chapter 6 of 12
What Studies in People Show
What studies in people show
Two green kiwifruit daily improved stool frequency and comfort in adults with functional constipation, comparable to psyllium.Moderate evidence
Three kiwifruit daily modestly lowered blood pressure in adults with mildly raised readings.Emerging evidence
Chapter 7 of 12
Preparation and Kitchen Use
Halve and scoop with a spoon, the fastest way to eat one.
Peel with a vegetable peeler and slice into rounds.
Eat the skin if you can: rub the fuzz off and it doubles the fibre.
Add to a fruit salad last, because the enzyme softens everything it touches.
In the kitchen: two green kiwis after dinner for a slow bowel. Sliced over yogurt with honey and walnut; blended into a smoothie with banana and mint.
Chapter 8 of 12
What It Goes With
Dairy:
Yogurt
Slice it in just before eating. Leave it standing and the enzyme turns the yogurt bitter.
Pairing:
Walnuts
Fat and crunch against soft, sharp fruit. Both are Gilani. Which isn't a coincidence.
Fruit:
Orange
Two winter fruits on one plate, and between them a whole week of vitamin C.
Honey:
Honey
A little honey takes the edge off a kiwi that turned out sharper than you hoped.
Chapter 9 of 12
Who Should Be Careful
Allergy:
Kiwi is one of the main triggers in latex-fruit allergy. If bananas or avocados make your mouth itch, be careful with the first one.
General caution:
The enzyme that helps digestion also curdles milk and dissolves gelatine. Keep kiwi out of any dessert you want to set.
General caution:
It is acidic enough to sting a mouth ulcer or an irritated stomach.
Allergy:
Known kiwi or latex allergy.
Chapter 10 of 12
Medicines and Interactions
Medication interaction:
Warfarin — Kiwi carries vitamin K, which opposes warfarin. Steady weekly intake is what matters; tell your clinic if your habit changes sharply. (moderate concern)
Medication interaction:
Blood pressure medication — A small trial found a modest pressure drop with three kiwis a day. Additive rather than dangerous. (low concern)
Chapter 11 of 12
Pregnancy, Children and Older Adults
Pregnancy and breastfeeding
Pregnancy and breastfeeding:
Safe and useful. The folate matters early, the vitamin C helps you absorb iron from plant food, and the fibre answers the constipation that most pregnancies bring. Wash the skin before peeling.
Children
Children:
Fine from about a year, mashed or in small pieces. Kiwi is one of the more common fruit allergies in young children, so introduce it alone and watch for a rash or mouth swelling the first few times.
Older adults
Medication interaction:
Soft, needs no chewing, and does something no other fruit on the plate does for a slow bowel. Anyone on warfarin (a blood-thinning medicine) should keep the amount steady from week to week rather than stopping and starting.
Chapter 12 of 12
Through the Year
Why does kiwi ruin jelly?
The actinidin digests the gelatine protein and it never sets. Cook the fruit first, or use agar instead.
Spring:
Spring
Stored fruit from the autumn harvest is still sound but softening. Use it in smoothies.
Summer:
Summer
Out of season in Iran. Imported fruit is expensive and unremarkable.
Autumn:
Autumn
Harvest. Caspian kiwi comes in from Ābān and is at its best straight from the orchard.
Winter:
Winter
The season on the table. This is when kiwi belongs in the fruit bowl beside orange and pomegranate.
