Update with Dr Alan Barclay
The bountiful benefits of fruit.
Whatever your beliefs are about the origin of human life, one fact is relatively common to all. Be it from the trees in the Garden of Eden or the berries and fruits consumed by our ancient hominid ancestors – the first solid food consumed by our kind was fruit.
In today’s increasingly obesogenic environment, it’s refreshing to know that most fresh fruits have a low energy density due to their high water and dietary fibre content. This means that for most of us, it’s hard to over eat fruit – it fills us up too quickly. Indeed, dietary guidelines recommend that adult men and women eat at least two serves of fruit each day. A serve is:
- 150g/5oz of fresh fruit (1 piece of a medium sized fruit or 2 small), or
- 150g/5oz of diced, cooked or canned (not in syrup) fruit (1 cup), or
- 30g/1oz of dried fruit (a small palm full)
In most fruit, carbohydrate is the primary source of energy. Fruit contains a mixture of sucrose, glucose and fructose and a small amount of starch, in varying proportions between the many different varieties. Despite some peoples concern about the fructose content of fruit, it’s important to note that on average, total fructose (from fructose and sucrose) makes up about half of the total carbohydrate in fruit: a typical serve of fruit contains around 17g of total carbohydrate, and 8.5g of total fructose. Most fruit is a good source of fibre, containing on average around 4g per typical serve.
What about glycemic index? Temperate climate fruits like apples and pears, berries, citrus fruits and stone fruits all have low GI values as do bananas. Some tropical fruits and melons have moderate or high GI values, but their glycemic load tends to be low because they are low in carbohydrate. Dried fruit counts, too. But remember drying not only concentrates the flavour, it concentrates the calories, so a little goes a long way. You can check out the GI values of your favourite fruit in the GI database or in The Shopper’s Guide to GI Values. A range of fruits are certified as low GI by the GI Foundation including, apples, pears and grapes.
Nutrition There are many good reasons why fruit is such an important part of our diets, both past and present. Most are a good source of the water soluble vitamins, in particular vitamin C, with around 28mg per typical serve, which is just over half Australia’s Recommended Daily Intake (RDI) of 45 mg per day. They also contain small amounts of important B group vitamins including thiamine, riboflavin, niacin and folate along with the minerals potassium and magnesium. And with the notable exceptions of avocados and olives, fruit is also low in fat and sodium.
Health benefits With so much goodness packed into a relatively small package it is perhaps not surprising that daily consumption of moderate amounts of fruit (at least 2 pieces) is associated with the prevention of heart disease, stroke, certain cancers (mouth and upper digestive tract), obesity and weight gain.
Sadly, most of us don’t eat enough – the most recent Australian National Nutrition Survey found for example that less than half of average adults eat two or more serves a day. This is one instance where most of us need to be eating more, not less…
For more information about the GI Symbol Program
Dr Alan W Barclay, PhD
Chief Scientific Officer
Glycemic Index Foundation (Ltd)
For more information about GI testing in Australia
Research Manager, Sydney University Glycemic Index Research Service (SUGiRS)