Fruit-rich diet makes obese and rotting animals at Melbourne Zoo

Selective breeding meant that the fruits we eat are so rich in sugar, the Melbourne Zoo had to wean its animals.

The fruit is vital in human nutrition and we all need to eat more. But at the Australian Zoo, guards discovered that fruit-based diets made some animals obese – and rotten.

"The problem is that the grown fruits have been genetically modified to have a much higher sugar content than their natural and ancestral fruits," said Dr. Michael Lynch, the zoo's senior veterinarian.

"It's interesting, having done a lot with nutrition here, I tend to eat less fruit."

Monkeys like bananas. But now, says Lynch, the zoo's primates are not getting any fruit.

For humans, fruit consumption is associated with reduced risk of coronary artery disease, stroke, obesity, stomach cancer and lung cancer, revealed a commissioned study by the federal government.

Despite the sugar content of fruits, increasing your fruit intake does not increase your risk of type 2 diabetes. Fruits contain important nutrients and natural fruit sugars are very different from "sugars" free "harmful soft drinks.

But the experience of the zoo is interesting for what it tells us about how agriculture has changed the fruits we eat.

"Almost all varieties grown at present are sweeter than their wild counterparts," said Dr. Senaka Ranadheera, a food science scientist at the University of Melbourne.

"For example, wild apples are smaller and more bitter than modern crop varieties."

Ranadheera said some fruits, such as plums, have almost doubled their soluble sugar content over the last 20 years (fruit sugar levels are still far from those of soft drinks or fruit juices).

And farmers have raised watermelons inside fleshy red when they are ripe. Wild watermelons have a much smaller edible interior.

Wild bananas are filled with seeds; in the varieties we pick up at Coles or Woolies, the seeds have been shrunk so small that they are almost invisible.

This has occurred over the decades, and in some cases even selective breeding.

"Through the ages, agriculture has promoted plants that are pleasant to eat, such as those that have less bitterness and sweetness," said Dr. Nenad Naumovski, a professor of food science at the University of Toronto. University of Canberra.

"It also masks the bitterness of the phytochemicals that this fruit has."

The Melbourne Zoo has traditionally fed its animals with a diet rich in fruit, said Lynch.

This caused a whole host of health problems, but it was also difficult for the guards to ensure that everyone had a balanced diet.

"The fruit is a highly sought-after product because of its sugar content, so many animals, including primates and red pandas, will eat the fruit selectively, but not other elements."

Like children, red pandas only eat fruits and bamboo.

Thus, the zoo now produces "panda granules" that contain all the vitamins and minerals needed for a red panda, mixed with a little pear. Pandas find them delicious.

Since Lynch started at the zoo, they have systematically replaced most fruits with green leafy vegetables. Lynch has done the same thing for her diet and is now trying to get as many green vegetables as possible.

The seals of the zoo have a different problem. If you freeze and defrost a piece of fish, you may lose some of the fish's vitamins. Guards must ensure that a lot of fresh fish is also available.

"A seal in the wild eats fresh fish, we feed them something that has been caught, frozen, thawed, and fresh is best for most things," Lynch said.