Fruit vs veggies: good or bad for you?

An interesting find was recently reported in the press regarding attractiveness of a range of items to a group of very young babies. The Telegraph reports that two American behavioural researchers have examined young babies preferences when reaching for organic and non organic items.

What the study reports is that the young participants showed a significant preference for artificial non-edible things like keys, pipe cleaners and spoons.

What they found was that there was a measurable hesitance in reaching for a stem of nutritious broccoli or a piece of celery.

What is the reason for this observed behaviour?

The researchers, Dr Annie E Wertz and Dr Karen Wynn at the Department of Psychology at Yale University, discuss the possibility that what they were observing was an adaptive behaviour similar to the yuck factor most people experience when they see a spider or a snake.

Primates have co-evolved with their food plants over eons and this co-evolution has matched the defenses of certain plants to behavioural changes in herbivores or omnivores like us. The change in behavour that the plants have forced upon us serves to protect green plants from over grazing thus promoting the spread of genes of the plants over the surface of the earth.

Plants are devious in their defenses against herbivory but sometimes a mismatch between defense and attack in plants and animals occur. A good local example being introduced trees of Northern hemisphere origin in our gardens in Melbourne and Sydney that are over grazed by possums.

Here is an example of an animal herbivore, the possum, that has been isolated from the Northern hemisphere trees for 90 million years since the Australian continent separated from Antarctica and South America and thus developed totally different response to plant defense mechanisms.

The trees are essentially defense less against the possums which have tough digestive systems used to survive on the leaves of native trees full of nasties and the introduced European and North American trees succumb to grazing especially when the trees are stressed by prolonged drought.

It would have been interesting if the researchers repeated the same experiments with brightly coloured fruits which are appealing to the adult eye and palate.

Do the human young reach for the fruit? The bright pigments in fruits and berries being natural anti oxidants and thus health promoting. Evidence has benn found that anitoxidants llike anthocyanin are actively protecting humans that ingest them from the ill effects of heart disese and different form of cancer.

Tomatoes are brighly coloured and contain lycopene which has been claimed to have health benefits. In a recent study on the basis for aerthosclerois a group of researchers at the Unviversity of California in LA found that Low Density Lipoproteins or 'bad' Cholesterol which was thought to be packaged and excreted form our livers actually is produced and formed in the small intestine of us humans. In additon they discovered another culprit in the Cholesterol saga , lysophosphatidic acids (LPAs), and evidence for LPAbeing a major culprit in the inflammatory process of the walls of the arteries that lead to heart attacks

Addition of parts per million of LPAs in the diet of mice made them produce the same amount of LPAs as if they were given a high fat high cholesterol diet. LPAs seemed to be very powerful upregulator of molecules associated with heart disease. Interestingly the LPAs were down regulated by the additon of a short peptide from the HDL 'good' cholesterol complex.

The researcher reasoned that for humans and mice to be more willing to eat the peptide that lowered LPAs it should be presented as brightly colored tomato puree or ketchup.The researchers engineered Tomatoes that expressed the peptide and ground them up and freeze dried the resulting paste which was reconsittuted into GM tomatto puree and fed to mice.

The mice that were fed the GM Tomatoes showed a significant reduction in LPAs which correlated with less cholesterol beign deposited in their arteries.

The control mice that were fed GM free tomatoes showed no effect on LPA.

The next step is obviously human trials with the GM tomato puree with proven health benefits in mice. So colour of food and health in this case will hopefully be correlated and scientifically proven. It is also an interesting example where a clear helath benefit is engineered into our food. Will this be acceptable to the consumer? The anti GMO lobby will probably reject it.

The above raises the question if there has been another co-evolution between plants species that promote herbivory of their large coloured fruits containing tough seeds that can be spread by animals?

If this is the case we have here two very different co-evolving responses in primates to non-edible and edible plants – for green plants where the edible parts are the shoots and thus need some protection against herbivory and for red or orange coloured fruits like tomatoes and apples that requires to be eaten by herbivores and spread wide and far ensuring the germination of the seeds contained within the fruit , increasing the reproductive success.

Then one can also speculate if the coloured pigments in the different plants are acting as signals to primates like us in the approach –avoidance behaviour that our young seems to have inbuilt for particular foods but need to learn for more complex social interactions to ensure that our genes are given the best opportunities to spread through compatible matings.

The naturally occurring pigments have been purified and are sold as nutritional supplements in our health food stores but the fascinating coupling to co-evolution of the source of these nutraceuticals and us has until recently been a field of research that has been under funded and under researched.

Here is an empty knowledge space that urgently requires some more research. And if Australia wants to be the future food bowl of Asia I suggest that it would be a good place to start.

Proving the increased health benefits of the food we grow here down under is very important if we want to build our reputation as the producer of health promoting foods and become the first choice for Asian markets.