Geoffrey Savage
14th February 2007
On a recent trip through the United States, I noticed the following sign fixed to each table at the outside pizza restaurant at Camp Curry in Yosemite National Park, California.
“Why is it bad to feed the animals? Eating human food is not healthy for wildlife as their bodies don’t adjust well to the salt, fat and preservatives often found in our food. They gain weight and lose their fur and become dependent on human food. In addition, predators such as mountain lions are attracted to areas with a concentration of well fed squirrels and raccoons.”
Is there a message here? Is human food, especially pizzas, good for us? While we can’t blame the general increase in the nation’s body size to pizzas alone, we can say that as a nation we are eating too much and that we are eating an unbalanced diet unfit for wild animals.
Sometimes we hear people say “well mankind has become adapted to a high fat, high salt, high sugar diet.” There is no evidence at all that our digestive or metabolic systems have changed over the centuries. We have undoubtedly changed our diet drastically and there is good evidence that we are not coping with our modern food.
By adapting to a new diet these people mean that there has been a change in our digestive or metabolic systems. These changes are only possible by selective breeding. Human reproduction is not selective in this sense. People do not choose a mate on their capacity to cope with high salt or high fat diets. Other forces are at work. Farmers understand selective breeding. Animals with positive features are allowed to breed allowing the possibility that these good traits will be found in the offspring. Animals that are unproductive or cannot cope with modern farming systems are eliminated.
It is interesting to note that humans develop health problems from poor nutritional habits. They can become overweight, develop diabetes and hypertension and suffer heart problems in later life. By this time their own children have probably already been born so, even if it is possible, it is too late to select a mate who can cope better with the modern diet we choose to consume. There is no selection for good health traits related to nutrition in humans. We are not adapting to our modern diet so we are suffering its consequences.
So while we should consider the dietary needs of wild animals it is even more important that we should take care of our own diets to protect our long term health.
Salt, the first item on the not-to-feed to the wild life list, is essential in the diet but on average we eat 6g salt per day (a level teaspoonful). This is at least two and a half times more than we need. Excess salt consumption can lead to an increase in blood pressure. People with high blood pressure are three times more likely to develop heart disease or have a stroke than people with normal blood pressure. The problem is that most of our salt comes from processed foods. It is possible to make a nutritious and tasty pizza containing less fat and salt, but so far we are not in the habit of requesting one when we go to our local pizza parlour.
In many countries around the world, including New Zealand, food manufacturers are being encouraged to slowly reduce the salt content of their processed foods. The worry is that if the salt level in processed foods is reduced then people will increase the amount of salt added at the table. In fact adding of any salt to a meal at the table is usually unnecessary.
Perhaps there should be a warning notice fixed to every dining room table to help us protect our health.
Professor Geoffrey Savage is a Food Biochemist at Lincoln University.