Feature

Food Fads -- Food Follies

Is a high-fibre, cholesterol-free, non-dairy diet the answer to one's health problems? It may be for some, but for others it can pose a downright danger.

By Vicki Hyde, NZSM

Exhortations to adopt a healthier lifestyle are having a good effect on New Zealanders' eating habits and exercise patterns. They are also tending to encourage a whole host of food fads and fallacies which can present more of a danger than an "unhealthy" diet.

The recent Hillary Commission survey on life in New Zealand reported that two-thirds of New Zealanders have made their diets more healthy within the last year. Common methods were to reduce fats, eat more fruits and vegetables and eat more fibre, such as wholemeal products.

The commission also pointed out that there were common misconceptions about food and health. People incorrectly believed poultry to be much leaner than red meat and thought that margarine had much less fat than butter. It suggested that people need to be better educated about food per se, rather than about individual nutrients.

Pamela Williams goes along with that. She's had 30 years in the field of nutrition and is president of the NZ Dietetic Association. As deputy chairperson of the NZ Nutrition Foundation, she's been involved in the current campaign to encourage healthy eating habits, seeing it as a means of "putting some common sense back into food".

Food "Experts"

"Food is one aspect of [people's] lives that they can control and that they are `experts' in," Williams says. Unfortunately, changes in family lifestyles and a declining interest in food education has meant that few people really understand more than the basics of nutrition, she adds. Even the "real" experts have problems, she admits.

"It happens so often that so many of the nutrition trends come from epidemiological studies," Williams says. "It's easy to find an association using population studies."

The hard thing is proving a causal relationship. Williams recalls one WWII study in the UK where the health of the population was found to be directly related to the decrease in the number of silk stockings worn.

Spurious relationships and sweeping generalisations can cause real problems. In addition, people often take announcements of scientific research at the laboratory level and apply it to food on the plate.

"The science may be correct, but you can't necessarily translate it from the test tube to real life," Williams maintains.

Fibre Fallacies

The rise in fibre consciousness was one area fuelled by epidemiological studies. Population studies suggested that a high fibre diet improved bowel function and reduced bowel cancers. People were encouraged to increase their fibre intake by eating more grains and cereals.

"When we started saying `eat more fibre'...we were talking about adults," Williams states. Fibre was seen as being of particular benefit for overweight, under-exercised adults. Public focus on the fibre issue has meant it's spread a lot further, however.

Williams was dismayed to find one child care centre where the diet was bran cereals, wholemeal toast, raw fruit and nuts. Not surprisingly, she remarks, the children were suffering from diarrhoea as their gut could not cope with the large quantities of fibre.

"Caregivers are often scared into it rather than using their own common sense," Williams says. It can lead to what she has dubbed "malnutrition in the museli belt", with children failing to get adequate levels of proteins and easily digestible carbohydrates. The elderly are another group who can have problems with too much fibre. Ironically, "healthy" fibre can disturb their absorption of vital minerals, such as zinc.

Vitamin Hype

A great deal of money is spent each year in New Zealand on vitamins and dietary supplements. Much of it goes down the drain, say nutritionists, as most water-soluble vitamin intake is passed in the urine.

One can state quite emphatically that most people will derive no benefit at all from supplements, says the Nutrition Foundation. All the vitamins and minerals required can be provided by standard foods. They admit that it is difficult to combat people's perceptions of vitamins as a means of "balancing" the diet.

"How do you counter a Nobel Prize winner when he talks about Vitamin C?" asks Williams. Linus Pauling's advocacy of the vitamin as a cure for the common cold has gained a broad public following. There is no acceptable scientific evidence to back up the claims. This hasn't stopped 12% of the population taking it in one form or another as a supplement. The problem with taking large quantities of Vitamin C is that the body's biochemistry adjusts to cope with the massive amounts of ascorbic acid. Should the person stop, they often end up with the vitamin-deficiency disease scurvy beacuse their body has become reliant on the high levels of vitamin.

Vitamin B6 has been popularised as a treatment for problems associated with pre-menstrual tension. Again, there is no accepted evidence for this. The daily recommended allowance is 2 milligrams, but people have been known to take as much as 250 milligrams a day. In high concentrations, B6 affects the nerve endings, causing loss of sensation in the extremities.

Vitamin A is another vitamin often taken to excess. It can be easy to spot, as high levels of carotene tend to turn a person yellow. It's a fat-soluble vitamin, being retained in the liver, and people have died through excessive self-dosing.

"Many of them take supplements without knowing what the dangers are," Williams observes.

Allergies And Intolerances

"It's a fashionable thing to have a dairy food intolerance," notes Williams. Concern about fat in the diet and increasing emphasis on allergies has meant that more and more people are adopting non-dairy diets.

Cutting down on fat, such as through using low-fat milk, can be a good thing, but again there is a high degree of misinformation, according to Williams. True dairy allergies affect about 2% of the population, with milder intolerances often occurring for only short durations.

Williams has been particularly worried by a trend for pregnant and breast-feeding women to avoid milk. There is the "urban legend" that if they drink milk, their babies will contract dairy allergies. Williams was also disturbed to see non-fat milk given to geriatric and cancer patients in a local hospital. Most of these people were suffering from a wasting disease and needed the benefits of whole milk. Children, particularly under the age of five, need whole milk as it is an important source of calcium, vitamins A and D, and energy.

There is increasing interest in "raw", untreated milk as a "natural" product that is allergy-free. As with many health claims, there is no scientific evidence for any benefit from raw milk. There is, however, concern about the dangers of contamination in unpasteurised products. Although the provision of raw milk and raw milk products is illegal, they are appearing more often on health food shelves.

One study in the UK recently looked at people's allergic reactions. Drops of distilled water were used to test allergic reactions and, when the subjects were told the water was a substance to which they were allergic, an allergic response resulted. Allergy testing has become a big business in the UK and looks set to do well in New Zealand.

Health Concerns

Dietary changes are often espoused  -- sometimes correctly, sometimes not -- as a means of reducing the chances of suffering from allergies or a range of diseases. New Zealanders are eating fewer saturated fats than they were ten years ago and, partially as a consequence, are suffering less from heart disease.

Considerable attention has been paid to the high cholesterol levels of New Zealanders. Numerous campaigns have been run to get people to reduce their cholesterol intake. This has succeeded to a certain extent. The Hillary report shows a "very large reduction" in the average person's cholesterol intake. It also notes that the role of dietary cholesterol remains controversial. Recent findings suggest that genetics, obesity and exercise are more significant factors that diet in determining an individual's cholesterol levels.

The reduction in heart complaints has meant that cancer has become the most common killer. It is thought that diet is a contributing factor in about 35% of all cancer deaths, and is particularly associated with bowel cancers. Some popular diets label certain foods as "bad" for the health and others as "good". Williams is quick to dismiss these claims.

"All food in moderation is healthy food," she says, citing the main theme of the nutrition campaign.

Health Fraud

As a member of the National Council Against Health Fraud, Williams is familiar with many of the claims put forward by health food advocates.

"Somebody is making a lot of money out of people's insecurity and lack of knowledge," she says. She cites the case of "pond scum" --  spirulina alga-based supplements. It would cost over $200 and take 3.5 kilograms of the alga to reach the recommended daily allowances of vitamins and minerals, she states.

"Unfortunately the community doesn't have the scientific background or evaluation to make an informed decision," Williams maintains. As such, they can be vulnerable to claims clothed in technical language uttered by people of apparent learning. Often scientific language is teamed up with traditional jargon -- "free radical scavengers and organ builders" -- to provide a semblance of medicinal standing.

It's not just limited to alternative approaches. Nutritionists have been amused to see avocados touted by their marketing authority as a "cholesterol-free" fruit. Avocados are indeed cholesterol-free, but they also have a high fat content.

A less amusing matter has seen the NZ Dietetic Association protest the appointment of a naturopath to the West Auckland health district. The association was concerned at the use of public funding for non-qualified alternative practitioners, particularly given that the naturopath was to provide nutritional advice. It warned of cases where dubious alternative practices had led to people requiring hospitalisation.

Willaims concedes that sometimes alternative approaches have validity, in that many problems respond to time and the placebo effect.

"What concerns me are people, and particularly children, who do not have control over their lives," she adds. Children and elderly dependents often have no choice in following family food habits. When those habits are based on misconceptions or misinformation, they can suffer unnecessarily.

Vicki Hyde is the editor of New Zealand Science Monthly.