1. Eating Behaviour

2.  There are many factors shown to influence our attitudes to food. These include:  innate/evolutionary influences,  early learning experience  familiarity,  neophobia,  Parental attitudes,  weight concern,  cultural factors,  the food industry etc.

3.  Many factors influence our diet – psychological, social, cultural – showing that despite feeding behaviour having basic biological functions, it can be modified by many other influences.

4.  Babies are born with taste receptors for sweet, sour, salt, bitter and umami taste qualities.  This means that they can identify and distinguish between foods from an early age.

5.  They like sweet tastes – and sweet foods even reduce distress in babies. (Benton, 2002).  This suggests that we have innate preferences for foods that are genetically programmed.

6.  Widespread in the animal kingdom as a basic survival mechanism (avoids poisoning).  Neophobia is also found in babies and children although it decreases with age.

7.  Experience and familiarity increase food preferences.  Birch and Marlin (1982) found that exposure of 2 year-olds to a new food over 6 weeks increased preference for that food, a minimum of 8 – 10 exposures was necessary for the initial dislike (neophobia) to change to a preference.  Children learn that food is safe.

8.  The mother’s attitude to food is a strong influence on the child’s preferences.  If the mother is aware of health issues she will work harder to make sure her child has a balanced diet.  If the mother is less aware or less concerned over health issues such as obesity, she will take less care over the child’s diet.  There is a significant correlation between the diets of mothers and children (Ogden, 2007).  Parents, especially mothers provide key role models for the child.

9.  Once the child reaches school, peers become important. Studies have shown that modelling using admired peers can increase consumption of fruit and vegetables (Lowe, Dowey and Horne, 1998).  Throughout childhood children are also exposed to widespread food advertising on television, using peer models, animations etc. to make food seem more attractive. This can be effective in developing preferences, but unfortunately advertised foods tend to be high in fat and carbohydrates, probably contributing to problems such as childhood obesity.

10.  Used by many parents and based on operant conditioning, rewards consumption of a dislike food with a desired food –  ‘You can have some ice cream if you eat your vegetables’. Unfortunately studies have shown that while this technique may work in the short term it increases the desirability of the reward food and decreases liking for the non-preferred food (Ogden, 2007; Birch 1999). Similarly, punishing poor eating habits by denying access to a desired food simply increases the preferences for the desired food.

11.  Based in France  This study collected data between 1982 and 1999 on the food preferences of children aged 2 – 3 at nurseries.  Children were allowed free choice of a variety of foods and these preferences were recorded.  In 2002 the children and parents were contacted and invited to take part in a follow-up study.

12.  Correlations between food preferences at age 2-3 and at ages 4 – 7 were significant.  Correlations at later ages were not significant.  Preferences for cheese and, to a lesser extent, vegetables, remained fairly stable between ages 2 – 3 and 17 -22.  There was some increase in preference for vegetables with increasing age.  There were decreases in preference for meat products in females as they got older, but this remained fairly stable in males.

13.  Preferences in adolescence and early adulthood become influenced by exposure, for example to vegetables.  There may also be ethical concerns over killing and eating animals and health concerns (less meat and more vegetables) especially in females.  This supports a role for psychological, social and cultural factors in influencing food preferences in adolescence and early adulthood.  However, individual preferences at later ages were related to preferences at age 2 – 3, especially for cheese, and around 50% of foods in other categories, showing the importance of early experience.

14.  Food preferences at 2-3 years old were recorded from actual choices, but the follow-up study had to use questionnaires and interviews. These may not provide a completely accurate picture of food preferences, as participants may feel a need to present a ‘healthier’ view in their answers. Foods were also categorised into groups, so some data on individual foods might be lost. However, the results support previous research on the role of familiarity and social/cultural variables on food preferences.

15.  Attitudes to health  In the Western world there is increasing concern over diet and health.  Obesity is increasing, along with its associated risks of heart disease and diabetes.  There is growing awareness of the need for diets that are less fatty and include more fruit and vegetables, and this has led to many adults altering attitudes to food and changing their diets and those of their children (Ogden, 2007).

16.  Mothers dissatisfied with their body size or shape can pass this concern on to their daughters, affecting the girl’s attitude to food and feeding.  This can lead to eating disorders.

17.  Parents who are aware of the health consequences of poor diets may try to change the family’s eating habits. However, this depends on the knowledge of healthy diets, the motivation to change, and the time and perhaps the financial resources to put the changes into effect. Those higher up the socio-economic scale are more likely to be aware of healthy diets and try to follow them.

18.  The TV chef Jamie Oliver began a campaign in 2007 to improve the diets of young children and their parents, but the slow progress of this campaign shows how hard it is to shift established attitudes to food. In an age when both parents may be working, the availability of cheap fast food that is quick to prepare and easy to eat in front of the TV is a major problem in changing attitudes to food.

19.  Food has many other functions besides dietary ones, e.g. Religious functions.  Special meals on certain festivals, or ceremonial banquets at weddings. Providing meals can be an expression of love and caring, and the vast number of recipe books and TV cookery programmes shows the widespread interest in food and preparing meals. However, a key area concerns the emotional aspects of food and feeding behaviour.

20.  Hunger is associated with increased arousal, vigilance and irritability, while after a meal we feel calm and sleepy. More strikingly, studies have shown that people who are stressed or depressed increase the carbohydrate (especially sugar) and fat content of their meals (Gibson, 2006). This change is associated with better mood and more energy.  We also know that most people find sweet tastes (as in carbohydrates like sugar) pleasurable.

21.  The serotonin hypothesis:  Carbs such as chocolate contain the amino acid tryptophan.  This is used by the brain in the manufacture of the neurotransmitter serotonin. Low levels of serotonin are associated with depression and it has been proposed that people with stress or depression take in more carbs because it leads to increased levels of serotonin in the brain. This reduces their depression (Gibson, 2006).

22.  This increase in serotonin only occurs when we take in pure carbohydrates, which is extremely rare. The presence of even a small amount of protein, as in chocolate, prevents the tryptophan entering the brain and so serotonin levels will not change (Benton, 2002). The serotonin hypothesis is unlikely to explain the antidepressant effects of high carb diets.

23.  In the brain there are also opiate (or opioid) neurotransmitters.  Two examples are enkephalin and beta-endorphin. They are released from neurons and act at synapses with opiate receptors. As their name suggests, opiates (endorphins) are chemically very similar to the drug heroin. Heroin acts on these brain opiate pathways. Heroin is a highly addictive drug which can also produce pleasurable feelings and euphoria. Therefore, it seems likely that the brain’s opiate pathways are part of our reward system, a network of pathways that control our feeling of pleasure and reward.

24.  Is activated by natural rewards such as food and drink.  If the rewarding properties of food depend upon the opiate/endorphin system, then we would expect some interaction between opiates and feeding behaviour.  This is what we find (Grigson, 2002; Gibson, 2006)

25.  Opiate drugs increase food intake and increase the perceived tastiness of food.  Blocking the endorphin system with the drug nalaxone reduces food intake, especially in sweet foods, and suppresses thoughts about food. This shows that the system is involved in the feeding regulation.  Sweet foods increase the release of endorphins in the brain.

26.  We feel better after eating sweet carbohydrates as these foods in particular activate our natural reward pathways.  This effect would be more obvious in people with depression or those highly stressed, but even in normal circumstances sweet foods can improve mood.

27.  We are very efficient at learning associations between taste and consequences (e.g. Taste aversion learning).  This applies to positive effects as well – we learn to associate the mood-improving effects of carbs, especially sugars, with the sweet taste. So when we taste the food we have expectations about the consequences, and this applies to physiological systems as well.

28.  Glucose reliably improves performance on cognitive tasks. However, if people are given a glucose drink but are told it is a placebo (an inactive solution with no glucose), then the effect disappears. Our expectations override the actual intake of glucose.

29.  The sweet taste of a glucose solution immediately produces a release of insulin from the pancreas gland, anticipating a rise in blood glucose levels. This happens even with drinks sweetened with saccharine, a compound that is not processed by the body. However, we have learnt that sweet tastes usually mean glucose, so our body prepares itself. Anticipation and expectation on the basis of learning and experiences are vital parts of our feeding behaviour (Gibson, 2006).

30.  In some parts of the world, food is scarce and there are high levels of malnutrition and starvation. A second major effect of culture is the availability of different types of food. Eskimos live largely on seal meat because that is what is available.

31.  Although the globalisation of the food market means that even in remote communities food choice is increasing, at least in the sense that fast food is now available worldwide, differences are still found.  Wardle et al, (1997) surveyed the diets of 16,000 young adults across 21 European countries. In general the number eating a basic and healthy diet was low, with females doing better than males.

32.  People in Sweden, Norway, Denmark and Holland eat the most fibre; and those in Portugal, Spain and Italy eat the least fibre.  People in Italy, Portugal and Spain eat the most fruit, and those in England and Scotland eat the least.  People in Poland and Portugal have the highest salt intake, and those in Sweden and Finland have the lowest intake.

33.  People in these countries seem to have lower levels of heart disease and obesity than in other European countries.  Key differences are:  Use of olive oil (the fat in olive oil is unsaturated and thought to be healthier than saturated animal fats widely used in the UK.  High levels of fruit and vegetables  Moderate levels of cheese and other dairy products  Moderate levels of fish and poultry  Low levels of red meat  Low to moderate intake of wine.  In general, lower levels of processed foods and more natural products are used.

34.  Cultural differences are being reduced with the spread of highly processed fast foods with high saturated fat content.  Exposure of ethnic groups to new diets can have dramatic effects.

35.  Studies on the Pica Indians of New Mexico show that those who stay in their communities have low levels of obesity.  Whereas those who move areas are heavily influenced by American culture and diet and develop high levels of obesity.

36.  On the other hand, a series of studies by Leshem shows the persistence of cultural effects on diet.  He compared Bedouin Arab women living in desert encampments with Bedouin Arab women who had lived for at least a generation in an urban setting. He compared both with a group of Jewish women also living in an urban environment.

37.  The diet of urban Bedouins was hardly different from that of desert Beouins, with both groups differing significantly from the Jewish women.  Bedouin groups had a much higher intake of energy, especially carbs and proteins.  The Bedouin groups had significantly higher levels of salt intake (associated with the high fluid and salt loss as a result of living in the desert).

38.  This adaptation survives the move to an urban community with easy access to a range of foods.

39.  Compared diets of ethnic communities living close to each other in Israel with equal access to shops and food.  In the Muslim community the intake of carbs was twice that of the Christian group, and they also took in higher levels of proteins, fats and salt although the mean average body mass index was virtually identical.

40.  Cultural differences on diet are profound and persist even where there is equal access to the same foods.  These differences may originate in adaptations to previous environments, as with salt intake in the Bedouin people.  In some groups there are strict religious guidelines on what may or may not be eaten, and these will survive whatever the surrounding environment.

41.  Diet can show clear cultural variations, as Leshem’s work demonstrates. However, we cannot conclude that these are environmental or ‘nurture’ effects rather than inherited tendencies (‘nature’). Where groups such as the Beduoin have lived in the same environment for may generations, it may be that their diet today is a mixture of innate (genetic) factors and culturally transmitted preferences (nurture).

42.  A wide range of factors influence our attitudes to food and our eating behaviour, and it is impossible to say which ones are most important. You need to be aware of the different factors and the relevant evidence. Most importantly, you need to be aware that eating behaviour depends on early experience and learning, media, family and cultural influences, but also our biological requirements for a balanced diet.