Lecture 7 Flashcards
Can our diet affect our behaviour?
Yes, although scientists were sceptical at first, it is know well known that there is a relationship. It can even be involved with abnormal behaviour/mental problems.
Discuss what Mackarness did with his wife in terms of diet
He started off by giving her safe food like carbohydrates. Slowly, he built this up until the wife’s behaviour changed. He then knew which food caused the behavioural change as it was isolated. Scientists now test this using an intravenous line in a lab.
Discuss the differences between food aversion and food intolerance
Food aversion is psychological and can involve psychological food intolerance.
Food intolerance is biological and involves allergies, enzyme defects, toxins and fermentation.
Discuss the media coverage of food affecting behaviour
Many claims are bold and lack evidence. For example, at one point people thought sugar causes ADHD. Some media articles claim that a lack of minerals increases one’s risk of cancer or that omega 3 improves brain health (it actually just improves development). The mail claimed that the phytonutrients in broccoli reduces one’s risk of cancer. However, the genetic engineering of broccoli has reduced the amount of phytonutrients as it makes the vegetable less bitter.
Discuss the Netherlands food famine
In 1944 there was a food famine. Mothers were consuming less than 1000 calories a day. They then measured the rates of schizophrenia of the people born during the famine. They found that the maternal food famine doubled the rates of schizophrenia. This was especially present in the female offspring. They compared these to base rates.
Discuss the development of recommended daily allowances
They emerged during WW2 and developed into everyday allowances. However, they are only guidelines as they’re designed for the average person. However, the average person is constantly changing, for example the UK on the whole are gaining weight. Also, it doesn’t tell us the optimum level of nutrition - e.g. if you have more than 5 portions of fruit/veg a day then is this better for you.
Discuss research about the effects of micronutrients
Micronutrients; vitamins and minerals. Macronutrients; protein, glucose, carbohydrates etc.
Benton did a double blind study. It consisted of 2 phases; food diary and analysis of diet, one group was given and vitamin C pill for 8 months and the other group weren’t. The results showed that the participants who were poorly nourished had increased IQ scores from the vitamin C. However, participants that were already nourished did not have increased IQ. This shows that nutrients only affect behaviour in certain circumstances.
Discuss diet and criminal behaviour
In Quolla India, there is a high incidence of family feuds and murder rates. Research has also found the same population also experiences extreme sugar cravings so there could be a link between the two.
Additionally, 2 studies have found similar things. One explored aggressive people and one explored prisoners. The participants completed a glucose tolerance test; fasting for 12 hours and then drinking a small glucose drink. Both studies found a strong relationship between the aggressive participants and hypoglycemia (falling glucose levels) as the levels dropped, aggression increased.
Why is it likely that glucose affects behaviour?
Because glucose is the main source of energy to the brain - increased carbohydrates increases energy for the brain. Therefore, many systems in the brain associated with behaviour are effected, e.g. emotion centres like the amygdala. Also, glucose response levels change constantly; time of day or age for example.
Briefly discuss the history of eating disorders
Eating is one of our core behaviours and therefore it can be argued that it’s the easiest to abuse. If this is true then eating disorders must have been around for a significant amount of time. There is evidence of bulimia during the Greek era and recordings of anorexia in the 1500s.
Discuss the possible causes of anorexia nervosa and bulimia
Biological: There is 50% concordance in MZ twins for anorexia and 30% for bulimia, this is significantly lower in DZ twins. There is also biological evidence for it; serotonin and dopamine receptors are involved.
Environmental: Stress during pregnancies, neglect and sexual abuse increase one’s chances of developing an eating disorder. Also, family attitudes towards food in general, e.g. Family dieting, can affect the likelihood of a child developing an eating disorder as they become more body sensitive.
Social/cultural: Some argue that they develop due to the perception of an ideal body size from the media, however, it doesn’t explain why only a few people develop eating disorders as a result. It is argued that people have a predisposition to developing an eating disorder, which makes one more sensitive to body size information.
Body dysmorphia like bigorexia can also result in one developing an eating disorder.
Psychological: It’s the most common cause of death rates among mental illnesses and as a result, it’s becoming easier to be diagnosed as they want to prevent death before it’s too late. Cognitive theories about the cause of eating disorders are the strongest, they believe that people over emphasise on eating, self esteem and perfectionism. People with eating disorders have a differences in their executive functioning. For example, people with eating disorders generally find it harder to switch tasks in the Wisconsin card sorting task, perhaps because they are pre-occupied with their extreme dieting behaviour so there are less mental resources for cognitive tasks.
Discuss obesity and binge eating
Although anorexia and bulimia are classed as psychiatric problems, obesity is just classed as a medical condition as it is presumed to be a choice. This is because they haven’t found associations between obesity and psychological problems and if the patients do have psychological problems then it’s just diagnosed as a problem affecting obesity.
However, there is a psychological condition called bing eating disorder which is similar to bulimia except without the vomiting/laxatives etc. There are specific factors that make it differ from obesity and only about 20% of those with obesity have binge eating disorder so it doesn’t explain the widespread problem of obesity.
Obesity has become a big problem recently as we live in an obesogenic environment; unhealthy foods are cheaper, we have evolved maladaptive brains that prefer fatty foods and our culture celebrates over-eating like man vs food. Obesity is caused by a positive energy balance, we eat more than we use. Also, our average portion sizes have dramatically increased, muffins have almost doubled in weight in the last 20 years so we have portion distortion.
Finally, the classification of obesity isn’t very good; usually BMIs are calculated (30+ = obese) but they don’t account for different body characteristics. A better test is to measure waist size as this is where a lot of fat is stored which can result in fat being stored in liver cells for example, which can then lead to disease.
Discuss Freidman’s work on mutant mice and food consumption
He removed the OB gene which produces leptin and found that the mice didn’t stop eating and they increased their weight 3 times more than their peers. This suggests that leptin is involved with telling the body when you’re full and when to stop eating. Leptin is also involved with telling the body when you’re hungry and when to eat. However, it’s hard to transfer this data onto humans as obese people tend to have high leptin levels which is contradictory of Friedman’s research. Some people argue that people are obese because they’re resistant to high leptin signals.
Discus Katz’s study
Previous research has claimed that zinc deficiency initiates anorexia and if it doesn’t then it is definitely an accelerating factor involved with it. Katz’s study found that anorexic patients had zinc deficiency and when given zinc supplementation, the patients’ levels of anxiety and depression significantly reduced. This suggests that maybe a lack of zinc causes depression which then accelerates the decline of the patient’s health.
Discuss Sinn’s study
They researched whether giving children with ADHD polyunsaturated fatty acids would reduce their symptoms of inattentiveness, hyperactivity and impulsiveness. The results show that polyunsaturated fats do decrease their symptoms, therefore, showing evidence for food affecting one’s behaviour.
