Biology Symposium
Sixth Former Tia O’Kelly writes: On Wednesday 22nd September, Sixth Form Biology pupils attended a series of lectures on the topic of nutrition. The symposium was titled ‘Are We What We Eat?’ and four lecturers gave their take on the question.
The first speaker was Dr Peter Scarborough with his lecture on ‘Diet, Health and Sustainability’. Dr Scarborough’s lecture was particularly insightful on the topic of linking poor diet with disease, and also how one’s diet affects the planet. Scarborough first outlined diseases caused by poor diet, including an extensive list caused by obesity alone. Obesity can increase the risk of over 15 diseases, 9 of which are cancers. I also learnt that diet is responsible for more diseases than smoking at a population level (since the number of people smoking has dropped to 1 in 5). Diet is multifactorial, as illustrated by the government’s ‘Eat well Guide’ found on the NHS website. However, the studies Dr Scarborough discussed showed that fruit and vegetables reduced the risk of stomach cancer, heart disease, coronary disease and many other diseases, whilst large quantities of, meat proved to be not only detrimental to our health, but also the environment. Mass-producing meat and other crops cause a cycle producing an unsustainable amount of greenhouse gas emissions. About 25% of greenhouse gas production is from farming before the produce has even left the site. Ruminants (cows and sheep) produce the most greenhouse gases per kg. Dr Scarborough also illustrated some data that suggested over 5 million deaths would be avoided by 2050 with a low meat diet.
Dr Jamie Hartmann-Boyce’s lecture on ‘Adjusting lifestyle’ explored the options for changing people’s attitude to food, and some of the challenges that presented themselves when attempting to implement them. Dr Hartmann-Boyce discussed the techniques already in place that raise awareness of nutrition, including the traffic-light colour-coded labels; however, he then went on to suggest presenting this in a more effective and understandable manner. For example, a label on a can of coca cola states that it includes 50g of sugar, which doesn’t sound like an excessive amount, until it’s illustrated as 9 teaspoons. Dr Hartmann-Boyce also suggested portion control by companies; changing supermarket lay outs to encourage healthy choices; and taxation on companies that produce products with sugar/salt contents over a certain limit. Some possible suggestions up for debate included rationing, a more controversial option. Rationing would include restrictions on foods that are particularly detrimental to health, and whilst this could reduce the abundance of diet related diseases, it could also be seen as a restriction on freedom.
Dr Andrew Walley who discussed the ‘Genetics of Obesity’ started the afternoon lectures. Dr Walley also mentioned the environment – but for a geneticist the environment is everything that isn’t the person in question. The environment that causes obesity included energy dense foods combined with low physical activity. A gene is a DNA sequence that carries instructions. Genes make up 2% of the genome and even the slightest changes can cause disease. However, Dr Walley illustrated how both genes and the environment cause obesity. 20-30% of the population in Britain is obese, however the majority of these cases are common obesity, in which there is no inheritance, and is caused mainly by the environment. Monogenic obesity (a single gene disease) is rare, with a clear inheritance pattern. In this case the environment is irrelevant. Monogenic obesity is caused by a deficiency in the production of Leptin, which goes on to cause significant weight gain. Dr Walley backed up his lecture with evidence from a twin study (looking at both identical and non-identical twins) showing that 70-80% of body shape is genetically determined.
Dr Michael Moseley gave a fascinating insight to his 5:2 diet, and how fasting could be beneficial to our health, and even a means of weight-loss. This 5:2 diet consists of eating normally 5 days a week, and fasting (eating 600 calories or less) for the other two. Studies found that this caused significant weight loss due to reduced food consumption. Dr Moseley also discussed the argument of sugars vs. fat causing obesity, and showed how when low fat diets became popular (in 1980), obesity rates soared when fats were replaced with sugar. In fact, sugar is so influential to our health that even the amount of sugar one is exposed to in the womb can affect you for the rest of your life.