Review of the Findings of Purnell and Yang

a. Outline the findings of Purnell, et al. (5 pts)

In your own words, what were Purnell, et al. expecting to see with this study? (Include region of interest and type of measurement in your explanation of the hypothesis). (1 pt)

Purnell was expecting to see and evaluate the neural impact of fructose and glucose sugars. He used fMRI to measure outcomes and took blood samples at certain intervals. The hypothalamic region in the central cortex is the area of interest (Purnell, 2011). 

How were the glucose, fructose, and control levels administered to each subject? In your own words, why didn’t Purnell, et al. have their subjects ingest the respective dietary carbohydrate? (2 pts)

They were administered intravenously. Purnell didn’t have the subjects ingest the sugars because he was specifically looking for the impact the sugars had on the brain, excluding ingestion processes (Purnell, 2011).

was no significant change in the region of interest detected during glucose or fructose infusion. Why do Purnell, et al. say these results do not necessarily represent an absence of glucose [or fructose] responsiveness in the region of interest? (1 pt)

The study used relatively low doses of sugars which can impact outcomes. In addition, the stimulatory and inhibitory neuron impacts may have canceled one another out, impacting the outcomes (Purnell, 2011). 

What were the findings in cortical control regions (with respect to glucose and fructose)? (1 pt) 

Glucose increased activity while fructose decreased it (Purnell, 2011).

Extra Credit: What is an fMRI looking at? (Give me a brief technical explanation of the technique (explain BOLD), as well as the type of data collected (ie: MRI gives us anatomical images, what does fMRI give us?). Just telling me what it stands for will not count as extra credit. (1 pt). 

The fMRI looks at the neurological activity of the brain. It shows a color-coded map of its activity.

Outline the findings of Yang. (5 pts) 

What percent of the population was regularly using artificial sweeteners in 2004? (1 pt)

15 percent (Yang, 2010).

Yang reviews several studies involving diet soda’s effect on children. Briefly summarize the findings. (1 pt) 

Soda’s effect on children caused them to have high body mass indexes and experience weight gain (Yang, 2010).

Aspartame-sweetened water leads to an increase in appetite, but not aspartame capsules. What is the significance of this finding? (1 pt)

When patients know they are taking aspartame, they tend to overcompensate for the lower calorie count by eating more of other things (Yang, 2010).

What is the neurotransmitter system responsible for the sensory / pleasure branch of food reward? (1 pt)

The Mesolimbic dopamine system (Yang, 2010).

The hypothalamus secretes neuropeptides to regulate energy, osmotic balance, and feeding behavior. How did sucralose (artificial sweetener) affect the hypothalamus? (1 pt). Explain what this means for extra credit (1 EC pt). 

It suppresses and depresses its signal, meaning its processes and chemical output is somewhat numbed (Yang, 2010).

Yang suggests that “unsweetening the world’s poor diet may be the key to reversing the obesity epidemic” (106). Compare the article to Oliver’s talk. What else does he suggest to help with America’s obesity problem? (5 pts)

Compare the article to Oliver’s talk. (3 pts)

Why does Yang suggest this? What exactly is it about sweeteners that lead to obesity and weight gain? (hint: “Artificial sweeteners do not activate food reward pathways in the fashion as natural sweeteners.” Think: postingestive component of the food reward system! (artificial vs natural sweeteners)) (2 pts)

He suggests this because people generally eat more when they use artificial sweeteners and it is also more difficult to satisfy them. They get used to the taste of artificial sweeteners and are unable to be satisfied by natural ones (Yang, 2010).

What do both Yang and Oliver say about the prevalence of processed and artificial sweeteners in foods and processed foods? (1 pt)

It contributes and leads to obesity.

What else does he suggest to help with America’s obesity problem? (2 pts)

What does Oliver suggest every child should leave school knowing how to do? Why? (1 pt). 

Knowing how to create a balanced meal and determine natural food from processed or genetically altered in order to understand how to be healthy (Oliver, 2010).

What does Oliver suggest happen in supermarkets? (1 pt). 

Processed foods are pushed, making it more difficult to shop for natural foods (Oliver, 2010).

Discuss and critique the role the media plays in educating the public about food. (3 pts)

The ABC clip regarding aspartame quotes a commercial: “if you eat and drink more calories than you burn off, you’ll gain weight.” Yang claims that aspartame can lead to weight gain due to a food reward pathway unrelated to caloric intake. Briefly describe this food reward pathway and why aspartame could lead to weight gain. (1 pt). 

This food reward pathway does not satisfy individuals, making them overcompensate by eating more. As a result, they intake more calories and gain weight (ABC, 2013).

How do you think the media plays a role in the way Stacy Edwards’ chose her weekly meals for her family? (1 pt)

They influenced her desires, tastes, and expectations with marketing and advertising (ABC, 2013).

Who does Oliver see as responsible for her choices? (1 pt)

Oliver sees Stacey’s poor nutrition education and the influence of the media as the sole responsible party for her choices (ABC, 2013).

What sensations did the glucose infusion subject group and fructose infusion subject group of Purnell, et al. express feeling? (2 pts)

Glucose infusion subjects: (1 pt)

Subjects felt a flushing sensation and a feeling of warmth or urgency to urinate (Purnell, 2011).

Fructose infusion subjects: (1 pt)

Fructose patients experienced feeling cold, with some chest tightness and shortness of breath (Purnell, 2011).

References

ABC (2013). New Coke Ads Defend Safety of Artificial Sweeteners. ABC News. Retrieved from  http://abcnews.go.com/GMA/video/coca-cola-artificial-sweetener-ad-coke-ads-defend-19955465 

Oliver, J. (2010). Teach every child about food, Jamie Oliver. TED Talk. Retrieved from http://www.ted.com/talks/jamie_oliver.html

Purnell, B. A. Klopfenstein,  A. A. Stevens, P. J. Havel, S. H. Adams, T. N. Dunn, C. Krisky, W. D. (2011). Brain functional magnetic resonance imaging response to glucose and fructose infusions in humans. Diabetes, Obesity and Metabolism, 13: 229–234. Blackwell Publishing Ltd

Yang, Q. (2010). Gain weight by “going diet?” Artificial sweeteners and the neurobiology of sugar cravings. Yale Journal Of Biology And Medicine, 83, 101-108.