Good evening all,
As I noted in lecture on Wednesday, we remain on-schedule with out lecture chapters, and do not have a chapter scheduled for tomorrow (Friday 25 Oct). So, I would like once again to propose that we do not meet in person for lecture tomorrow, and ask instead that you consider the reading that I am forwarding here.
In our last lecture on the endocrine system, we noted the central role of the pancreas and its hormones in the regulation of blood glucose ("blood sugar") levels. When levels of blood glucose rise (such as when we are absorbing digested sugars into our bloodstream after a meal), the hormone insulin is released by the pancreas. Insulin causes our cells (especially liver and muscle cells) to uptake glucose - that is, to take glucose out of the bloodstream and move it into cells by means of membrane transporters. This allows cells to have glucose available for fuel, and also allows cells to store the excess glucose for later use.
On the flip side, when our blood glucose levels decline (such as when we are several hours past a meal and done absorbing nutrients), other cells in the pancreas release the hormone glucagon, which causes our cells (especially liver and muscle cells) to release some of their stored glucose. Together, the use of the two hormones allows us to maintain a relatively even profile of blood glucose levels.
As we discussed yesterday, when blood sugar levels are not well-controlled, diabetes may result. The primary symptom of diabetes is high (and poorly controlled) blood glucose levels. This causes a number of immediate effects, such as excess urination, thirst, and excessive fat metabolism. Over the long term, high levels of blood glucose are very damaging to our tissues, particularly through scarring of the inner lining of our blood vessels. This can lead to the failure of organs with extensive capillary beds (such as the retina of the eye, and the kidney), and has negative effects on circulation in general, especially in the lower periphery. Persons with uncontrolled blood sugar often suffer poor wound healing (especially of the feet), which can lead to infections and, in some cases, require amputation.
In lecture, we distinguished the two general types of diabetes as well. "Type I" diabetes occurs when our own immune system causes the destruction of the insulin-producing cells of the pancreas. This is classified as an auto-immune disorder, as the disease stems from a problem with the immune system. Type I diabetes is often called "juvenile diabetes", because it is typically first diagnosed in one's youth. It can be treated (usually successfully) with injections of insulin - daily, often multiple times. Insulin pumps can also be used - these are small, battery powered pumps that infuse gradual, small amounts of insulin into a catheter. They are expensive and require maintenance, but are effective solutions for many.
"Type II", or "adult onset diabetes" is more challenging. It tends to appear in people with a combination of risk factors: obesity, poor diet, little exercise. Over time, the cells of their body gradually become resistant to insulin, and stop responding to it. Their pancreas produces normal amounts of insulin, but it is ineffective - blood glucose remains elevated, cells become starved for sugar fuels, and metabolize other fuels (mostly fats). Tissue damage accumulates because of the persistently elevated blood glucose levels. Additional insulin (injections) can help somewhat, but the most effective treatment is improvements in diet and exercise. Some people can almost completely reverse their condition through these lifestyle changes, and nearly everyone can benefit at least somewhat from them.
There is a lot of biology associated with diabetes: its causes, effects, and treatments. There also is a lot of sociology to it as well. Diabetes strikes populations very unevenly, and impacts populations of relatively poorer socioeconomic levels most severely. This is believed to be due to a number of factors, including reduced access to high-quality food, more-restrictive employment and familial responsibilities that limit time to exercise, and less access to good information about health. It has also been suggested that food corporations specifically target these populations with advertising and vendors for "fast food", including soft drinks ("soda", or "pop", depending upon where you were raised).
As a food, soda is of very low quality. It is mostly water, but the other primary ingredients are sugar, and often caffeine. It is also quite acidic, and has quite damaging effects on our teeth. So, why do we buy/drink it? We do so at least in part of because of very successful, and very prominent, advertising, which has allowed some soda companies to develop enough clout that they can contractually deliver soda to schools, hospitals, corporations, and even cities.
Think back to your middle- and high-school education: did soda vending machines exist in your school? Were fountain drinks available over the counter in the cafeteria? For most of us, the answer to these questions is "yes". Do you buy bulk quantities of soda? Do you see others around you who do? Again, for most of us, the answers here are "yes" as well.
In recent years, public health experts have recognized the dangers of over-consumption of soda, and more importantly, the danger of exposure to it in our youth. Too often, adolescents develop a "soda habit", and maintain it into adulthood. This, in combination with other lifestyle choices, has led to skyrocketing rates of juvenile obesity. Even more alarming, "adult onset" diabetes is now diagnosed in adolescents at alarming rates.
So what can be done? Well, the debate rages, because to eliminate soda from communities and diets is not really an option. Soda companies are large, and powerful, and they have an avid user base that wants their products. This is a situation similar to that faced years ago with the tobacco industry: large and powerful corporations, well-paid lobbies, a desirous user base, and mounting evidence of the dangerous health effects of the product. Here, too, numerous solutions were discussed and tried. One of the remedies that seemed to be most effective was to implement larger and larger taxes on tobacco, to the point at which fewer people were willing, or able, to financially support their tobacco habit.
Because of the success of this strategy to reduce tobacco usage, we now live in an era of the "soda tax". The idea here is the same: if a popular consumer product is legal, but unhealthy, tax it in order to reduce the number of people using it, and/or the amounts that they use. This remains a controversial idea. Why should companies producing a legal, desirable product be punished? Is this ethical? Does this not also punish the people that work for them, and their suppliers, accountants, and all of the other people who work in associated jobs? Does this also punish consumers of relatively lower income unfairly, because they would be the ones least likely to be able to afford a price increase?
With soda, too, the application of a tax is more complicated. Tobacco and alcohol are relatively uniform in how they are packaged and purchased, but sugary drinks exist across the spectrum (from soda, to sweetened milk, to orange juice and yogurt). Wait -- aren't milk, orange juice, and yogurt good for us? Well, yes, but less so if they have a lot of added sugar. Should they be taxed less than soda, because they are relatively more healthy? What about sugary cereals and granola bars? What about foods with artificial sweeteners? The lines are less clear in this current health debate.
The news report I am forwarding describes a recent assessment of the effectiveness of "sugar taxes". Dozens of other countries, and multiple large cities in this country, have imposed this tax. They have existed for a relatively short time, so there is much yet to be learned about them. They do appear to cause a drop in soda consumption, but whether that translates into improved health of the population is still to be determined. Not surprisingly, the soda companies have responded aggressively, with a variety of tactics. This battle is far from settled.
The next time you are at the grocery store, ask yourself if you are planning to put soda into your cart. And, look around: how many people do? It's common to see people pushing shopping carts with 6-packs of bottled soda (often multiple of them) draped over the edges of the cart. This behavior didn't exist 10 years ago! Have the bottles changed to make this more convenient? Or are we buying more? Our fast food restaurants and convenience stores offer *enormous* fountain drinks - 30, 40, even 50 ounces at a time! Does anyone rally need that much soda at once?
On this, and all of our topics, stay informed. Healthy habits require good information, and wise choices. There is plenty of information available on the health aspects of soda and its social implications. Be wise shoppers and consumers!
And, have a great weekend. See you on Monday for Chapter 17.
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