Slate Reports on Different Types of LDLs
As a follow-up to my post "The Truth About Cholesterol", here's a report from Slate showing that all LDLs are not created equal, and some types are more dangerous than others. Moreover, the article discusses how America's "War on Fat" steered us away from butter and lard, but led us to an arguably more dangerous food, the refined carbohydrate. Post your thoughts!
As a follow-up to my post "The Truth About Cholesterol", here's a report from Slate showing that all LDLs are not created equal, and some types are more dangerous than others. Moreover, the article discusses how America's "War on Fat" steered us away from butter and lard, but led us to an arguably more dangerous food, the refined carbohydrate. Post your thoughts!
Sugar-coated Laziness
Check out this study. Researchers found that when "teenage" rats (30-45 days old) consumed massive amounts of sugar, they became extremely difficult to train as adults. For two weeks or so during adolescence, one group of rats had free access to a tasty 5% sucrose solution, while the control group only had water available. Similar to some American teenagers, the experimental group of rats consumed about 20% of their daily caloric intake as simple sugar.
Check out this study. Researchers found that when "teenage" rats (30-45 days old) consumed massive amounts of sugar, they became extremely difficult to train as adults. For two weeks or so during adolescence, one group of rats had free access to a tasty 5% sucrose solution, while the control group only had water available. Similar to some American teenagers, the experimental group of rats consumed about 20% of their daily caloric intake as simple sugar.
To give you some background, it's extremely easy to train adult rats to perform simple tasks, such as pulling levers or pressing buttons in return for a food reward. However, the researchers couldn't motivate the rats that had consumed large amounts of sugar as teenagers to learn the task. My first reaction while reading this paper was: "Big deal. That group of rats just had sugar overload. It no longer had any real value for them, so there was no incentive to learn the new task".
But here's where the story gets interesting: if you repeat the experiment, but replace the teenage rats with adult rats, you get strikingly different results. When adult rats have free access to a sugary drink for two weeks, they never lose motivation for the sweet reward, and easily learn the new lever-pull task later in life. So it's not that rats are simply sick of the sweet reward, but rather, it seems the sweet drink over-stimulated the reward pathway in the brain during adolescent development, leading to problems with motivation in adulthood.
Were the calories in the sugary drink or the sweet taste to blame for hyper-activating the reward circuits in the brain? To answer this, the authors took another group of teenage rats and gave them free access to a drink flavored with artificial sweetener, which has no calories. These rats were also unmotivated and rather difficult to train later in life, so the authors concluded that the sweet taste, but not the sugar itself, was hyper-activating the brain's reward circuits.
Besides, ahem, crazy neuroscientists writing for health blogs, who cares about lazy rats? Well, the authors argue that a sign of depression in rodents is lack of motivation to perform simple tasks. Given that incidence rates for depression and other psychological illness are increasing in today's society, it's interesting to see how seemingly benign events during adolescence -- a critical time in brain development -- affect the mental state of adult animals.
Can High Blood Glucose Levels Cause Cancer?
Diets high in simple sugars and refined carbs cause metabolic disorders and Type II diabetes in millions of Americans. But to make matters worse, new evidence suggests that high sugar diets may be even more dangerous than we initially thought. Having too much excess sugar in the bloodstream is never a good thing, and can lead to medical complications such as kidney failure, cardiovascular disease, and eye problems. But could high blood sugar also cause cancer? A Swedish research team addressed this question by tracking over 500,000 patients for 10-25 yeas, and published their results in the December issue of PLoS Medicine.
Diets high in simple sugars and refined carbs cause metabolic disorders and Type II diabetes in millions of Americans. But to make matters worse, new evidence suggests that high sugar diets may be even more dangerous than we initially thought. Having too much excess sugar in the bloodstream is never a good thing, and can lead to medical complications such as kidney failure, cardiovascular disease, and eye problems. But could high blood sugar also cause cancer? A Swedish research team addressed this question by tracking over 500,000 patients for 10-25 yeas, and published their results in the December issue of PLoS Medicine.
Similar to the findings of a study conducted in Korea in 2005, the European research team discovered that having elevated blood glucose levels increased the risk of developing certain types cancer later in life, such as pancreatic tumors in women and liver tumors in men. Not only had more cases of cancer occurred when people had high blood sugar, but the chance of survival also plummeted, especially when the person had cervical, espohageal, or colorectal cancers.
The authors present two theories on why elevated blood glucose levels could cause cancer: 1.) high sugar diets may cause an overproduction of insulin or insulin-like growth factor 1 (IGF-1), both of which promote rapid growth of new cells, the catalyzing step to tumor formation. 2.) More glucose in the blood stream could simply be adding fuel to the fire, feeding rogue tumor cells that need lots of energy to run.
Because the studies lacked certain controls, we can't say for sure whether elevated blood glucose levels cause certain tumors to form. For example, the people with high blood glucose levels may have been sedentary, and so the lack of exercise may be what's actually increasing the chances of developing cancer. Regardless, this study gives yet another example of unhealthy lifestyles contributing to comorbidity, a topic discussed at length by Thomas in The Decision Tree book.
Much Ado About Sugar
Since the 1980's, American soft drinks have been sweetened with high fructose corn syrup (HFCS), and it's rapidly becoming the sweetener of choice in most processed foods. Critics are quick to point a finger at this enigmatic sugar as the root of all evil, claiming its empty calories are contributing to the obesity epidemic, and the numerous chemical processes needed to make it are simply "unnatural". These accusations didn't sit well with "King Corn", and The Corn Refiners Association fired back with a series of TV commercials stating that HFCS was in fact natural, and completely safe in moderation. Government officials have been talking out of both sides of their mouths on the issue, first allowing HFCS to be called natural, then recently proposing it be taxed, thereby equating it to other unhealthy items, such as cigarettes. With all this conflicting information, what should the public think? Should we avoid HFCS at all costs? How does HFCS compare to other sugar sweeteners?
Since the 1980's, American soft drinks have been sweetened with high fructose corn syrup (HFCS), and it's rapidly becoming the sweetener of choice in most processed foods. Critics are quick to point a finger at this enigmatic sugar as the root of all evil, claiming its empty calories are contributing to the obesity epidemic, and the numerous chemical processes needed to make it are simply "unnatural". These accusations didn't sit well with "King Corn", and The Corn Refiners Association fired back with a series of TV commercials stating that HFCS was in fact natural, and completely safe in moderation. Government officials have been talking out of both sides of their mouths on the issue, first allowing HFCS to be called natural, then recently proposing it be taxed, thereby equating it to other unhealthy items, such as cigarettes. With all this conflicting information, what should the public think? Should we avoid HFCS at all costs? How does HFCS compare to other sugar sweeteners?
Let's start with the science. I recently came across two blog posts (links below), which centered on a study in the Journal of Clinical Investigation that compared the health effects of consuming different dietary sugars -- one experimental group's sugar of choice was glucose, the other group's was fructose. The study boosted the subject's sugar consumption to 25% of their total daily calories by adding fructose or glucose to unsweetened Kool-Aid. The results showed that both groups put on weight, which is not surprising given the sheer volume of sugar consumed. However, the group with the fructose-based diet had higher visceral fat, triglycerides, plasma LDL and oxidized-LDL levels, plasma glucose level, as well as signs of increased insulin resistance, compared to those in the glucose group, all of which are signs of deteriorating health.
There were some shortcomings of the study, which were pointed out nicely in the blog posts: 1.) it was a small study (n=32), 2.) its only participants were obese people (i.e. will the results hold true for normal weight people?), 3.) subjects consumed much more sugar than the average American (mean=15.8% of total calories), and 4.) fructose is more than 2x sweeter than glucose, so in theory, you'd need less fructose calories to obtain the same level of sweetness. Despite the study's limitations, similar results have been shown in primates, which further substantiate the main finding -- fructose-based sweeteners cause secondary health problems. So what do these results mean to us? First, it seems the sweetener used in this study was either 100% glucose or fructose. We typically don't use such pure sugars, as we primarily satisfy our sweet tooth with either table sugar or the high fructose corn syrup that's hidden in the ingredient list of processed foods. What exactly is the difference between these two sugars, and how does using them affect our health? HFCS is a 55/45 mixture of fructose and glucose, respectively. The Journal of Clinical Investigation study claimed that HFCS may be just as bad for you as pure fructose, as the results of a short-term experiment showed comparable negative health effects between subjects that consumed either of these sugars. Table sugar (sucrose), on the other hand, is a 50/50 mixture of glucose and fructose, which is surprisingly similar in composition to HFCS. The primate study I cited earlier reported that diets high in both HFCS and sucrose increased triglyceride levels. So it seems possible that added fructose, regardless of the source or relative concentration, may be detrimental to our health. So if fructose causes a barrage of negative health effects, does that mean eating an apple is bad for you? After all, fructose is the main sugar in fruits. Michael Pollan address this question best in his book "In Defense of Food" (which I just finished reading, and I hope to get a review posted here soon). Pollan states that, opposed to the fructose in the Kool-Aid given to the study participants, the fructose in an apple is not an isolated monosaccharide -- it exists in a complex micro-environment where it is surrounded by lots of fiber, which prevent the fructose from causing a sugar spike, and allow it to be metabolized slowly. Simply put: with food, context is everything. Mother Nature made fruits sweet for a reason -- they are good for us, and contain vital nutrients. But perhaps fructose was never meant to be isolated in a lab and poured into soft drinks, as the results I've discussed show that processed fructose is rapidly metabolized, and leads to negative health.
While more stringent scientific studies need to be conducted to investigate the effects of HFCS on a diverse population, I think it's safe to say that regardless of the source, the 39 grams of sugar in the average soft drink isn't helping the obesity problem in the United States.
Sources: Some Sugars Worse Than Others? The Bittersweet Fructose/Glucose Debate