Sugar --> Diabetes, Cancer, Obesity, Metabolic Syndrome?

In this Sunday's New York Times Magazine, Gary Taubes writes about Sugar and whether it has unique metabolic effects apart from "empty calories" (as we're often told by public health authorities).

The article is now available online. Must read.

In a related topic, which I think ties in nicely with the article above: I had a message board assignment this week on carbohydrates and diabetes. I thought I would share the commentary, questions, and my responses, below:

From the Moderator:

Carbohydrates sure do get a bad rap. We hear it all the time, “don’t eat “carbs” because you will gain weight.” The Atkins diet is a famous low carb diet that has gained attention from mass amounts of people. Often times, when one food group is severely limited, people consume other food groups in excess. For example, cutting out carbs may cause a person to consume more fat which can be just as harmful. Many people talk about the wonders of low carb diets and how they trick your body into extreme weight loss. While cutting out carbs will likely result in weight loss, it can send the body into a state of ketosis. People are confused when it comes to the topic of carbohydrates, and the truth is, they are an important part of a balanced diet--especially for diabetics. Carbohydrates are the body’s primary source of energy, and as health professionals, it is crucial to emphasize the healthy sources of carbohydrates. Diabetes is growing in epidemic proportions, and patients should be educated to distinguish between a “good” carb and a “bad” carb. According to the article we need to get away from the terms of what is “good” and “bad” and educate people on what is healthy. It is important that diabetic patients understand the glycemic index and how foods affect the body’s glucose levels.

Click on the following link to read the article:
http://www.buffalonews.com/life/health-parenting/health/article384918.ece

1. What is the effect of a low carbohydrate diet on the body, and why do people rely on it for weight loss? Is this a harmful approach for diabetics, Why or Why not?

2. Distinguish the difference between a complex carb and a simple carb.

3. Are potatoes that bad for us? The article insinuates that baked potatoes are not the best choice, would you agree with this statement?

4. Define the terms: glycemic index and glycemic load and explain how we can use these terms to help diabetic patients improve their diets.

5. Evaluate this statement to be true or false and justify your answer: Eating too much sugar causes diabetes.

My Response:

First, I want to address the commentary that preceded the article link and questions.

“Often times, when one food group is severely limited, people consume other food groups in excess.”

Agree. Dietary trade-offs are an inescapable reality.

“For example, cutting out carbs may cause a person to consume more fat which can be just as harmful.”

I feel like this needs to be substantiated with evidence. For example, much of the research conducted in the last ten years in randomized-controlled trials of low-carbohydrate (ad libitum) diets compared to low-fat (calorie-restricted) diets have observed beneficial effects in terms of both weight loss, lipids, and other risk factors for the subjects adhering to the low-carbohydrate diet. Further, most studies show that when people replace saturated fats with carbohydrates, their health prospects worsen.

“Many people talk about the wonders of low carb diets and how they trick your body into extreme weight loss.”

I guess this is true, but for the people that claim that a low-carbohydrate diet “tricks” your body into weight loss, they’re missing the point. For many people going on a low-carbohydrate diet, they shift toward oxidizing relatively more fat for fuel than they have been accustomed to on a high-carbohydrate diet (which can elevate insulin, which promotes fat storage and inhibits fat mobilization). I would argue that when these people lose weight, they’re shedding the excess fat accumulation that has occurred in large part to the quality of their diet. They’re not losing fat because they’re losing weight; they’re losing weight because they’re losing fat.

“While cutting out carbs will likely result in weight loss, it can send the body into a state of ketosis.”

Ketosis is a natural physiological state in the body. In fact, most of us are technically in ketosis overnight (when we sleep) and our brains are primarily using ketones for fuel. The ketone level in our bodies upon waking will be around 5 mg/dl - and on an severely restricted carbohydrate diet (i.e., Atkins induction) the level is around 5 to 20 mg/dl. While you are reading this, it is likely you are in ‘ketosis,’ which is another way of saying you’re burning fat for fuel.

The ketone level in diabetic ketoacidosis typically exceeds 200 mg/dl.

Many diets that are low-carbohydrate are going to be more ketogenic in nature which is not a bad thing and is quite normal from an evolutionary standpoint. It's basically being more 'fat adapted' and using more of your body fat for fuel rather than glucose derived from dietary carbohydrates, which is "the body's preferred fuel" because it wants to get rid of it, i.e, bring blood glucose back to stable levels.

“Carbohydrates are the body’s primary source of energy, and as health professionals, it is crucial to emphasize the healthy sources of carbohydrates.”

This is false. The primary source of energy in the body is derived from fatty acids. You could argue that the body needs glucose to survive, and is vitally important, however there is no dietary need for carbohydrates. They are a nonessential exogenous nutrient.

As health professionals, we should emphasize healthy sources of carbohydrates, over what? Unhealthy sources of carbohydrates? Or emphasize them over all other foods in general? How would you define healthy sources of carbohydrates?

“Diabetes is growing in epidemic proportions, and patients should be educated to distinguish between a “good” carb and a “bad” carb.”

Agree, and at its core, I would say that diabetes is a disorder of carbohydrate metabolism. Even if you’re trapped in the diet-heart paradigm, restricting or virtually eliminating carbohydrates in a diabetic patient has a greater benefit-to-risk ratio.

Again, I would appreciate a definition of what a good carb is and a bad carb is going forward.

1. What is the effect of a low carbohydrate diet on the body, and why do people rely on it for weight loss? Is this a harmful approach for diabetics, Why or Why not?

I would say that most people rely on a low-carbohydrate diet for weight loss because it gets them the results they want. When they stay on a low-carbohydrate diet, they maintain their weight loss from the low-carbohydrate diet, and when they stray from it, i.e., increase their carbohydrate consumption, they gain the weight they lost back, so in that sense, they rely on a low-carbohydrate diet because it’s what makes them lose weight and what keeps it off.

The effect of a low-carbohydrate diet on the body, while this depends on the level of carbohydrate restriction, especially on people who are overweight and obese, generally speaking, is that insulin levels are lowered. Elevated insulin, when working properly, is a signal that there are elevated levels of glucose in the body. Insulin drives nutrients into their tissues, including adipocytes. Insulin also inhibits lipolysis, or the breakdown of triglycerides to be used for fuel. Carbohydrates, especially the most refined and easily digestible, drive insulin secretion. When carbohydrates are removed, insulin levels are lowered and the opposite effect occurs; less nutrients are being partitioned to the fat cells and we observe an increase in lipolysis.

A low-carbohydrate diet is generally not harmful for diabetics, however, since low-carbohydrate diets actually correct some of the abnormalities in diabetic patients (i.e., a low-carbohydrate diet is healthful for diabetics), one of the problems is a reason for contraindicating medications such as insulin and high blood pressure medications because a low-carbohydrate diet has an anti-hypertensive effect and creates a reduced requirement for insulin.

Also, I wanted to add here a quote from the article and my response:

“Everyone agrees that replacing saturated fats with unsaturated fats is good, but citing numerous studies that show an elevated risk of heart disease when carbohydrates replace saturated fats, scientists have been rethinking the role of carbs in cardiovascular disease.”

Everyone does not agree. There are people who believe that saturated fats from animal sources are just as good, if not more beneficial, than unsaturated fats.

Also, it’s not as clear-cut as replacing one type of fat for another. For example, lard, yes, lard, is mostly monounsaturated fat. And the saturated fat in lard has qualities that raise HDL and have no effect on LDL.

Gary Taubes wrote about this in Good Calories, Bad Calories:

"Consider a porterhouse steak with a quarter-inch layer of fat.  After broiling, this steak will reduce to almost equal parts fat and protein.  Fifty-one percent of the fat is monounsaturated, of which 90 percent is oleic acid.  Saturated fat constitutes 45 percent of the total fat, but a third of that is stearic acid, which will increase HDL cholesterol while having no effect on LDL.  (Stearic acid is metabolized in the body to oleic acid, according to Grundy’s research.)  The remaining 4 percent of the fat is polyunsaturated, which lowers LDL cholesterol but has no meaningful effect on HDL.  In sum, perhaps as much as 70 percent of the fat content of a porterhouse steak will improve the relative levels of LDL and HDL cholesterol, compared with what they would be if carbohydrates such as bread, potatoes, or pasta were consumed.  The remaining 30 percent will raise LDL cholesterol but will also raise HDL cholesterol and will have an insignificant effect, if any, on the ratio of total cholesterol to HDL.  All of this suggests that eating a porterhouse steak in lieu of bread or potatoes would actually reduce heart-disease risk, although virtually no nutritional authority will say so publicly.  The same is true for lard and bacon."

And how about human fat? What are we made of?

Ren et al. (2008): Human adipose tissue is composed largely of triglycerides. Seven fatty acids predominate as follows (number of carbons:number of double bonds, typical abundance): myristic (14:0, 3%), palmitic (16:0, 19–24%), palmitoleic (16:1, 6–7%), stearic (18:0, 3–6%), oleic (18:1, 45–50%), linoleic (18:2, 13–15%), and linolenic (18:3, 1–2%) ( 22, 23). These fatty acids account for well over 90% of the fatty acids in human adipose tissue. Odd-carbon fatty acids, longer chain fatty acids, and shorter chain fatty acids account for the remainder. Each of these less-abundant fats individually contributes much less than 1% ( 22).

So our adipose tissue is comprised of the same composition of the foods the public health authorities tell us to avoid. Interesting?

2. Distinguish the difference between a complex carb and a simple carb.

Complex carbohydrates are generally a polymer, containing multiple mono-saccharides linked together. Simple sugars generally refer to the mono-saccharides occurring in foods individually, i.e., no polymer.

Generally, simple and complex carbohydrates refer to sugars and starches, respectively.

Complex carbohydrates, in and of themselves, do not significantly affect the absorption rate of carbohydrates in the body.

3. Are potatoes that bad for us? The article insinuates that baked potatoes are not the best choice, would you agree with this statement?

I feel a little like Bill Clinton here, but, define “us”?

For a metabolically sound, lean individual, a potato may not be particularly deleterious.

If you were to tell the Kitavans that eating tubers were going to compromise their metabolic systems, they would probably argue otherwise and have reportedly lived on a diet high in tubers and starches:

From WholeHealthSource.com:

There's a lot to be learned from the Kitava study. Kitavans eat a diet of root vegetables, coconut, fruit, vegetables and fish and have undetectable levels of cardiovascular disease (CVD), stroke and overweight. Despite smoking like chimneys. 69% of their calories come from carbohydrate, 21% from fat and 10% from protein. This is essentially a carbohydrate-heavy version of what our paleolithic ancestors ate. They also get lots of sunshine and have a moderately high activity level.

Eating potatoes is eating akin to eating glucose. Yams and sweet potatoes, for instance, contain very little amounts of fructose, which may be the necessary agent - in excessive amounts - in causing metabolic disease in otherwise healthy individuals and further exacerbating it in the rest of the population.

For a diabetic, who by definition, has a disorder of carbohydrate metabolism, a potato may not be a good choice at all. Diabetics have a hard time clearing glucose, so it would probably be wise not to challenge the system with a bolus of carbohydrate in any form.

For a diabetic, I would agree that a baked potato is a bad choice of food to eat. For otherwise healthy, lean individuals, I would certainly still argue that potatoes are not “the best choice,” but I also believe that these people can consume this food without inducing damage (but would have to be taken in the context of the exclusion of excess fructose; sugar and HFCS among the major culprits).

4. Define the terms: glycemic index and glycemic load and explain how we can use these terms to help diabetic patients improve their diets.

From The Glycemic Index website (www.glycemicindex.com):

The glycemic index or GI describes this difference by ranking carbohydrates according to their effect on our blood glucose levels... The glycemic index (GI) is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating. Foods with a high GI are those which are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels. Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood sugar and insulin levels, and have proven benefits for health.

Measuring the GI:

To determine a food's GI rating, measured portions of the food containing 10 - 50 grams of carbohydrate are fed to 10 healthy people after an overnight fast. (From wikipedia: The glycemic index of a food is defined as the area under the two hour blood glucose response curve (AUC) following the ingestion of a fixed portion of carbohydrate (usually 50 g).) Finger-prick blood samples are taken at 15-30 minute intervals over the next two hours. These blood samples are used to construct a blood sugar response curve for the two hour period. The area under the curve (AUC) is calculated to reflect the total rise in blood glucose levels after eating the test food. The GI rating (%) is calculated by dividing the AUC for the test food by the AUC for the reference food (same amount of glucose) and multiplying by 100 (see Figure 1). The use of a standard food is essential for reducing the confounding influence of differences in the physical characteristics of the subjects. The average of the GI ratings from all ten subjects is published as the GI of that food.

According to Wikipedia: 

The glycemic load (GL) is a ranking system for carbohydrate content in food portions based on their glycemic index (GI) and the portion size. Glycemic load or GL combines both the quality and quantity of carbohydrate in one ‘number’. It’s the best way to predict blood glucose values of different types and amounts of food. The formula is: GL = (GI x the amount of available carbohydrate) divided by 100.

In theory, glycemic index and glycemic load can help diabetics because they help determine what the impact of a particular food will be in the body, and for diabetics especially, they should want to avoid any food that is going to significantly elevate their blood glucose.

One of the severe limitations of glycemic index and glycemic load is that it doesn’t properly account for the amount of fructose consumed in the diet. For example, sucrose (glucose-fructose) has a lower GI than a potato, but I would rather have people eating potatoes than sucrose, if I had to make the choice.

From the subject article: “By contrast, fruit sugars are simple carbs, but they minimally impact blood sugar levels and insulin production.”

Again, we’re talking about fructose here, which many argue is a dose-dependent hepatotoxin. It minimally impacts blood sugar levels because fructose travels straight to the liver, and when consumed in excess, it can create the metabolic damage that is found in metabolic syndrome, insulin resistance, and diabetes.

5. Evaluate this statement to be true or false and justify your answer: Eating too much sugar causes diabetes.

I would say that eating too much sugar [sucrose/HFCS] is a cause of type 2 diabetes. Type 1 diabetes is less clear, but it is possible that excess sucrose can create, promote, or exacerbate an autoimmune disorder in the body.

To say that excess sugar is a cause of diabetes because anything in excess leads to weight gain, which leads to diabetes, wildly misses the point.

There are unique effects of fructose on human metabolism that implicate its consumption in the development of metabolic syndrome, which is virtually synonymous with insulin resistance, which is virtually synonymous with type 2 diabetes. The mechanisms of action are observable and have been shown to uniquely contribute to hepatic insulin resistance, leading to type 2 diabetes, among other issues.

And to come full-circle, this final question is comprehensively addressed in Gary Taubes's New York Times Magazine article (set to print: April 17, 2011) and Robert Lustig's Sugar: The Bitter Truth lecture.