The Definitive Guide to Sugar

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You’d think this post would come with a blaring alarm, flashing strobe light or at least an ominous gong. Sugar, after all, gets little welcome around these parts. It’s on one hand a dastardly devil, shameless snare for many a man, woman and child. Beyond this luring, ignoble reputation, however, you’ll find (as is so often the case in life and biology) the story is a bit more complicated — and compelling — than the proverbial black hat. Sugar comes in many forms of course, and each of these leaves a certain amount of damage and destruction in its path. Yet, what do we do when sugar naturally accompanies some of the healthiest fare out there? Do we forgo it altogether when a touch ties an otherwise good Primal recipe together? Are the typical substitutions any better when we choose to use a sweetener? We’ve covered the artificial options in the past, but today I’ll give several natural varieties of sugar their due — the obligatory facts, the practical details and a final Primal analysis.

Why Avoid Sugar?

How could I possibly talk sugar without the warning? If you’ve spent any time around MDA, you likely know the drill. Despite its beloved place (not to mention omnipresence) in our culinary culture, sugar offers the following gifts that keep on giving:

  • Sugar stimulates a physiological stressor-reaction cascade that provokes adrenaline and cortisol release and thickens the blood.
  • Sugar effectively disables your immune system by impairing white blood cells’ functioning.
    Sugar decreases your body’s production of leptin, a hormone critical for appetite regulation.
    Sugar induces significant oxidative stress in the body.
  • Sugar appears to fuel cancer cells. (Check out Free the Animal for much more on the cancer connection.)
  • Sugar promotes fat storage and weight gain.
  • Sugar disrupts the effective transfer of amino acids to muscle tissue.
  • Sugar intake over time spurs insulin resistance, subsequent Type II diabetes and the entire host of related health issues like nerve damage and cardiovascular disease.
  • Yes, sugar is one insanely powerful drug. Addictive, to boot.

Different Types of Sugar

Public service message aside, let’s get into the nitty-gritty now. Chemically speaking, there are different kinds of sugar. The natural sweeteners and sugary foods we eat contain varying proportions of these. Let’s look at a few of the most common forms.

Glucose

Glucose is the cornerstone of most carbohydrates. It’s a monosaccharide that often combines with and creates other forms of sugar (e.g. sucrose, lactose). In plants, glucose is formed through photosynthesis and stored as starch. In our own bodies, glucose is a precursor for (and product of) glycogen. It’s the common currency of carb-based fuels. In fact, our bodies manufacture glucose (through gluconeogenesis) when our blood levels get too low. Dextrose, a common isomer (same formula, different structure) of glucose, is also referred to as dextroglucose or glucose. Insulin directs glucose processing in the body when blood glucose is already sufficient or high. Glucose supply can be routed to cells throughout the body (e.g. brain cells, red blood cells, etc.) and used right away for energy, or it can be condensed and stored in both the liver and muscle as glycogen for later use. Maltose is a disaccharide joining two glucose molecules. Although it is significantly less sweet (about half of glucose’s sweetness), it is metabolized in the same way glucose is.

Fructose

Then there’s fructose, which is an isomer of glucose. It’s also called crystalline fructose, laevulose/levulose, or fruit sugar. (Crystalline fructose isn’t the same as the manufactured concoction called high fructose corn syrup. We’ll get to that one shortly.)

Some people have a harder time digesting fructose than others. Fructose (in the form of certain fruits, corn syrup, etc.) can cause everything from bloating to diarrhea in these folks. Some experts argue that fructose is a better choice for those with diabetes/insulin resistance because it’s more densely sweet, which encourages people to use less. It also has a lower glycemic value than glucose or sucrose. Indeed, fructose raises insulin less than glucose; however, fructose results in higher ghrelin levels, which boost rather than suppress appetite like insulin does. It also appears to throw off mineral levels (PDF) in the body. Finally, fructose is processed almost solely by the liver. There is some evidence that this concentrated burden on the liver over time can contribute to non-alcoholic fatty liver disease. The liver’s metabolism of fructose also produces uric acid, a predictor of cardiovascular disease. Fructose appears to be some pretty nasty stuff. For more information on fructose see Dr. Lustig’s video presentation, Sugar: The Bitter Truth, and then follow it up with a counter-perspective from Don Matesz: Paleo Basics: Fact vs. Fiction.

Sucrose

Sucrose is a disaccharide sugar comprised of fructose and glucose in a 1:1 ratio. It’s perhaps the most familiar of the sugars, since sucrose is also known as table sugar. Although it’s found in fruit and other plants (often with varying amounts of free fructose), sugar cane and sugar beets are the most popular sources for commercial production. Given that sucrose contains a large amount of fructose, it shows similar metabolic patterns to the monosaccharide fructose and particularly to high fructose corn syrup, which is commonly blended to an approximate 55% fructose: 45% glucose mixture.

Common Sugar Sweeteners

Now that we’ve covered the basics on the most common sugars, there’s the question of how all this plays out in our everyday choices. Clearly, we want to avoid sugar as a whole, but few of us achieve full sugar abstinence 100% of the time. Consider this run-through a quick and dirty snapshot of common sweeteners that can inform your decision-making.

Glucose Syrup/Corn Syrup

Glucose syrup in this country is usually made from corn, but it can be produced from other starches like potatoes and rice. Chemically speaking, true glucose syrup/corn syrup consists mainly of glucose sugar; however, some companies like Karo add fructose to their products. It’s commonly used as a sweetener plus emulsifier for food items that require a smooth texture like hard candy. Although glucose itself rates a 100 on the glycemic scale, corn syrup generally falls around 75.

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