Friday, March 7, 2014

Sugar - Sweet Poison? Part I

Sugar seems to be the word on everyone's lips (and on their tongue and sliding down into their stomachs) lately. The leaked release of the World Health Organisation's draft report on the effects of sugar on health has sparked debate once again.

When we say the word 'sugar', we all think of the white or brown crystally stuff pictured above. This is actually called sucrose and is a disaccharide of glucose and fructose. Read on for further explanations.

Pictured above is semi refined sucrose, or raw sugar. It comes from pressing the sugar cane and then mixing it with lime. It's then evaporated and spun in a centrifuge to produce the crystals.  This is then further refined to produce white sugar by using sulphur dioxide to bleach the crystals. These are then filtered through carbon to remove the molasses (where the actual nutrition lies) content.

Sugar is a dietary carbohydrate, the main source of energy for our body. The body can use protein to a limited extent and will use fat when no carbohydrates are available. Carbohydrates exist in many other forms and are actually sugars. Confused? Don't be, it's not terribly complex at all. Let me explain briefly.

Monosaccharides (meaning one sugar molecule) are the simplest form of carbohydrate. They are glucose, fructose and galactose. Combinations of these three form disaccharides (two sugar molecules) . Glucose and fructose make sucrose (table sugar); glucose and galactose make lactose (milk sugar) and glucose and glucose makes maltose (occurs naturally as a part of starch digestion in the body and can be produced through malting of grain such as barley).

Polysaccharides, therefore are made up of many molecules of glucose, sometimes with the other monosaccharides all strung together and are known as complex carbohydrates. Just as there are three types of monosaccharides and disaccharides, there are three types of polysaccharides. These are simply known as glycogen, starch and fibre. Still with me? Good....

Glycogen isn't found in food, it is manufactured in the body and stored in the liver and muscles. It is made of many glucose molecules linked together.  When you are needing energy, it is this glycogen that is broken down by enzymes to release glucose into the bloodstream.
Muscle cells also store glycogen, but hoard it to use during exercise. Glycogen holds water and can only be stored for short periods of time. Less than a day when the body is at rest and a few hours during activity.

Starch, on the other hand, must be obtained from plants as plants store glucose as starch.

By eating a plant, our body converts the starch into glucose for our energy needs. Starches are found mostly in grains and in plant foods such as tubers and legumes.

Fibre also comes from plants.

It is obtained from eating the whole plant - e.g. whole grain flour rather than white grain flour. The body doesn't break down this type of polysaccharide, so no energy is obtained from dietary fibre. However, it is vital to the health of our digestive system.

There are two types of fibre - soluble and non soluble.
Soluble fibre either dissolves in water or forms viscous gels and is easily fermented and broken down by the natural bacteria in the colon (bowel). They help to maintain a healthy bowel. When this natural bacteria are no longer present due to poor eating habits or illness, the body doesn't deal with soluble fibre very well. Irritable Bowel Syndrome and Crohn's Disease are two conditions where this may occur.
Insoluble fibre does not form gels or dissolve in water and is less easily fermented in the colon.
Some starches are classified as dietary fibre because they escape the digestion process and are broken down in the colon. Insoluble fibre assists with bowel movement and prevents such conditions as diverticular disease.

Now, what do we need all this different form of sugar for? The main role of carbohydrates are to provide the body with glucose for energy. Starch is the main form of glucose provision, but the monosaccharides (simple sugars derived from the disaccharides) can also provide glucose if it is needed.
Brain cells, other nerve cells and developing blood cells prefer to use glucose for energy.

When sufficient carbohydrate intake has met the body's energy requirements, guess what happens if you consume more? The liver can only hold a certain amount, as mentioned previously, so it has to deal with this excess by breaking down those glucose molecules into smaller ones. These are then put together into another compound - fat.  The little fat molecules then travel through the blood stream to be deposited in fat cells in the tissues throughout the body. Fat can be stored for years in the body's fat cells.

Still reading?

Okay, so we need carbohydrates, but we need the complex ones more than the simple ones, because they provide other components that our bodies need such as protein, fibre, vitamins and minerals.
When we compare the carbs in white sugar to an equivalent amount in kidney beans, dates and apricots, we have the following data:

Excuse the crappy Google Docs chart. It took me a long time to get it to even show up, let alone look good too.

If we add fibre into the above chart, the results would show the high amounts in the dates, kidney beans and apricots with 0 for sugar. Therefore, white sugar provides our body with empty calories. Lots of glucose to provide instant energy, if that's what you need, but no nutrients or value in any other way.

Fibre also helps slow down the processing of carbohydrate, so though dates and apricots are high in carbohydrate, the fibre content prevents quick assimilation of the glucose content. Energy is released slowly over a period of time. Glycaemic Index is a way of measuring the how quickly blood sugar (glucose) levels rise after eating a particular food. It doesn't take into consideration the amount of carbohydrate actually consumed. This is measured by multiplying the GI of the food by the carbohydrate content of the serving. Thus, a food like watermelon may have a high GI, but it has a low GL. You need to eat a lot of it to obtain a large amount of carbohydrate.

Eating well is all about choosing carefully. If you have a sweet craving at 4pm, do you choose a sugary processed biscuit or cake or a couple of dates and some watermelon or apricot? Cool drinks would probably have to be one of the worst choices a person can make when choosing a beverage. There are over 9 teaspoons of processed white sugar in a can of Coca Cola which is 11% of a person's daily requirement of carbohydrate with no other nutritional benefit.

That's probably enough information to be assimilated in one blog post. In the next post, I'll discuss ways to sweeten your foods in a far more healthy way than with processed white sugar.


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