Evidence Based Health Care:
Before I enter contentious territory I think it’s important to state my position on modern western medicine. I am under the care of a Gastroenterologist, Dr David Hetzel to manage Crohns disease and a Physician and Allergist Dr Alan Gale (www.agale.com.au) who I consult for management of insulin resistance.
I support Evidence based practice. Evidence based practice means that anything that health professionals tell us to do should be supported by evidence. Evidence is not logical deduction. For example “fat makes you fat” is as persuasive an argument as “tomatoes make you red”. In addition correlation does not equal causation. If that were the case then we could blame global warming on the rise in the US postal stamp as this correlates more closely to global temperature than CO2 in the atmosphere. Anything science tells us should be backed up by studies such as randomised control trials or empirical research.
The Facts About Carbohydrate:
There are 3 macronutrients, Carbohydrates, Lipids (Fat) and Amino Acids (Proteins). The human body can produce many lipids and some amino acids but the liver can make enough glucose to meet all the body’s carbohydrate requirements. This process is called gluconeogenesis, the production of new glucose out of other chemicals including amino acids (found in proteins) and fatty acids.
Essentially all carbs are made up of glucose molecules (or frutose or galactose but normally glucose) joined together to make longer chain molecules. Glucose is how plants store sunlight as energy for later use. Glucose and fructose make up sucrose, glucose and galactose form lactose (found in milk) and 2 glucose molecules form my favourite disacaride, maltose, every brewers friend. Longer chains form complex carbs such as the dextrins found in stout that gives it it’s mouthfeel. In whole grains, even longer chains form soluble fibre. Large glucose polymers form cellulose which is indigestible to humans and are known as indigestible fibre.
Current nutritional guidelines in Australia recommend 5 serves on vegetables and 2 of fruit. One of the vegetable serves can be a potato. This is mad. A potato is basically a ball of glucose with skin on. Most root vegetables and fruits contain considerable amounts of carbohydrate and even wholegrain is still mostly carbohydrate.
All that is absorbed by the gut passes through the liver. These nutrients are altered into forms suitable for the general circulation and any toxins are removed. Fructose and galactose are converted to glucose. In addition the liver acts as a glucose buffer, storing a few hundred grams of glucose in the form of glycogen. Inevitably carbohydrate in a meal becomes glucose in the blood stream, the only real question is how quickly blood glucose rises. In the healthy person glucose is regulated in a fairly narrow range (100 – 140g/dl or 5 to 7.8 mmol). This is where beta cells in the pancreas come in. They sense this rise in blood sugar and release insulin to force glucose out of the circulation and into the tissues, either as glycogen or into adipose tissue (fat) after it is converted to triglycerides by the liver. In the insulin resistant individual more of this glucose is moved to adipose tissue.
This spike in blood glucose happens very quickly. Christiansen demonstrates in this presentation ( http://www.diabetes-symposium.org/index.php?menu=view&id=322 what is normal glucose? See slide 30 in particular) that even in a healthy individual blood glucose peaks at 30 minutes after they eat. A fasting and 2 hour glucose doesn’t give the entire picture as it doesn’t show this peak. If your peak glucose is over 140 then you are likely insulin resistant and your system is able to compensate by producing huge amounts of insulin, given enough time. The problem is this flogs your beta cells and causes burnout. Christiansen’s overarching point is that frequent blood sugar measurement is the best way to see what effect a meal has on your blood sugar. This information arms you to maintain a steady blood glucose and preserve beta cell function.
Diabetes is an insulin related disorder that leads to glucose storage dysfunction. Why, if diabetes is a disorder related to the balance of glucose in the blood stream should they receive a significant percentage of their energy needs from carbohydrate?
Next time; What’s the deal with GI?
Other References: Guyton and Hall “Medical Physiology 11th ed”, “Dr Bernstein’s Diabetes Solution: The Complete Guide To Achieving Normal Blood Sugars” Dr Richard K. Bernstein, MD. A link to the first chapter is here http://www.diabetes-book.com/cms/articles/9-dr-bernstein-shares-his-insights