A Short Guide to Understanding Carbohydrates

Richard_Harding_02Copyright © Richard Harding – A Short Guided to Understanding Carbohydrates – by Richard Harding. (See bottom of article for more on Richard).

A Brief History of Low-carbohydrate Diets

Much passionate debate occurs, mainly by popular commentators on the internet, magazines and books, regarding the evils of carbohydrates. It has been implicated (incorrectly) in causing cancers, heart disease, auto-immune diseases and diabetes.

William Banting was a very overweight English carpenter and undertaker. At age 66, he weighed 92 kg [202 lb] and was 165 cm [5 feet 5 inches] tall. He wrote a very successful pamphlet, Letter on Corpulence, in 1864 in which he describes his experience in reducing his weight to 76 kg [167 lb]. A big improvement, but not exactly slim. He did this by eating “any fish except salmon, any meat except pork, any vegetable except potato.” Bacon, however, was allowed. He “scrupulously avoided those beans, such as milk, sugar, beer, butter, &c., which were known to contain them”.  Meat was a large part of his diet, as well as “two or three glasses [a day] of good claret, sherry, or Madeira – Champagne, Port and Beer forbidden”.

Low-carbohydrate diets have regularly disappeared and reappeared. Some popular examples include:

  • Alfred Pennington – DuPont Diet (1950)
  • Herman Taller – Calories Don’t Count (1961)
  • Irwin Stillman – The Doctor’s Quick Weight Loss Diet (1967)
  • Robert Atkins – Dr Atkins’ The Diet Revolution (1972)
  • The Scarsdale Diet – Herman Tarnower (1978)
  • Barry Sears – The Zone Diet (1995)
  • Peter J. D’Adamo – Eat Right for Your Type (1996)
  • Loren Cordain – The Paleo Solution (2003)
  • Arthur Agatston – The South Beach Diet (2003)
  • Aseem Malhotra – The Pioppi Diet (2017)

Definition of Carbohydrates

There are only three major components of food: carbohydrates, fats and protein. Much research and popular commentary focus on the proportion of these major components, ignoring that fact that we eat food, not a collection of macro-nutrients.

Carbohydrates are synthesised from plants from carbon dioxide and water. The contain carbon, hydrogen and oxygen with approximately twice as much hydrogen as oxygen—the same as water.

There are many types of carbohydrates.

  • Simple sugars: fructose, glucose, galactose
  • Disaccharides: sucrose (sugar), lactose (milk sugar)
  • Raffinose and stachyose: short chained carbohydrates that present in beans, brassicas and whole grains that are broken down by bacteria in the intestine. These bacteria are essential for our well-being.
  • Starches are the predominant food reserve in plants and provides 70–80% of the calories consumed by humans world-wide. It is comprised of a large number of glucose units.
  • Cellulose is composed of very long chains of glucose units. It is a very stable polysaccharide and is not digestible by humans.
  • Gums are water-soluble polysaccharides that are constituents of plant wounds.
  • Mucilages are soluble in hot water and are present in seaweeds and some plants.
  • Pectic substances are abundant in citrus fruit, sugar beet, apples, and some root vegetables.

Americans eat a diet of approximately 33% fat, 16% protein and 50% carbohydrates by energy. They consume, on average, 15-20 g/day of fibre which is well short of the very conservative recommendation of 25 g/day. Sugars comprise of about 20% of diet by energy, most being added sugars in the form of sweeteners.
Added sugars are detrimental – sugars that are obtained from fruit or the digestion of starches have a significantly different effect on insulin and our health than consuming sugars in isolation.

In the 1950s, it was thought that dietary fibre was an inert component of food. It is contained in fruit, vegetables, bean and grains. It has since been shown to be essential to maintain healthy intestinal bacteria.

Diabetes

The result of Type 2 diabetes is that the body does not process sugar effectively, which results in high levels of glucose in the blood. High levels of glucose over an extended period of time places you at risk for many serious health problems.

The usual medical advice is to prescribe a diet with very little sugar and limit starch in the diet since glucose is formed when starch is digested.

This does seem to be the logical solution to having too much glucose in the blood.

It has been known since at least 1927 that high fat diets increase insulin resistance. Healthy, young medical students were divided into four dietary groups:

  • high-carbohydrate diet consisting of sugar, candy, syrup, baked potatoes, bananas, and oatmeal, rice, and white bread
  • high-fat diet consisting of olive oil, butter, mayonnaise, egg-yolks, and cream
  • high-protein diet consisting of lean meat, lean fish, and egg-whites
  • the fourth group was placed on a fasting regime

The students were fed their diets for two days and a glucose tolerance test was performed on the morning of the third day.

The students who consumed the high-carbohydrate showed an increase in tolerance for dextrose; those on the high-protein diet showed a mild inability to remove sugar from the blood; those on the high-fat and starvation diets showed a significant decrease in their tolerance for sugar.

After only two days on their experimental diets, the only group showing a normal, healthy response to the glucose tolerance test was the high-carbohydrate group.

Normally, insulin attaches to protein receptors on the cell’s surface and signals the cell membrane to allow glucose to enter. If there is an accumulation of fat in the cell, it interferes with insulin’s signalling process and glucose cannot enter the cell. Fat can accumulate inside muscle cells even in slim people. The real cause of type 2 diabetes is not an excess of sugar or carbohydrates. It is an accumulation of fat inside the cells that interferes with the muscle cells’ ability to respond to insulin. The muscle cells are unable to access glucose, which is required for energy production.

Dr James Anderson is emeritus Professor at the University of Kentucky who has been researching diabetes for more than 30 years. He advocates a high-carbohydrate, high-fiber diet for treating diabetes.

Ideally, diets providing 70% of calories as carbohydrate and up to 70 gm fibre daily offer the greatest health benefits for individuals with diabetes. However, these diets allow only one to two ounces of meat daily and are impractical for home use for many individuals.

It should be noted that living with diabetes is not practical either.

Ancestors

Dr Katharine Milton is a professor of physical anthropology at the University of California in Berkeley. She received her Ph.D. in anthropology from New York University in 1977.

Her field of expertise is the dietary ecology of primates, including human ancestors and modern humans. So, she is a real expert in paleo-nutrition.

According to Professor Milton:

In fact, we do not know much about the range of foods Paleolithic hunter-gatherers consumed in almost any environment.

Chimpanzees, bonobos, orangutans and gorillas obtain most of their food from carbohydrates. They spend up to 5-6 hours a day chewing food. The big difference between these primates and humans is that we produce a lot more amylase, which is an enzyme required to breakdown starch and we also cook food which means we spend much less time chewing.

Professor Milton’s conclusion is:

It is prudent for modern-day humans to remember their long evolutionary heritage as anthropoid primates and heed current recommendations to increase the number and variety of fresh fruit and vegetables in their diets rather than increase their intake of domesticated animal fat and protein

A whole-food, plant-based diet is high in complex carbohydrates, unprocessed sugars, starches, fibre, and a myriad of phytonutrients, minerals and vitamins as well as being low in fats, saturated fats and protein. Concentrating on one component of our diets is not conducive to optimal health.


REFERENCES
1. Banting, W. (1864) Letter on Corpulence. Third Edit. London: Harrison, 59 Pall Mall.
2. U.S. Department of Agriculture (2014) What We Eat in America, NHANES 2011-2012.
3. Manzano, S. & Williamson, G. (2010) Polyphenols and phenolic acids from strawberry and apple decrease glucose uptake and transport by human intestinal Caco‐2 cells. Molecular nutrition & food research. 54 (12), 1773–1780.
4.  Petta, S. et al. (2013) Industrial, not fruit fructose intake is associated with the severity of liver fibrosis in genotype 1 chronic hepatitis C patients. Journal of Hepatology. 59 (6), 1169–1176.
5.  Torronen, R. et al. (2013) Berries Reduce Postprandial Insulin Responses to Wheat and Rye Breads in Healthy Women. Journal of Nutrition. [Online] 143 (4), 430–436.
6. Torronen, R. et al. (2012) Postprandial glucose, insulin, and free fatty acid responses to sucrose consumed with blackcurrants and lingonberries in healthy women. American Journal of Clinical Nutrition. [Online] 96 (3), 527–533.
7. Sweeney, J. S. (1927) Dietary Factors that Influence the Dextrose Tolerance Test. Archives of Internal Medicine. 40 (6), 818–830.
8. Sweeney, J. S. (1928) A comparison of the effects of general diets and of standardized diets on tolerance for dextrose. Archives of Internal Medicine. 42 (6), 872–876.
9.  Bachmann, O. P. et al. (2001) Effects of Intravenous and Dietary Lipid Challenge on Intramyocellular Lipid Content and the Relation With Insulin Sensitivity in Humans. Diabetes. 50 (13), 2579–2584.
10. Jacob, S. et al. (1999) Association of Increased Intramyocellular Lipid Content With Insulin Resistance in Lean Nondiabetic Offspring of Type 2 Diabetic Subjects. Diabetes. 48 (21), 1113–1119.
11. Anderson, J. et al. (1987) Dietary fiber and diabetes: a comprehensive review and practical application. Journal of the American Dietetic Association. 87 (9).
12. Milton, K. (2002) ‘Hunter-Gatherer Diets: Wild Foods Signal Relief from Diseases of Affluence’, in Peter S. Ungar & Mark F. Teaford (eds.) Human Diet – Its Origin and Evolution. 113.
13.  Milton, K. (2000) Hunter-gatherer diets – a different perspective. 667.


Richard Harding is a lecturer in Nutrition at Newcastle, Australia at WEA Hunter.  Newcastle is Australia’s largest regional city.  WEA Hunter offers Degree and Diploma courses in Health Sciences. More about Richard Harding

Richard’s website: Wise Nutrition Coaching