What is Sugar?
A disaccharide comprised of the monosaccharide glucose and the monosaccharide fructose, bound together. GLUCOSE + FRUCTOSE = SUCROSE.
Sweet. Examples of carbohydrates made mostly of fructose are apple juice, agave syrup and dates. Fructose does not immediately spike blood sugar, nor insulin, BUT it directly creates triglycerides (fat), promotes visceral fat accumulation and leads to insulin resistance over time, along with many harmful effects.
NOT so sweet. Examples of carbohydrates made of glucose are rice and potatoes. Glucose spikes blood sugar and insulin in the short-term, but can be attenuated by eating fibre and having a healthy metabolism. Glucose is found in varying quantities, and along with fibre, in most plant foods.
What is Blood Sugar?
The amount of glucose circulating in the blood. Glucose is used by many of the body’s cells as an energy source and the body has an intricate system of regulating how glucose from the foods we eat gets into the cells to be used as energy. The system keeps blood glucose levels within a tight range, and it depends partly on the effective functioning of hormones such as insulin and glucose transporters on cell membranes.
When a food causes a spike in blood glucose, we say it has a high ‘glycaemic index’ (GI). High blood glucose is very harmful. What makes it high?
Fructose does NOT cause an immediate spike (i.e. it would count as ‘low GI’, which is why GI is not enough to consider), yet over time, chronic high-fructose consumption causes constantly higher blood glucose and higher spikes after eating. High-fructose diets cause insulin resistance. This leads to elevated blood glucose and insulin, causing metabolic dysfunction, and ultimately Type 2 diabetes. Type 2 diabetes is when specific cells in the body stop responding appropriately to insulin signaling. The result? Elevated blood glucose and insulin, both of which independently and together have many harmful effects and increase the risk of all of the major chronic diseases.
Bottom line: If the blood glucose regulatory system does not function well, and blood glucose gets into a high range frequently, and/or for longer durations, this causes damage to arteries and tissues, and has many detrimental health consequences, including but not limited to metabolic syndrome. Fructose interferes with this system and increases the risk of insulin resistance and chronically high blood glucose, hyperinsulinemia and harmful spikes in blood glucose.
Sugar tastes sweet due to FRUCTOSE
Sugar tastes sweet mainly because of the FRUCTOSE part. Unless sweetened with artificial sweeteners or natural healthy sweeteners (stevia, erythritol, xylitol, allulose, monk fruit extract, katemfe extract (thaumatin)), if something you are eating tastes sweet, it contains fructose. Usually, the sweeter it tastes, the more fructose it contains. For example, a ripe brown banana has formed more fructose than a green one. Fresh grapes contain c. 8% fructose, but after drying to become raisins, the fructose percentage quadruples to c. 32% fructose, and the total sugars (fructose, glucose, sucrose, maltose (two glucoses bonded together)) make up 67-80% of the raisins (i).
Fructose consumption generates visceral fat; fat around the waist is usually indicative of this type of fat. Visceral fat is fat between and within key organs such as the liver and pancreas, where the altered tissue structure disrupts the functioning of these crucial organs. Associated risks of this include fatty liver disease, insulin resistance, Type 2 diabetes, cardiovascular disease and obesity.
Fructose is the chronically toxic part of sucrose and you can avoid it by checking labels and by tasting if what you are eating a) tastes sweet and b) does not include natural, sugar-free sweeteners.
(i) Alnuwaiser M.A., (2017), Content of Sugars in Fresh Grapes and Raisins, and Fresh and Dried Apricot: A Comparative Study. Int. j. res. granthaalayah. 5, pp. 1770186
Human Beings & Sugar
Evolution, Body Fat-Generation and Energy
Human beings have not evolved to adapt to the high-sugar environment we live in. Fruits were not cross-bred to increase their sweetness (sugar-content) as they are now, and we ate what we could find, allowing us to store fat, most likely in autumn, particularly useful ahead of a cold, food-scarce winter. Our Palaeolithic ancestors are unlikely to have had regular access to honey, dates or maple syrup.
One mechanism (means) by which fructose increases fat generation and storage, and reduces fat-burning, is via its generation of uric acid. While many mammals have an enzyme (uricase) that helps them to break down uric acid, humans do not. Genetic research reveals that our ancestors lost the uricase enzyme during the early Miocene, when progressive climate-cooling challenged early hominids’ diets, particularly in Eurasia. Losing uricase – elevating uric acid levels – likely provided a substantial survival advantage by increasing fructose’s fat-storage effects in these then-frugivorous species (i, ii).
In human history, the time during which sugar consumption began to increase until what it is today is less than c. 0.1% of our existence as a species: it is clear that the biology of human beings has not had time to evolve to deal with the large quantities of sugar we currently consume. In fact, our biology is still geared towards reacting to fructose by storing body fat, a great survival mechanism in the food-scarce past, a harmful one in the sugar-filled present food environment.
(i) Kratzer, J. T. et al. (2014) ‘Evolutionary history and metabolic insights of ancient mammalian uricases’, Proceedings of the National Academy of Sciences of the United States of America, 111(10), pp. 3763–3768
(ii) Cicerchi, C. et al. (2014), ‘Uric acid‐dependent inhibition of AMP kinase induces hepatic glucose production in diabetes and starvation: evolutionary implications of the uricase loss in hominids’, The FASEB Journal, 28, pp. 3339-3350
SUGAR OVERCONSUMPTION CAN BE A MAJOR CAUSE OF:
- Metabolic Syndrome
- Type 2 Diabetes
- Alzheimer’s Disease
- Cardiovascular Disease
- Acne, Cellulite, Ageing Skin, Wrinkles
- Colon Cancer
- Pancreatic Cancer
- Non-Alcoholic Fatty Liver Disease
- Liver Cancer
- Tooth Decay
- Hair Loss
- Polycystic Ovarian Syndrome
- Inflammatory Bowel Disease
DO THESE INGREDIENTS DIFFER?
Is there any difference between raw cane sugar, table sugar, honey, agave syrup, maple syrup and high fructose corn syrup?
The below ingredients are biochemically almost identical. They all contain high amounts of fructose. We do NOT need them to survive, and it is best for our health to avoid them.
- Agave Syrup
- Raw Cane Sugar
- High Fructose Corn Syrup
- Maple Syrup
- Coconut Sugar
- Table Sugar
- Date Syrup
- Fruit Juice Concentrate
Just because it is natural...
Sugar (sucrose and fructose) comes in many forms. Simply because it is ‘natural’, does not mean it is healthy. Table sugar is arguably just as natural as maple syrup. Raw cane sugar and table sugar both come from sugar cane and/or sugar beet – i.e. sourced from nature. The only differences between all of the above sources of sugar are their – actually relatively similar – ratios of sucrose, fructose, glucose and maltose. They are all mostly comprised of fructose and glucose, in free form, and/or bonded together as sucrose.
Brown sugar is biochemically and practically identical to white sugar. It contains c. 1% more fibre and just a small amount of iron. It has 373 kcal/100g vs. 396 kcal/100g and is still c. 97% sucrose. There is NO meaningful health benefit of choosing brown, muscovado, raw cane sugar and/or coconut sugar.
What are Carbohydrates?
Carbohydrates are molecules made of Carbon, Hydrogen and Oxygen. Complex carbohydrates are comprised of simpler molecules that are broken down in digestion. Indigestible fibre is not metabolised by us, yet it is essential for gut and overall health, including the health of our microbiome and thus metabolic and immune system functioning. People often say ‘sugar’, when they mean carbohydrates. This is misleading and confusing. Remember, harmful sugar (fructose, sucrose) is sweet-tasting. Carbohydrates are either monosaccharides such as glucose and fructose, disaccharides such as sucrose and polysaccharides such as starch and fibre. They differ significantly in their metabolism and biological effects.
Lactose: We’ve discussed what glucose and fructose are, and their combination as sucrose. Lactose is another common dietary carbohydrate found in milk that is a disaccharide, made of the monosaccharides glucose and galactose. Those who are lactose intolerant no longer have the ability to secrete the enzyme lactase that helps to break down lactose. They are often still able to eat butter, which contains only a tiny amount of lactose. For those who can tolerate lactose, there is no definitive health reason to avoid lactose.
What is Fibre?
Fibre may be one of the most under-appreciated macronutrients. It is essential for digestion, gut and immune health. A key function is that it is food for our gut microbiome. The bacteria in our gut perform many crucial functions: they maintain intestinal barrier integrity, aid in micronutrient absorption and even production, and help to regulate immunity, amongst other functions. If we do not provide them with sufficient fibre, they will not perform these crucial functions effectively, and they may even cause damage by starting to consume the intestinal wall (a critical membrane between our bodies and the external world) and/or by forming health-undermining imbalances in the gut ecosystem, causing negative health consequences.
Confusion Clarified: There are many types of fibre. They share a similar structural feature in being long chains of molecules that are not readily cleaved by our digestive enzymes. Some have names that sound foreign to us. These are all healthy fibres for example: fructo-oligosaccharides, inulin, glucomannan.
Carbohydrates differ significantly in their metabolism and health effects. Very healthy fibres are labelled often as carbohydrates, yet do not add to energy intake and instead feed essential gut bacteria – keep this in mind when reading food labels.
Within the category of carbohydrates, most humans living in urban environments would do best to avoid/limit consumption of fructose, sucrose and refined carbohydrates and consume more high-fibre plant foods.
It is essential that we consume sufficient healthy fibre in our diet. Evidence suggests that our ancestors consumed >100g fibre/day, and the average adult eats only c. 18g/day (i, ii). Current governmental guidelines suggest 30g/day are required for adults to maintain health.
There are many healthy natural dietary fibres such as insoluble and soluble fibre, fructans, fructo-oligosaccharides, inulin, glucomannan and beta glucans, which can all be found in foods.
Cacao contains significant insoluble fibre, and its consumption has been demonstrated to improve bowel function for example (ii).
(i) Eaton S. B., (2006). The ancestral human diet: what was it and should it be a paradigm for contemporary nutrition? Proceedings of the Nutrition Society, 65(1), 1-6
(ii) Sarriá, Beatriz et al. (2012). “Effects of regularly consuming dietary fibre rich soluble cocoa products on bowel habits in healthy subjects: a free-living, two-stage, randomized, crossover, single-blind intervention.” Nutrition & metabolism vol. 9 33