In the previous article on carbs metabolism, we have seen how blood sugar is regulated in the body. We have learnt that every time we take a meal, blood glucose or sugar (as popularly called) goes up. Insulin level also goes up to bring blood sugar to normal level. In this article, the implication of glucose metabolism in health will be discussed. In this article glucose and sugar word will be used interchangeably.
Glucose Metabolism and Genesis of Chronic Diseases
Our body requires glucose in small amount. Around 250-300 grams of glycogen (storage form of glucose) is stored in liver and additional 200-300 grams is stored in muscles and other tissues. The main warehouse of energy is Fat, which is utilized when the glycogen stores are consumed. In olden days, people use to eat only once or twice, so blood and insulin level were high for very short periods only. In modern times, the consumptions of carbs (glucose) has increased tremendously in quality, quantity and frequency, leading to numerous health problems of todays era.
Lets examine food habits of a typical Indian adult. Morning starts with a cup of tea. Most Indians have a habit of taking very sweet tea (two or more tea spoonful of sugar). Some also take biscuits or other snacks with tea (full of carbs). This is the first spike of glucose and insulin in a day. Before this spike settles to fasting level, next spike comes with breakfast. Our breakfast is carbs rich (parantha, sabji or roti sabji, or bread, jam, sandwiches etc). People take snacks at around 10-11 am (tea break), when tea and snacks (like samosa, pakora etc) are consumed resulting in the third spike. After the tea break, there comes lunch (which is again rich in carbs) causing a fourth spike. Fifth spike comes with evening tea & snacks and sixth spike with dinner. Some people take snacks before sleeping also. These are planned spikes on a day. Additional spikes can come due to socializing, when carbs are consumed (tea, snacks or carbonated drinks). Due to repeated consumption of carbs, the insulin levels never comes back to normal levels and remain elevated constantly throughout the day and night. Some people are insulin hyper secretors. They secrete much more insulin for a given glucose load, which takes more time to settle. Due to action of insulin more glucose is converted to fats by the liver and deposited into organs like heart, kidney, abdomen and its own tissues. The person starts gaining weight (obesity starts). Later on, when the fat deposition becomes too much, tummy starts bulging out, starting the onset of central obesity. Just look at people around you. Protruding abdomen has rather become a common scene. Earlier such bulge came only in 5th or 6th decade (middle age spread).
Fast or Processed Foods : Tasty Slow Poisons
The consumption of fast and processed foods (Pasta, pizza, burgers, bakery products, breakfast cereals, sugar sweetened beverages, commercial fruit juices, biscuits, confectionary etc) has added ghee to the fire. These foods raise blood sugar sharply as compared to the traditional foods. We can compare it to a tsunami of glucose like situation. To handle this large influx of glucose in short period of time, the liver and the pancreas have to overwork in emergency mode. The pancreas is pressed into action to secrete more insulin for getting this flooding of glucose cleared. The liver has to convert this glucose to fat and dispatch it to various fat depots. High blood sugar has potential harmful effects in the body. High glucose concentration causes faster Glycation reaction, (also called as browning reaction or Maillard’s reaction or caramelization reaction, first described by Professor Louis Camille Maillard in 1912). Its basically a reaction between an amino acid and sugars (glucose, fructose etc). Glycation is responsible for ageing process. Though intrinsic mechanism exists to clear the products of glycation, it is often inadequate due to rapidly developing high glucose levels. The mismatch between the generation of advanced glycation end products (AGE) and its clearance, results in accumulation of AGE in the body. Dementia and Alzheimer’s have been linked to AGE accumulation in the brain. High level of glucose in blood damages the Glycocalyx layer of the blood vessels. Glycocalyx is a thin layer separating blood and wall of blood vessel. It secrets nitrous oxide which dilates the blood vessel to maintain blood pressure. In one research study, only 6 hours of exposure to high blood sugar reduced glycocalyx volume by a whopping 50%. So a party, can cost you 50% of your glycocalyx layer within six hours. Recovery of this glycocalyx takes more than 24 hours. High blood sugar may also cause the mitochondria (the energy factories in each cell) to overproduce too many free radicals, including reactive oxygen species (ROS). ROS are key signaling molecules that regulate the natural inflammatory responses in our bodies. Processed foods are devoid of fiber and micronutrients, the lifeline for gut bacteria. Lack of fiber alters the gut microbiome. Gut microbiome has now been linked to variety of diseases like asthma and other allergic disorders, dementia, Alzheimer’s, rheumatoid arthritis, ankylosing spondylosis etc.
Insulin Resistance: The Mother of all Chronic Diseases
When consumption of processed foods, and increased frequency of high carbs meals, carries unabated for years (may be 15-20 years or more), a threshold is reached, when the cells get overloaded with glucose and refuse to accept glucose further. The cells reduce insulin receptors leading to reduced glucose clearance and rise in blood sugar level. The brain signals the pancreas to secrete more insulin to push more glucose into cell. With progress of time, more and more insulin is required to clear the glucose from blood. This stage is called Insulin Resistance (IR) characterized by normal blood glucose level but high insulin level. Later, a stage is reached, when even higher amount of insulin is not able to clear glucose. The blood sugar levels remain elevated throughout (Hyperglycemia), heralding the onset of diabetes mellitus Type-II, characterized by high blood sugar level and high insulin level. Over a period of time, the pancreas burns out, and insulin secretion decreases, requiring insulin injections for control of blood sugar. Rarely, if complete burnout takes place we may have Type 1 Diabetes like situation. So a Diabetes Mellitus has three stages; Stage 1; Blood Glucose normal, but Insulin is high. Stage 2; High blood glucose and high insulin (Prediabetes and diabetes). Stage 3; High blood glucose and low insulin (burn out stage). Stage 1 can only be diagnosed by measuring blood insulin level. It may take 20-25 years from transition from stage I to stage II. Insulin resistance (IR) in liver creates havoc. The glucose is converted to fat and deposited in liver cells or hepatocytes. Fat deposition in liver cells leads to onset of Non Alcoholic Fatty Liver Diseases (NAFLD), which may ultimately lead to liver cirrhosis and liver failure. The fat is packed to form triglycerides (TG) and released in blood, leading to increase in serum TG (Hypertriglyceridemia). Other lipids also get deranged in this IR stage. Fat gets deposited in organs like liver, kidneys, heart, intestines and abdomen (called visceral fat or ectopic fat). This visceral fat is metabolically active and secretes chemicals that are inflammatory in nature, fueling a low grade inflammation in the body. It postulated that this low grade inflammation is responsible for heart attacks and angina. High levels of insulin has its own effects. Insulin is an anabolic and storage hormone. It causes cell proliferation (meaning growth and division). It triggers smooth muscle proliferation in blood vessels (causing loss of elasticity) of coronary arteries and kidney, and more risk for high blood pressure (Hypertension), heart attacks (Myocardial Infarction) or kidney failure. IR also inhibits sodium excretion by kidney increasing the blood pressure. Cellular proliferation action of insulin triggers cell division and cancerous growth starts. Few authors have postulated cancer as a metabolic diseases. Insulin resistance in brain has been linked to origin of diseases like Dementia and Alzheimer’s (also called as Type III diabetes), which is caused by deposition of advance glycation end products (AGE) in brain. High Insulin blocks the action of leptin hormone in brain, resulting in obesity. Leptin (also called satiety hormone), tells the brain that the body has adequate energy stores and further feeding and storage of energy is not required. Due to lack of leptin signal, the brain assumes that the body is starving and signals for feeding are not suppressed. The individual eat more even it is not required. Obese people are usually insulin and leptin resistant. The whole spectrum of obesity, hyperglycemia, hyperlipidemia, hypertension has been termed as Metabolic Syndrome. If we search the internet, lots of articles on IR linking it to above diseases can be seen.
IR corelates well with the abdominal girth. Abdominal girth more than 94 cm (male) and 80 cm (female) shows IR. The risk of metabolic derangement is severe, if abdominal girth is more than 102 cm (males) and 88 cm (females). Another measure of IR is WHR or waist to hip ratio. WHR more than 0.85 (women) and 1.00 (Men) is another warning sign of IR. Presence of darkening, thickening and ridging of skin (acanthosis nigricans) at the back of neck, armpits and knuckles, though often mistaken as dirt, is due to excess insulin acting on the skin. To start with, one simple test can be done. I call it bathroom test. After removing clothes, stand straight and look down. If one can see genitals, then he/she is not having IR. If one can see ankle joint, IR may or may not be there. But, if the tip of toes cannot be seen, IR is definitively present. One may have IR with normal weight or BMI. About 40% of normal weight individuals have IR and 20% of these individuals have fatty deposits in liver. Dr Robert Lustig in his book “Metabolical”, referred such individuals as TOFI (Thin outside but fat inside). In my hospital, a large number of my staff (including young persons of 30-35 years of age) had protruding tummies. They were not concerned about it, as their weight was within normal limits. Few people think that protruding tummy is harmless and a sign of prosperity. When ultra sound examination of abdomen was done, most of them had Grade I or Grade II fatty liver changes. Abdominal girth is true representative of metabolic health. Its not a cosmetic issue.
Glucose is like petrol. Petrol is vital for our car running, but it is dangerous. The fuel tank of a car should be filled only up to the level recommended by the manufacturer. Problems occur when people try to fill the tank up to beyond maximum. Similarly glucose is essential for our body fuel requirements, but we require only a little amount to keep us moving, which can be even synthesized by the body. If we consume too much glucose (or carbs), all types of metabolic derangements can occur. Experts and doctors may disagree to this viewpoint, but one thing is sure; the guidelines given by WHO, US govt and other expert bodies (which advocates 60% energy from carbs), have failed to check the onslaught of chronic diseases. We cannot blame the people all the times for not exercising or eating too much. Our ancestors used to consume much more calories (5000-6000 calories) without suffering from chronic diseases. Chronic diseases are hallmark of western food habits (which is full of processed foods and refined grains). People of blue zones (lands of centenarians) loose their advantage of long life, once they adopt western food habits. Its time to think alternative solutions. Carbs or sugar consumption patterns do match with the increase in the chronic diseases. In fact chronic diseases acquired epidemic proportions only after the food guidelines were promulgated in 1970 by US Govt. It also fits into human physiology principles. Lots of literature exists in scientific world to link high carbs with chronic disease. Internet is full of stories of people who cured themself of diabetes and other diseases by adopting a low carbs diet.
In this article we have seen how carbohydrates are affecting our health. Large number of health problems can be addressed by regulating our carbohydrate intake.
The message is clear
(a) Eat those carbs which raise blood sugar slowly. The capacity of a particular food to raise blood sugar is governed by Glycemic Index (GI).
(b) Say NO to Processed Foods or consume them infrequently (not more than once a month).
(c) Reduce the numbers of meals in a day to the extent possible. No frequent snacking in between meals.
Hope this article has shattered your conventional teachings about the food we eat. In the next article metabolism of fructose will be discussed.
Your suggestions, queries and criticism are welcome.
Brilliant article.