# RKS: VEGETARIANS & VEGANS (II)

THE CONTROVERSIAL ROLE OF CARBS

1st January 2024

THE DISADVANTAGEOUS VEGETARIAN

CARBS LINKED TO DIABETES

Dear Reader,
There are a total of 7 nutrients that one gets from food:
Proteins
Carbohydrates (Carbs)
Lipids (commonly referred to as fats)
Vitamins
Minerals
Water
The energy providers are three amongst these and include proteins, carbohydrates and lipids which are termed as macronutrients. One gets zero calories from vitamins, minerals and water.
The 3 macronutrients could be referred to as:
Good - Proteins
Bad - Fats
UGLY - Carbs
There has been an increasing recent focus on demerits of carbs and much discussion and awareness has already been spread. It is imperative to have a precise scientific explanation on the controversial role of carbs for humans to enable one to take a well-informed decision.

CLASSIFICATION OF CARBS

There are 4 main classes of carbs:
Monosaccharides: Single carb molecules like glucose, fructose and galactose are monosaccharides.
Disaccharides: Carbs with 2 sugar molecules like lactose, maltose and sucrose are referred to as disaccharides.
Oligosaccharides: The carbs containing 2 to 10 sugar molecules like raffinose are called oligosaccharides.
Polysaccharides: Starch, glycogen and many others give rise to larger number of sugar molecules (>10) when they breakdown (undergo hydrolysis).
All the disaccharides, oligosaccharides and polysaccharides ultimately undergo hydrolysis to form glucose. Hence, in humans, the only forms of carb that persist in the body are:
Glucose in blood.
Glycogen as stores in liver and skeletal muscles (all those voluntary muscles as present in limbs).
Glucose is converted to energy in the form of adenosine triphosphate (ATP) via glycolysis. The excess glucose is converted to glycogen by a process called glycogenesis; when necessary glycogen is broken down to glucose via glycogenolysis.

BASICS ON CARBS

Glucose comes from the Greek word for "sweet." Each 1 gram (gm) of carb provides 4 kcal (kilocalories or small calories). The most common and abundant forms of carbs in foods are sugars, fibres and starches. The sugars found as in diet food items are:

GLUCOSE: table sugar, juices, some fruits (grapes, bananas), honey
FRUCTOSE: fruits
GALACTOSE: milk products, avocados
LACTOSE: dairy foods
MALTOSE: germinating grains
SUCROSE: sugar cane, sugar beet plant, some fruits (apples, oranges, carrots), few vegetables

Except for galactose, all forms of carbs mentioned above are converted to glucose. Excess glucose peps up muscle glycogen stores, whilst fructose preferentially restores the liver glycogen. Galactose is preferentially stored in the form of glycogen in liver, rather than be utilized for energy generation.

Starchy foods, which make up one-third of foods eaten, include potatoes, bread, rice, pasta and cereals. Besides being difficult to digest, high starch foods tend to be bulky and result in feeling full or causing lethargy.

All the carb types mentioned are digestible and enter blood (absorbed) to either provide energy or undergo glycogenesis. Fibre is the indigestible carbs and most worthwhile component which is never absorbed and, whatever is consumed, is excreted out. Fibre has multiple benefits, including fighting obesity, especially when taken in recommended amounts of 30 gms daily per 2,000 kcal consumption - as per National Institute of Nutrition (NIN) and Indian Medical Research Council (ICMR).

GLUCOSE HOMEOSTASIS

The expected value for normal fasting plasma (liquid part of blood) glucose concentration ranges between 70 mg/dL (3.9 mmol/L) and 110 mg/dL (6.1 mmol/L). In one's body there is approximately 5 litres (L) of blood circulating i.e. 50 dL (decilitre) and hence the total glucose present in blood in a non-diabetic ranges between 3,500 to 5,000 mg or 3-5 gms - equivalent to one-half to one tsf of sugar!

Glucose homeostasis entails maintaining these normal blood glucose levels by balancing intake vs its utilization.

GLUCOSE INTAKE

The average daily consumption recommended at each meal can be broken down as follows: 300 to 400 kcal for breakfast, and 500 to 700 kcal each for lunch and dinner, i.e. a total of 1300-1800 kcal/day. When the tea, coffee, juice and extra snacks are added the total calories sums upto 2000-2500 kcal/day.

According to a study done by the ICMR and India Diabetes (INDIAB) over a period of 12 years (2008-2020), the diet of average Indians include 60% to 70% carbohydrates! Since Indians consume approximately 2,200 kcal the daily intake of carbs is 330 gms!

GLUCOSE DISPOSAL

Brain and nervous tissue are the only two organs / tissues that utilize glucose during resting phase. 60% of blood glucose is metabolized in brain.

Besides, glucose there are 3 sources of ATP supply stores for the body's requirement depending on the level of activity:

Very short-term reserve: Creatine phosphate
Short-term requirement: Glycogen
Long-term storage: Triglycerides

Depending on the body's activities the fats or glucose are broken down for generating ATP:

Day-to-day body functions without any physical activity: Free fatty acids circulating in blood are utilized everyday throughout 24 hours to move various chemicals in brain and nerves and for day-to-day operation of the machinery of each cell. The explanation could be that over 100 ATP molecules can be synthesized from 1 molecule of fatty acid whilst only 2 are generated from 1 molecule of glucose.
Short burst of activity like running to close a leaking tap or catching a moving bus: Creatine phosphate can support muscles required to run for 8-10 seconds.
Short duration activities: Even 2-5 minutes walking utilizes glucose of blood for energy. A 10-minute walk can lower blood glucose by 22% - i.e. ~25 mg/dL (presuming plasma glucose is 110 mg/dL). Glycogen of liver, via glycogenolysis then replenishes the blood glucose that has been utilized.
Persistent exercise / gymming: After 60-90 minutes of continuous training all glycogen stores are depleted and fatty acids from adipose tissue are employed utilized for providing ATP.

At night, the glucose in brain is utilized by the brain at the rate of 0.1 gm/minute and as a result the glycogen stores in liver declines from 90 to 20 gms. Thus, the next day's meals compensate to restore the depleted glycogen stores.

THE GLYCOGEN EQUATION

Glycogen is a convenient way to store glucose and the conversion occurs within 4 hours following a meal. The total body store of glycogen is 600 gm. Most human cells have glycogen, but only liver and skeletal muscle cells are able to store significant quantities of this molecule.

Out of the 1.5 kg weight of liver, 6-10% is constituted by glycogen i.e. 90-150 gms.
Skeletal muscles comprise 30-40% of body mass i.e. 20-25 kgs and stored glycogen can be 1-2% i.e. 200-500 gms.

The liver can accumulate 100 gms glycogen whilst 500 gms can be stored in all the skeletal muscles put together.

Fig: Structure of glycogen molecule.

5,000 glucose molecules can be packaged together for storage as a single glycogen molecule. There are 2,000 branches in liver and 60,000 in muscles. Although the average number of glucose molecules sticking to each branch are 8-12, these are 10 times more in the liver.

Since the total body store as glycogen is worth not more than 2000 kcal, and total reserves in liver and muscles is 500 gm, it means that 1 gm of glucose is converted to 1 gm of glycogen. Hence, from the perspective of energy, on a weight-to-weight basis, 1 gm of glucose and 1 gm of glycogen provides equivalent energy i.e. 4 kcal.

UTILIZING GLYCOGEN

The blood glucose can maintain all the body's functioning (cellular processes) for only 3-4 hours. After this, the carbs in blood need replenishing and, for this, the glycogen in liver is broken down to maintain the normal plasma glucose levels.

The carbs are stored inefficiently as compared to triglycerides by the body. Hence, the glycogen stores are always first depleted. Even fasting for 12-16 hours can deplete 25-50% of liver glycogen stores, besides exercising and physical routine activity.

The glycogen stores that persist in body post-meals (during intermittent spells between food intake) include:

Brain: 2 gms
Blood cells: 15 gms
Liver: 25-50 gms
Muscles: 4-25 gms

The liver (weighing 1.5 kg) releases 1 gm (40 mmol/kg of liver weight/min) glucose from its glycogen stores every minute during the fasting spells, and this can keep on contributing 20 mg/dL to the blood glucose levels. The liver stores thus last for 1.5 to 2.5 hours and a total of 90-150 gms carbs supplied provides 480 kcal in-between meals. This is more or less what would be required to fulfil the ATP needed for all activities / or inactivities over 8 hours between food intake during a sedentary living.

If any physical activity is indulged in which lasts even after no more ATP is possible to derive from liver stores, muscle glycogen, that was untouched during 'fasting state' post-meals, is broken down. Only after 90% of the muscle glycogen is used up, with 10% remaining untouched, the adipose tissue starts crumbling to release fatty acids. Since every gram of glycogen retains 3 gms of water, loosing 400-600 gms of glycogen results in release of 1.2-1.8 kg of water and hence the initial weight loss is on account of the same (and not because one has lost fats at the waist line). The enigma is how these glycogen stores are repleted by body's normal mechanisms.

BALANCING GLYCOGEN RESERVES

Besides the enzymes participating in glycogenesis, foods containing sugars having higher glycemic index (GI) leads to 25% faster synthesis and larger glycogen molecule size as opposed to consuming low GI carbs. The enzyme glycogen synthase ties the glucose molecules into a chain whilst the hormone glucagon separates the glucose by dismantling the glycogen chain.

The glycogen stores in the body include: (Starvation and Diabetes. https://www.rose-hulman.edu/~brandt/Chem330/EndocrineNotes/Chapter_6_Diabetes.pdf.)

Brain: 2 gms
Blood cells: 15 gms
Liver: 100 gms
Muscles: 400 gms
Adipose tissue: 20 gms

After the liver stores are full the glucose enter the muscles, whose capacity is 300 gms. And only after the latter can no more store glucose as glycogen, the remaining carbs are transported to adipose tissue. The latter can store glucose as glycogen upto a maximum of 20 gms, and the excess will thereafter, between 4 to 8 hours post-meals, will be converted to triglycerides which makes one look fat.

Hence, the amount of glycogen available in liver as reserve carb is adequate to maintain blood glucose even during fasting spells. 44 gms of glycogen per kg of liver tissue, or 25-50% of stores, persist even after the 12-16 hours fasting period.

Since 24 hours or more are available for glycogen restoration, the frequency of carbohydrate intake is less important than the total amounts of carbohydrates and energy consumed.

INSULIN

Insulin is a hormone produced by a gland called pancreas that lies just down below the stomach. A human pancreas weights 91.8 g (ranging between 40.9 and 182 gms). It contains approximately 1 billion β cells, which corresponds to 1 gm of tissue and 10 mg of insulin - sufficient to control blood glucose levels for 2 weeks. Beta cells have an average diameter of 10 μm and contain about 20 pg insulin per cell.

The insulin produced by pancreas is 50% during the fasting state at a rate of 0.5-1 Units (U)/hour (or 9-10 U/day) and an equal amount of another 9-10 U/day after meals. The post-meal production rate is however 6 times more vis-a-vis fasting, and occurs in 2 spurts namely, 5 minutes and 20 minutes. Peak levels of insulin are obtained within 60 minutes but the duration of its action lasts for 2 hours and hence one does postprandial (PP) blood glucose estimation 2 hours after lunch.

The only work of insulin is to remove the carbs out of the blood that has entered during the eating spells so as not to disturb the normal range of 70-110 mg/dL of plasma glucose.

INSULIN RECEPTOR

Glucose can be used as a preferred fuel even by those cells that do not possess mitochondria (brain cells, red blood cells as well as retina and lens of eyes) or possess mitochondria but do not employ these power houses to synthesize ATP (white blood cells). However, wherever the glucose is transported, there will be receptors to receive the insulin.

Insulin facilitates the entry of glucose by stimulating insulin receptors present mainly in liver, muscles and adipose tissues.

https://www.wikidoc.org/images/5/53/Insulin-intracellular-signalings_1.gif?20171005141758

The mechanism is as follows:

Insulin sits in the insulin receptor.
Message sent to nucleus of cell.
Cell opens a special gate called GLUT-4.
Glucose in blood enters the liver, muscle or adipose tissue.

When the glycogen stores are broken down and glucose has to replenish the plasma glucose levels, it is also via the GLUT-4. Irrespective of glucose entry or exit, the GLUT-4 transporters remain available only for 30-60 minutes.

THE CARBS EQUATION

Carbs intake is plentiful for an individual with a sedentary lifestyle - defined as someone who spends six or more hours per day sitting or lying down, and lacks significant physical movement in daily life.

Fig: Indians (state-wise) consumption of macronutrients.

Hence, it has been documented that the average Indian consumes 2300 kcal per day of which 80% is contributed by carbs!

Normal Indian weighing 65 kgs:

Indians averagely consume 2300 kcal per day total.
Carbs constitute 80% of total calories i.e. 1840 kcal per day.
Fats provide 11-12% of total calories i.e. 264 kcal per day.
Total maximum utilizable calories for ATP from food is 1840 + 264 = ~2100 kcal per day.
2000 kcal per day necessary for usual functioning of glands, organs and chemicals, as well as fluid movement within body, to stay alive even when sedentary.

Table: Calories consumed for performing daily activities whilst leading a sedentary lifestyle.

Hence, in a normal weight-balanced Indian the calories available for ATP and the energy needs of the body are finely balanced.

TYPE 2 DIABETES MELLITUS

India is the world capital of Type 2 Diabetes Mellitus (T2DM) and there are 100 million suffering from this disease with 25% of these being pre-diabetic. The hallmark of T2DM is the presence increase in blood insulin concentrations which is termed as hyperinsulinemia.

HYPERINSULINEMIA

An increase in fasting plasma insulin levels above 15 mIU/mL or PP more than 80 mIU/mL is termed as hyperinsulinemia.

The overweight Indian consumes 2450 kcal whilst the intake of those obese is 2880 kcal per day. When 11% intake from fats and 9% from proteins is factored, the carbs intake is:

Overweight Indian: 490 gms carbs
Obese Indian: 575 gms carbs

Lets' calculate the consequences of consuming carbs in a normal weighing Indian whose daily diet provides 345 gms glucose equivalents.

125 gms glucose is used up by brain and eyes directly.
25-50 gms are converted to glycogen in liver since 25-50% of liver stores (100 gms) are exhausted pre-meal in an effort to maintain normal blood glucose in-between the two meals. >80 gms of glucose that was converted to glycogen will be required to replenish the 4 gms needed to maintain blood glucose levels of 70-110 mg/dL during the fasting spell.
150 gms may be stored in muscles as glycogen since even those leading a sedentary life, 30% of 2,000 kcal spent every day is by breakdown of muscle glycogen.

Hence, total disposed of carbs thus disposed of from blood is 325 gms. But in the overweight and in obese Indian additional 165 gms and 250 gms (respectively) needs to be disposed of.

One unit of insulin can reduce blood glucose by 50 mg/dL i.e. 2.5 gms of carbs. Presuming one eats breakfast, lunch, evening snacks and dinner, and insulin produced by pancreas during these spells persist for 2 hours each time, the fasting period during a 24-hour day is 16 hours. At the rate of 1 U insulin per hour during fasting, the body manufactures 16 U per day during these spells when one is not consuming any food, and this amount can tackle 40 gms. Hence, 125-210 gms remains in blood and the body tries various means to dispose off the same.

Although liver can store 100 gms and muscles 400 gms, the maximum total glycogen that can be accommodated by the body is 15 gm/kg i.e. near about 1 kg in an average 65 kg weighing Indian. Why dose God provide for such a reservation for the glycogen reserves?

When one come consumes more carbs and the usual daily needs are fulfilled, as explained above, there is some storage space yet available for the excess glucose entering the blood. To push excess 165-250 gms daily intake of carbs, usually by an overweight / obese Indian, the pancreas needs to produce additional 66-100 units of insulin daily to push the same into the glycogen stores which are already filled. This will increase blood insulin levels by 13-20 microU/mL. Since the normal concentrations are 12 mU/mL, the extra insulin will raise concentrations to 25-32 mU/mL which is above the normal fasting insulin levels. Any fasting plasma insulin concentrations above 25 mU/mL is to be diagnosed as hyperinsulinemia - the most common feature of T2DM.

INSULIN RESISTANCE

In addition to excess carbs intake, hyperinsulinemia also occurs when the insulin either does not combine with its receptor, or does not snuggly affix with the same for sufficient time to enable signalling mechanism to transfer the glucose primarily from blood to muscle, liver or adipose tissue via GLUT-4.

Insulin resistance is triggered when the muscle, fat and liver cells - all those which have insulin receptors, don't respond as they should to insulin. One glaring reason is obesity since the cellular mechanisms in those overweight are not easily stimulated to respond to insulin and the carbs transported remain in blood. This means the sensitivity to insulin's action is decreased.

VEGETARIANISM / VEGANISM vs NON-VEGETARIAN DIET & T2DM

There are umpteen studies and evaluations revealing lesser incidence of insulin resistance in vegetarians and vegans. In fact, increasing intake of fruits from 95 to 200 gms/day, vegetables from 100 to 260 gms, and at the same time decreasing red meat intake from 129 to 55 gms/day improves the plant-based dietary index by 10 units, which can increase insulin sensitivity by 13%.

When insulin cannot optimally function it is referred to as diminished sensitivity of the target organs and tissues to insulin's action. The 3 primary reasons for the same are:

Overweight and obesity
Inactive lifestyle
Diet HIGH in CARBS!

The paradox however is, although the vegetarians and vegans have a lower incidence of insulin resistance, the true non-vegetarians are less prone to becoming diabetic!

OBESITY & SEDENTARY LIFESTYLE

The proximate cause of obesity is an imbalance in the energy input and energy expenditure. Although obesity has a genetic basis, it cannot be attributed to a signal gene or even to a few genes. Over nutrition especially due to consumption of fast food and soft drinks appears to be the major cause for the current epidemic of obesity in which the energy balance is tilted in favor of excess energy storage.

Fig: Contribution of macronutrients to energy (kcal) taken via junk foods.

Always a single meal of fast food is typically 1200-1500 kcal dense - 225-280 gms of carbs are consumed during a single feasting on fast food! If such junk foods are regularly indulged in over and above the usual 3 meals the consequences of weight gain is but to be expected.

A recent study has revealed that over 70 per cent of Indian adults have poor muscle health characterized by lower muscle mass because especially vegetarians consume less protein, besides their sedentary lifestyle. Television-watching for long duration also came out as an important factor for weight gain because watching TV not only reduces physical activity, but also tends to be associated with consumption of fast foods and junk snacks.

EXCESSIVE CARBS

Presuming one has consumed his normal three meals on a particular day, the fast food additionally contributes 250 gms carbs on an average. Since body can release only upto 10 U of insulin per day, which is required to take care of glucose entering during breakfast, lunch and dinner, an additional of 100 U of insulin extra will be necessary to tackle the carbs consumed as junk food.

The US Institute of Medicine’s recommended daily allowance for carbohydrate consumption in sedentary adult men and women is 130 gms. But junk foods provide additional carbs and, in the case of overweight / obese Indian, there is already an excess intake of 165-250 gms carbs daily!

When one continuous to relish fast food regularly, the body starts getting used to the extra insulin manufactured and slowly and gradually the higher insulin levels cannot as efficiently push the glucose for glycogen conversion in body stores as before. This is the beginning of insulin resistance and also the onset of suffering from T2DM.

Thus, overweight and fast foods are entwined and so is the sedentary lifestyle which also participates in obesity syndrome. Even at rest, each muscle cell contains roughly 1 billion ATP molecules, all of which will be used and replaced every 2 minutes during intense exercise.

CONCLUSIONS

A 2016 analysis by the India State-level Disease Burden Initiative found that NCDs (non-communicable diseases like diabetes, heart ailments, etc.) accounted for 61.8 per cent of deaths compared to communicable, maternal, neonatal diseases, and undernutrition, which together accounted for 27.5 per cent of deaths. This has all been attributed to excessive consumption of carbs besides salt and fats.

"... the Indian diet has long been overwhelmingly dominated by carbohydrates." When human civilisation first hit upon agriculture, it was food grains, which are almost entirely carbohydrates, that were the most amenable to mass production. They offered quick and immediate energy to the body. Before that, people hunted animals or foraged for plants, which meant that food was primarily protein-driven. India has a double whammy on the carbs front. For one, it has in large part a vegetarian diet. There might be more non-vegetarians in the country but these are flexitarian since, for them, meat is an occasional fare and not a daily staple.

A 2018 paper in Indian Journal of Medical Research has concluded: “There is evidence to suggest that excess carbohydrate is linked to both the susceptibility to T2D (type 2 diabetes) and also to poor control of diabetes and proneness to complications of diabetes, particularly in Asian populations." Members of the low carb and keto dieting community have long been arguing that the real problem of people becoming fat is not fat, but carbs. And vegetarianism and veganism and also a flexitarian diet is the root cause.

Stay tuned for more on carbs associated maladies! Carbs are UGLY. Be Ware!

DR R K SANGHAVI

Prophesied Enabler

Experience & Expertise: Clinician & Healthcare Industry Adviser

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Dr R K Sanghavi