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Basics of nutrition

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Basics of nutrition

March 31, 2024, 5:14 PM IST 

Having discussed the basics of physiology, describing how nutrients are ingested and distributed throughout the body and waste is collected and excreted, we will now delve into the types of nutrients and their role in bodily functions. Nutrients are categorized into three groups:

1. Macronutrients: Provide energy.

2. Micronutrients: Provide essential nutrients without energy.

3. Other Nutrients


Macronutrients are energy-providing nutrients, measured in kilocalories but often referred to as calories. The three macronutrients are proteins, carbohydrates, and fats.

1.1 Proteins

We previously discussed proteins in the context of nutrition myths. To recap, proteins, providing 4 calories per gram, are vital for every cell. They consist of chains of twenty different amino acids in various permutations and combinations. Out of these, nine are essential, meaning our body cannot synthesize them, so they must be ingested through food. A typical human body utilizes approximately 200 grams of protein daily, recycling about 85% of it, leaving a deficit of about 30 grams. The body lacks a storage system for proteins; excess intake is converted into fat and nitrogen in the liver. The fat is stored subcutaneously, while nitrogen is transformed into ammonia, then uric acid, and finally excreted as urine. Excessive protein intake can strain the liver and kidneys, shortening their productive life. This is the reason why dialysis is becoming so common among the baby boomer generation.

1.2 Carbohydrates

Carbohydrates are composed of carbon, hydrogen, and oxygen, providing four calories per gram. They include starch, glucose, fructose, lactose, and glycerols. Starch is converted into glucose in the liver, which is then distributed throughout the body via the bloodstream. The liver can convert fructose into glucose or fat, depending upon the need of the body. This key difference plays an important role in influencing metabolism significantly.

1.3 Fats

Fats, offering nine calories per gram, are a dense energy source and the preferred storage form for excess calories. Fats are categorized by saturation level or chain length:

• Saturated Fats: Each carbon atom is bonded to hydrogen, predominantly found in animal products and considered unhealthy in excess.

• Monounsaturated Fats: Contain one double bond and are found in plant foods like nuts, seeds and avocados, beneficial for health.

• Polyunsaturated Fats: Contain multiple double bonds. These include essential omega-3 and omega-6 fats. Of the two, Omega-6 is found in plenty in nature but Omega-3 is scarcer so special attention needs to be paid. Our body needs both omega-3 and omega-6 in equal amounts.

Many vegetable oils are too rich in omega-6 and have hardly any omega-3.  Any ratio of Omega-6 to Omega-3 higher than 3 is problematic and should be avoided. The richest plant based sources of Omega-3 are Flaxseeds, Chia seeds, Hempseeds, Mustard seeds and walnuts. Mustard which is found in abundance has an omega-6 to omega-3 ratio of 3:1 which is very healthy. That is why mustard seeds should be consumed regularly and mustard oil is the least harmful of all oils.

• Trans Fats: When oils undergo hydrogenation, they transform into a solid form at room temperature. These hydrogenated oils are known as trans fats and are highly detrimental to health. They gained popularity at the turn of the 19th century when saturated animal fats were discouraged due to heart health concerns. Trans fats are commonly found in products like vegetable shortening and margarine. Owing to their adverse health effects many countries, including the U.S., have banned them. However, they are still permitted in India. Dalda, introduced in India about a century ago, is a prominent example of trans fats; in the U.S., Crisco is a well-known equivalent.

Fats can also be classified by the length of the fatty acid chains, which can be short, medium, long, or extra-long. When we consume whole plant-based foods fiber is digested by bacteria in the lining of our colon, producing short and medium-chain fatty acids that are beneficial to our health.


Micronutrients are crucial for health but they do not provide any energy. They include following:

2.1 Vitamins

Vitamins are essential organic compounds that the body requires in small amounts for nutrition. There is a variety of vitamins readily available in plant-based foods. However, two vitamins that warrant particular attention are B12 and D3. Vitamin B12 is produced by bacteria found in soil, which can enter our bodies through groundwater or direct contact with the soil, such as when farming barehanded and barefoot. In modern times, we often avoid direct contact with soil, and our water, sourced from municipal tanks, is chlorinated, killing all bacteria. Consequently, B12 deficiency is quite common among vegans. Although B12 is present in green water plants, commonly known as seaweeds, which make a regular part of diets in Japan, Korea and China, they are not consumed in India and the rest of the world. These seaweeds can also be good sources of vitamin D3 and Iodine.

2.2 Minerals

Minerals are found in air, water, and soil and plants absorb them effectively. These minerals enter our bodies through plant-based foods. However, the use of inorganic fertilizers and practices like monoculture farming can deplete the soil of these vital nutrients and seeds leading to deficiencies in our diet. To counteract this, it is crucial to consume organically grown produce and utilize rock salts, which are abundant in trace minerals. Among these, iodine deserves special attention. It is advisable to incorporate iodine-enriched salts into your diet to ensure adequate intake.

2.3 Antioxidants

When various metabolic reactions occur in our body, they often release a single atom of oxygen. These oxygen atoms are highly reactive and can cause oxidation of other molecules nearby, leading to a phenomenon known as oxidative stress. Certain chemical compounds, known as antioxidants, are effective in neutralizing these single oxygen atoms. Many plant foods are abundant in antioxidants and consuming them can help reduce oxidative stress. While all fruits and vegetables contain antioxidants, berries, leafy greens, herbs, and spices are particularly rich sources and should be included in one’s daily diet.

2.4 Phytonutrients

Phytonutrients are phytochemical compounds produced by plants to protect themselves against attacks from fungi, bacteria and plant viruses, as well as from insects and other small animals. In large concentrations, some of these compounds can also be poisonous. Approximately 10,000 different phytochemicals have been identified, but discussing them all is beyond the scope of this blog. However, I would like to highlight two of them: carotenoids and polyphenols. The most well-known carotenoid is beta-carotene, discovered nearly two centuries ago and linked to eye and heart health. It is found in carrots, hence the name carotene. Today, we understand that there are 750 different carotenoids, and the human body requires about 50 of them. Supplementing with beta-carotene was a common practice until recently, but it can lead to imbalances in the absorption of other carotenoids and should therefore be avoided.

Polyphenols are phytonutrients that help protect body tissues against oxidative stress and associated pathologies, such as cancer, coronary heart disease, and inflammation.


Water is an essential nutrient and must be consumed regularly. The human body does produce some water when it burns fat, but not enough to sustain itself. It is challenging to survive beyond a week or two without water. I recommend consuming two glasses of warm water first thing in the morning, even before brushing your teeth. This practice is beneficial because our body produces saliva overnight, which is good for our health. We should swallow this saliva with water. Additionally, one should drink a glass of water an hour after every meal and another glass before going to bed. Except for the water consumed in the morning and at night, which should be drunk as is, it is a good habit to obtain most of your water intake from eating fresh fruits and vegetables, which are primarily water anyway. Hence the saying “eat your water.”


Fiber is an essential nutrient that is often misunderstood and neglected. Here are some key benefits of fiber:

– Fiber aids in the motility of our intestines.

– It slows down nutrient absorption in our small intestines, allowing certain foods, such as resistant starch, to reach the colon where they serve as nourishment for bacteria.

– Fiber moderates the absorption of sugar in our liver, preventing its overload. An overloaded liver can lead to several issues, including (1) fatty liver, potentially progressing to Non-Alcoholic Fatty Liver Disease, (2) the accumulation of visceral fat, and (3) the formation of intramyocellular lipid, which can cause insulin resistance, leading to Type 2 diabetes.

– Fiber supports the beneficial bacteria in our gut, helping them produce short- and medium-chain fatty acids, which are vital for our health.


All nutrients play a crucial role in our health, functioning in a complementary manner akin to a symphony performed by an orchestra. We should obtain these nutrients from plant-based foods, which are their primary sources. It is advisable to avoid secondary sources and supplements.

To Read this article on Times of India click here

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