Food: Basics

Food. Even the word itself can conjure up thoughts and feelings, both positive and negative. We need to eat every day, so it is no wonder that the topic of food consumes us. Numerous books, articles, and movies have been made on the subject.

Yet, the phrase, “it’s just food,” is still commonly said. Many of us tend to fill ourselves up with any food that tastes good or that is convenient or we may skip meals because we are “too busy.” There is widespread information on why certain foods are good for us, such as kale and blueberries, but very little is given on how food in general works. Food, and the process of eating, has a number of crucial functions and by gaining a better understanding of these, we can become more aware of how the choices we make are affecting us.

What is food, really?

Food can be defined as “any substance that can be taken into the body to maintain life and growth; nourishment” (1). Eating can be defined as, “take into the mouth, chew, and swallow” (2). These definitions may sound simple. However, the process of eating food is complex and involves the coordination of a number of different organs and processes.

Why do we need to eat?

Our bodies are made of energy. This energy comes from the food we eat. We know that we must eat to survive. Food gives us the energy that sustains us and keeps us moving. 

Nutrients are substances needed for growth, nourishment, and maintenance of our bodies. They are components of food that can be metabolized by the body for energy, growth, development, and reproduction. The word nutrient is derived from the Latin word nutrire, meaning “to nourish, feed, nurse, and support.” 

There are six classes of nutrients: carbohydrates, proteins, lipids (fats), vitamins, minerals and water. Carbohydrates, proteins and fats are classified as macronutrients because they are required in relatively large amounts. Minerals and vitamins are classified as micronutrients because they are needed in small or trace amounts. 

Vitamins are also further classified as either water soluble or fat soluble. Water soluble vitamins dissolve in water and are carried to the body’s tissues. They are excreted more quickly and need to be replenished through diet. Fat soluble vitamins are absorbed into the small intestine and dissolve in fat. They are stored in the body, primarily in the liver and adipose tissues.

Micronutrients are nutrients required in trace (small) amounts. They possess little to no calories, but provide nourishment for proper growth and development. 

Calories

A calorie is a unit of measurement for determining energy. A small calorie is the amount of heat energy needed to raise 1 gram of water by 1 degree Celsius, while a large calorie refers to the amount of heat energy needed to raise 1 kilogram of water by 1 degree Celsius.

In terms of nutrition and food, calories refer to energy consumption, through eating and drinking, and energy usage, through physical activity, by the body. The body “burns” calories in foods through metabolic processes, in which they eventually release their stored energy. This energy is required for proper function of all organisms. Without it, they would cease to function, and we would die.

We need a certain amount of calories, or energy, each day in order to survive. Too little or too much, and we face severe health consequences. The exact amount of calories a person requires each day is a subject of much debate, with no definite answer. It is dependent on age, gender, activity level, and other means.

The amount of calories in food, also known as “food calories,” refers to the amount of potential energy that food possesses. The amount of energy in 1 gram may seem like a small amount, but food calories represent a large calorie, or kilocalorie. One kilocalorie equals 1000 small calories. The foods we eat may contain a lot more energy that we would original believe.

Some places use joules and kilojoules to measure energy instead of calories. One joule is equal to 0.239 calories (small calories).

There is also what is known as “empty calories.” These are foods, such as refined sugar, that provide energy, but no other nutrients. These are the calories that should be avoided.

Carbohydrates, proteins, and fats

The three main sources of food calories are macronutrient carbohydrates, protein, and fat.

Carbohydrates are a large group of organic compounds containing carbon, hydrogen, and oxygen.  They are broken down in the body to create glucose, which is a primary source of energy.

Proteins are large molecules composed of one or more chains of amino acids. The body breaks the protein down into these amino acids, and uses them for essential functions, including building, strengthening, and repairing muscles and tissues; making antibodies, hormones, and enzymes; transporting substances, such as oxygen through the blood; and mediating cell response.

Fats consist of a wide group of compounds. The body breaks these down into fatty acids. These dietary fats are used in a number of functions in the body, including providing a concentrated source of energy, providing a cushion and insulation for vital organs, making tissues, manufacturing hormones, helping in the absorption of vitamins, and maintaining cell membranes. 

Vitamins and minerals

Micronutrients include: vitamins and minerals.

Vitamins are a group of organic substances found in plants and animals that the human body cannot produce on its own, or only produces it in insufficient amounts, so has to get it from food. There are 13 recognized vitamins that come in two types: fat-soluble and water-soluble.

Fat-soluble vitamins dissolve in fat. They require fat in order to be absorbed and can be stored in the fat tissues of the body as well as liver.

Water-soluble vitamins dissolve in water. They are not stored for long as the body takes what it needs and excretes the rest as waste. Because of that, you need a continuous supply.

Minerals are solid, inorganic, naturally occurring substances. Living organisms cannot synthesize them on their own. Plants absorb them from the soil, and humans and animals get them from consuming plants and water. There are two types: macrominerals and microminerals. Macrominerals are minerals needed in larger amounts, while micronutrients are needed in small amounts.

Our body and its organs need particular vitamins and minerals to survive and perform properly. For instance, vitamins A, D, and K are essential in bone formation; vitamin A helps in cell health and proper vision; and iron helps move oxygen throughout the body.

The three main functions of food

The food we eat performs three main functions: physiological, psychological, and social.

Physiological

The physiological function is when the food goes through the process of digestion, absorption, assimilation, and excretion.

The process begins before the food enters the mouth. At the sight and smell of food, the body will prepare for digestion by secreting more saliva, producing hydrochloric acid in the stomach, and increasing blood flow to the digestive organs. The stomach begins secreting a mucus that creates a protective lining to protect the surface against the highly acidic gastric juices. The muscles will also prepare for peristalsis, a series of wavelike muscle contractions that propel food along the digestive tract. 

The digestive system involves the organs of the gastrointestinal or digestive tract as well as the “accessory” digestive organs. Despite how the term “accessory” sounds, these organs play an equally vital role in the process. 

The organs of the digestive tract include the:

• Mouth
• Pharynx
• Esophagus 
• Stomach
• Small Intestine
• Large Intestine

The accessory digestive organs include:

• Teeth
• Tongue
• Liver
• Gallbladder
• Pancreas

The food enters the mouth, where it is ground, crushed, and broken down by the teeth into smaller and smaller pieces in what is referred to as mastication. Saliva also contains enzymes such as salivary amylase, salivary kallikrein, lingual lipase, and lysozyme. 

These enzymes serve different roles, including helping to: chemically break down the nutrients into its smaller components, such as breaking down starches and fatty acids; break down specific proteins to produce a protein known as bradykinin that helps dilate blood vessels; and protect against bacteria by breaking down a type of carbohydrate found in the cell walls of many bacteria.

Once the food is moistened and broken down, it is swallowed and passes through the pharynx into the esophagus. Through peristalsis, the food moves along the esophagus and into the stomach, where it mixes with digestive juices that consist of hydrochloric acid, water, and enzymes such as pepsin. The highly acidic nature of these juices help in killing bacteria and in further breaking down food into smaller particles.

The muscles of the stomach help mix the food with the digestive juices until it becomes an acidic, semi-fluid mass of partially digested food called chyme. Once it reaches the right consistency, it passes into the small intestine.

The small intestine consists of three parts: the duodenum, jejunum, and the ileum. The chyme enters into the duodenum, where it mixes with more digestive juices. The rate and volume of chyme must be adjusted as it enters the duodenum to prevent it from overloading the small intestine. 

The chyme moves through the intestine through the action of peristalsis. If the chyme is high in lipids, or fatty foods, then a hormone known as gastric inhibitory peptide is secreted. The gastric inhibitory peptide hormone slows down this movement to allow more time for digestion and absorption.

Once the stomach is emptied, a hormone known as somatostatin is released to prevent further secretion of hydrochloric acid.

The digestive juices of the small intestine consist of secretions of enzymes from the pancreas and bile from the gallbladder. The enzymes need an alkaline environment to work, so the pancreas releases a high concentration of sodium bicarbonate to neutralize it.

The enzymes from the pancreas include chymotrypsin, amylase, and lipase. These help to further break down carbohydrates, proteins and fats into their smallest components. Before the fats can be broken down by lipases, they must first be emulsified by bile fluid. 

Bile is a greenish yellow fluid containing water, cholesterol, bile salts, phospholipids and bilirubin that is made in the liver and stored in the gallbladder. It helps break down large fat globules into smaller droplets, making it easier for the digestive enzymes to break it down further. The process of emulsification also allows the fat to mix with water molecules more easily so that it can be absorbed. In addition, bile plays a role in protecting against infections (3). 

The pancreas releases hormones such as insulin to help cells take up glucose and to keep blood sugar levels from getting too high in the blood.

The inner wall of the small intestine, known as the mucosa, has deep folds known as plicae circulares. Extending from these are microscopic fingerlike projections called villi. These contains smaller projections known as microvilli. This structure increases the surface or contact area between the chyme and intestinal walls, allowing for improved absorption of nutrients.

As the chyme moves through the intestines, the nutrients pass into the blood vessels and lymphatic vessels in the walls through the process of diffusion. This occurs mainly in the second (jejunum) and final part (ileum) of the small intestine. 

Remaining undigested food passes into the large intestine, also commonly referred to as the colon. It enters through the cecum, or first part of the large intestine. From there it goes through the ascending colon, transverse colon, descending colon, sigmoid colon, and rectum and then out the anus. 

Bacteria in the large intestine helps to break down remaining nutrients, such as complex carbohydrates and fatty acids, and play a role in synthesizing vitamin K and some B vitamins. The main source of vitamin K in the body is from intestinal bacteria. This bacterial fermentation process can also produce gases as a byproduct, including nitrogen, carbon dioxide, and methane.

Similar to the esophagus and the small intestine, the contents pass through the large intestine through contractions. Electrolytes, vitamins, and remaining water are absorbed for use in other metabolic processes. The resulting solid waste is known as stool.

The stool is stored in the descending colon until it becomes full. It then passes into the rectum, where stretching of the rectal wall triggers an urge to defecate, or empty the bowels. The stool is then expelled from the body through the anus. 

Digestion is a complex, intricate process involving extensive energy and coordination of a number of the body’s organs and systems. To perform most effectively, the body should be in a relaxed state. 

Stress and anxiety activates a “flight or fight” response. This diverts energy away from the digestive organs and into other muscles and processes. This can result in issues such as insufficient mucus production in the stomach and increased or decreased contractions (movement) in the intestines, which can result in diarrhea or constipation.

How hydrated we are and the foods we eat – how they are prepared, the level of processing they have gone through, the addition of additives or chemicals, and the amount of fats, carbohydrates, and protein – all influence the digestive process. How well we are able to break down food, absorb nutrients, and get rid of bacteria and waste affects how healthy we are and how well the body is able to function as a whole.

Psychological

This leads into the next function of food: the psychological function. This includes the sensation of eating the food – the texture, smell, and taste – as well as the feeling of relief from hunger. Eating food provides a deep sense of satisfaction and pleasure. Food can also provide a sense of security. Since the day we are born and being fed from our parents, we are made to feel a sense of comfort and safety in the process. In addition, we need food to live, so if we have food, we feel safe in knowing that we have what we need to survive. 

The makeup of the food, the blend of proteins, fats and carbohydrates, also affect the sense of pleasure and fullness we get. This relationship with food has changed drastically in recent years due to the increase in additives and chemicals in processed foods. These highly addictive foods make it hard for us to know when to stop, and make us crave more high-intensity flavoured foods. 

Current issues on weight and self-esteem have also changed this relationship. Because our weight and sense of self-control affects our self esteem, food can begin to hold negative connotations and can lead to diet/food related conditions such as anorexia, bulimia, and obesity.

Social

Another function of food that is closely related to the psychological aspects is the social, or cultural, function. The preparation of food for family and friends brings people together and creates a sense of love and affection. It has been used as a symbol of hospitality and friendship for centuries. Even in today’s world, social class, religious beliefs, and economic conditions still affect the foods we eat and our unique preference for certain flavours and flavour combinations. 

In social gatherings, food can provide a means of communication, interaction, and connection. Laughter and a positive atmosphere in these situations may result in us eating less, though it depends on the person, because we aren’t turning to food to give us that sense of pleasure. The function of food extends beyond solely what we put into our mouths.

What does it mean to eat healthy?

Certain foods contain a higher concentration of energy and nutrients that are easier for the body to absorb. The body is not able to efficiently absorb the nutrients in highly processed and hydrogenated foods. Instead, we must look to foods such as legumes, fruits, vegetables, and nuts. These foods contain the right amount of nutrients in a form that is more available to the body. This means that we are getting more out of the food we are eating.

By eating a balanced meal that consists primarily of these types of foods, we are giving our bodies the vitamins and minerals needed for the body to support itself. We will begin to feel more energized and satisfied.

Not only are the vitamins and minerals important individually, they also provide unique benefits when consumed together. Vitamin E helps the absorption of vitamin A; vitamin D helps to get calcium from food sources rather than from the bones; and vitamin C helps in the absorption of iron. 

Conversely, some vitamins and minerals do not interact together as well. Vitamin C can block the body’s ability to assimilate the mineral copper, and an overload of the mineral manganese can worsen iron deficiency. Not all foods are created equal, so we must be careful when choosing what to eat; and what to eat together.

The fact that not all foods are created equal extends to eating plant-based foods or animal-based. In today’s society, we are led to believe that we need copious amounts of protein and calcium, and that we obtain these from meats and dairy. However, it is not necessarily about how much we are getting, but the source we are getting it from. “For example, beef contains only about 20% usable protein. Spirulina and chlorella [algae], on the other hand, average 75-80%” (4). 

Likewise, very little calcium in dairy is stored in the body. “Like all animal protein, milk acidifies the body pH which in turn triggers a biological correction” (5). To neutralize the acidity, calcium is pulled from the bones, often resulting in a calcium deficiency. 

Sometimes the most obvious choice isn’t the best. This includes vitamin and mineral supplements, which possess nutrients in high amounts, sometimes too high and not necessarily with the right combination. These nutrients are better available directly from plant-based sources, and in many cases in smaller amounts, as long as we make sure to add a variety of balanced foods in our diet, to get the most out of each.

Processed foods

Processed foods also damage the balance of nutrients and minerals. The amount of processing can range from minimally processed foods such as bagged spinach or cut vegetables to heavily processed foods such as crackers, granola, deli meat and frozen or premade meals like frozen pizza and microwavable dinners. 

Two main categories of process are: mechanical and chemical. 

Mechanical processing

Mechanical processing can include putting single ingredient, or uncooked foods, into bags or jars. No chemicals are added.

Chemical processing

In chemical processing, refined ingredients and artificial substances are added. Processed foods, particularly chemically processed, tend to be loaded with sugar, sodium, and fat. These are added to improve taste, speed up cooking time, and improve shelf life. 

Even worse than the refined sugars are the artificial sweeteners, preservatives, colouring agents, and other chemicals. Sodium and fats, in large amounts, are detrimental to the body and upset the balance. Increased sodium can cause high blood pressure while large amounts of fats, particularly bad fats, can lead to an increase in bad cholesterol. 

Your body then has to work harder to achieve homeostasis (equilibrium). Refined sugar, artificial sweeteners, preservatives, and colouring agents offer no nutrients.

Nitrates and nitrites are also often used as additives. They can form the compound nitrosamines in the body. There are different forms of nitrosamines, and most of them are potent carcinogens, or substances that can cause cancer. 

Nitrates can be found naturally in vegetables and even our own saliva. These vegetables, however, contain vitamins and other compounds, such as vitamin C, that inhibit the formation of nitrosamines. Vitamin C instead converts nitrite into nitric oxide, a compound that plays a number of important roles in the body, including increasing circulation and stimulating the release of certain hormones.

Processed meats have an abundant amount of the compound amines. Nitrosamines are produced when amines and nitrite react. The presence of these compounds, especially when the food is exposed to high heat, promotes the formation of nitrosamines.

Processing and food preservation

It’s important to note that methods of food preservation, such as dehydrating and freezing, are also classified as forms of processing. They may involve mechanical processing, chemical processing, or both. 

Methods such as dehydrating involves extracting moisture in foods by subjecting it to heat or using salt or chemicals, while flash freezing involves exposing freshly picked fruits and vegetables to extremely low temperatures. Both methods are done to inhibit growth of bacteria and slow down spoilage. 

Dehydration is a viable method of preserving food, so long as a low, constant heat is used and no harmful chemicals or excessive salt are added. This method can also be done at home. 

For those who are unable to pick or purchase fresh fruits and vegetables due to their location, frozen foods can be a good alternative. You want to choose organic when possible to reduce exposure to chemicals and genetic modification.

Other types of food preservation and processing can include fermenting, canning, pickling, and smoking as well as irradiation and pasteurization. You want to avoid any type of processing that destroys nutrients or significantly alters the molecular structure of a food, such as subjecting it to high heat or gamma-rays. 

In the case of canning or pickling, be cautious of what other substances you are adding and in what quantity. These types of processing can result in the overconsumption of salt, sugar, and fats. The acidity created in food processing such as pickling can irritate the digestive system in some individuals. It may also result in the growth of unhealthy bacteria in the pickled food.

The dangers of refined foods

If the definition of food is “nourishment,” than artificial additives and refined foods cannot be considered food. They offer no nourishment and instead are linked to a number of health problems including heart disease, diabetes, obesity, and cancer. 

The incredibly sweet, salty, and fatty tastes in processed foods overstimulate our senses. Our taste buds are designed to like sweet, salty, and fatty foods because we know instinctively that natural foods that possess these qualities contain the energy and nutrients we need to survive. In the past, people needed all the energy they could to compensate for the amount of work and activity they did. 

However, things have changed. People are living more sedentary lifestyles, and certain flavours are added to foods without the nutritional quality, so we aren’t getting what we think we are. The overconsumption of these foods have led to a craving for intense flavor. Our taste buds have changed, but not for the better. We are turning to the wrong foods to fill our insatiable hunger for taste.

Another problem that can occur is when we make meal choices based on convenience. Convenient foods tend to be processed or fast foods, since they are usually easier and quicker to prepare, but they sacrifice nutritional content. Less nutrition means that your body craves more food to try and get what it needs. Taking the time to make healthy meals means that you are giving your body more nutrients. The food goes further in that it meets your body’s nutritional demands. 

Takeaway

In our busy lives, it is also all too easy to fall back to the highly processed foods that are available at food stands. They are called “fast food” for a reason. Nevertheless, these foods can adversely affect our body and how it functions. We must learn to choose our foods wisely so the body is able to function at its best.

Eating healthy doesn’t have to take long if we know what we are doing. To find out more about how to prepare these foods, please check out our section on cookware.

The role of food is complex. From the actual foods we’re eating to the speed that we eat and what we are thinking when we are eating – it all plays an important role in how our body responds to the food. The phrase, “it’s just food,” does not capture the depth and significance of the issue. 

Food is necessary for survival, and our sense of wellbeing. It also isn’t enough to eat whatever tastes good or is convenient. Food involves more than the process of chewing. It involves an understanding of chemistry, biology, and our own mindset. 

Consuming foods that are high in certain vitamins or minerals may not be enough. What we get from each individual food depends on what else we eat with it. Researching how specific foods are good for us is not enough either if we neglect to truly value the importance of food in general. We must look at the whole and not just the parts, of each individual food item. It is how it comes together that makes the biggest difference on our health and wellbeing. Food fills our body, mind, and soul. By understanding the many roles that food, and eating, play on the body, we can begin to make more conscious decisions towards creating a healthier future.

References

1. Paperback Oxford Canadian Dictionary, Second Edition, 369.
2. Paperback Oxford Canadian Dictionary, Second Edition, 296.
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4091928/
4. “Protein Types: The Difference Between Meat, Soy, Whey, Dairy, and Vegan Types of Protein.” http://www.nutribodyprotein.com/protein-types.php
5. “Debunking The Milk Myth: Why Milk Is Bad For You And Your Bones.” http://saveourbones.com/osteoporosis-milk-myth/

Read Next:

• Calories: Basics
• Carbohydrates: Basics
• Protein: Basics
• Dietary Fats: Basics
• Vitamins: Overview
• Minerals: Overview