Food

Availability: Earth

Introduction

Food is defined as any substance or combination of substances, in any physical state, intended for human consumption—whether raw, semi-processed, or fully prepared. This definition also includes any substance intentionally added during the food production process.

Nutrition is the process by which an organism obtains the substances essential for sustaining metabolic activity and carrying out its vital functions. These substances—known as nutrients—are found in the foods we consume, and they are indispensable to life. The human body requires a complex array of macronutrients and micronutrients to grow, repair itself, produce energy, and maintain physiological balance.

As a result, the act of eating is far more than just satisfying hunger: it is a fundamental biological need driven by the necessity to acquire these nutrients. To support this, humans and many animals have evolved sensory mechanisms—most notably the sense of taste—that help identify which foods are likely to be nourishing or harmful.

An organism’s diet—the total range of foods it consumes—is shaped by both the availability of those foods and their perceived palatability. Over the course of history, humans have identified and selected a wide variety of edible resources based on their accessibility and nutritional value. Beyond their role in sustaining life, foods often hold deep symbolic and cultural significance within different societies.

Nutrients

Nutrients are the essential substances that the body needs to function properly. They provide energy, support growth and repair, and regulate vital physiological processes. The energy provided by nutrients is measured in calories (kcal), a unit that indicates how much energy the body can obtain from a specific food. Each macronutrient provides a different amount of calories per gram: carbohydrates and proteins supply 4 kcal/g, while fats provide 9 kcal/g, making fats the most energy-dense macronutrient.

However, nutrients are broadly classified into two main categories based on the amount required by the body: macronutrients, which are needed in large quantities, and micronutrients, which are required in much smaller amounts but are equally vital for health.

Macronutrients

• Carbohydrates: The body’s primary and most immediate source of energy, carbohydrates are rapidly metabolized into glucose—the fundamental “fuel” for cellular activity. Carbohydrates include simple sugars (like those in fruit or table sugar) and complex carbohydrates, which encompass starches and dietary fiber. While sugars provide quick energy, fiber is not digestible and contributes to digestive health by regulating intestinal transit and supporting the gut microbiome. Carbohydrates are abundant in foods such as pasta, bread, starchy vegetables (e.g., potatoes), legumes, fruit, and sugar.
• Proteins: Essential for the growth, maintenance, and repair of tissues and organs, proteins also play a vital role in immune function and hormone regulation. Major dietary sources include some animal source foods and legumes (such as soybeans, beans, and peas). When evaluating protein sources, their biological value—the efficiency with which the body can utilize their amino acids—is a key factor.
• Fats (Lipids): Fats provide a long-term energy reserve and are critical for the integrity of cell membranes, as well as for the absorption of fat-soluble vitamins (A, D, E, and K). They are found in butter, oils, lard, and nuts. The nutritional quality of fats depends primarily on their fatty acid profile:
  • Saturated fats, mostly from animal sources (e.g., butter, cheese, fatty meats), tend to be solid at room temperature and, when consumed in excess, can negatively impact cardiovascular health.
  • Unsaturated fats, found in plant oils (such as olive oil), nuts, seeds, and fatty fish, are generally considered beneficial. These include:
    • Monounsaturated fats (e.g., in olive oil and avocados)
    • Polyunsaturated fats, including omega-3 and omega-6 fatty acids, essential for brain function and inflammation regulation.
  • Cholesterol is a lipid molecule distinct from fats. It is present in animal-based foods and also produced by the body. Cholesterol is essential for building cell membranes and synthesizing hormones. However, high levels of certain types of cholesterol in the blood, particularly low-density lipoprotein (LDL), are linked to an increased risk of cardiovascular diseases. Maintaining a balanced diet helps regulate cholesterol levels and supports overall heart health.

Micronutrients

• Vitamins: Organic compounds required in small amounts, vitamins perform diverse regulatory functions. These include vitamin A; the B-complex group (B1, B2, B6, B12), pantothenic acid, folic acid; as well as vitamins C, D, E, K, and biotin.
• Minerals: Inorganic elements essential for numerous physiological processes, minerals are typically categorized into macro-elements and micro-elements (or trace elements) based on the quantities required.
  • Macro-elements (required in gram amounts per day): calcium, phosphorus, potassium, sodium, chloride, magnesium, and sulfur. Sodium, a key component of table salt (sodium chloride), is present in higher amounts in foods with more salt. It plays a vital role in maintaining fluid balance, transmitting nerve impulses, and supporting muscle function.
  • Micro-elements / Trace elements (required in milligrams or micrograms per day):
    • Trace elements (mg/day): iron, zinc, copper, cobalt (in organic form only), iodine, fluoride, chromium, manganese, molybdenum, selenium, vanadium, silicon, and boron.
    • Ultratrace elements (µg/day): lithium, nickel, and arsenic.

However, the nutritional table below will be used throughout the site:

Nutrients	Per 100 g
Calories (kcal)
Total fat (g)
———Saturated fat (g)
Cholesterol (mg)
Sodium (mg)
Total carbohydrates (g)
———Dietary fiber (g)
———Total sugar (g)
Protein (g)

Tastes

Humans and many other animals usually experience five fundamental tastes: sweet, sour, salty, bitter, and umami. These taste sensations play a crucial role in helping animals identify foods that are nourishing versus those that could be harmful due to toxins. Throughout evolution, tastes associated with high-energy foods have generally become more enjoyable, while others tend to be less appealing. Humans, uniquely, can sometimes develop a liking for tastes they initially found unpleasant. It’s important to note that water, despite being vital for survival, lacks any flavor.

Sweetness is typically triggered by simple sugars like glucose and fructose, or by sucrose, which combines the two. Sourness comes from acids, such as the acetic acid in vinegar or the citric acid found in lemons and limes. This taste may serve as a warning, signaling that food could be spoiled.

Saltiness results from minerals like sodium and potassium ions and is widespread in many foods in small to moderate amounts, enhancing their overall taste. The bitter flavor is usually sharp and unpleasant, found in substances like unsweetened dark chocolate, coffee, lemon peel, and some fruits. Finally, umami, often described as savory or meaty, signals protein-rich foods and is typical in broths, cooked meats, cheeses, and mushrooms.

The impact of diet on health

The relationship between nutrition and health has been recognized since antiquity. As early as 475 BCE, Anaxagoras suggested that food contains essential elements that are absorbed by the human body. In 400 BCE, Hippocrates famously stated, “Let food be thy medicine, and medicine be thy food.” In 1747, British physician James Lind conducted one of the first clinical trials, demonstrating that lemon juice could cure scurvy. It was not until the 1930s that this effect was linked to the presence of vitamin C in lemons.

Today, it is well established that a poor diet can lead to nutritional deficiency diseases such as scurvy, beriberi, and rickets, while overconsumption of food is associated with obesity and widespread chronic conditions such as cardiovascular disease, diabetes, and osteoporosis.

Food security and the Human Right to Nutrition

The protection of food safety and public health is overseen by a number of international bodies, including the European Food Safety Authority (EFSA), the World Resources Institute, the World Food Programme, the Food and Agriculture Organization (FAO) of the United Nations, and the International Food Information Council. These organizations address critical global issues such as environmental sustainability, biodiversity conservation, climate change, the economics of food systems, population dynamics, water availability, and equitable access to food.

Access to adequate food is recognized as a universal human right under the International Covenant on Economic, Social and Cultural Rights (ICESCR). The treaty guarantees the right to an adequate standard of living, which includes nutritional well-being, and underscores the fundamental right to freedom from hunger. Signatory nations are obligated to strengthen systems for food production, storage, and distribution, while promoting a just and equitable sharing of the world’s food supplies.

Food classification

The way human food is sorted can differ widely, depending on whether the focus is on its ingredients or the methods used to prepare it. There isn’t a fixed number of categories, as different systems organize food in their own way. A basic structure often used divides food into four main types, reflecting both their source and nutritional role: fruits and vegetables, grains, dairy products and meat.

More detailed analyses, especially those assessing diet quality, tend to break food down into more specific groups. These include things like unrefined and refined grains, fresh produce, nuts and legumes, eggs, milk-based items, fish, red and processed meats and sugary drinks. Such groupings help researchers understand how different eating habits influence overall health.

Organizations like the World Health Organization and the Food and Agriculture Organization use a much broader system, dividing foods into nineteen distinct classes. These range from cereals, roots and legumes, to animal source foods like milk, eggs, fish, shellfish, meat and even insects. Other categories include vegetables, fruits, fats, sugars, condiments, drinks, specialized nutrition products, food additives, ready-made meals and savory snacks. This kind of classification is used to monitor food availability and consumption patterns across the world.

In this context, for logistical reasons, food has been categorized as follows:

• Algal source foods
• Animal source foods
• Culinary bases (broths, flour-based foods, sauces)
• Multicellular fungal source foods
• Other items (e.g., inorganic items, leavening agents, sugar-sweetened beverages, or miscellaneous products)
• Plant source foods