Here’s what nutrition experts say about dietary fat

atom: The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.

blood pressure: The force exerted against vessel walls by blood moving through the body. Usually this pressure refers to blood moving specifically through the body’s arteries. That pressure allows blood to circulate to our heads and keeps the fluid moving so that it can deliver oxygen to all tissues. Blood pressure can vary based on physical activity and the body’s position. High blood pressure can put someone at risk for heart attacks or stroke. Low blood pressure may leave people dizzy, or faint, as the pressure becomes too low to supply enough blood to the brain.

bond: (in chemistry) A semi-permanent attachment between atoms — or groups of atoms — in a molecule. It’s formed by an attractive force between the participating atoms. Once bonded, the atoms will work as a unit. To separate the component atoms, energy must be supplied to the molecule as heat or some other type of radiation.

calcium: A chemical element and alkali metal common in minerals of the Earth’s crust and in sea salt. It is also found in bone mineral and teeth, and can play a role in the movement of certain substances into and out of cells.

calorie: The amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius. It is typically used as a measurement of the energy contained in some defined amount of food. The exception: when referring to the energy in food, the convention is to call a kilocalorie, or 1,000 of these calories, a “calorie.” Here, a food calorie is the amount of energy needed to raise 1 kilogram of water 1 degree C.

carbohydrates: Any of a large group of compounds occurring in foods and living tissues, including sugars, starch and cellulose. They contain hydrogen and oxygen in the same ratio as water (2:1) and typically can be broken down in an animal’s body to release energy.

carbon: A chemical element that is the physical basis of all life on Earth. Carbon exists freely as graphite and diamond. It is an important part of coal, limestone and petroleum, and is capable of self-bonding, chemically, to form an enormous number of chemically, biologically and commercially important molecules.

cardiovascular: An adjective that refers to things that affect or are part of the heart and the system of vessels and arteries that move blood through the heart and tissues of the body.

cell: (in biology) The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.

cell membrane: A structure that separates the inside of a cell from what is outside of it. Some particles are permitted to pass through the membrane.

chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H₂O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

chemical bonds: Attractive forces between atoms that are strong enough to make the linked elements function as a single unit. Some of the attractive forces are weak, some are very strong. All bonds appear to link atoms through a sharing of — or an attempt to share — electrons.

chemistry: The field of science that deals with the composition, structure and properties of substances and how they interact. Scientists use this knowledge to study unfamiliar substances, to reproduce large quantities of useful substances or to design and create new and useful substances. (about compounds) Chemistry also is used as a term to refer to the recipe of a compound, the way it’s produced or some of its properties. People who work in this field are known as chemists.

cholesterol: A fatty material in animals that forms a part of cell walls. In vertebrate animals, it travels through the blood in little vessels known as lipoproteins. Excessive levels in the blood can signal risks to blood vessels and heart.

chronic: A condition, such as an illness (or its symptoms, including pain), that lasts for a long time.

colleague: Someone who works with another; a co-worker or team member.

dairy: Containing milk or having to do with milk. Or a building or company in which milk is prepared for distribution and sale.

data: Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.

diabetes: A disease where the body either makes too little of the hormone insulin (known as type 1 disease) or ignores the presence of too much insulin when it is present (known as type 2 diabetes).

diet: (n.) The foods and liquids ingested by an animal to provide the nutrition it needs to grow and maintain health. Sometimes this is a specific food-intake plan.

dietitian: An expert who works out what an individual should eat to attain and maintain a healthy weight. Dieticians also can work out meal plans to help people with special medical problems, such as heart disease and diabetes.

double bond: Also known as a covalent bond, it’s a type of bond between two atoms within a molecule. In a single bond, atoms share two electrons. Here, they share four. This bond is slightly less stable than a single bond.

enzymes: Molecules made by living things to speed up chemical reactions.

fat: A natural oily or greasy substance occurring in plants and in animal bodies, especially when deposited as a layer under the skin or around certain organs. Fat’s primary role is as an energy reserve. Fat also is a vital nutrient, though it can be harmful if consumed in excessive amounts.

fatty acid: A large molecule made of up chains of carbon and hydrogen atoms linked together. Fatty acids are chemical building blocks of fats in foods and the body.

federal: Of or related to a country’s national government (not to any state or local government within that nation). For instance, the National Science Foundation and National Institutes of Health are both agencies of the U.S. federal government.

fiber: Something whose shape resembles a thread or filament. (in nutrition) Components of many fibrous plant-based foods. These so-called non-digestible fibers tend to come from cellulose, lignin, and pectin — all plant constituents that resist breakdown by the body’s digestive enzymes.

fruit: A seed-containing reproductive organ in a plant.

heart attack: Permanent damage to the heart muscle that occurs when one or more regions of it become starved of oxygen, usually due to a temporary blockage in blood flow.

high blood pressure: The common term for a medical condition known as hypertension. It puts a strain on blood vessels and the heart.

hydrogen: The lightest element in the universe. As a gas, it is colorless, odorless and highly flammable. It’s an integral part of many fuels, fats and chemicals that make up living tissues. It’s made of a single proton (which serves as its nucleus) orbited by a single electron.

immune system: The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.

infection: A disease that can spread from one organism to another. It’s usually caused by some type of microbe.

inflammation: (adj. inflammatory) The body’s response to cellular injury and obesity; it often involves swelling, redness, heat and pain. It also is an underlying feature responsible for the development and aggravation of many diseases, especially heart disease and diabetes. Anti-inflammatory players of the body’s immune system help to limit inflammation so that it doesn’t get out of control. Certain medicines can also play an anti-inflammatory role.

internal medicine: A branch of medicine where doctors diagnose and treat adults for conditions that don’t need surgery. Doctors who work in this field are known as internists.

legumes: Beans, peas, lentils and other plants with seeds that grow in pods. Legumes are important crops. These plants also host bacteria that help enrich the soil with nitrogen, an important nutrient.

linoleic acid: A fatty acid that the body needs to get from fats in our diet.

lipoprotein: A structure that the body makes to shuttle cholesterol around the body via the bloodstream. Lipoproteins tend to be known by how densely the cholesterol is packed within them. High density lipoproteins (or HDLs) are usually considered good for health. Low density lipoproteins are considered generally harmful. Their size is not the issue so much as where they release the cholesterol that they’re carrying.

liquid: A material that flows freely but keeps a constant volume, like water or oil.

membrane: A barrier which blocks the passage (or flow through) of some materials depending on their size or other features. Membranes are an integral part of filtration systems. Many serve that same function as the outer covering of cells or organs of a body.

molecule: A group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in air is made of two bound oxygen atoms (O₂). Water is made of two hydrogen atoms and one oxygen atom (H₂O).

nut: (in biology) The edible seed of a plant, which is usually encased in a hard protective shell.

nutrient: A vitamin, mineral, fat, carbohydrate or protein that a plant, animal or other organism requires as part of its food in order to survive.

nutrition: (adj. nutritious) The healthful components (nutrients) in the diet — such as proteins, fats, vitamins and minerals — that the body uses to grow and to fuel its processes. A scientist who works in this field is known as a nutritionist.

obesity: (adj. obese) Extreme overweight. Obesity is associated with a wide range of health problems, including type 2 diabetes and high blood pressure.

oleic acid: A monounsaturated fatty acid that is an ingredient of many vegetable oils and beef tallow. In the diet, it’s a relatively heart-healthy type of fat. Industrial uses for this natural product include soap-making, cosmetics, lubricants and polishing compounds.

organ: (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that makes sense of nerve signals and a plant’s roots are organs that take in nutrients and moisture.

organelle: Specialized structures, such as mitochondria, found within a cell.

oxygen: A gas that makes up about 21 percent of Earth’s atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).

palm: A type of evergreen tree that sprouts a crown of large fan-shaped leaves. Most of the roughly 2,600 different species of palms are tropical or semitropical.

parallel: An adjective that describes two things that are side by side and have the same distance between their parts. In the word “all,” the final two letters are parallel lines. Or two things, events or processes that have much in common if compared side by side.

pressure: Force applied uniformly over a surface, measured as force per unit of area.

protein: A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Antibodies, hemoglobin and enzymes are all examples of proteins. Medicines frequently work by latching onto proteins.

pyramid: A monumental structure with a square or triangular base and sloping sides that meet in a point at the top. The best known are those made from stone as royal tombs in ancient Egypt.

ratio: The relationship between two numbers or amounts. When written out, the numbers usually are separated by a colon, such as a 50:50. That would mean that for every 50 units of one thing (on the left) there would also be 50 units of another thing (represented by the number on the right).

risk: The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)

salt: A compound made by combining an acid with a base (in a reaction that also creates water). The ocean contains many different salts — collectively called “sea salt.” Common table salt is a made of sodium and chlorine.

saturated fat: A fat molecule made from chains of carbon atoms, where each carbon has at least two hydrogen atoms attached to it (those on the ends have three). These chains have no double bonds. Saturated fats are found in animal fats (such as butter and lard), as well as in vegetable fats (such as coconut oil). Their long, straight chains allow them to become solid at room temperature.

smoking: A term for the deliberate inhalation of tobacco smoke from burning cigarettes.

solid: Firm and stable in shape; not liquid or gaseous.

stroke: (in biology and medicine) A condition where blood stops flowing to part of the brain or leaks in the brain.

unsaturated fat: A fat molecule made of chains of bonded carbon atoms, where at least one bond is a double or triple covalent bond. These bonds replace some hydrogen atoms, which results in the molecule not being entirely saturated with hydrogen. Unsaturated fats are a type prevalent in vegetable fats such as canola, olive and corn oil. Their double bonds create kinks in the molecules. Those kinks generally keep the fats  liquid at room temperature.

vitamin: Any of a group of chemicals that are essential for normal growth and nutrition and are required in small quantities in the diet because either they cannot be made by the body or the body cannot easily make them in sufficient amounts to support health.