Nutrition and Health

Nutrition is a recall topic with a small, stable syllabus. The deficiency diseases in particular are asked almost every time, and there are only a handful of them.

The macronutrients

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Needed in large amounts, and all three supply energy.

Fat carries more than twice the energy per gram of the other two, which is why it is what the body stores.

Carbohydrates

Simple carbohydrates are sugars - glucose, fructose, sucrose - and are absorbed quickly.

Complex carbohydrates are starches and fiber, built from long chains of sugars, and take longer to break down.

Glucose is the form the body actually uses. Everything else is converted to it, and it is what cellular respiration burns.

Fiber is a carbohydrate the body cannot digest. It supplies no energy and its job is to keep material moving through the digestive tract.

Proteins

Proteins are built from amino acids. There are 20, and nine are essential, meaning the body cannot make them and they must come from food.

Protein is used for building and repair first. The body burns it for energy only when carbohydrates and fats are short, which is why prolonged starvation costs muscle.

Fats

Saturated fats are solid at room temperature and come mostly from animals. Unsaturated fats are liquid and come mostly from plants and fish.

Saturated fat is the kind most closely linked to raised blood cholesterol. Cholesterol travels in two carriers, and the test asks which is which: HDL is the "good" cholesterol, because it carries cholesterol away from the artery walls; LDL is the "bad" one, because it deposits it there. H for healthy, L for lousy.

Fats insulate, cushion organs, and are required to absorb vitamins A, D, E and K.

The micronutrients

Needed in small amounts, and they supply no energy at all. That is worth stating plainly because it is a question: vitamins do not give you energy, they enable the reactions that release it from food.

Vitamins and their deficiencies

This table is the most tested content in the topic.

Vitamin C and scurvy, and vitamin D and rickets, are the two that come up most.

Fat-soluble: A, D, E and K. They dissolve in fat, are stored in the liver and fatty tissue, and can build up to harmful levels. Everything else is water-soluble, is not stored, and excess is excreted - which is why a daily intake matters more for those.

Minerals

Iron and anemia is the mineral pair the test asks.

Water

Often left out of study lists and it is a nutrient.

The body is roughly 60 percent water. It transports nutrients, regulates temperature through sweating, cushions joints and removes waste. It supplies no energy.

Calories and metabolism

A calorie is a unit of energy. What food labels call a Calorie is a kilocalorie, a thousand of the scientific unit, which is a distinction the test occasionally asks about.

Metabolism is the sum of the chemical reactions in the body. Basal metabolic rate is the energy used at rest, just to stay alive.

Energy in against energy out determines weight: more calories consumed than used are stored, mostly as fat.

What you can skip

The nutrition questions stay on the tables above. Across all 2,104 General Science questions in our bank:

• Diet science - glycemic index, probiotics, antioxidants, the basal metabolic rate - comes up once at most, and usually not at all.
• Riboflavin never appears, and folic acid once. The seven vitamins in the table carry the questions.
• Recommended daily amounts in milligrams are not asked. Which nutrient does what, and what goes wrong without it, is.

Where people lose points

Saying vitamins provide energy. They do not. Only the three macronutrients do.

Swapping the deficiency diseases. Scurvy is C, rickets is D.

Thinking protein is the body's first energy source. Carbohydrates are.

Getting the fat-soluble list wrong. A, D, E, K.

Assuming all fats are equivalent. The saturated and unsaturated distinction is asked.

Forgetting fiber is a carbohydrate that supplies no energy.

Work one in under a minute

A sailor on a long voyage without fresh fruit or vegetables develops bleeding gums and slow-healing wounds. Which deficiency explains this?

Bleeding gums and poor wound healing both point at connective tissue, and fresh produce is the source that has been missing.

Vitamin C, and the condition is scurvy.

This is the historically famous one and it is the version of the question the test most often asks.

Where this leads

The nutrients here are what the digestive system processes and what cellular respiration burns.