A measure of acidity or alkalinity (basicity). Pure water has a pH of 7.0, which is said to be neutral. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are said to be basic or alkaline. The pH of blood is usually slightly basic with a value of pH 7.4. This value is often referred to as “physiological pH”.

Parkinson's disease

A disease of the nervous system caused by degeneration of a part of the brain (basal ganglia), and by low production of the neurotransmitter dopamine. Symptoms include muscle rigidity, tremors, and slow voluntary movement.


A disease caused by having too little vitamin B3 (niacin) or the amino acid tryptophan in the diet. It can also occur if the body fails to absorb these nutrients, after gastrointestinal diseases or with alcoholism. Symptoms of pellagra include diarrhea, mental confusion, and scaly skin sores.


Liquid component of blood, in which the blood cells in whole blood would normally be suspended. Blood plasma is mostly water (92% by volume) and contains dissolved proteins, glucose, clotting factors, mineral ions, hormones and carbon dioxide (CO2).

Polyunsaturated fatty acids

fatty acid that contains more than one double bond (=) between its carbon (-C) atoms which are unsaturated with hydrogen (-H).

Among the polyunsaturated fatty acids (PUFAs), the omega-3 and omega-6 fatty acids are essential as they need to be included in the diet because the human metabolism cannot create them from other fatty acids. These fatty acids use the Greek alphabet to identify the location of the first double bond (=) in the molecule : “omega” marks the last carbon of the carbon chain and “3” (or “6”) indicates that the fatty acid has its first double bond three (or six) carbons away from the “omega” carbon. The double bond position is also abbreviated as “n-3” (or “n-6”).

Scientific abbreviations for fatty acids tell something about their chemical structure. Alpha-linolenic acid (ALA), for example, is abbreviated as “18:3n-3”. The first part (18:3) means that ALA is an 18-carbon fatty acid with three double bonds, while the second part (n-3) indicates that the first double bond is in the n-3 position, which defines it as an omega-3 fatty acid.

Population Reference Intake (PRI)

The PRI, in most countries called “Recommended Daily Allowance (RDA)”, defines an adequate nutrient intake level that most, if not all, individuals of a population or a specific population group should obtain to satisfy their requirements. PRIs were set by the European Scientific Committee on Food (SCF).


A disease that is unique to pregnancy and may occur anytime after 20 weeks of pregnancy through six weeks following birth. The condition is characterized by a sharp rise in blood pressure, protein in the urine (proteinuria), and severe swelling (edema). Approximately 5% of women with preeclampsia go on to develop seizures (eclampsia), which is a significant cause of maternal death.

Premenstrual Syndrome (PMS)

A cluster of symptoms, including fatigue, irritability, moodiness/depression, fluid retention, and breast tenderness, that begin sometime after ovulation (mid-cycle) and subside with the onset of menstruation (the monthly period).

Primary prevention study

A study aimed at avoiding disease development in healthy people. Most population-based health promotion activities are primary preventive studies.

Prospective cohort study

An observational study in which a group of people ─ a cohort ─ are interviewed or tested for risk factors (e.g., nutrient intake), and then followed up at subsequent times to determine their status with respect to a disease or health outcome.

Prospective study

In evaluations of the effects of healthcare interventions, a study in which people are identified according to current risk status or exposure, and followed forwards through time to observe outcome. Prospective studies ask how a suspected risk or protection factor (e.g., a specific nutritional behaviour) affects a specific pathogenesis. They first recruit appropriate participants, and then look how the exposures influence disease risk in these people over the following months or years.

Prospective studies are considered to generate more accurate results of stronger evidence than retrospective studies.