Nutritional epidemiology examines dietary and nutritional factors in relation to disease occurrence at a population level. Nutritional

epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and Risk factor (epidemiology), determinants of health and disease conditions in a defined population, and application of this knowledge to prevent dise ...

is a relatively new field of

medical research Medical research (or biomedical research), also known as health research, refers to the process of using scientific methods with the aim to produce knowledge about human diseases, the prevention and treatment of illness, and the promotion of ...

that studies the relationship between

nutrition Nutrition is the biochemistry, biochemical and physiology, physiological process by which an organism uses food and water to support its life. The intake of these substances provides organisms with nutrients (divided into Macronutrient, macro- ...

and health. It is a young discipline in epidemiology that is continuing to grow in relevance to present-day health concerns. Diet and physical activity are difficult to measure accurately, which may partly explain why

has received less attention than other

risk factors In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often ...

for disease in

. Nutritional epidemiology uses knowledge from

nutritional science Nutritional science (also nutrition science, sometimes short ''nutrition'', dated trophology) is the science that studies the physiological process of nutrition (primarily human nutrition), interpreting the nutrients and other substances in food ...

to aid in the understanding of human nutrition and the explanation of basic underlying mechanisms. Nutritional science information is also used in the development of nutritional epidemiological studies and interventions including clinical, case-control and

cohort studies A cohort study is a particular form of longitudinal study that samples a cohort (a group of people who share a defining characteristic, typically those who experienced a common event in a selected period, such as birth or graduation), performing ...

. Nutritional epidemiological methods have been developed to study the relationship between diet and disease. Findings from these studies impact public health as they guide the development of dietary recommendations including those tailored specifically for the prevention of certain diseases, conditions and cancers. It is argued by western researchers that nutritional epidemiology should be a core component in the training of all health and social service professions because of its increasing relevance and past successes in improving the health of the public worldwide. However, it is also argued that nutritional epidemiological studies yield unreliable findings as they rely on the role of diet in health and disease, which is known as an exposure that is susceptible to considerable

measurement error Observational error (or measurement error) is the difference between a measured value of a quantity and its unknown true value.Dodge, Y. (2003) ''The Oxford Dictionary of Statistical Terms'', OUP. Such errors are inherent in the measurement pr ...

History of nutritional epidemiology

Nutritional epidemiology started as a subdiscipline of epidemiology in the 1980s before advancing into a core disciple in epidemiology. It deals with the role nutritional exposures play in the occurrence of impaired health conditions. The assessment of these

exposures Exposures can refer to: *'' Andy Warhol's Exposures'' *'' Exposures – In Retrospect and Denial'' *The Exposures, a stage name of German electronic musician Jan Jelinek Jan Jelinek is a German electronic musician who also operates under the nam ...

and the investigation of the association between exposure and outcome form the core of nutritional epidemiology. It is through the understanding of how nutrients and vitamins affect

deficiency A deficiency is generally a lack of something. It may also refer to: *A deficient number, in mathematics, a number ''n'' for which ''σ''(''n'') < 2''n'' * Later in the twentieth century it gained further significance when the role of exposure in chronic disease became well understood. Since then, the application of information from nutritional epidemiology has led to significant scientific and social breakthroughs. Epidemiological methods have been used for centuries to study the relationship between diet and disease, yet were not considered definitive. Advancements to the ways in which dietary exposures were measured gave rise to the reliability of data. The inclusion of genetic risk factors in models of causation have made nutritional epidemiology an increasingly interdisciplinary field.

Nutritional science

Nutritional science Nutritional science (also nutrition science, sometimes short ''nutrition'', dated trophology) is the science that studies the physiological process of nutrition (primarily human nutrition), interpreting the nutrients and other substances in food ...

is a multidisciplinary study area concerned with the role of nutrition in health and disease across the human lifespan. Nutritional epidemiology and nutritional science are two fields that share knowledge about the interactions of nutrients, food consumption, and the human body. An understanding of the principles of nutritional sciences is required to understand nutritional epidemiology. The two fields explore diet-disease relationships to provide preventative measures for the public. Research in nutritional science also provides the basis for food regulations and

dietary guidelines A healthy diet is a Diet (nutrition), diet that maintains or improves overall health. A healthy diet provides the body with essential Human nutrition, nutrition: fluid, macronutrients such as protein, micronutrients such as vitamins, and adequat ...

. Knowledge from Nutritional science has raised societal awareness about links between food consumption and wellbeing. Examples of some of the successes nutritional science has contributed to findings which include linking

folate Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...

deficiency A deficiency is generally a lack of something. It may also refer to: *A deficient number, in mathematics, a number ''n'' for which ''σ''(''n'') < 2''n'' * neural tube defects Neural tube defects (NTDs) are a group of birth defects in which an opening in the spine or cranium remains from early in human development. In the third week of pregnancy called gastrulation, specialized cells on the dorsal side of the embry ...

vitamin C Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits, berries and vegetables. It is also a generic prescription medication and in some countries is sold as a non-prescription di ...

deficiency to

scurvy Scurvy is a deficiency disease (state of malnutrition) resulting from a lack of vitamin C (ascorbic acid). Early symptoms of deficiency include weakness, fatigue, and sore arms and legs. Without treatment, anemia, decreased red blood cells, gum d ...

, consumption of

trans fat Trans fat is a type of unsaturated fat that occurs in foods. Small amounts of trans fats occur naturally, but large amounts are found in some processed foods made with partially hydrogenated oils. Because consumption of trans fats is associated ...

to a higher risk of

cardiovascular disease Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheumati ...

and linking consumption of fish during pregnancy to reduced risk of

preterm birth Preterm birth, also known as premature birth, is the Childbirth, birth of a baby at fewer than 37 weeks Gestational age (obstetrics), gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 ...

. These occurrences continue to be discovered with increasing scientific information and evidence, leading to more opportunities for successful intervention and prevention.

Nutritional epidemiological studies

Nutritional epidemiological studies form the foundation for nutrition-related discoveries. The studies reveal the relationship between nutrition and health, with a focus on

aetiology Etiology (; alternatively spelled aetiology or ætiology) is the study of causation or origination. The word is derived from the Greek word ''()'', meaning "giving a reason for" (). More completely, etiology is the study of the causes, origin ...

chronic disease A chronic condition (also known as chronic disease or chronic illness) is a health condition or disease that is persistent or otherwise long-lasting in its effects or a disease that comes with time. The term ''chronic'' is often applied when the ...

. They provide a comprehensive view of the way in which diet affects or maintains health and wellbeing in individuals and populations. A prominent controversy lies within the ability to reliably and accurately measure

as they are subject to measurement errors and variation. Nutritional epidemiological study designs are required to establish a definitive relationship between diet and disease to be able to develop interventions and policies that will be implemented for the health of the public. There are observational and experimental investigations which have applicable study designs that fall under them including

ecological Ecology () is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...

cross-sectional In statistics and econometrics, cross-sectional data is a type of data collected by observing many subjects (such as individuals, firms, countries, or regions) at a single point or period of time. Analysis of cross-sectional data usually consists ...

cohort Cohort or cohortes may refer to: Cohort Sociological * Cohort (military unit), the basic tactical unit of a Roman legion * Cohort (educational group), a group of students working together through the same academic curriculum Scientific * Cohort ...

, case control, clinical and community trails. Investigators in experimental studies have the control of assigning exposures, whereas in observational studies exposures are observed only with no intervention. Experimental studies can therefore provide stronger evidence for the effect of exposure on outcome, which would otherwise be considered unethical in an observational study as exposure could be harmful. But Observational studies are simpler to carry out and more cost effective. Observational studies are able to detect rare or unusual findings over long periods of time (diet-related diseases develop over time) which would otherwise burden subjects and be expensive in Experimental studies. In nutritional epidemiology, Experimental studies may be used to draw causal conclusions between dietary exposures and health outcomes, however for some diet-disease relations there are ethical considerations. Nutritional policy and procedure decisions are therefore guided by findings from a combination of sources to ensure

accuracy Accuracy and precision are two measures of ''observational error''. ''Accuracy'' is how close a given set of measurements (observations or readings) are to their ''true value''. ''Precision'' is how close the measurements are to each other. The ...

reliability Reliability, reliable, or unreliable may refer to: Science, technology, and mathematics Computing * Data reliability (disambiguation), a property of some disk arrays in computer storage * Reliability (computer networking), a category used to des ...

and validity. The measure of exposure is dependent on the question and study design. It can be objectively or

subjectively The distinction between subjectivity and objectivity is a basic idea of philosophy, particularly epistemology and metaphysics. Various understandings of this distinction have evolved through the work of countless philosophers over centuries. One b ...

measured on individuals or populations in the past or present. In nutritional epidemiological studies this refers to factors such as food including nutrients and non-nutrients and the social environment. The effect of these exposures is measured as outcomes. In nutritional epidemiological the outcome is commonly referred to as the disease state or the

anthropometric Anthropometry (, ) refers to the measurement of the human individual. An early tool of physical anthropology, it has been used for identification, for the purposes of understanding human physical variation, in paleoanthropology and in various a ...

physiological Physiology (; ) is the science, scientific study of function (biology), functions and mechanism (biology), mechanisms in a life, living system. As a branches of science, subdiscipline of biology, physiology focuses on how organisms, organ syst ...

state under either

continuous Continuity or continuous may refer to: Mathematics * Continuity (mathematics), the opposing concept to discreteness; common examples include ** Continuous probability distribution or random variable in probability and statistics ** Continuous ...

discrete Discrete may refer to: *Discrete particle or quantum in physics, for example in quantum theory * Discrete device, an electronic component with just one circuit element, either passive or active, other than an integrated circuit * Discrete group, ...

variables. The objective of nutritional epidemiological research is to provide scientific evidence to support an understanding of the role of nutrition on the causes and prevention of ill health. It is important to address the factors that affect food supply, including quality, quantity and balance and the factors that affect food after consumption. The development of a specific, feasible and relevant aim of study and target population is the first step in epidemiological research. The second step is the selection and correct use of a

method Method (, methodos, from μετά/meta "in pursuit or quest of" + ὁδός/hodos "a method, system; a way or manner" of doing, saying, etc.), literally means a pursuit of knowledge, investigation, mode of prosecuting such inquiry, or system. In re ...

that measures exposure and outcome followed by extensive analysis. Exposure and outcome of interest are measured to enable reliability of the relationship assessed. Studies that are well designed, have a strong foundation, detailed

methodology In its most common sense, methodology is the study of research methods. However, the term can also refer to the methods themselves or to the philosophical discussion of associated background assumptions. A method is a structured procedure for bri ...

and are governed by

ethical Ethics is the philosophical study of moral phenomena. Also called moral philosophy, it investigates normative questions about what people ought to do or which behavior is morally right. Its main branches include normative ethics, applied e ...

principles will have the derived conclusions used to improve health care. All steps require knowledge of past and current literature. The different nutritional epidemiological study designs offer advantages and limitations in different circumstances.

Ecological study

ecological study In epidemiology, ecological studies are used to understand the relationship between outcome and exposure at a population level, where 'population' represents a group of individuals with a shared characteristic such as geography, ethnicity, socio-ec ...

is an observational study that studies risk-modifying factors on health outcomes of populations based on their

geographical Geography (from Ancient Greek ; combining 'Earth' and 'write', literally 'Earth writing') is the study of the lands, features, inhabitants, and phenomena of Earth. Geography is an all-encompassing discipline that seeks an understanding o ...

and/or temporal ecological state. Ecological studies are useful in studying patterns of disease in large populations however may not accurately reflect true associations between individuals within those large populations. Ecological studies use geographical information to examine spatial framework of disease and exposure but there is potential for systemic difference in

classification Classification is the activity of assigning objects to some pre-existing classes or categories. This is distinct from the task of establishing the classes themselves (for example through cluster analysis). Examples include diagnostic tests, identif ...

language.

Cross-sectional study

cross-sectional study In statistics and econometrics, cross-sectional data is a type of data collected by observing many subjects (such as individuals, firms, countries, or regions) at a single point or period of time. Analysis of cross-sectional data usually consists ...

is an observational-individual study that measures exposure and outcome in the present. In examining the relationship between disease and diet, cross sectional studies provide a snapshot of the frequency of disease in a population at a given point in time. Cross-sectional studies offer advantages such as the ability to measure multiple outcomes and exposures and, in the planning, and allocation of health resources as it assesses the burden of disease in a specified population. The measure of the outcome is however heavily reliant on population responses. Non-response results in responder bias and therefore unreliable results.

Case control study

A case-control study is an observational-individual study that is defined by the outcome (i.e. measures outcomes in the present and past exposure is established). It involves two groups controls and cases (diseased), both which have two treatments; exposed and unexposed. Case-control studies can be used to study diseases that are rare and over long periods of time however are limited to examining one outcome and are also susceptible to the effects of bias if selected control groups are no representative of the population, so give rise to misleading results.

Cohort study

cohort study A cohort study is a particular form of longitudinal study that samples a Cohort (statistics), cohort (a group of people who share a defining characteristic, typically those who experienced a common event in a selected period, such as birth or gra ...

is an observational-individual study that measures exposure in the present over long periods of time and the outcome is determined in the future. Cohort studies allow for multiple outcomes to be measure per one exposure. In nutritional epidemiological studies it is advantageous in measuring outcomes that occur after exposure and can measure both incidence and

prevalence In epidemiology, prevalence is the proportion of a particular population found to be affected by a medical condition (typically a disease or a risk factor such as smoking or seatbelt use) at a specific time. It is derived by comparing the number o ...

. Cohort studies are however costly and time consuming. As outcome is determined in the future, any issues pertaining to the collection of information or

confounders In causal inference, a confounder is a variable that influences both the dependent variable and independent variable, causing a spurious association. Confounding is a causal concept, and as such, cannot be described in terms of correlation ...

cannot be resolved back in time.

Clinical and community trails

Clinical and community trails are experimental studies that involve active intervention in either individuals (clinical) or populations (community). Clinical trials often involve test and procedures carried on subjects placed in different treatment groups. Clinical trials allow for the evaluation of new therapies, drugs and procedures. Clinical trials however risk subject to experience

side effect In medicine, a side effect is an effect of the use of a medicinal drug or other treatment, usually adverse but sometimes beneficial, that is unintended. Herbal and traditional medicines also have side effects. A drug or procedure usually use ...

s and inadvertent harm from the intervention therefore should only be considered when supporting evidence is strong. Community trials involve assigning groups of individuals with and without disease to different interventions. This allows for larger scale findings however does not account for individual variability.

Social impact

The impact nutritional epidemiology had in the past has led to

social Social organisms, including human(s), live collectively in interacting populations. This interaction is considered social whether they are aware of it or not, and whether the exchange is voluntary or not. Etymology The word "social" derives fro ...

, physical and

economic An economy is an area of the Production (economics), production, Distribution (economics), distribution and trade, as well as Consumption (economics), consumption of Goods (economics), goods and Service (economics), services. In general, it is ...

changes. Nutritional epidemiological findings guide

dietary recommendations Human nutrition deals with the provision of essential nutrients in food that are necessary to support human life and good health. Poor nutrition is a chronic problem often linked to poverty, food security, or a poor understanding of nutrition ...

including the prevention of certain disease and cancers. They play a role in policies on diet and health given the works are published based on grounding evidence. The observational findings allowed for health interventions such as the

fortification A fortification (also called a fort, fortress, fastness, or stronghold) is a military construction designed for the defense of territories in warfare, and is used to establish rule in a region during peacetime. The term is derived from Lati ...

of foods and limits/bans of certain substances from food. These implemented changes have since enhanced human health and wellbeing by means of prevention and improvement. Research suggest its impact specifically on cancer patients has been promising. The nutritional support to some provides relief of side effects, improves response to therapy and reduces the risk of cancer reoccurring, all of which enhance the quality of life for cancer patients. Progressive impacts have also been seen on a variety of infectious diseases, chronic disease, and

congenital malformations A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth de ...

, ultimately elevating the burden on the healthcare system and striving for optimal function. Palmini Nutrition Label

Nutritional epidemiology is the scientific basis upon which public health nutrition is built. Nutritional epidemiology aims to deliver knowledge on how to cope with an imbalance between nutrients that causes illness such as

anaemia Anemia (also spelt anaemia in British English) is a blood disorder in which the blood has a reduced ability to carry oxygen. This can be due to a lower than normal number of red blood cells, a reduction in the amount of hemoglobin availab ...

goitre A goitre (British English), or goiter (American English), is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly. Worldwide, over 90% of goitre cases are ...

wasting and stunting. The understanding of the characteristics of exposures require measurement to understand the diet–disease relationship. The ability to relate exposure to steps in the causal pathway improves the value of findings in relation to public health recommendations.

References

{{Authority control Epidemiology Nutritional science Nutrition