An Introduction to

NUTRITIONAL EPIDEMIOLOGY

by ELISHA GAY C. HIDALGO, RND

DEFINITION OF EPIDEMIOLOGYEpidemiology is the study of the

distribution and determinants of diseases and other health outcomes in human populations. Epidemiology also deals with the natural history of diseases and it can provide evidence that contributes to their prevention.

EPIDEMIOLOGICAL INVESTIGATION OF A DEFICIENCY DISEASE

* include basic protein deficiency in starvation;  iron deficiency anemia; scurvy; iodine-deficiency and subsequent low thyroid  function; rickets from vitamin D deficiency;  beriberi from Vitamin B1 deficiency; and pellagra from niacin deficiency

PELLAGRA Affected people who relied on corn

as their staple food in 19th and early 20th century in Europe and United States.

Dr. Joseph Goldberger (United States Public Health Service) suspected that the disease might be due to a nutritional deficiency. He obtained funds to supply the residents with meat and milk to supplement their usual diet. Pellagra rapidly disappeared after these foods were introduced.

A few years later, scientists develop an animal model of pellagra and isolated niacin, the B vitamin that prevents this disease.

Heroes of the United States Medical Services

Dr. Joseph Goldberger(1874-1929) Public Health ServiceClimaxing years of outstanding research in yellow fever and other diseases, Dr. Joseph Goldberger probed one of the most baffling medical mysteries of the early Twentieth Century…Pellagra…and not only discovered its dietary origin, but identified a new pellagra preventive vitamin factor. But Dr. Goldberger gave the world more than a new vitamin…he gave it a better appreciation of the importance of nutrition to health…an appreciation that is reflected today in the thought and care which goes into the modern scientific feeding of children and adults in government stations, private institutions and millions of American homes.

Fighter with Foods

EPIDEMIOLOGICAL INVESTIGATION OF CHRONIC DISEASES

Current Focus of Epidemiological Studies: CHRONIC DISEASES (Coronary Heart Disease, Cancer, Stroke, Osteoporosis, Cataracts, Diabetes, Congenital Malformation)

Evidence from these studies provides a reasonable basis for action and a sound basis for further research.

SPECIFIC CHARACTERISTICS OF NUTRITIONAL EPIDEMIOLOGY

NUTRITIONAL EPIDEMIOLOGY: the study of the nutritional determinants of disease in human populations.It is one of the most exciting and difficult types of epidemiological research.

Exciting relevant to crucial health problems and some findings

have already been applied in ways that may improve public health.

Difficult complex nature of diet (maybe difficult to remember,

eating patterns may evolve, complex mixtures of substances in foods, eating habits may be correlated with other factors, etc)

multifactorial causation of chronic diseases

inherent limitations of epidemiological studies (although epidemiology is very effective in identifying strong links between an environmental factor and a disease, it is less effective in discerning weaker associations)

It may be impossible to determine, from epidemiology alone, whether relatively weak associations between diet and disease are real or whether they reflect subtle bias or measurement error.

GOALS OF NUTRITIONAL EPIDEMIOLOGY:

Monitor the food consumption, nutrient intake, and nutritional status of a population.

Generate new hypotheses about diet and disease, produce evidence to support or refute existing hypotheses, and assess the strength of diet-disease association.

Contribute to the prevention of disease and the improvement of public health.

Epidemiological studies can only identify possible associations, they cannot prove causal relationship. It must be combined with intervention trials or other scientific methods.

ADVANTAGES AND DISADVANTAGES OF NUTRITIONAL EPIDEMIOLOGY

Advantages: Disadvantages:Direct relevance to human

health (calculate direct estimates of risk which can then be translated into specific recommendations for changes in nutrient intakes or food consumption patterns)

Findings can have direct implications for food processing and technology (reformulation of food products, food fortification, etc).

Potential for many kinds of bias systematic error resulting in over- or underestimation of the strength of an association between an exposure and an outcome.

Difficulty in determining whether observed associations are causal.

May encourage the misuse and overinterpretation of data.

IN SUMMARYA theme in the history of nutritional epidemiology is the opening of previously unrecognized horizons. People didn't know there were subtle substances in food. We came to realize that there are stars beyond what we can see with the naked eye and forms of life too small, and similarly, there were many other subtleties that await technological enhancements to appreciate. In the field of nutrition, this involves the continuing development of equipment for testing or assaying tiny amounts of chemicals. 

Thank You!

Elisha Gay C. Hidalgo, RND