Introduction of Human Vitamins and Minerals...continued #3.

Reference from the joint report of FAO/WHO expert consultation on Human Vitamins and Minerals verbatim. (Chapter 1)

Upper tolerable nutrient intake level

Upper tolerable nutrient intake levels (ULs) have been defined for some nutrients. ULs are the maximum intake from food that is unlikely to pose risk of adverse health effects from excess in almost all (97.5 percent) apparently healthy individuals in an age and sex-specific population group. ULs should be based on long-term exposure from food, including fortified food products.

2. Anonymous. 1997. A Model for the Development of Tolerable Upper Intake Levels. Nutr. Revs., 55: 342-351.

For most nutrients no adverse effects are anticipated when they are consumed as foods, because their absorption and or excretion are regulated. The special situation of consumption of nutritional supplements which when added to the nutrient intake from food may exceed the UL will be addressed in the specific chapters. The ULs as presented here do not meet the strict definition of no observed effect level used in health risk assessment by toxicologists because in most cases a dose-response curve for risk from total exposure to a nutrient will not be available. For more details on how to derive ULs, see the model presented in Nutrition Reviews (2). 

The range of intakes encompassed by the RNI and UL should be considered sufficient to prevent deficiency while avoiding toxicity. If no UL can be derived from experimental or observational data in humans, the UL can be defined from available data on upper range of observed dietary intake of apparently healthy populations.

Protective nutrient intake

The concept of protective nutrient intake has been introduced in some cases to refer to an amount greater than the RNI, which may be protective against a specified health or nutritional risk of public health relevance (e.g., vitamin C intake with a meal to promote iron absorption or folic acid to lower the risk of neural tube defects). The text will indicate when existing data provide justifiable differences between RNI values and protective intake levels. These intakes are expressed as a daily value or as an amount to be consumed within a meal.

Report of the consultation

In welcoming the participants, Dr Nath, Assistant Director General, Regional Office for Asia and the Pacific, (FAO), recalled the previous Consultation and publication on this subject from 1974.

That and the present Consultation are part of a long series of such expert consultations, which have as a primary objective; a) the review of the state of knowledge on the role of various nutrients in the human diet; and, b) the formulation of practical recommendations where interpretation is needed or controversy exists. The most recent in this series was the joint FAO/WHO expert consultation on carbohydrates in human nutrition held in Rome in 1997.

Dr Nath spoke of the increasing evidence for the important role which vitamins and minerals play in preventing disease and promoting overall health. Indeed, the understanding of the role of micronutrients in foods and nutrition has significantly increased over the past 24 years. For many years the basic assumption – which still may be the best assumption – on which nutritionists make their projections has been that all nutrients can be obtained from a diet containing a variety of foods from a variety of sources. Some of the challenges to this assumption rest in the complexities and diversity of worldwide realities, culture, and traditions. 

Dr Nath pointed out that for many people with access to an adequate energy intake, an extensive freedom of choice exists in the selection of food. However, the existence of widespread poverty in the majority of the UN member countries precludes the opportunity to consume adequate energy let alone a diet balanced in micronutrients. He observed that the increase in the availability of a wide variety of foods and especially “fast foods” in almost every country in the world, coupled with the increasing pace of urban lifestyles across all cultures and countries, does not necessarily result in adequate vitamin and mineral intake.

The existence of the dichotomies in lifespan was also mentioned by Dr Nath. In different parts of the world and in different segments of society within the same countries, there are broad ranges of life spans in part due to nutritional adequacy. Especially in urban populations, as lifespan increases as a result of nutritional adequacy and despite improved access to health care, an increase in obesity, diabetes, some forms of cancer, and cardiovascular disease has been recorded in all regions of the globe.

Although epidemiological studies do not provide us with cause-and-effect explanations, they do provide impetus for future research into the role of vitamins and minerals in the prevention and management of some non-communicable diseases.