This summary is based on knowledge clips and modules available for student who follow(ed) the course
Food Components and Health (HNH-32206 – NUTR102x) and was made in December 2018. The
information provided via other learning material (lectures and assignments) has not been implemented
in this summary.
Module 1 – Basic Principles of Micronutrients
1.1 – Introduction
Bio-availability: how much of a nutrient is actually taken up in the body.
1.2 – Basic Principles of Vitamins and Minerals
Micronutrients (amount that we ingest is small among, < 1 gram per day): vitamins and minerals.
Macronutrient are ingested in larger amounts and provide energy which micronutrients do not. Also
structure, function and food contents is different. Vitamins are organic molecules (contain carbon
atoms), minerals are inorganic (mostly found in non-living matters).
Overview of vitamins. Are needed in small amounts for growth and for maintaining good health.
Essential component of our diet, insufficient intake might lead to specific deficiency. All animals need
vitamins but not every vitamin is needed in the diet of each animal species. Cats, dogs and rats make
vitamin C in their bodies. 13 groups of compounds. In some cases, the familiar name is actually the
generic descriptor for a family of chemically related compounds that have comparable metabolic
activities. Vitamin E: group of compounds that resemble the parent compounds tocopherol and
tocotrienol. In these cases, the members of the same vitamin family are called vitamers. Provitamin:
compound that can be converted within the body to a vitamin (e.g. carotenoids to vitamin A).
Vitamins are classified according to their solubilities: fat- or water-soluble. This characteristic depends
on the chemical structure. Fat-soluble: Vitamin A, D, E and K. Water-soluble: C and all the eight B-
vitamins; Thiamin (B1), Riboflavin (B2), Niacin (B3), B6, Folate, B12, Biotin and Pantothenic acid.
Distinguish between fat- and water-soluble since properties are different
1. Fat-soluble are more staple than heat and less likely to be lost during processing and cooking
of foods compared to the B-vitamins.
2. Fat-soluble vitamins are absorbed from the intestine along with fats in foods.
3. Fat-soluble is first absorbed into the lymph system, then into the blood whereas most water-
soluble vitamins move directly into the blood after absorption.
4. Fat-soluble vitamins are not soluble in blood, they require specific carrier proteins to transport
them through the body.
5. Water soluble vitamins are poorly retained by the body and any excess is mostly secreted via
the urine. Fat-soluble are not excreted in the urine, they are stored to a considerable extent in
the body, mainly in the liver and fatty tissues until they are needed. Because of that, deficiency
symptoms develop relatively slowly. Water-soluble need to be eaten more regularly than fat-
soluble. The storage of fat soluble vitamins is not all good because it may also lead to toxicity,
for example when using supplements. This is especially an issue for vitamin A and less for
vitamin D. Not a problem for fat-soluble since an overdose leaves through urine. Exception:
B12 is retained quite well.
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,Vitamins are compounds that are required in small quantities to ensure normal metabolism, growth
and physical well-being. Discovery of vitamins led to the recognition that diseases could be cured given
an adequate diet, such as scurvy, rickets, beriberi (Japanese sailors, neuropathy) and pellagra.
Minerals are inorganic molecules, not containing carbon atoms. Food contains all kinds of minerals,
some wanted, some unwanted. Dietary mineral (/elements): encompasses the chemical elements that
are essential for the human body. 21 elements are essential in our diet. 4 of them common present in
organic molecules; hydrogen, nitrogen, oxygen and carbon. 17 make the dietary minerals. Depending
on their abundance in our body, dietary minerals are further divided into major minerals and trace
minerals or trace elements. Major when it is present in the body in excess of 5 grams; calcium,
phosphorous, potassium, sulphur, sodium, chloride and magnesium. Trace elements; iron, zinc,
copper, manganese, molybdenum, fluoride, cobalt, iodine, selenium and chromium. Boron and silicium
may be essential minerals but we are not fully sure yet. Remaining nearly 100 chemical elements from
the periodic table are all non-essential and vary from being relatively harmless (e.g. helium) to
extremely toxic (e.g. polonium, plutonium). Even the essential elements can be toxic when taken in
excess (Paracelsus’ law). From high to low present in the body: calcium, potassium, sodium, iron.
Mineral bioavailability. It is important to realize that only part of the total amount of minerals present
in a food is available to the body. That is mostly because minerals are bound to compounds in the
foods that limit their absorption. The term bioavailability describes the extent to which ingested
minerals or other food components are absorbed and thereby available to the body.
Across the world, but especially in low income countries, a low bioavailability of minerals is a major
contributor to poor mineral status, even though total mineral intake may meet the recommendation.
This situation is mainly observed in people subsisting on monotonous plant-based diets. Accordingly,
strategies to improve mineral status should not only focus on increasing total mineral intake but also
on improving mineral bioavailability.
In general, plant foods have lower mineral bioavailability as compared to animal foods. Diet-related
factors in plant foods that affect bioavailability include the chemical form of the nutrient in food and/or
nature of the food matrix. In addition, many plant foods are rich in negatively charged compounds that
tightly bind cations (positively charged elements such as calcium, iron and zinc) and thus have lower
mineral bioavailability. These compounds include phytates, polyphenols, oxalate, and dietary fibre.
Finally, low mineral bioavailability may be caused by pre-treatment of a food as a result of processing
and/or preparation practices.
Mineral food content. Dietary minerals are present in nearly all foods. Notable exceptions are
vegetable oils and table sugar. The foods which are the most important contributors to our mineral
intake depend very much on the type of mineral in question. For instance, much of our calcium intake
comes from eating cheese and milk (at least in the Netherlands), whereas most of the dietary iron is
obtained via consumption of whole grain products, beans, and meat. A more detailed overview of food
products that contribute substantially to intake of the main minerals and trace elements will be
presented later.
Multi Vitamin/Mineral Supplement Reduce Fatigue. Only possible research design is an experimental
study, an intervention. Big chance for placebo effect. Hypothesis: both reduced but no difference
between the groups. Salt Intake Influence on Blood Pressure. Cross-sectional study could be an
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,option, collecting urine and measure salt excretion. Great risk for confounding, for example for BMI.
Blood pressure reacts fairly quickly, so an intervention test should not last very long. Parallel or cross-
over design. Taste difference is complicating this trial. Vitamin K and Risk of Bone Fractures.
Observational approach, taking advantage of existing cohort studies. Important to have a number of
bone fractures. Not known if the relation is causal, so not sure if the vitamin intake reduces the risk.
1.3 – Micronutrient Requirements
For nearly every nutrient, there is a particular value that we call the recommended dietary allowance.
Vitamin C: 60 mg/day, calcium: 1000 mg/day. RDA is part of a larger set of reference values for
nutrients, which are called the Dietary Reference Intakes. UK and EFSA: Dietary Reference Values
(DRV). Dietary Reference Intake (DRI) include the Estimated Average Requirement, the Recommended
Dietary Allowance, the Adequate Intake and the Tolerable Upper Intake level.
- Estimated Average Requirement (EAR) is the level of intake of a nutrient at which the
requirement of half of the healthy people is met.
- Recommended Dietary Allowance (RDA) is the level of intake of a nutrient that is sufficient to
meet the nutrient requirement of nearly all healthy people.
- Adequate Intake (AI) is defined when there is insufficient data to define a RDA.
- Tolerable Upper Level Intake (UL) describes the highest level of daily intake of a nutrient that
is safe.
DRIs are intended to assess and plan the diets of healthy people. Iron-deficient; anaemia. Also provides
scientific basis for the development of food guidelines in many countries. Many multi-vitamin and
mineral supplements provide nutrients at levels way above the RDA. DRI now serves as a scientific
standard for governmental nutrition guidance and is the de facto standard for virtually all nutrition
assistance programs. Dietary Reference Intakes. The Dietary Reference Intakes (DRI) are based on
scientifically grounded relationships between nutrient intakes and indicators of adequacy, as well as
the prevention of chronic diseases in apparently healthy populations.
DRI are established through extensive review processes. In the United States, the DRI values are
developed by the Food and Nutrition Board (FNB) at the Institute of Medicine (IOM). For each project,
the FNB appoints a committee of experts and holds open meetings to gather information and hear
from experts regarding specific topics. Once the data are gathered, there are closed discussions and a
report is drafted. Subsequently, the report is reviewed by outside experts in an anonymous process.
After being reviewed and accepted, the report is publicly released by the Institute of Medicine. Similar
procedures are followed by health councils around the globe, such as the European Food Safety
Authority, World Health Organization and region- and country-specific councils.
The DRI may be indicated by one of the following: the Estimated Average Requirement (EAR), the
Recommended Dietary Allowance (RDA), the Adequate Intake (AI), and the Tolerable Upper Intake
Level (UL). Please see the Table at the end of this section for brief definitions of each of the DRI
categories.
Estimated Average Requirement (EAR). The central question in determining dietary recommendations
is how much of a nutrient is required in the diet of a healthy person. This requirement is based on
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, information in the scientific literature, which includes hundreds of studies. The selection criteria for a
specific nutrient depend on the biological function of the nutrient in the body and its role in reducing
risk of diseases. For example, when direct functional outcomes such as connection with disease rates
are not available for a specific nutrient, the committees must focus on current intakes in healthy
populations, data from human balance studies, depletion-repletion studies, animal experiments, and
biochemical indicators of adequacy. Recommendations are divided into groups based on gender and
age. Looking at enough people might reveal that their individual requirements fall into a symmetrical
distribution, with most near the centre and only a few at the extremes, like a bell curve. Using this
information, an Estimated Average Requirement (EAR) for each nutrient is determined, i.e. the average
amount of a nutrient that appears sufficient for half of the population. Using the above values, the EAR
is 57 units. Therefore, the EAR is more informative at a population level rather than at the level of an
individual.
Recommended Dietary Allowances (RDA). Once
an average nutrient requirement is established,
the next step is to determine the recommended
intake, known as the Recommended Dietary
Allowance (RDA). Since EAR describes the
Estimated Average Requirement, an intake at the
level of EAR (57 units in the above example) does
not meet the requirements of all individuals. In
fact, about half of the people have an actual
requirement that exceeds the EAR. Because about
half of the people have an actual requirement that exceeds EAR, recommendations are set at a level
higher than the EAR in order to meet the needs of most healthy people in the population. Intake levels
that are slightly higher than the daily requirement don't do harm, whereas levels lower than the
requirement may compromise health. When an individual’s nutrient intake is consistently lower than
what is required, nutrient stores throughout the body decline, which may lead to suboptimal health
and even symptoms of deficiency. Therefore, to ensure that the nutrient RDA meet the needs of nearly
everybody, the RDA is set near the top end of the range of the population’s estimated requirements
to capture the needs of about 98 percent of the healthy people. Overall, the RDA is informative for an
individual, and less for the population as a whole.
For some nutrients such as vitamin K, there is insufficient scientific evidence to determine an EAR,
which is needed to set a RDA. In these cases, the committee establishes an Adequate Intake (AI)
instead of a RDA. An AI reflects the average amount of a nutrient that a group of healthy people
consumes. Although both the RDA and the AI serve as nutrient intake goals for individuals, there are
important differences between the two that are worth mentioning. The RDA for a given nutrient is
based on enough scientific evidence to expect that the needs of nearly all healthy people will be met.
An AI, on the other hand, must rely more heavily on scientific judgments, as sufficient evidence is
lacking. For this reason, AI values are more tentative than RDA values.
Tolerable Upper Intake Level (UL). As mentioned earlier, the recommended intakes for nutrients are
generous and may not be sufficient for every individual for every nutrient. Nevertheless, it is probably
best not to exceed these recommendations by very much or very often. Individual tolerances for high
doses of nutrients vary, and somewhere beyond the recommended intake is a point at which a nutrient
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