Case 1 – The double burden of malnutrition: nutritional problems, dietary guidelines
and environmental sustainability
LG1. How prevalent is obesity, overconsumption and undernutrition globally? What are the common types of nutritional
deficiencies? How does obesity and undernutrition cause nutritional deficiencies? What is meant by double burden of
malnutrition?
Obesity is highly prevalent throughout the world. Globally, this metabolic disease has almost tripled since 1975. In 2016,
there were more than 1,9 billion adults overweight. Of these, 650 million people were obese. This means that in total 39% of
the adult population was overweight and 13% was obese.
Undernutrition affected 462 million adults in 2014. In 2016, 224 million children were affected under 5 years of age. Of
these, 69 million children are wasted (too thin) and 155 million children are stunted (too short).
The most common types of deficiencies are vitamin and mineral deficiency:
❖ Vitamin A deficiency - Impaired dark adaptation of the eyes, leading to night blindness. Xerophthalmia can occur,
which is keratinization of the eyes (drying and thickening of cornea). It can also lead to impaired immune function.
❖ Vitamin B1 deficiency - Beriberi can occur, leading to nervous and cardiovascular system failure. Weight loss and
weakening of muscles also occurs.
❖ Vitamin B12 deficiency - can occur due to inadequate intake, malabsorption and lack of intrinsic factor. It can lead
to weakness, fatigue, dizziness, jaundice (yellow skin) or nervous system damage, affecting mood and vision.
❖ Vitamin C deficiency - Weakness, weight loss and scurvy (defects in connective tissue, leading to loose teeth and
swollen gums) may occur. In children it can lead to impaired bone growth.
❖ Vitamin D deficiency - Fatigue, increased risk of infections due to decreased immune function, osteoporosis or
bone weakening, due to decreased calcium absorption in intestine.
❖ Magnesium deficiency - Tremor, poor coordination, muscle spasms and cramps can occur due to this mineral
deficiency. It can cause chronic inflammation and thereby diseases.
❖ Iron deficiency - Weakness, fatigue, chest pain, headaches and inflammation all occur. It can result in anemia,
where there is a large amount of immature RBCs.
❖ Folic acid deficiency - leading to the same symptoms of vitamin B12 deficiency, therefore they are sometimes
mistaken for one another.
❖ Zinc deficiency - Growth retardation, loss of appetite and impaired immune function.
Many obese people have inadequate intake of iron, calcium, magnesium, zinc, copper, folic acid and vitamins A and B12.
This is because they have a poor diet quality or they can have changed nutritional needs. Vitamin C is commonly lacking in
obese people, since the higher BMI causes lower amounts of serum vitamin C. Iron is lacking due to either unbalanced
nutrition, increased needs or impaired absorption.
How does obesity cause nutritional deficiencies?
❖ Nutritional deficiencies can occur due to altered pharmacokinetics and altered interaction with other
pharmaceuticals. The increased adiposity in the body causes drugs to be distributed, metabolized and eliminated
differently. Maybe the micronutrient metabolism is also altered this way.
➢ Obese individuals have a higher blood volume, cardiac output, lead mass and organ size, which affects
the volume of distribution.
❖ Due to overconsumption and availability of high-calorie, low-nutrient foods, there is a overall lack in
micronutrients. The calories do not come from nutritious sources and therefore they do not meet the recommended
levels of micronutrients.
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, ❖ Higher body weight, due to increased adipose tissue causes lower serum levels of vitamin D. It is thought that
vitamin D hides in adipose tissue, thereby causing a lower level of vitamin D in the blood. Also, it is less available
for metabolically active tissues, which regulate calcium and bone metabolism.
❖ Metabolic changes in obese individuals may increase requirements for certain nutrients.
❖ Gut microbiota can be altered in obese individuals, affecting the absorption rate. Since less micronutrients will be
absorbed, it can lead to deficiencies.
Treatment with surgical procedures can sometimes worsen the nutrient deficiencies and develop new ones. This is because
certain parts of the stomach or colon will be unreachable due to gastric bypass, meaning that less micronutrients are able to
be absorbed. A gastric band causes individuals to ingest less food, meaning that there will be a decrease in ingested nutrients.
This can also cause a micronutrient deficiency.
LG2. What are the dietary recommendations from health organisations with respect to the EAR, RDA, AI and UL? What
are daily food recommendations and how are they developed?
According to the Dutch Health Council, there are certain guidelines, which we should adhere to to stay healthy. These
guidelines comprise:
❖ Eat more plant-based than animal-based products
❖ Eat 200 grams of vegetables and fruits
❖ Eat 90 grams of brown or wholegrain bread
❖ Eat 15 grams of unsalted nuts every day
❖ Take some diary every day
❖ Eat fish once every week
❖ Drink three cups of tea daily
❖ Replace unfiltered by filtered coffee
There are also some food that should be avoided, since they have negative health effects. These are:
❖ Red or processed meat
❖ Sugar containing drinks or alcohol
❖ Large amounts of salt (>6 grams per day)
Human nutrient guidelines are the common foundation for all countries to develop food-based dietary guidelines. These
guidelines are constantly developed every 10-15 years, and are reviewed for all age groups. These human nutrient guidelines
come from nutritional requirements. This is the amount of each individual nutrient needed to maintain an individual’s health.
It varies depending on age and gender. Based on these nutritional requirements, there are dietary reference intakes (DRIs),
which are used by policy makers in the EU to issue recommendations on nutrient intake to consumers (food labels or dietary
guidelines). There are four types of DRIs:
❖ EAR – Estimated Average Requirement is the daily intake value that is estimated to meet the nutrient requirement
of half of the apparently healthy individuals in a life stage or gender group. The risk of inadequacy is then 50% to
an individual.
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, ❖ RDA – Recommended Daily Allowances is the daily intake value that is estimated to meet the nutrient
requirement of nearly all healthy individuals in a life stage or gender group. The risk of inadequacy is small: 5%.
➢ The RDA is calculated from the EAR. Therefore, it is very reliable. However, when there is no EAR,
there is no RDA possible.
❖ AI – Adequate intake is based on experimentally derived intake levels of observed mean nutrient intakes by a
group of healthy people. It is less reliable than the EAR and RDA. The risk of inadequacy here is 0%, since you
take the actual intake values.
❖ UL - Tolerable upper intake level is the maximum amount of a nutrient that can be safely consumed with no risk of
adverse health effect over a long period of time.
LG3. What effect on the environmental sustainability do plant- and meat-based proteins have and which one is better?
Plant-based foods are more environmentally sustainable than animal-based foods. This is because the production of
plant-based foods requires less water, land and energy. Therefore, there is a lower environmental burden and a lower
financial cost of food production.
Even though plant-based foods are better for the environment, animal-based foods are consumed more than plant-based
foods. This is because it is made more efficiently and there is a higher demand of meat, eventually growing above the levels
that are sustainable. Meat-centric meals generate about 9x higher greenhouse gas emissions than plant-based meals. For beef
and cheese, this is even 10-20 more environmental impact. Also, an animal-based diet requires 2.5-5 times the energy inputs,
2-3 times the water, 13 times the fertilizer and 1.4 times the pesticide used per calorie produced, compared to a plant-based
diet.
❖ These impacts can be minimized by either using farming practices that are better suitable to the land type or
altering the feed into less environmentally damaging feed.
LG4. What are the effects on health following a plant- and a meat-based diet and which one is better? Which type of
protein is better and on what organs in the body does it work?
Skeletal muscle mass is regulated via changes in muscle protein synthesis (MPS) and muscle protein breakdown. MPS is
increased by food intake (mostly protein) and physical activity. Essential amino acids (EAAs) acts as signalling molecules to
induce the MPS response, besides acting as substrates for new proteins. This MPS response to food intake only lasts about
4-5 hours after ingestion, meaning that you have to consume protein throughout the day to maximize daily MPS.
Plant-based proteins result in lower muscle protein synthetic response when compared to animal-based proteins. They do not
increase MPS to the same extent. This can be due to lower digestibility (the proportion of AAs that effectively get digested
and absorbed to be used for protein synthesis), greater splanchnic extraction, thereby causing the plant-based proteins to
undergo ureagenesis. Also, plant proteins have a low leucine content (reducing anabolic properties) and a lower lysine and/or
methionine content (causing higher oxidation, leading to ureagenesis). .
❖ If there is too little essential amino acids (EAAs) in plant-based protein, there is an unfavourable mix, which goes
to the hepatic tissue and will then enter ureagenesis. Therefore, less is used for stimulating muscle anabolic
response and less is circulating in the bloodstream.
These anabolic properties can be increased for plant-based proteins, so that they will have the same effect as animal-based
proteins. These alterations are:
❖ Fortification of plant-based protein sources with amino acids methionine, lysine and/or leucine
❖ Selective breeding of plant sources to improve amino acid profiles
❖ Consumption of greater amounts of plant-based protein sources
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, ❖ Ingesting multiple protein sources to provide a more balanced amino acid profile
Plant-based proteins also have a lower dietary protein quality, which refers to the ability of a protein source to support the
increase in MPS after ingestion. This can be because of differences in digestion and absorption kinetics.
Increasing dietary protein overall can be beneficial for cardiovascular health by aiding in weight loss/maintenance,
improving lipid profile and reducing blood pressure. The amount in which these effects are beneficial are influenced by the
protein source and the macro- and micronutrient substitutions. Proteins from plant-based sources may reduce CVD risk
factors in comparison to animal-based sources.
❖ E.g. soy protein significantly reduced plasma cholesterol in comparison to animal protein.
Plant-based proteins are lower in essential amino acids, but are higher in nonessential amino acids. Plant-proteins have more
glutamate, cysteine, proline, phenylalanine and serine, which decrease systolic and diastolic blood pressure.
Case 2 – Vitamins and healthy procreation
LG1. What is the source of vitamin A, what is its function and how is it absorbed and metabolized? What are the dietary
recommendations for vitamin A? What is the teratogenic substance (toxic)?
Vitamin A is a liposoluble vitamin and is important for vision, immune function and cell growth. Its source is mainly from
orange-coloured food and can be from both plant- and animal-based source. The daily requirement is around 700 µg/day for
adult females and 900 µg/day for males. Pregnant women should consume around 1300 µg/day. The UL for vitamin A lies
around 3000 µg/day. Vitamin A can be found in three different forms:
❖ Retinol-fatty acid → found in animal-based foods
❖ β-carotene → found in plant-based foods
❖ Retinoic acid → the acidic metabolite, which is used as a ligand for transcription factors of the RAR nuclear
receptor. It switches them into activators instead of repressors.
Retinol fatty-acid and β-carotene can be transformed into retinoic acid. This is done via conversion into retinal (used for
vision) and then conversion into retinoic acid. This transformation happens in the enterocytes. Once the retinoic acid has
been formed, the reaction cannot be reversed.
1. Retinol-fatty acid is oxidized by enzymes into retinaldehyde. Cytosolic alcohol dehydrogenases (ADHs) control
the removal of excess retinol-fatty acid, while microsomal short-chain dehydrogenases/reductases (RDHs)
synthesize retinaldehyde.
2. Retinaldehyde is oxidized into retinoic acid by retinaldehyde dehydrogenases (RALDH1, RALDH2 and
RALDH3).
Only a small portion of vitamin A can be stored in the liver and the rest will be excreted. It is stored in both hepatocytes and
stellate cells as retinyl ester. Whenever it is needed, it can be released into the plasma.
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