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Summary - Food and Nutrition in Health and Disease (HFV1001)
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Summary of the course Food and Nutrition in Health and Disease (HFV1001). Covering all PBL sessions and information from lectures
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TUTORIAL 1 – SENSORY ASPECTS – THE SENSATION OF TASTEThe senses of taste and smell allow us to separate undesirable or even lethal foods from those that
are pleasant to eat and nutritious. The texture of food, as detected by tactual senses of the mouth,
and the presence of substances in the food that stimulate pain endings, such as pepper, greatly alter
the taste experience. The receptor capabilities, primary sensations of taste are:
• Sour (acids, hydrogen ion [H+], low pH; vinegar and lemons)
• Salty (ionized salt)
• Sweet (not caused by any single class of chemicals, but mostly organic; sugar)
• Bitter (not caused by any single class of chemicals, but mostly organic; cocoa)
• Umami / Savory (glutamate; meat extracts, ageing cheese, protein rich foods)
Taste buds are microscopic sensory organs
containing chemosensory cells which synapse with
afferent fibers of gustatory nerves. Due to the
abrasive environment of the oral cavity, gustatory
cells (tase cells) are highly regenerative with their
average turnover being 8-12 days. From the tip of
each taste cell, several microvilli, or taste hairs,
protrude outward into the taste pore to approach
the cavity(holte) of the mouth. These microvilli
provide the receptor surface for taste. Vesicles
contain a neurotransmitter substance that is
released through the cell membrane to excite the
nerve fiber(zenuwvezel) endings in response to
taste stimulation. Taste nerve signals the insula in the brain → aware of what you are tasting.
The taste buds are found on three types of papillae of the tongue:
• Circumvallate
Form a V-line on the surface of the posterior
tongue. Large amount of buds.
• Fungiform
At the flat anterior surface of the tongue.
Moderate amount of taste buds.
• Foliate
Along the lateral surface of the tongue. Moderate
amount of buds.
Adults have 3000 to 10,000 taste buds, and
children have a few more. Beyond the age of 45
years, many taste buds degenerate, causing taste
sensitivity to decrease in old age.
There are four types of cells found in taste buds:
• Type 1 (glial like) gustatory epithelial cells: supporting cells (maybe salt)
• Type 2 (receptor): gustatory epithelial cells: express G protein receptors for bitter, sweet and
umami taste.
, • Type 3 (presynaptic) gustatory epithelial cells: receptors for sour taste
• Type 4 gustatory epithelial/basal cells: onrijpe voorlopers van type I-III smaakepitheelcellen.
Taste bud development:
- Fetus still has very few taste buds
o Fully functioning taste buds 80 days after gestation (zwangerschap)
o Newborns (1-3 days) are clearly responsive to gustatory (smaak) stimulation
- Taste bud density matures at early childhood (4 years)
- Papillae density is much higher in children (mid-childhood), smaller tongue?
- Papillae are much smaller in children
- With a higher age, children can better detect and distinguish tastes.
Taste sensation and pleasure
- Bitter and sour => avoid, these can be poisonous substances.
o Wide variety in sensitivity to bitter taste
o Sodium blocks bitter taste and sucrose masks bitter taste
- Sweet and salty => approach, save substances, provide energy
o Sweet preference does not decrease until adolescence
o Children prefer sweetness vs adults (10 vs 6 cubes per 200ml)
o 11-15 year olds differed in bone growth depending on high or low sweet preference
o Children who are tall for their age prefer sweeeter foods than their shorter peers
Changes in taste acceptance in infants
- Slight decrease in sweet preference (3-6-12 months of age)
- Strong increase in salt preference
- No change in umami acceptance
- Sour and bitter tastings least preferred; no change
Disgust sensitivity and obesity
- Core disgust: offensiveness / aanstootgevend (rotting or unusual food)
- Contamination disgust: contagion / besmet (contaminated food)
- Animal disgust: reminder of our mortality (meat with bones)
From study ‘Houben & Havermans, 2012’: woman with higher BMI report less core and less
contamination disgust > corelated with stronger desire to eat high calorie foods.
Neophobia = the reluctance to eat, or the avoidance of, new/unfamiliar foods.
- Peaks between 2 and 6 years, then decreases gradually until adulthood
- Variety of food acceptance established before the peak of neophobia tracks into adulthood
- Tends to increase with older age
- Functional: reducing ingestion of potentially harmful toxins aka protective mechanisms
- Maladaptive: interfering with ‘growing a palate;
Establishing a taste for different vegetables
- Future moms need to eat a lot of vegetables
- Breastfeeding
- Offering a variety of solid healthy foods at early age
- Repeat exposure to specific foods/meals (food familiarizing
Picky eating = rejection of both famililar and unfamiliar foods
, - Problem because it can lead to severe malnutrition
The role of mouthfeel = tactile sensitivity
- Many (young) children like fruit and yogurt, but do not like pieces in their yoghurt
- Picky eaters do not like the touch of a lot of different textures
Nephoboia/picky eating and product development
- Children do not like unfamiliar foods and flavours
- Young children do not like complex food textures (bread with nuts and seeds; Ben & Jery’s)
- Foods should be:
o Sweet (or savaroy)
o Fairly homogeneous texture
o Have a familiar shape/color/aroma
o Include a gift or toy
Taste perception and acuity (scherpte) elderly
- Sensitivity for especially bitter taste was found to decrease from the age of 20 years
- Taste thresholds are ~2.5 times higher among elderly (+75 years old) as compared to young
adults.
- Prevalence taste disorder in general population (<1%) and in older persons, >60 years (5-20%)
Declining taste consequences:
- A declining perception of salty flavors may induce elderly people to season their foods with
excessive amounts of salt or to prefer very salty dishes
- A declining sweet taste perception may induce elderly people to add excessive amounts of
sugar to their food and beverages and/or to prefer sugary foods and drinks
- A declining perception of sour taste could mean that elderly people fail to recognize unripe
and spoilt foods, as well as they increase their consumption of acid foods and condiments
(citrus, vinegar), thus giving rise to changes in their gastric acidity and a higher risk of
developing acid-related diseases or aggravating existing conditions
- A more limited perception of bitter flavors can raise the risk of failure to avoid ingesting spoilt
food
Causes taste or flavor dysfunctionin elderly
- Hyposalivation/xerotomia (dry mouth)
=> without saliva you cannot really taste
- Aging mucous membrane
- Decreasing taste bud density
- Disease
- Poly-pharmacy
- History of smoking and drinking
Product meal development in elderly
- ONS or fortified foods that are similar to well-known and habitually eaten foods may have a
clear advantage
- Add spices / herbs, enhance flavor, easy to swallow, make it sweet
- Make sure it is recognized as food
, TUTORIAL 2 – PRE- & PROBIOTICS - MICROBIOM
Various types of microorganisms, known as gut microbiota or commensal bacteria, are inhabitants of
the human gastrointestinal tract. The gut microbiota are mostly dominated by bacteria, but also
viruses (bacteriophages), archaea, fungi (such as yeasts), and even single-celled eukaryotes. It has
been reported that there are 1010–1012 live microorganisms per gram in the human colon, 10x more
than human cells. The resident microbial groups in the stomach, small, and large intestine are crucial
for human health. The majority of these microorganisms, which are mostly anaerobes, live in the
large intestine. Most common species - Bacteroides - Firmicutes – Bifidobacterium.
Gram-negative and Gram-positive are terms used to categorize and differentiate bacteria based on
the characteristics of their cell walls. Gram-negative bacteria have a thinner peptidoglycan layer in
their cell walls and the outer membrane contains lipopolysaccharides (LPS), which can be toxic.
Gram-positive bacteria have a thicker layer of peptidoglycan in their cell walls and they lack the outer
lipid membrane found in Gram-negative bacteria.
The microbiome consists of microbes that are both helpful and potentially harmful. Most are
symbiotic (where both the human body and microbiota benefit) and some, in smaller numbers, are
pathogenic (promoting disease). In a healthy body, pathogenic and symbiotic microbiota coexist
without problems. But if there is a disturbance in that balance—brought on by infectious illnesses,
certain diets, or the prolonged use of antibiotics or other bacteria-destroying medications—dysbiosis
occurs, stopping these normal interactions. As a result, the body may become more susceptible to
disease.
Active mechanism / function of commensal microbiota:
- Nutrient metabolism
o Gut bacteria are involved in the breakdown and metabolism of certain nutrients,
such as bile acids and phytochemicals
- Fermentation
o Gut bacteria ferment dietary fibers and complex carbohydrates that are indigestible
by the host's enzymes.
▪ This fermentation process produces short-chain fatty acids (SCFAs), such as
acetate, propionate, and butyrate.
- Immune System Modulation
o The gut microbiota interacts with the host's immune system, training and regulating
it. A balanced gut microbiome can promote immune tolerance, while dysbiosis
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