Chapter 10 - Micronutrients Flashcards
classes of micronutrients
- vitamins
- minerals
vitamins
complicated organic molecules that must be consumed in the diet as the body either
- does not manufacture them or
- does not manufacture them in sufficient quantities
all vitamins are necessary for the body to function properly
destroyed easily by cooking with heat or chemical reagents.
minerals
simple, inorganic molecules found in soil and rock
not vulnerable to heat, sunlight, or chemical reactions.
Vitamins and minerals also differ in their originating sources and their vulnerabilities to heat, light, and chemical reactions
inorganic vs organic
Compounds not containing carbon).
componds containing carbon
types of vitamins
- water soluble
- fat soluble
describe water-soluble vitamins
- present in the blood and other bodily fluids
- CANNOT be stored in bodily tissues (meaning they must be consumed daily)
describe fat soluble vitamins
- disolve in fats and oils
- can be stored in bodily tissues
hypervitaminosis
Abnormally high storage levels of vitamins, which can lead to toxic symptoms
the vitamin K can lead to this!
atomic elements
A pure substance consisting only of atoms that all have the same numbers of protons in their atomic nuclei
what are the water soluble vitamins?
B complex
C
water soluble
b-vitamins
8 total
B1 (thiamine)
B2 (riboflavin)
B3 (niacin)
B5 (pantothenic acid)
B6 (pyridoxine, pyridoxal, pyridoxamine)
B7 (biotin)
B9 (folic acid)
B12 (cobalamin)
vitamin B1 (thiamine)
RDI 1.1 - 1.2 mg
is involved in the metabolism of glucose and amino acids
deficient in vitamin B1 can develop diseases (e.g., beriberi)
found in fortified
1. enriched grains
2. meats (beef, pork, and salmon)
3. squash
4. black beans
5. flax seeds
peas, nuts, wholegrain breads, some fortified breakfast cereals, liver, flax seeds
vitamin B2 (riboflavin)
RDI 1.1 - 1.3 mg
- critical in macronutrient metabolism
- is a component of flavin adenine dinucleotide (FAD), an essential part of the body’s antioxidant system
milk, eggs, fortified breakfast cereals, mushrooms, plain yoghurt
vitamin B3 (niacin)
RDI 14 - 16 mg
- exists in two forms: nicotinic acid and nicotinamide
- critical for macronutrient metabolism
meat, fish, wheat, flour, eggs
Nicotinamide adenine dinucleotide (NAD)
RDI 1.3 mg
co-enzyme central to metabolism
Vitamin B5 (pantothenic acid)
RDI 1.3 ug (micrograms)
- part of co-enzyme A (CoA) - serves as a molecular link between glycolysis and the Krebs cycle, which means that it is involved in the metabolism of proteins, carbohydrates, and fatty acids
- fundamental in producing cholesterol, fatty acids, and other molecules, such as coenzyme Q10 (CoQ10).
chicken, beef, liver and kidneys, eggs, mushrooms, avocado
Vitamin B6 (pyridoxal, pyridoxine, and pyridoxamine)
RDI 2.4 ug
- refers to a class of several structurally similar molecules (pyridoxal, pyridoxine, and pyridoxamine
- critical to exercise metabolism, as they function in amino acid metabolism and glycogen breakdown
pork, poultry, fish, peanuts, soya beans, wheatgerm, oats, bananas, milk, some fortified breakfast cereals
Vitamin B7 or biotin
RDI 30 ug
- is needed in very small quantities (about 30 µg/day) and is predominantly synthesized by gut bacteria, so it is unclear if biotin is required from the diet
- found in many common foods in small amounts. It is a cofactor for four ATP-dependent carboxylases:
1. acetyl-CoA carboxylase
2. pyruvate carboxylase
3. propionyl-CoA carboxylase
4. β-methylcrotonyl-CoA carboxylase - biotin deficiency is uncommon and there is no evidence that biotin supplementation has any health benefits
Bacteria that live naturally in the bowel are able to make biotin
B9 (folic acid)
RDI 400 ug
- important for DNA synthesis and amino acid metabolism
- There is no evidence that exercise affects folate status. Like vitamin B6, however, dietary intake of folate in athletes is worth consideration. When energy intake is low, folate intake also appears to be poor, which has been reported in male and female figure skaters
broccoli, brussels sprouts, cabbage, kale, spring greens, spinach, peas, chickpeas, kidney beans, liver, breakfast cereals fortified with folic acid
Vitamin B12
RDI 5 ug
- is a coenzyme that is required for DNA synthesis and the formation of red blood cells
- predominantly found in animal products including meat, fish, poultry, eggs, milk, and milk produce
- vegetarian and vegan are more likely to have a B12 defficiency
meat, fish, milk, cheese, eggs, some fortified breakfast cereals
vitamin c (ascorbic acid or AA)
RDI 90 mg
- essential nutrient with roles in the body’s antioxidant defense system. Low intakes of AA may, however, increase the risk of certain chronic diseases and accelerate several indicators of the aging process
- Overall, no evidence-based rationale exists to justify the use of AA and α-TOC in an adaptive setting in AA- and α-TOC-sufficient athletes
Citrus fruit, such as oranges and orange juice, peppers, strawberries, blackcurrants, broccoli, brussels sprouts, potatoes
retinoids
Compounds chemically related to vitamin A
retinol
- vitamin A
- A family found in food and used as a dietary supplement
retinal
the chemical basis of animal vision
solutes
A substance that can be dissolved by a solvent to create a solution
can come in many forms, including gas, liquid, or solid
bioavailability
the fraction of the ingested nutrient that is absorbed and subsequently used for normal physiological functions
factor affecting bioavailability
chemical form
The same micronutrient may have different chemical forms that affect its bioavailability.
Ferrous compared with ferric iron
factor affecting bioavailability
dietary factors/interactions
Other dietary factors may enhance or inhibit the bioavailability of a micronutrient
Fats and antioxidants enhance carotenoid bioavailability.
Polyphenols and phytate inhibit iron bioavailability
factor affecting bioavailability
concentration (quantity ingested)
As the amount ingested of some micronutrients increases, the bioavailability decreases
As the concentration of bioavailable zinc ingested increases, the efficiency of zinc absorption decreases
factor affecting bioavailability
supplemental form
In some cases, supplemental forms of a micronutrient are better absorbed than dietary forms are
Carotenoids and folic acid are both better absorbed in supplemental form
factor affecting bioavailability
host status
Host nutritional status has a major effect on absorption for specific micronutrients
Vitamin A status can decrease iron bioavailability by preventing hemoglobin formation
factor affecting bioavailability
host pathophysiology
Some individuals lack factors necessary for the absorption of certain micronutrients
Lack of intrinsic factor limits vitamin B12 absorption through the small intestine to the bloodstream
are multivitamins effective at filling micronutrient defficiencies?
yes
common micronutrient defficiencies
vitamin B1(thiamine)
Vitamin B1 is
* found in high concentrations in skeletal muscle, likely because it is important in glucose metabolism and, thus, in energy production
vegetarians and vegans are at higher risk of low B1 who do not consume enough foods fortified with B vitamins or consume supplements
If low vitamin B1 is confirmed, thiamine status can be evaluated in 2 ways:
1. by erythrocyte transketolase (ETK) assay
2. measuring thiamine metabolites in accessible tissues
*The ETK assay is more informative, because it demonstrates functionality of the thiamine
common micronutrient defficiencies
vitamin B6
in certain foods such as bananas, meats, grains, and legumes, a preference against these foods will significantly reduce B6 intake in the diet. Therefore, dietary assessment and meal planning with whole foods rich in B6 would be the most effective means to ensure optimal B6 intake
vitamin A
- group of compounds called retinoids
- critical for vision, immune function, and human development
- deficiency can lead to impaired vision and, in extreme circumstances, even blindness and death
- Vitamin A deficiency is rare in developed countries
Oily fish, liver, egg yolk, milk, butter carrots, apricot
.7 - .9 mg
common micronutrient defficiencies
vitamin D
- inadequate sun exposure can cause defficiency
- Vitamin D status is indicative of calcium absorption and bone mineralization and there is a wealth of evidence describing the relationship between 25[OH]D deficiency and bone health (particularly in nonathletes).
- vitamin D has major immune function implications and decreases the likelihood for disease and infection
- decrements to muscle function are only observed when athletes present with very low vitamin D concentrations.
Oily fish, eggs, and fortified foods; mainly obtained via sunlight
it’s paramount to maximize athlete vitamin D year-round - 15 ug (m, f)
common micronutrient defficiencies
iron
highly abundant element that is essential for life
In the United States, most of the human requirement for iron comes from fortified breakfast cereals, red meat, some plant sources, and tofu. However, depending on the source of iron, only 5–35% is typically absorbed. Humans require iron for hemoglobin and myoglobin synthesis
From a sporting perspective, iron is an intensely studied micronutrient due to the impact of exercise on iron status. Evidence suggests that highly active people, especially endurance runners, have about a 70% increased requirement for iron intake when compared to non-runners
hemoglobin
Red protein responsible for transporting oxygen in the blood of vertebrates
its molecule comprises four subunits, each containing an iron atom bound to a heme group
myglobin
A red protein containing heme, which carries and stores oxygen in muscle cells; structurally similar to a subunit of hemoglobin.
