FNH 351 High Yield Information

Protein, carbohydrates, water-soluble vitamins, and minerals travel from the small intestine directly to the ________ via the __________.

liver, hepatic portal vein

The difference between active absorption and facilitated diffusion is that

Nutrients move against their concentration gradient

the correct pathway of food through the gastrointestinal tract is

mouth, stomach, duodenum, jejenum, ileum, large intestine, rectum

After absorption, the nutrients that travel to body tissues before reaching the liver include:

Fat and fat soluble vitamins

Most digestive enzymes are secreted from the:

 

Pancreas and small intestine

Requirements are defined as the intake levels that are associated with reduced risk of adverse functional outcomes.

False

• in the context of DRIs a requirement is defined as the lowest continuing intake level of a nutrient that will maintain a defined level of nuriture in an individual.

The difference between an AI and an RDA is that:

 

An RDA is based on measures of nutrient requirements but an AI is not

Which of the following is TRUE regarding the Recommended Dietary Allowance (RDA)?

 

The RDA is mathematically derived from the EAR.

In planning your own diet, you should aim to meet the:

 

 

RDA or AI

The RDA is calculated as the EAR + ____

2 SD from the EAR

The difference between a macromineral and a micromineral is that…

macrominerals are required in the diet in amounts >100 mg/d

True or False (if false explain): all minerals with a potential toxicity have a UL

False

• the absence of a UL does not mean a mineral is safe at any dose; rather, it often means there is a lack of sufficient scientific data to establish a specific threshold where adverse effects consistently begin

• in addition some trace minerals that may be toxic (lead, mercury) do not have ULs becuase they are not considered nutrients; they are simply environmental toxins

a main difference between non-essential minerals and essential minerals is…

Non-essential minerals do not have an AI or RDA

a micronutrient is defined as:

a substance that must be provided in the diet, but does not provide energy to the body

True or False: The process of digestion and absorption is similar for all vitamins because they are all organic compounds.

False

It is recommended that ___________ take a daily supplement containing _____ of folic acid.

all individuals who could become pregnant, 0.4 mg

Ken is an adult male with an MTHFR TT variant. What is most likely true for Ken?

 

1. Ken’s DNA may be undermethylated at certain sites (because of methyl donor/SAM shortage)

2. elevated homocysteine

List all that are functions of folate:

• Prevention of vitamin B12 deficiency

• Methyl group transfer

• Synthesis of homocysteine

• Initiation of DNA replication

methyl group transfer

(folate does not prevent B12 deficiency, in fact it can dangerously mask one; folate is responsible for the remethylation (removal) of homocysteine, not its synthesis; folate is essential for the synthesis of DNA precursors but it does not initiate the process of replication itself;

Folate deficiency in Canada is…

 

Rare, because of folic acid fortification of flour

With zinc deficiency, what would be impaired (decreased):

1. digestion and absorption of folate

2. digestion and absorption of vitamin B6

3. digestion ot proteins in general (and in turn nutrients bound to proteins)

Folate functions interact with which of the following nutrients?

 

B12, riboflavin, and B6

folate trap

If B12 is deficient, folate becomes "trapped" in its 5-MTHF form, meaning it cannot be recycled to participate in DNA synthesis.

folate’s reliance on B12

Folate provides the methyl group (as 5-MTHF), but it requires Vitamin B12 as a coenzyme for the enzyme methionine synthase to actually transfer that group to homocysteine.

folate’s reliance on B6

While folate helps recycle homocysteine back into methionine, Vitamin B6 (in its active PLP form) is required for the alternative "cleanup" route—the transsulfuration pathway—which converts homocysteine into cysteine.

• For individuals with the MTHFR TT variant, the interaction with B6 becomes even more critical because his body must rely more heavily on B6-dependent pathways to compensate for sluggish folate metabolism.

folate’s reliance on riboflavin (vitamin B2)

The MTHFR enzyme, which creates the active form of folate (5-MTHF), requires FAD (a derivative of Vitamin B2) as a cofactor to function.

• Genetic Interaction: In people with the MTHFR TT variant, ensuring adequate Riboflavin intake is essential to stabilize the less efficient enzyme.

what is the genetic variant that causes people to typically have only about 30-35% of the normal methylenetetrahydrofolate reductase enzyme activity compared to those with the “standard'“ variant

MTHFR TT variant

• this is known as being gomozygous for the C677T mutation

(a specific genotype where an individual has inherited two copies of the “T” allele (one from each parent) for the MTHFR gene)

To retain tetrahydrofolate (THF) in cells, it is converted to: 

 

THF-polyglutamate

Jane ate the following meal:

	Folic acid (mcg)	Naturally occurring folate (mcg)
White bread (2 slices)	70	10
Peanut butter (1 tblsp)	0	23
Orange juice (1/2 cup)	0	39

How many mcg DFE (dietary folate equivalents) did Jane consume?

189

(1 mcg food folate = 1 mcg, 1 mcg folic acid = 1.67 mcg DFE;

10 + 23 + 39 + 70×1.67 = )

True or False (and explain): The Tolerable Upper Intake Level for folate is specific to folic acid and reflects the folic acid intake level above which someone can develop megaloblastic anemia.

False

the UL for folate is indeed specific to synthetic folic acid but the reason is wrong; the UL was set because high levels of folic acid can mask a vitamin B12 deficiency

Which of the following would impact absorption of naturally occurring vitamin B12 but not necessarily vitamin B12 supplements?

Proton pump inhibitors

(Naturally occurring Vitamin B12 is found in animal products and is bound to proteins; while supplements are in free form.

• The Cleaving Process: To absorb this B12, the body must first "cleave" or separate the vitamin from the food protein.

• Acid Dependency: This separation requires gastric acid (hydrochloric acid) and the enzyme pepsin, both of which are produced in the stomach.

• PPI Impact: PPIs significantly reduce the production of stomach acid. Without enough acid, the pepsin cannot be activated to release the B12 from the food, meaning the vitamin stays "trapped" and is eventually excreted)

What statement best explains the interaction of B12 and folate:

 

Vitamin B12 is needed for the remethylation of homocysteine to methionine.

Make a statement regarding the dietary requirements for vitamin B12 across the life span?

 

Adults older than 50 years should meet their dietary requirements through the consumption of B12 supplements and fortified foods.

True or False (and explain): The Dietary Reference Intakes (DRIs) for vitamin B12 include a Tolerable Upper Intake Level, given the toxicity of vitamin B12 at high supplemental intake.

False:

the DRIs for B12 does not include a UL; high supplemental intakes have not been consistently liked to adverse health effects in health humans

Vitamin B12 deficiency causes _____ because of its role in the ____

megaloblastic anemia, folate cycle