NUTR 337-6

• Lowering blood pressure
• Blunting the adverse blood-pressure effects of salt intake
• Reducing the risk of kidney stones
• Potentially reducing bone loss

4.7g/day

no

Most potassium is intracellular

Sweat potassium is a small percentage of available potassium, BUT sweating does increase the dietary requirement (athletes)

~1.5g/day

Because the more a person sweats, the more a person excretes

• Primary route of loss is urine
• Kidneys can conserve or excrete Na as needed

No

• Maintain the increase in plasma volume
• Provide for the products of conception
• This accumulation occurs over 9 months

Present in the amino acids (methionine, cysteine and cystine) in proteins

A component of essential compounds such as glutathione (a potent antioxidant)

A potent antioxidant involved in the detoxification reactions of drug and toxins

North American diet is adequate-to-excessive protein intake, so there is no need to set RDA

Functions as a coenzyme in the metabolism of CHO and branched-chain amino acids

• Thiamin needed to achieve and maintain RBC transketolase activity
• Without excessive thiamin excretion

• Erythrocyte transketolase activity
• [thiamin] and its phosphorylated esters in blood
• Urinary thiamin excretion under basal conditions or after thiamin loading

Function as thiamin pyrophosphate (TPP) in the metabolism of CHO

Increased by ~30%

• Increased growth in maternal and fetal compartments (20%) 
• Small increase in energy utilization (10%)

1.4mg/day

Coenzyme in numerous oxidation-reduction reactions

• Erythrocyte glutathione reductase activity coefficient
• RBC [riboflavin]
• Urinary riboflavin excretion

Yes, additional riboflavin requirement of 0.3mg/day

• Increased growth in maternal and fetal compartments
• A small increase in energy utilization

Cosubstrate or coenzyme for the transfer of the hydride ion with numerous dehydrogenases

• Different niacin sources have different bioavilability
• Allows for some conversion of the a.a. tryptophan to niacin

no direct evidence to suggest a change in the niacin requirement during pregnancy

Vitamin B6 (pyridoxine and related compounds) functions as a coenzyme in the metabolism of amino acids, glycogen, and sphingoid bases

Maintenance of adequate blood 5'-pyridoxal phosphate levels

Yes, there is significant fetal uptake of vitamin B6

• ~2mg/day of supplemental B6 in the 1st trimester
• 4-10mg/day in the 3rd trimester
• Additional average pregnancy need is 0.25mg

Fetus and placent accumulate ~25mg of B6

Coenzyme in single-carbon transfers in the metabolism of nucleic and amino acids

• Erythrocyte folate
• Blood [homocysteine] and [folate]

To adjust for the nearly 50% lower bioavailability of food folate compared with that of folic acid

Yes, requirements increase substantially

• Marked acceleration in single-carbon transfer reactions
• Including those for nucleotide synthesis and thus cell division
• Uterine enlargement
• Placental development
• Expansion of maternal erythrocyte number
• Fetal growth

• Maternal serum and erythrocyte [folate] is decreased
• Megaloblastic marrow changes may occur
• Megaloblastic anemia may develop if inadequate intake continues

Erythrocyte folate maintenance (reflects tissue stores)

• EAR for nonpregnant women+supplementation=EAR for pregnant women
• 320ug/day+200ug/day=520ug/day

Decrease risk of NTD for women capable of becoming pregnant

• Coenzyme for a critical methyl transfer reaction that converts homocysteine to methionine
• A separate reaction that converts L-methylmalonyl-coenzyme A (CoA) to succynyl-CoA

Based on the amount needed for the maintenance of hematological status and normal blood vitamin B12 values

Due to an increased number of intrinsic factor-B12 eceptors

• Serum total [B12] begins to decrease in the 1st trimester (more than could be accounted for by hemodilution)
• Further decrease through the 6th month to about half of non-pregnancy concentrations (some of the later decrease is due to hemodilution)

• No, only newly absorbed B12 is readily transported across the placenta
• Maternal liver stores are less important source of the vitamin for the fetus

When the mother has been a strict vegetarian for only 3 years

EAR is increased by 0.2ug/day to give 2.6ug/day

Functions as a coenzyme in bicarbonate-dependent carboxylation reactions

• Ingestion of large amounts of raw eggwhite (avidin binds biotin)
• Biotinidase deficiency (genetic)
• Anticonvulsants (induce biotin catabolism)
• Pregnancy

Precursor for acetylcholine, phospholipids, and the methyl donor betaine

Prevention of liver damage as assessed by serum alanine aminotransferase levels

• Free choline
• Bound as esters such as phosphocholine, glycerophosphocholine, sphingomyelin, or phosphatidylcholine

• Used as a treatment to lower blood cholesterol
• lecithin-cholesterol acyltransferase plays an important role in the removal of cholesterol from tissues

Sequential methylation of phosphatidylethanolamine using S-adenosylmethionine as the methyl donor

Modified by the metabolic methyl-exchange relationships between choline and three nutrients: methionine, folate, and vitamin B12

• Decreased plasma [choline] and [phosphatidylcholine] 
• Develop liver damage

• The availability of methionine and folate in the diet
• Gender, pregnancy, lactation and stage of development

Based on only one study

During embryogenesis and perinatal development

Component of coenzyme A and phophopantetheine (fatty acid metabolism)

Intake adequate to replace urinary excretion of pantothenic acid

5mg/day- set using only one study of the relationship between daily intake and excretion in adults

• No information showing that usual intakes in US and Canada are inadequate to support a healthy pregnancy outcome
• Rounding up from the average intake in AI of 6mg/day for pregnant women

• Water-soluble antioxidant
• Cofactor for enzymes involved in the biosynthesis o collagen, carnitine and neurotransmitters

• Maintain near-maximal neutrophil concentration
• With minimal urinary excretion of ascorbate

• 90mg/day for men
• 75mg/day for women

Maternal plasma [vitamin C] decrease with the progression of pregnancy due to hemodilution and active transfer to the fetus

7mg/day

• Users of street drugs and cigarettes
• Heavy users of alcohol
• Regular users of aspirin

• Normal vision
• Gene expression
• Reproduction
• Embryonic development
• Growth
• Immune function

The assurance of adequate stores

• Preformed vitamin A abundant in some animal-derived foods
• Provitamin A carotenoids abundant in darkly coloured fruits and vegetables, oily fruits and red palm oil

12, 24, and 24 respectively

The body pool size will assure vitamin A reserves to cover increased needs during periods of stress and low vitamin A intake

• Accumulation in the liver of the fetus during gestation
• Assumption that liver contains ~1/2 the body's vitamin A when liver stores are low, as in the case of newborns

~70%

Increased by 50ug/day during the last trimester

• Enhances absorption efficiency of small intestine (Ca, P)
• Maintains blood [Ca], [P]
• Potent antiproliferative and prodifferentiation effects in a variety of tissues

• Vitamin D2 (ergocalciferol) from yeast and plant serols)
• Vitamin D3 (cholecalciferol) from 7-dehydrocholesterol, when synthesized in the skin

Found naturally in a few foods but is photosynthesized in the skin

• No
• Quantities of 25(OH)D transferred to fetus are small
• Do not affect overall vitamin D status of pregnant women

• A specific role for vitamin A in a required metabolic function has not been found
• Major function: non-specific chain-breaking antioxidant preventing the propagation of lipid peroxidation

• Induced vitamin E deficiency in humans
• Correlation between H2O2-induced erythrocyte lysis and blood [alpha-tocopherol]

Tocotrienols have an unsaturated side chain

Esters of either RR- or synthetic mixture of all racemic forms

15mg/day

Dependant on the affinity of hepatic alpha-tocopherol transfer protein (a-TTP)

2R-stereoisomeric forms are used to estimate the requirement

The 2S-stereoisomeric forms, the other tocopherols and the tocotrienols fail to bind with a-TTP and are therefor not used to estimate the requirement

Vitamin E deficiency in premature newborns

• No evidence that maternal supplementation would prevent deficiency symptoms in premature newborns
• Supplementation of pregnant females appears to be unwarranted

During the synthesis of the biologically active form of a number of proteins involved in blood coagulation and bone metabolism

Based on representative dietary intake data from healthy individuals

Phylloquinone

Form of vitamin K produced by bacteria in the lower bowel