Plasma tocopherol concentrations to supplemental vitamin E13 Nikolay Wanda

V Dimitrov, Chenoweth,

ABSTRACT various

Normal doses

schedules. or

Cheryl Meyer, Dennis and Winfred Malone

of

healthy

Administration

1200

IU)

of dl-a-tocopherol a-tocophcrol

12-24

h. Chronic

administration

mg/d

affected diet

by dietary

showed

trations of this similar

fat intake.

significantly

WORDS humans

that

in dcpeaked

at

(440,

state

that

Discontinuation with a decline

Individuals

greater

880,

occurred

of the treatof plasma a-

consuming

plasma

was

a high-fat

a-tocopherol

healthy

concen-

Am J C/in

individuals.

Vitamin

a-tocopherol,

E (a-tocophcrol)

E acts in concert cell from

vitamin

E, bioavailability,

has attracted epidemiologists, in free radical

with a number

damaging

oxidative

icals

are

that

radical-scavenging

cells

against

involved

cancer-chemopreventive The protective dependent

on

In addition,

such

(4-6). suggest

that

ki-

The

agents absorption

E may

E may

and

is fat soluble,

utilization

lipids are

copherol-binding

protein

Am J C/in Nutr

depends

kinetics properly

199l;S3:723-9.

(16).

on

This

can

by other

other

factors

be predicted

in question. of vitamin evaluated

investigators by clinical

a thorough

studies but

in rat-liver was

also Printed

in USA.

micro-

may interfere a-tocopherol

on the

cytoplasm demonstrated

and

sub-

tocoph-

(17-19).

The

ofa

given

studies

study

E will be necessary before in cancer-chemoprevention

trials. The plasma kinetic a great deal of information

the

on plasma

on bioavailability only

Thus,

of mi-

in part,

of the

of the plasma

vitamin

E can intervention

done in the past lack some details

be

contributed that are

of

clinical importance (19-21). For example, the frequency of blood samplings was insufficient and the plasma clearance (to baseline) in single-dose and chronic dosing was not always determined (19-23).

To

obtain

developed

more

information,

a program

the

for testing

National

new

that

used

single

and

experimental

multiple

doses

Cancer

Institute

chemopreventive

agents

intervention trials. In from a phase-I study

of a-tocopherol

under

dif-

conditions.

and methods

Subjects

62 y were

healthy assigned

individuals to the protocol

of the ages of the subjects 21; 41-50

y, 16; 51-60

were

Pregnant

(males

and

for this

study.

24-30

y, 8; and 61-65 study

ifthey

any medication,

women

or those

females) The

y, 15 subjects;

aged

31-40

y, 4. Individuals had

no acute

vitamins, ofreproductive

24-

distribution

y, were

or chronic

or mineral age who

is usually or plasma. for short or

tract in plasma

bioavailability

explain,

variations

reported and

the

may

interindividual

of food

micronutricnt

supplements.

be a valuable

ofdifferent

substantially

and bile in the gastrointestinal the carriers for tocopherol

lipoproteins

and

erol concentrations net effect

influence

drugs

considered eligible for this illness and were not taking

studies

of an agent

utilization

radand

protect

epidemiologic

nutrients is influenced by a variety of factors that with its form before it reaches the plasma. Because

low-density

intra-

Sixty-four

the living

is evidence that carcinogenesis

in the target tissue preferential organs

use

of basic because Vitamin

to protect

vitamin

(7, 8). activity

its concentration

attention

as vitamin

Several

agent or therapeutic

certain

storages.

ofreactions

agents

experiments

the

and clinicians technology (1-6).

effects. There types ofchemical

in some

carcinogens

animal

ofdietary poproteins

stantial

ferent

nutritionists, advances

a complex and

Subjects

scientists, ofimportant

long

exerts

as potential candidates for use in large this communication we report the results

Introduction

and

intake

micronutrient

those fed a low-fat diet. The results plasma kinetics of a-tocopherol are of 440, 880, or 1 320 mg d/-a-to-

copherol are given to normal, Nutr 199 1 ;53:723-9.

netics,

resulted

Ruppenihal,

cronutrients

800,

mg (400,

dose

in a steady

after

different

to the pretreatment concentrations plasma elevation of a-tocopherol

as compared with study indicate that when supplements

KEY

1320

of d/-a-tocopherol

for 28 d) resulted

which returned 1 2 and 20 d. The

on

concentrations

by days 4-5 of supplementation. ment after day 28 was associated tocopherol, between

or

Mary

studied

ingested

as a single

of plasma

1 320

440, 880,

Giiiland,

were

were

of

vation or

volunteers

dl-a-tocopherol

in response

presence

(9-1 1). Li(12). Tothe

role

(1 3-15). © 1991 American

of

Food Society

Downloaded from https://academic.oup.com/ajcn/article-abstract/53/3/723/4731870 by Washington University School of Medicine Library user on 06 June 2018

I From the Department of Medicine, College of Human Medicine, Michigan State University, East Lansing, MI; the Departments of Statistics and Probability, and Food Science and Human Nutrition, Michigan State University; and The Chemoprevention Division ofCancer Control and Prevention Branch, National Cancer Institute, Bethesda, MD. 2 Supported by PHS grant N0l-CN-45 167, awarded by the National Cancer Institute, NIH, DHHS. 3 Address reprint requests to NV Dimitrov, B-220 Life Sciences Building. Michigan State University, East Lansing. MI 48824. Received June 7, 1990. Accepted for publication September 12, 1990.

for Clinical

Nutrition

723

724

DIMITROV

ET

AL

did not follow a contraceptive program were not eligible; women taking oral contraceptives were eligible. Individuals with body weights exceeding ±20% ofdesirable body weight were excluded.

a midday sufficient

All participants (including normal

had normal-range leukocyte differential

peripheral count

dl-a-tocopherol,

normal

urinalysis

and

biochemical

cluding

plasma

normal-range

concentrations

of

(HDL) and low-density-lipoprotein prerequisites for participation. was done in the Clinical Center

was

blood counts and platelets). A profile,

in-

high-density-lipoprotein

methods. For (Roche-Cobra

total and HDL cholesterol the enzymatic method Fara Kit, Diagnostic Chemicals, Monroe, CT)

was

The

used

(24).

accepted LDL

LDL

value

was obtained

by using

Participants erage

(total

HDL

-

cholesterol

All subjects

eligible

to participate

in the

by a physician

before

entrance

the study.

entered

the study

after

into

signing

trial

an appropriate

by the University Committee Subjects at Michigan State

Committee

on

Safety

accordance

with

the

Helsinki

NCI.

evaluated

Inthe

done

in

Declaration.

Roche

of d/-a-tocopherol

Inc,

for vitamin study were IU/d).

Nutley,

by Hoffmann-La

contained

the

studies

were by the

given

schedule. the

studies

and

E at 0800.

daily

with

a designated

took

single-dose

wk intervals

from

The

subjects

capsules

with

three

received Blood

150 mL

monitor,

phosphate Blood

from samples

tubes I 500

containing X g for

frozen

at -20

>

vehicle

subjects

whole

milk

assuring participating

skim

were

for the

a single dose of440, samples were collected

in the

concentrations

at 8-

880, or 1 320 mg every 3 h during

solution

dilutions

= 8), 880 mg (n for 28 d. Each subject

only

(no

=

Blood

samples

were

taken

(25).

absorption wavelengths

stock determined

nm for D-a-tocopherol plasma (0.5 mL)

of

the

an

and upper

was then layer

5

ability

in intake

stricted

foods

peanuts,

and

and

unrelated included

oils (wheat

germ,

low-fat high-fat

was

studied

in

six

diet for 5 d and diet. The other

the

E supplements.

almonds,

safflower,

fat on response

reverse order. Approximate was 18-24 g. The midday consuming

vitamin

kale,

Re-

sunflower

cottonseed,

were

mixture added

was

vortex

solution

of

and

low-fat

subjects.

after three

to vitamin Three

an 8-wk subjects

fat content meal provided diet

ate

a fat-free

subjects

rest were consumed ofthe

E supplemena

changed to a the diets in

high-fat breakfast 45 g fat. The subjects

breakfast

followed

the

HPLC

amounts added

by

Downloaded from https://academic.oup.com/ajcn/article-abstract/53/3/723/4731870 by Washington University School of Medicine Library user on 06 June 2018

(San

MA)

S jzm

Isocratic Liquid were used. The

daily.

Actual

ultraviolet

Extinction coefficients for D-a-tocopherol

mixed

and and

to a 1 .5 mL

poly0.05 pro-

This was (I : 1) was

for 60 s. Finally,

0.15

monohydrogen

was

vortex

mixed

for 30

1 3 000 X g for I mm. The to a I .5-mL polypropylene again organic

organic micro-

for 1 mm at I 3 000 matrix was directly

apparatus.

of D-a-tocopherol

to 0.50

A Beckman

rapeseed,

consumed

into

made

by measuring

dipotassium

the solution

centrifuged at was transferred

ofthese compounds and used to generate

seeds,

(Milford,

sunflower). The effect ofdietary

tation

to the cereals,

Known tate

for

by dis-

tube; 0.05 mL acetonitrile and solution were added to initiate

injected

the

at was

was stored

and provide the internal standard. 1 5 5, 0.25 mL butanol-ethylacetate

aqueous

phosphate

studies vari-

sample

prepared

acetate. transferred

was

weekly

until

evacuated

in 20 mL acetonitrile. were

nm

determination

in the chronic E to minimize

acetate

from Midwest monohydrogen

tubes were centrifuged was removed and

was

daily

copherol

twice

HPLC Burdick and ace-

D-a-tocopherol

acetate

centrifuge tube and was centrifuged x g. A 0.025-mL sample of this

collected

by the were

purchased from MI), methanol

solutions

supplementation. for plasma a-to-

were

samples

oil in 20 mL acetonitrile. The solution was prepared by dissolving

ofthe study and twice weekly during last dose was given, blood samples Subjects participating foods rich in vitamin

consuming

No sample

with a spectrophotometer. used were 75.8/292

and

mL

the

The plasma

beginning After the

baseline was reached. were asked to avoid

with

determined

(Pittsburgh). directly into

evaluation.

propylene microcentrifuge mL D-a-tocopherol acetate

440 mg

before

subject

All solvents

NJ),

D-a-tocopherol were

43.6/285 Human

23), or I 320 mg (n = 1 8) vitamin E daily was allowed to participate in one treatment

crossover).

The

of D-a-tocopherol

ofthese

added,

(n

av-

kcal

diet was 2410 kcal received 880 mg dl-

was

Lester

Scientific drawn

#{176}C for later

diets containing For chronic

by fat. received

The

1840

skim milk. Blood 1-5 and day 14.

concentration and

Fisher were

tein precipitation vortex mixed for

kcal with 38% provided three groups of subjects

days.

lithium heparin. 10 mm and the

wk. The stock

Serial

24 h and daily thereafter until baseline was reached. samples were taken for 2 consecutive days before the

I 770 studies

5 diet

of

2

100%

milk.

hospitalized

diet

JT Baker(Phillipsburg,

beginning ofthe study and averaged to produce a baseline value. During the 24-h hospitalization period, the subjects consumed

group

was

400 mg crystalline

low-fat-diet

the first Baseline

capsules

consumed.

capsules supervised with

vitamin

Placebo

supplied

of all foods low-fat

solving 100 mg D-a-tocopherol D-a-tocopherol acetate stock

compliance For

daily

ingestion self-selected.

for the

E, which was soybean oil. The doses used in this 440, 880, and 1320 mg/d (400 lU, 800lU, and 1200

The

(6 g fat)

NJ.

were

were

and BHT from Sigma (St Louis), absolute ethanol Solvent Company (Pekin, IL), and dipotassium

Protoco/ Capsules

h after

meals

diet took the capsule with before breakfast on days

of Nierenberg

tonitrile

on Research University and were

6-8

of the

grade. Butanol1 and ethylacetate were and Jackson Laboratories (Muskegon,

participants

All studies

within

records

a-tocopherol

method

informed-consent

form approved volving Human

at DCCP,

were

intake

meals

Methods

a generally

The

remainder

days was considered If 100% compliance

provided by fat; intake for the high-fat 43% provided by fat. All participants

the low-fat were taken

triglyceridcs)/5

-

two

the daily

daily

Plasma

cholesterol

for kept

total

a-tocopherol

formula =

maintained

25% with

(LDL) cholesterol, were Determination ofthese variables Laboratory by using automated

meal providing ‘--6 g fat. Five to obtain the needed information.

mL water

and

D-a-tocopherol

to correspond

in the plasma. The standards a daily standard curve. Ramon, C18

CA) bondapak

Chromatograph, mobile phase

1 lOB

ace-

to concentrations

pump

column.

were

extracted

with

a Waters

a Beckman

and a Beckman was methanol-water

427

331

Integrator (95:5) at a

flowrate of 2.5 mL/min. Peak identification was made by comparing retention times to times for known standards. Peak areas were measured and the ratio of D-a-tocopherol to D-a-tocopherol acetate was obtained for several standards. The ordinate

was

D-a-tocopherol:D-a-tocopherol

acetate

and

the ab-

SUPPLEMENTATION scissa

represented

concentration

ear-regression The

lines

correlation

of D-a-tocopherol.

were

calculated

coefficient

methods

organized

control.

to be

Institute

0.99

>

intraday

PLASMA

116.1

for each

92.88 440

outside-ex-

was 4.9%. quality-control

In addition, program

and

46.44

Technology

23.22

MD).

116.1

Statistics No statistical to the

assessments

single-dose

plasma

ofsignificance

study,

the multiple-dose

which

studies,

rate

were

paired-difference

t

with

times

the

statistic,

SPSS

Inc,

Chicago).

made

three

the

For

in a-tocopherol

for

a group

on

Wilcoxon

sta-

analysis

of

(SPSS/PS,

of a-tocopherol

at any given time between groups rates were made with the t statistic. to indicate statistical significance.

plasma receiving P values

contwo