Vitamin David

C and cardiovascular

risk factors13

L Trout

ABSTRACT

The

supplementation

protects

oped

in the tate

nations

were

shown

concept

l970s

lower

when than

to lower plasma

men,

to

raise

that

against

ascorbic

vitamin

blood

with

pressure

vitamin

C status.

blinded

study.

systolic

and

pertensive

has

pulse

acid

pressure

KEY WORDS

Ascorbic

mellitus,

of essentially

group

sex,

doubleto lower

of borderline

hy-

cholesterol,

di-

free

for free in the

radicals

radicals. blood

The

and

diet

disease its

many

(3).

The

the

world

may

aspects

review

range

how

ofvalucs

affect

risk

extra

commonly

factors

AA on risk factors

tations,

values

Plasma

AA

sex, smoking,

then

diabetes

been

examine

describe

and

in health for men

for diabetics

and

has

first

found

of vitamin

terol, blood

high-density lipoprotein pressure will be described.

of vitamin

vitamin

C status reviewed

several effects

100 tmol/L

near is subject

sometimes

the body

most

pool level

of

commonly

are not infrequently

to change

which with

re-

with

reported.

day-to-day

variation

in

may have little effect on body stores. plasma AA as a measure of AA status

uncertain

association

with

cholesterol,

extra

AA

of CVD increases for smokers than

nondiabetics.

C status

of

between

Effects

of age,

with

hormones, the ability

and

serum

chotcs-

especially

of AA measures

with

pool

body

the

diseases, ofsome cells

such data,

tribution

types

ofcell

subject in AA

rate,

AA have proved

C status

elimination

to be difficult

need

to be considered.

The

in body stores, is ofgreat theoof measuring the metabolism,

rates,

and

size

and sometimes

of the

body

misleading. Am J C/in Nuir

pool

size

and states to concentrate

cell types

storage

however,

The

of

of leukocytes

of AA

in the body.

care is required fraction

is daily

l99l:53:322S-5S.

ofthe study,

AA intakes

high-AA

as the

association

that the dis-

is similar

in subject

AA intake.

Intakes

accounted

high day-to-day with 7 d of diet were

tow-AA

between

In two studies

close. intake

because recent

estimated

on the

plasma

involving for only

3-d 25-27%

are

found

day

(8).

AA

and

variability recall data

to be 4.7 times AA

intake

as

is not

food records, estimated AA of the variance for plasma

10).

In describing research results, two used. The National Canada Interpretive

the Carbohydrate Research

Nutrition

Center,

of Agriculture,

reference Standard

Laboratory,

Agricultural

Bettsvitte,

Research

standards of 1973

will be defined

Beltsville

Human Depart-

Service,

US

MD.

are those ofthe author and do not necessarily express those of the US Department of Agriculture. 3 Address reprint requests to DL Trout, Carbohydrate Nutrition Lab2

Views

oratory,

of

Based

Downloaded from https://academic.oup.com/ajcn/article-abstract/53/1/322S/4691357 by guest on 27 February 2018

of cellular

in the leukocyte

to uncertainty intake. In one

per subject, great

ment

amount ofAA Methods

or in specific

In interpreting

Nutrition

status ofvitamin

first ofthese, the retical importance.

in leukocytes as an index

AA (9,

will first be examtotal

AA taken

From

322S

and

3

usually estimated from food intake records kept by the subjects. Methods ofestimating nutrient intakes for free-living people are highly subject to error. Estimates of AA intakes are especially

measures

of feeding

the association

on AA nutriture

Associations

turnover

at least AA losses

as yet unknown is the

groups to be compared (7). A fourth measure ofAA status

for cardiovas-

recently

surveys. Risk than women, than

med.

Four

size

intakes,

increase,

at some

AA concentration

daily AA intakes, The major concern

is often

AA

actions

between

health

for CVD

and

the biological

relation

will

It will

status and risk factors with age and is greater nonsmokers,

the

of human

C status.

Measures

plasma

size

a pool

increased

excretion

to a maximum

Third,

are commonly

is to understand

about

and

present

vitamin

now

within

literature

metabolism,

and

peroxidation

(CVD).

The extensive C.

lipid

rote in atherogenesis (1 , 2). Ascorbic component in the scavenging systems

need

in the industrialized cular

and

to play a major is an important

(AA)

and

indicate

With

AA (6).

Oxidative believed

(5).

for AA; for some drugs, stress are known to impair

Introduction

acid

tissues

mg figure

oxidation

1 500 mg AA has often been (4). However, actual measure-

ported measure of vitamin C status. Values between 20 and 80 mol/L are commonly found among apparently healthy people who are not taking vitamin supplements; and, with supplemen-

is its

factors

a pool size of and adequate

in human

I 500

Second,

199 l;53:322S-5S.

hypertension,

age

effects healthy

negatively

for 6 wk was observed

acid,

smoking,

increases intake.

to correlate

J C/in Nutr

the

through

these

studies, as typical of AA

times

However,

C nutriturc,

in a small

Am

then

some elderly

cholesterol.

found

on tracer accepted ments

was

in a placebo-controlled,

ascorbic

subjects.

abetes

been

Recently,

extra

devel-

in industrialized

and, among

lipoprotein

among people in initially good vitamin arc usually not seen. In five populations people,

disease

Supplementation

total cholesterol

C)

(vitamin

heart

C intakes

at present.

high-density

acid

coronary

expressed

Beltsville

Department Bettsville.

Human

Nutrition

of Agriculture, MD 20705.

Printed

in USA.

Room

Research

Center,

315,

Building

© 1991 American

Society

ARS,

United

307,

for Clinical

States

BARC-East,

Nutrition

VITAMIN 23 tmol AA/L levels for adults

AND

C

plasma as the lower limit of safe and (1 1). In 1980, the US National Research

(4) accepted 60 mg allowance (RDA)(4).

AA/d Both

but

for comparative

are convenient

as the official these standards

recommended are subject

CARDIOVASCULAR than

adequate

Council

plasma

AA

estimated

dietary to question

3235

RISK in the

diabetics.

been

eating,

to have

In a later on

plasma AA was lower among diabetics still averaged 70 mol/L (1 8). However,

purposes.

cocytes

can

be similarly

high

study

average,

with 140

>

subjects

mg

AA/d,

than control subjects AA in plasma and

in diabetic

and

but Icu-

nondiabetic

sub-

jects(18). A likely

Age

explanation

has developed.

Elderly

people

or middle-aged and

appear

adults

inadequate

people

to be somewhat

to consume

amounts

more

likely

than

C. Populations

of elderly

with both low- (I 2, 13) and high-AA status (9, 10) have described. In one study of nearly 700 people aged 60-100

been

y living

in the

found

greater

Boston

to consume

and,

the

72%

Canadian

plasma

standard

of the

subjects

were

also

to transport

the

hyperglycemia

subject

to increase

(17).

It

(4);

normal

57 zmol/L,

2.5

into the urine.

a 40-y

age

span

Total

serum

It has

the Canadian standard not most populations indicate such

that high

much

levels

and

regression

periods,

the

feeding

of 280

mg

to men

were estimated

curves (10).

in elderly

same

relating

These

AA

(62

mol/

of 90 mg of the vitamin

(14).

from

plasma

formulas

plasma

In a second

diet records,

AA

and

indicated

AA

that,

study

in

least-square

intake

were

to maintain

the

remain

degree

to which

the

difference

occurs

all

at younger

three

is also

number

extra

AA

by

is excreted

plasma

Canadian

or

is an initial

AA

concentration

standard;

a second

is

The subjects may ( 16) or may not decrease in 1-Chol exceeded 10% in

even

including

a substantial

persisted

for a full year.

to be without

Spittle

with (22)

nonresponder

continued

AA supple-

has reported

that

the daily

effect

initially

good

on serum

1-Chol

AA status

in three

(with

initial

studies

plasma

of people

AA

averaging

4 1 Mmol/L).

Some in

people

1-Chol,

Yoshioka healthy group having

respond

to marginal

others

whereas

of vitamin

to be determined.

ofO.5

in a majority

A first condition

ic, with

of the

feeding

(T-Chol)

feeding of 1 g extra AA to one of three of her normocholesterolemic groups reduced serum 1-Chol by -‘8%; but this report was unusual. AA supplementation has been reported (8, 23, 24)

cal-

ages

conditions.

range

studies,

the daily

cholesterol

intake,

and the reductions

mentation

plasma

>

special of AA

or in the

with

AA levels 45 tmot/L, men required 3 times as much dietary AA as women. Sex is clearly an important factor in determining AA status for elderly people. Mechanisms for the sex difference and

AA

meat,

10 y that

>

total

elevated serum cholesterol. (20, 2 1) be diabetic. The

group;

to maintain

the daily

AA intakes

culated

required

with

for

which

are

3-wk

takes

to women

intakes

subjects

in which

of AA

AA

for many, if Two studies

men than in elderly women. were fed different controlled in-

In one study L) was observed

ie, 2 times

(1 1), have become typical in industrialized countries. higher

plasma

plasma,

for

serum

level

below AA/L

known

under

marginal 45 mol

in transporting carrier

is believed to be low in diabetics is not taken up by cells at a

AA

an AA-containing

lowers

ofsubjects

Sex >

The

conserves

cholesterol

been

I .0 g AA

of

after

and

when

in diabetics in its partially

which is promptly for AA transport

is inhibited (19).

cells

of

standard (11).

concentrations

that,

the US RDA

(1 1). Within

rate

and

by insulin

appears

C status

into

acid, carrier

of diabetics

ie, 2 times

subjects (10), age did not affect plasma AA. Among chronically ill elderly women with initially low AA status, a 30 mg/d supplement proved sufficient usually (12) to meet the Canadian

Fasting

glucose

AA exceeded

120 mg AA/d,

for 75% of subjects,

times

area,

vitamin

transported

oxidized form as dehydroascorbic verted to AA within the cell. The

young

little fresh fruits and vegetables

of vitamin

for a lower

AA is actively

C status

extra

et at (25) have men aged 30-39

do

AA deficiency

not.

dietary

It is not AA

reported y, plasma

clear

ceases

with

a rise

at what

level

to affect

1-Chol.

that, among 194 apparently 1-Chol was higher for the

having plasma AA of 3 1-48 still higher concentrations.

zmol/L

than

among

those

Smoking Smoking Hornig

fasting

has been known since the et at (3) cited 8 papers, seven

plasma

underlying

observed AA pool

AA

for smokers

the effect

have

than been

nonsmokers.

Mechanisms

examined.

Kallner

There

ct at (15)

that with controlled AA intakes smokers had a smaller that had a higher fractional turnover rate.

Diabetes Diabetics

marginal.

to have

a control

lower

reported

plasma

AA ofthe

and 26 zmol/L group.

concentrations

than nondiabetic important when

et at (16)

in Czechoslovakia,

L for men

of the

that HDL

extra

cholesterol

AA can elevate

component

of plasma

the plasma total

con-

cholesterol;

HDL-Chol concentrations. In two reports, the correlation was observed in men but not in women, and the AA status of the men was low, with plasma AA averaging 26 gmol/L (26) or

are reported

Ginter

is evidence

centration

lipoprotein

but the data are confined mainly to elderly subjects. Three health surveys observed a positive correlation between plasma AA and

mellitus

plasma and leukocytes difference is clinically

for

also

Plasma high-density (HDL-Chol)

l960s to lower AA status. of which indicated lower

that,

for women

Leucocyte

AA

ofAA

in

people (16, 17). This AA intakes are low or at the

diabetics

end

of a winter

averaged

18 zmol/

and were was

even

33% tower more

than

depressed

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variable,

extending

below

1 1 mol/L

for

some

subjects

Subjects of a third report (9) of a positive correlation AA status and HDL-Chol were mostly (65%) women a high AA status, with 75% of subjects having 57 L plasma, 2.5 times the concentration ofthe Canadian A positive not

observed

association

in a younger

between

group

plasma

AA

of 30-39-y-old

and

(27).

between and had mol

AA/

standard.

HDL-Chol

men.

Yoshioka

was

324S

TROUT

TABLE Reports pressure

1 of a negative

association

between

AA status

and blood

tween

plasma

lation

for an AA

The Location

I. Southwest 2. Southwest 3. Series

Subject

Mississippi Mississippi

ables

group

304 blacks, both sexes, aged 6-80 y (29) 439 blacks and Caucasians, both sexes, (30) aged 34 y

of places

10 4 19 people,

both

throughout USA5 4. Series of places throughout USA5

10 372 people, (32)

essentially

5.

194 apparently

healthy

men.

aged

healthy

men,

aged 54 y

Yagoshima,

lapan

sexes,

1 8 y (31)

same

Finland

722 apparently

Salonen plasma pretcd

7. Kuopio,

Finland

Same

(34)

divided

tration and intermediate The

his subjects

observed group.

daily

according

to plasma

HDL-Chot

for the

a lower

feeding

of a 1 g supplement

Blood

status

AA

of AA to one

elderly subjects with an initially low AA leucocytes, raised HDL-Chol (28). Three subjects in good AA with AA supplementation

AA conccnhigh

did not find (8, 23, 24).

status, studies

than

group

of

as assessed in with younger

changes

in HDL-Chol

the

adjusted

significant also

AA

(P

looked

effects

corre0.0008).