Effect of diets high in butter, sunflower oil on serum lipids Gordon

M Wardlaw

ABSTRACT

This

andfean

TSnook

randomized

blind

pared serum lipid and men consuming 37-43% corn

oil,

of the

high-oleic

sunflower

design

butter-based

rum

diet,

oil,

included

bowed by 5 wk ofdesignated wk washout period between the

study

apolipoprotein concentrations of energy as fat from diets

acid

crossover

crossover

corn oil, or high-oleic and apolipoproteins

the

and

butter.

vegetable-oil-based phases. Compared

tween

com-

in 20 based on Each

phase

2 wk of butter-based

diet

fol-

diet with a 7with values for

vegetable-oil-based

diets

reduced

se-

total

cholesterol by 16-21% (p < 0.001), LDL cholesterol by 2 1-26% (p < 0.001), triglycerides by 10-21% (p < 0.01 for the higher figure), and apolipoprotein B-l00 by 22-29% (p < 0.001). When values fell, they fell further on the corn-oilbased diet. There were no significant changes in serum HDL cholesterol or apolipoprotein A-l These data suggest that when men on diets high in saturated fatty acids reduce their saturated fatty acid intake but not their total fat intake, many can still experience a significant lowering in serum total cholesterol. Am J Clin Nuir 1990;5 I :815-21. .

KEY WORDS

Serum monounsaturated

poproteins, fatty

acids,

saturated

cholesterol, fatty

fatty

acids,

HDL acids,

cholesterol, apolipolyunsaturated

phospholipid

fatty

One

goal of the National


4.66 mmol/L (n =

39) were

tailed Roche

further

screened

by physical

examination

and

a de-

blood-chemistry analysis (Diagnostic Multi-Chem, Biomedical Laboratories, Columbus, OH). On the basis

of these

examinations,

for inclusion

a physician

in the study.

recommended

Ofthese,

serum cholesterol concentrations ± 1.5 y (1 ± SEM, range 27-47

37 subjects

the 22 men with the highest were enrolled. y) and weight

Age

was

34.7 ± 3.6

was 84.5 kg (range 70-1 16 kg). For randomization, subjects were grouped into intervals ofbody mass index [wt (kg)/ht2 (m2)] of 20-22.9, 23-24.9, and 25 and then assigned in equal numbers from these groups to the Poly or Mono diet for the first phase of the study. Two subjects (one on each vegetable-oilbased diet) resigned from the study after the first phase. This report includes data from the 20 subjects who completed both crossover phases as well as data for the 17 subjects who completed the final higher cholesterol, low-saturated-fatty-acid diet period. Diets

Breakfast toast,

meat

french

sandwich,

comprised toast,

fruit or pancakes;

cookies,

fruit,

juice;

eggs and

and

milk.

and diet soda.

toast,

cereal

and

Lunch

comprised

Dinner

comprised

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breakfast

at the study

checklists

were

site and

combined

On weekends

at the

site and were given

the total

a sack lunch.

and

based diets for an additional 2 wk at the end ofthe second crossover phase. During this period cholesterol was given (as eggs) to

were

to yield

given

a week’s

they consumed

a carryout

intake

lunch

and

and

analyzed

for nutrient content with Food Processor I Software (ESHA Research, Salem, OR) to which values for monounsaturated and polyunsaturated fatty acids were added according to Pennington

and

Church

(20).

Seven-day

rotating

menus

were

used in which most of the dietary lipid was incorporated into cakes, cookies, and bread. In this way the overall composition ofthe diet stayed constant in the two crossover phases; only the type oflipid used in food preparation was changed. Serum

lipid

and

apolipoprotein

analyses

Blood samples for serum lipid analyses were obtained after an overnight fast before breakfast by venipuncture seven times (days 1, 13, 15, 21, 35, 45, and 50) during each phase of the study. Values from days 13 and 15 (end of the butter-based diet) as well as those from days 45 and 50 (end ofthe vegetableoil-based diets) were averaged to dampen the effect of day-today variation in serum lipid concentrations. Depending on requirements of the analytical procedure, serum samples obtamed by centrifugation were analyzed fresh or were frozen at -70

#{176}C for lipid

analysis

at a later

time.

Serum total cholesterol was analyzed in previously frozen serum by using an enzymatic assay (procedure 352, Sigma Chemical Company, St Louis, MO). Serum HDL cholesterol was determined by first precipitating non-HDL serum lipoproteins with dextran sulfate (Stanbio Laboratory, Inc, Houston, TX). Then HDL cholesterol was determined in the supernatant by using an enzymatic method as before. Serum triglycerides

DIET TABLE

AND

LIPIDS

817

I

Composition

ofthe

diets5 Butter-based

Energy (Mi) Carbohydrate (en%)t Protein(en%) Fat(en%) Saturated fatty acids (en%) Monounsaturated fattyacids(en%) Polyunsaturated fatty acids (en%) Cholesterol(mg) 5

SERUM

i±

SEM; n

20. Range

=

I 2.0

±

50 ± 13± 40± 21± 14 ± 5 ± 480±20

0.6 1 1 1 1 I 1

diet

Mono

(80- 15.7) (47-53) (10-15) (37-42) ( 19-22) (13-16) (3-5) (345-658)

12.3 ± 49 ± 12± 41 ± 7 ± 28 ± 6 ± 190±

0.6 1 1 1 1 1 I 10

diet

Poly diet

(8.95- 16.0) (46-5 1) (11-14) (37-43) (5-9) (26-30) (6-7) (157-253)

12. 1 ± 50 ± 13± 41 ± 8 ± 14 ± 19 ± 185±

0.6(9.0-15.4) I (46-52) 1 (11-14) I (37-43) 1 (7-9) 1 (12-15) I ( I 8-20) 10 (131-261)

isgiven in parentheses. ofdiet energy.

t En% refers to the percentage

were

measured

enzymatically

Company). as follows:

LDL

Values

total

=

Portions

with

Sigma

Chemical

Deerfield,

were

calculated

procedure

HDL

serum

the standards

in most

runs.

ofvariation)

and

cholesterol, 4.3%.

determination

standards providing

from 5.39,

sample

The

for the various

total

triglycerides,

triglycerides

-

The

was

were

analyzed

run-to-run

preci-

serum

lipid

HDL

cholesterol,

ofthe

serum

2.2%; accuracy

by using

assessed

X 0.16

analytotal

cholesterol

the American College ofPathobogy (Skokie, 6.82, and 9.30 mmol/L. Our values (tested

from

itin-ring

On days were taken was

a standard

diameter

and

curve

antigen

13 and 50 ofeach for phospholipid

extracted

with

IL) on

using

the square

ofthe

precip-

concentration.

phase ofthe study, serum samples fatty acid analysis. Fresh serum

chloroform-methanol

(2: 1) and

then

tered. Saline was added to the filtrate, creating two layers. mixture was centrifuged and then the saline-methanol was removed. A small amount of chloroform-methanol-saline (3:47:48) was line-methanol

added to the chloroform-lipid was again removed (21).

The

stored at -20 #{176}C under nitrogen ofthe chloroform layer, serum

fatty using

isolated

were

glass plates

coated

by thin-layer

with

ark, DE). The solvent system tic acid (80:20: 1, vol:vol:vol).

scraped ters were

from

the plate

prepared

Silica was

chromatography

n-hexane-diethyl The phospholipid

BF3-methanol

Fatty (22)

sa-

until assayed. phospholipid

Gel G (Analtech,

for esterification.

by using

fib-

This layer

layers and the chloroform-lipid

extract was then After evaporation acids

Fatty

(TLC)

were

with

authentic

Company

identified

by comparison

standards

and Supelco,

oftheir

reten-

from

Sigma

obtained

Inc (Beblefonte,

PA).

Data analysis Phase I and II serum lipid and apobipoprotein concentrations were compared for both the starting and butter-based diet by using paired I tests to examine if subjects returned to phase I values (SAS, SAS Institute, Cary, NC). For each ofthe vegetable-oil-based

diets,

percent

changes

in serum

lipid

and

apolipo-

concentrations from both the prestudy and butterbased diets and the last week on the vegetable-oil-based diet were again analyzed by using paired t tests (Minitab, Minitab, Inc, State College, PA). Differences between the Poly and Mono diets were analyzed with repeated-measures analysis of variance (ANOVA) for crossover designs (BMDP, BMDP Statistical Software, Los Angeles, CA) (23). In this design possible fixed sources ofvariation include the overall mean, differential carry-over, period, and diet effects. Because there were repeated measurements taken of the serum concentrations over time (weeks), additional sources ofvariation include week as well as the interaction ofweek with the other factors(differential carryover, period, and diet effect). The analysis showed an absence of differential carry-over effects. This means that any possible carry-over from phase I to phase II did not affect the response to the diets in phase II more in one group than in the other group. Thus we are able to combine data from both crossover phases of the study. However, some carry-over effects were present for serum total cholesterol and LDL cholesterol when both butter-based-diet periods were compared (p < 0.02). In the absence of significant differential carry-over effects for all analyses, it was then necessary to analyze all serum lipid and apolipoprotein

Inc, Newether-aceband was

acid

methyl

es-

and

purified

by

TLC as before. Fatty acid methyl esters were then separated and quantitated by using a gas chromatograph (model 417, Packard Beckman, Downers Grove, IL) equipped with a flame ionization detector and two glass columns packed with 20% Silar 1OC on 100/120 mesh Anakrom Q (Altec Associates,

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acids

the fatty

protein

one occasion) for these standards were 5.39, 6.88, and 9.17 mmol/L, respectively. Fresh serum samples on days 15, 21, and 50 of both phases were analyzed for apolipoproteins A-b (apo A-b) and B-bOO (apo B-lOO) by radial immunodiffusion (Tago, Inc, Burlingame, CA). Three levels of reference sera were run with each determination, and serum apolipoprotein concentrations were calculated

IL). Samples of fish oil were taken throughout to check for oxidation of polyunsaturated

times

Chemical

cholesterol frozen

as follows:

cholesterol

tion

of a previously

(coefficient

ses were

2.8%;

338,

cholesterol

cholesterol

-

sion

LDL

acids.

cholesterol

along

(procedure

for serum

data

in terms

ofchanges

from

phase

I prestudy

and butter-based-diet serum concentrations (24). The measurements taken at the start of phase I are the only bonafide starting and baseline values, for it is only then that all the subjects are comparable (aside from random differences) in their values. At the start of phase II, the subjects have already received the treatment diets, and so there may be some carry-over effect onto the butter-based phase II values, possibly because of a change in food-consumption patterns during the washout period that contrasted with the self-selected-diet phase that preceded the study.

818

WARDLAW

s--

l-_$.

i-

AND

fl-I

confidence

7.0-

the Told

SNOOK

cholsstsrol