European Journal of Clinical Nutrition (1999) 53, 644±653
ß 1999 Stockton Press. All rights reserved 0954±3007/99 $12.00
http://www.stockton-press.co.uk/ejcn
Carotenoids in young and elderly healthy humans: dietary
intakes, biochemical status and diet-plasma relationships
YL Carroll1, BM Corridan1 and PA Morrissey1*
1
Nutritional Sciences, Department of Food Science and Technology, University College Cork, Cork, Ireland
Objective: To determine dietary carotenoid concentrations using an established and newly developed food
frequency questionnaire (FFQ) method, to determine plasma carotenoid concentrations and to determine the
relationship between these dietary and plasma variables in 24 ± 45 y and 65 y groups.
Design: Descriptive assessment of (FFQ), 7 ± d estimated records, and plasma carotenoids and their relationships
in 24 ± 45 y and 65 y groups.
Setting: Free living urban adults in Ireland.
Subjects: Sixty-four volunteers aged 24 ± 45 y and 54 volunteers aged 65 y.
Results: b-carotene was the predominant plasma carotenoid, but older groups had lower plasma concentrations
of several carotenoids compared to younger groups (P < 0.005). b-carotene and lycopene were the major dietary
carotenoids reported by estimated records and FFQ. Several estimated record and plasma carotenoid concentrations were positively associated in younger groups but not in older groups. FFQ overestimated dietary
carotenoids relative to estimated records (P 0.05), generally did not re¯ect estimated record carotenoid
concentrations and showed positive associations with plasma carotenoids only in older men. Neither of the
dietary methods revealed a positive association between plasma and dietary b-carotene concentrations, whereas
b-cryptoxanthin was strongly associated.
Conclusions: Dietary and plasma concentrations of individual carotenoids are documented in young and elderly
groups of a European country. Estimated record data reveals positive associations between diet and plasma
carotenoids in younger, but not elderly groups. Further work examining diet-plasma relationship in older groups
and developing a common FFQ suitable for use in several European countries is required.
Sponsorship: Commission of the European Communities: AAIR Project (AIR2-CT93-0888).
Descriptors: carotenoids; dietary assessment; elderly; biomarkers
Introduction
High fruit and vegetable consumption is associated with
reduced incidence of several chronic diseases. Evidence for
a protective effect of greater vegetable consumption is
consistent for cancers of the stomach, oesophagus, lung,
oral cavity and pharynx, endometrium, pancreas and colon
(Steinmetz & Potter, 1996). Mortality from coronary heart
disease, has been reported by several prospective studies, to
be inversely associated with consumption of fruit and
vegetables (Knekt et al, 1994; Key et al, 1996). Biological
concentrations of antioxidants derived from fruits and
vegetables are also inversely associated with risk of coronary heart disease. An inverse association between serum
carotenoids and risk of coronary heart disease, was reported
in a prospective study (Morris et al, 1994), while a nested
case-control study, concluded that low serum levels of
carotenoids, were associated with an increased risk of
subsequent myocardial infarction among smokers (Street
et al, 1994). A cross-sectional, multicentre study, also
reported an inverse association between high adipose
*Correspondence: Prof PA Morrissey, Nutritional Sciences, Department of
Food Science and Technology, University College Cork, Cork, Ireland.
Received 7 October 1997; revised 18 February 1999; accepted
26 February 1999
tissue b-carotene concentrations and risk of myocardial
infarction (Kardinaal et al, 1993).
Data from several studies support a role for carotenoids
in protection against chronic disease in elderly as well as
middle-aged groups. A prospective study of residents of a
retirement community, reported reduced risks of colon and
all sites combined cancers, with increasing intake of
vegetables and fruits in elderly women (Shibata et al,
1992). Another prospective study on cardiovascular disease
mortality, reported that the bene®cial effects of increased
fruit and vegetable consumption are apparent in the elderly
(Gaziano et al, 1995). Age related macular degeneration is
another condition which has been shown to be inversely
associated with consumption of foods rich in carotenoids
(Seddon et al, 1994).
In view of the inverse relationships between carotenoids
and disease, both dietary and biochemical status of carotenoids are individually worthy of further study. Little
published data is available on tissue carotenoid concentrations in Irish population groups. Research studies generally
tend to exclude those over the age of 65y and studies
addressing this age group are warranted. Dietary data on
consumption of carotenoids were, in the past, usually
expressed as b-carotene, b-carotene equivalents or retinol
equivalents. More recently, an extensive carotenoid food
composition database listing values for the ®ve major
carotenoids occurring in fruits, vegetables and multi-component foods, has been compiled in the USA (Mangels et
Carotenoids in diet and plasma
YL Carroll et al
al, 1993; Chug-Ahuja et al, 1993). In Europe, analysis of
dietary carotenoids, other than b-carotene, is dif®cult
because many national food composition databases only
provide limited values for individual carotenoids (Souci et
al, 1987; Holland et al, 1991b). However, analysis of foods
in Finland, Spain, the Netherlands and UK has generated an
extensive body of published data on the carotenoid composition of foods consumed in Europe (Heinonen et al,
1988, 1989; Ollilainen et al, 1988, 1989; Granado et al,
1992; Olmedilla et al, 1993; Vollebregt & Feskens, 1993;
Hart & Scott, 1995). As part in a multi-centre European
study, a common carotenoid food composition database,
based mainly on data from the above sources was agreed
between participants. This database, providing data on
lycopene, a-carotene, b-carotene, b-cryptoxanthin and
lutein zeaxanthin concentrations in 106 food descriptors,
was used in the present study.
Biomarkers of dietary intakes of nutrients are becoming
increasingly popular in nutrition research. The ability of
plasma to act as a biomarker of dietary intakes of individual
carotenoids is of interest. Several intervention studies have
shown that plasma carotenoids are responsive to increased
and reduced intakes of fruits and vegetables (Brown et al,
1989; Micozzi et al, 1992; Rock et al, 1992; Fuller et al,
1993; Yeum et al, 1996). However, data from the USA
indicate that under usual dietary conditions, the associations
between dietary and plasma carotenoid concentrations are
moderate and generally do not exceed correlation coef®cients more than r 0.5 (Ascherio et al, 1992; Forman et al,
1993). As far as we are aware, in Europe, only one
published study has examined the association between
individual carotenoids in diet and serum and was limited
to a group of women aged 50 ± 65 y (Scott et al, 1996).
As participants in a multi-centre study, leading on to an
intervention phase, volunteers were required to complete an
especially developed, but not previously evaluated FFQ.
The FFQ which was devised by reference to existing FFQ
in use at participating centres, necessitated inclusion of a
suf®ciently wide range of foods to facilitate its use in each
of the ®ve participating European countries.
The primary aim of this present study was to assess
dietary concentrations of individual carotenoids using an
established dietary method, to assess plasma concentrations
of individual carotenoids and to examine the associations
between these dietary and plasma carotenoid concentrations
in younger and older groups of Irish adults. A secondary
aim of this present study was to evaluate the performance of
the FFQ, by reference to an established dietary method and
by reference to plasma carotenoid concentrations, in
younger and older groups of Irish volunteers.
Methods
As part of a multi-centre European study, 69 healthy
volunteers aged between 25 ± 45y and 57 healthy volunteers 65 y were recruited for this study and two follow-on
supplementation studies. The studies on the younger and
older groups were carried out ten months apart. All volunteers were screened by a medical history, physical examination, and biochemical and haematological pro®le.
Subjects had normal lipid metabolism as indicated by
fasting serum cholesterol and triacylglycerol concentrations. Body Mass Index (BMI) ranged from 19 ±
31 kg=m2. Subjects were not adhering to any special diets
and were non-smokers. Informed consent was given by all
volunteers. All procedures were approved by the Clinical
Research Ethics Committee at University College, Cork.
Following screening, eligible subjects completed a 7d
estimated record. The FFQ was administered on the day
following completion of the estimated records. Fasting
blood samples were obtained at screening and on the day
after completing the 7d estimated record.
Biochemical analysis of plasma carotenoids
Samples were protected from natural light. Plasma was
immediately separated and stored at 7 70 C until analysed. Plasma carotenoids, tocopherols and retinol were
extracted from 0.2mL plasma with 0.2 mL 10 mmol SDS
solution, 0.4mL ethanol and triplicate extractions with
0.4 mL n-hexane (0.05% w=v butylated hydroxy toluene
(BHT)) (Burton et al, 1985). The hexane extracts were
dried under nitrogen and reconstituted in 20mL dichloromethane followed by 180 mL acetonitrile-methanol (75:20
by volume). A 50mL sample was injected onto a temperature controlled (25 C) reverse phase HPLC system (Scott &
Hart, 1993). The column system included Spherisorb ODS2 Guard Cartridges (Alltech, Lancashire, UK) in line with
Spherisorb ODS-2, 5 mm, 150 mm64.5 mm pre-column
(Alltech, Lancashire, UK) and Vydac 201TP54
250 mm64.5mm analytical column (Separations Group,
California, USA). The mobile phase was acetonitrilemethanol-dichloromethane (75:20:5 by volume) containing
0.05% v=v triethylamine and using 0.05 mol ammonium
acetate in the methanol component of the mobile phase.
Detection involved two on-line UV=VIS detectors (Shimatzu, Japan), with all carotenoids detected at 450 nm,
while the UV detector was programmed to change from
wavelength 325 ± 295 nm during the analysis, in order to
detect retinol, g-tocopherol and a-tocopherol. The data
were processed using Millennium 2.1 software data processing package (Waters Corporation, Milford, USA). Six
carotenoids including lutein, zeaxanthin, b-cryptoxanthin,
all-trans lycopene, a-carotene and all-trans b-carotene
were quanti®ed by reference to ®ve point calibration
curves. Total plasma carotenoids were computed by summing the ®ve individual carotenoids. For each subject,
triplicate plasma samples from screening and from the
day following completion of the estimated records were
run on the same day. Plasma b-carotene concentrations in
samples from the Fat soluble Vitamin Quality Assurance
Program deviated in the range 3 ± 8% from the mean of the
analyte concentration, in the programme conducted by the
National Institute of Standards and Technology (NIST,
Gaithesburg, USA). By the criteria of this programme,
our laboratories performance is evaluated as acceptable
relative to the current state of the practice for measurement
of b-carotene.
Dietary analysis
Volunteers completed seven consecutive days of estimated
records. Detailed written and verbal instructions on how to
record the amount of food and drink consumed during the
7 d were given to volunteers. Volunteers were visited four
times during the recording period and any discrepancies
corrected. The weights of all foods were calculated (g=d),
with the aid of a photographic atlas and standard portion
sizes (Ministry of Agriculture, Fisheries and Food, 1993).
FFQ relating to eating habits over the previous three
months was also completed by all volunteers. The FFQ was
comprised of a list of 110 food items and was divided into
645
Carotenoids in diet and plasma
YL Carroll et al
646
seven sections: green, red-orange, white-yellow coloured
vegetables, fruits, processed foods, dairy products, other
foods. Eleven options for frequency of consumption including; 1, 2, 3, 4, 5, 6, 7 (times per week), fortnightly,
monthly, seldom and never, were given in all sections
except the dairy and other food sections. Foods were
quanti®ed in the most appropriate units, for example,
slices of cucumber, tablespoons of baked beans, with
reference to standard portion sizes (Ministry of Agriculture,
Fisheries and Food, 1993). Intake of foods from the FFQ
was calculated in g=d.
The estimated records and FFQ from both studies were
coded by one person. Dietary carotenoids were quanti®ed
by reference to a comprehensive database which was
incorporated into a computerised dietary analysis programme, Comp-Eat (Nutrition Systems, London, UK).
Compiled as part of the larger multi-centre study, this
carotenoid food composition database was based on published values, many of which were established in laboratories of participants in this multi-centre study (Granado et
al, 1992; Olmedilla et al, 1993; Hart & Scott, 1995). Most
of the data was derived from Finnish, Dutch, Spanish and
UK sources (Heinonen et al, 1988, 1989; Ollilainen et al,
1988, 1989; Granado et al, 1992; Olmedilla et al, 1993;
Vollebregt & Feskens 1993; Hart & Scott, 1995), with
reference to data from other sources limited to a small
number of food items that had not been analysed in the
above publications (Holland et al, 1991; Tonucci et al,
1995; Burlingame, 1993; Mangels et al, 1993). Values for
®ve categories of carotenoids including lutein zeaxanthin,
b-carotene, a-carotene, lycopene and b-cryptoxanthin were
included in the database.
Statistical analysis
Sixty four subjects in the younger and 54 subjects in the
older groups, completed the studies. Five subjects in the
younger groups were excluded from analysis because FFQ
were not completed. Three subjects in the older group were
excluded because they did not complete either the diet
record or the FFQ. Statistical analysis was performed with
Datadesk 4, 2 statistical software package (Data Description Inc., New York, USA) and SPSS (SPSS Inc, Chicago,
USA) statistical software package (Norusis SPSS Inc.). The
effects of age group and dietary methods on dietary
carotenoid intakes were examined by ANOVA with twoway interaction. Differences between estimated record and
FFQ carotenoid intakes in younger and older males and in
younger and older females were examined by post-hoc
Bonferroni tests. The Mann ± Whitney U test was used to
examine differences between older and younger groups
Table 1
carotenoid intakes expressed as nutrient densities. The
Mann ± Whitney U test was also used to examine differences in plasma carotenoid concentrations in younger and
older groups. Differences between male and female estimated record carotenoid intakes (expressed as nutrient
densities) and differences in plasma carotenoids were
examined by the Mann ± Whitney U test. Spearman's
rank correlation coef®cients were calculated to investigate
the associations between dietary and plasma data and
between the two dietary methods. Plasma carotenoids
were also adjusted for BMI, plasma triglycerides and
plasma cholesterol by General Linear Models. Adjusting
for these variables did not improve correlations and the
crude correlations are presented. The ability of the FFQ to
correctly classify volunteers into the highest and lowest
tertiles of the estimated record carotenoid distribution was
examined. The ability of each of the dietary methods to
correctly classify volunteers into the highest and lowest
tertiles of the plasma carotenoid distribution was also
examined. The Cochran Q test was used to determine
whether the percentage of volunteers correctly classi®ed
by estimated records into the same tertile of the plasma
carotenoid distributions were signi®cantly different from
the percentage of volunteers correctly classi®ed by FFQ.
The extent of misclassi®cation into opposite tertiles, was
also recorded and examined by the Cochran Q test. The
within- and between-person coef®cient of variation of
individual carotenoids in plasma and estimated records
were calculated by reference to values of within- and
between person variances, obtained from repeated measures ANOVA.
Results
Characteristics of the study populations are shown in Table
1. The average age of volunteers was 31 y in the younger
groups and 70 y in the older groups. All volunteers were in
good health and had biochemical and haematological
values within the reference range.
Mean dietary carotenoid intakes of males and females,
assessed by estimated records and FFQ, are presented in
Table 2. In both age groups, the predominant dietary
carotenoids reported by both estimated records and FFQ
were b-carotene and lycopene. There was no signi®cant
difference between males and females in absolute carotenoid intakes, assessed by either dietary method, in any of
the age groups. The effects of age group and dietary
method on dietary carotenoid intake in male and females
were evaluated by ANOVA with two-way interactions. In
males, dietary method had a signi®cant effect on the dietary
Characteristics of groups aged 24 ± 45 y and 65 y
24 ± 45 y
Males (n 32)
Age (y)
BMI (kg=m2)
Plasma lipids (mmol=L)
Total cholesterol
HDL cholesterol
Triacylglycerols
Haemoglobin (g=dL)
Albumin (g=L)
65 y
Females (n 32)
Males (n 25)
Females (n 29)
Mean
s.d.
Mean
s.d.
Mean
s.d.
Mean
s.d.
31
24
6
2
32
24
7
3
70
26
4
2
71
26
4
3
4.7
1.3
1.1
15.4
46.9
0.9
0.3
0.4
0.7
2.3
4.8
1.7
0.9
13.3
44.9
0.7
0.4
0.3
0.6
2.2
5.3
1.1
1.2
14.7
42.8
0.9
0.3
0.6
0.8
2.2
5.9
1.3
1.2
13.3
42.6
0.7
0.3
0.4
0.8
1.9
Carotenoids in diet and plasma
YL Carroll et al
Table 2
647
Dietary carotenoid intakes (mg=d) assessed by estimated records and FFQ in groups of men and women aged 24 ± 45 y and 65y
Younger Males (n 32)
Estimate records
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanathin
Total carotenoids
Food frequency questionnaire
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanathin
Total carotenoids
Older Males (n 25)
Younger Females (n 32)
Mean
s.d.
Mean
s.d.
Mean
775
2921
189
3198
1005
8089
656
1797
288
4129
675
5002
812
3099
116
2092
778
6899
651
2060
153
1809
320
4624
771
2850
165
2877
943
7605
2285
8077
471
7642
2323
20800
1470*
4463*
466*
6262*
1436*
9563*
1217
5277
295
2026
1877
10693
1375
4607
346
2211
1462*
8475
2426
8795
727
8045
2615
22608
s.d.
Older Females (n 29)
Mean
s.d.
598
1539
157
2066
385
3007
973
3358
108
2285
1015
7739
530
1447
160
2367
463
3245
1872*
6022*
803*
9393*
2120*
16368*
1223
5496
317
4615
2120
13773
797
3035*
338
5368
1277*
8823*
*P 0.05; signi®cantly different from estimated records by post hoc Bonferroni tests.
intake of all carotenoids examined. Age group had a
signi®cant effect on the dietary intake of the following:
a-carotene (P 0.016), b-carotene (P 0.05), lycopene
(P 0.007) and total carotenoids (P 0.001). There was
also a signi®cant interaction between age group and dietary
method for these carotenoids. In females, dietary method
had a signi®cant effect on the dietary intake of all carotenoids examined. Age group had a signi®cant effect on the
dietary intake of the following: a-carotene (P 0.014), bcarotene (P 0.034), b-cryptoxanthin (P 0.006) and total
carotenoids (P 0.015). There was also a signi®cant interaction between age group and dietary method for these
carotenoids. In the younger group, FFQ gave approximately
3-fold higher estimates of carotenoid intakes than estimated
records which the post-hoc Bonferroni test found to be
signi®cant (Table 2). In the older group, FFQ carotenoid
intakes were signi®cantly higher than estimated records for
all carotenoids except a-carotene, b-cryptoxanthin and
lycopene.
The most consistent association between FFQ and estimated records was observed for b-cryptoxanthin (Table 3).
Spearman correlation coef®cients ranged from r 0.55 ±
0.62 (P 0.001) and 59 ± 75% of volunteers were classi®ed
into the same tertiles of the estimated record b-cryptoxanthin distribution. With the exception of younger males,
there was little association between intakes of most carotenoids, assessed by estimated records and FFQ, in the
Table 3 Effect of age and dietary method on dietary carotenoid intake in
groups of men and women aged 24 ± 45 y and 65 y
Males
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanthin
Total carotenoids
Females
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanthin
Total carotenoids
Effect of
age group
P
Effect of dietary
method
P
Age group6
dietary method
P
0.016
0.048
0.055
0.001
0.106
0.001
0.001
0.001
0.001
0.007
0.001
0.001
0.010
0.025
0.418
0.005
0.597
0.002
0.014
0.034
0.006
0.054
0.368
0.015
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.004
0.036
0.172
0.227
0.012
other groups. The percentage of volunteers classi®ed into
the same tertiles of the estimated record carotenoid distributions also tended to be higher in younger men than in
other groups. A high proportion of volunteers (6 ± 36%)
were misclassi®ed by FFQ into opposite tertiles of the
estimated records carotenoid distributions. In younger
women, there was more misclassi®cation by FFQ into
opposite (36%), than correct classi®cation (32%) into the
same tertiles of the estimated record b-carotene distribution.
In younger volunteers, there was no signi®cant difference between men and women in estimated record carotenoid intakes expressed in terms of nutrient density (Table
4). In the older groups, the intakes of a-carotene (P 0.05),
lutein zeaxanthin (P 0.01) and total carotenoids
(P 0.05), expressed as nutrient densities, were higher in
women than in men (Table 5). The intakes of carotenoids,
assessed by estimated records and expressed as nutrient
densities, did not differ signi®cantly between the older and
younger groups.
The plasma concentrations at screening and baseline
were averaged and the mean plasma concentrations are
shown in Table 6. Spearman correlation coef®cients in the
range r 0.63 ± 0.91 were observed between repeat screening and baseline plasma carotenoid concentrations in both
age groups. In the younger groups, plasma carotenoids
were ranked in the order: b-carotene, lycopene and lutein
in males, whereas in women the order was: b-carotene, bcryptoxanthin and lycopene. In the older groups, b-carotene, lutein and a-carotene were the predominant plasma
carotenoids in men and women. There were no signi®cant
differences observed between plasma carotenoid concentrations in men and women in any of the age groups. With
the exception of a-carotene and b-carotene, the younger
men and women had higher plasma carotenoid concentrations than the older men and women (P < 0.005). Plasma acarotene concentrations were signi®cantly higher in older
women and in the total older group than in younger women
and the total younger group (P < 0.005).
In both younger men and women, positive correlations
between estimated record and plasma values were observed
for several carotenoids, with the exception of b-carotene
(Tables 7 and 8). In the older groups, there was little
association between estimated record and plasma carotenoid concentrations, except for b-cryptoxanthin in men
(r 0.46, P 0.04) and total carotenoids in women
Carotenoids in diet and plasma
YL Carroll et al
648
Table 4 Spearman's rank order correlation coef®cients and percentage of subjects correctly classi®ed in same tertile and
misclassi®ed in opposite tertile for dietary carotenoid concentrations assessed by estimated records and FFQ in groups of men
and women aged 24 ± 45y and 65y
24 ± 45y
Spearman
correlation
coef®cients
r
Same
tertiles
0.29
0.27*
0.55***
0.30***
0.37**
0.39**
0.06
0.03
0.61***
0.32
0.32
0.42
Males
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanathin
Total carotenoids
Females
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanathin
Total carotenoids
65y
% of classi®cation
Opposite
tertile
Spearman
correlation
coef®cients
r
% of classi®cation
Same
tertiles
Opposite
tertile
55
41
64
45
50
64
27
27
9
23
23
23
0.25
0.23
0.62***
0.12
0.40
0.27
38
38
75
31
44
58
25
19
6
31
13
19
32
32
59
45
41
55
27
36
14
23
18
18
0.14
0.24
0.48
0.28
0.44*
0.33
30
50
60
45
55
50
30
25
10
20
10
25
*P 0.05; **P 0.01; ***P 0.01 signi®cant correlation between estimated records and FFQ.
Table 5 Energy intakes (MJ=d) (excluding alcohol) and nutrient
densities (mg=MJ) measured by estimated records in groups of men and
women aged 24 ± 45 y and 65y
Younger
males
(n 32)
Energy
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein
zeaxanathin
Total carotenoids
Younger
females
(n 32)
Older
males
(n 25)
Older
females
(n 29)
Mean s.d. Mean s.d. Mean s.d.
Mean
s.d.
10.4
85
320
19
314
111
2.4
73
205
24
346
85
8.6
101
370
21
379
119
1.5
82
222
19
302
49
9.4
87
335
13
227
86
1.9
63
203
17
201
34
7.8
129
441
13
307
135
1.4
80*
216
18
357
68**
852
486
989
480
749
475
1025
517*
*P 0.05; **P 0.01 signi®cant difference between males and females in
median carotenoid intakes expressed in mg=MJ energy (Mann Whitney U
test).
Table 6 Average plasma carotenoid concentrations (nmol=L) of
screening and baseline plasma samples in groups of men and women
aged 24 ± 45 y and 65y
Younger
males
(n 32)
Mean
a-carotene
92
b-carotene
393
b-cryptoxanthin
191
Lycopene
297
Lutein
207
Zeaxanathin
97
Lutein zeaxanathin 304
Total carotenoids
1693
s.d.
Younger
females
(n 32)
Older
males
(n 25)
Older
females
(n 29)
Mean s.d. Mean s.d. Mean s.d.
43
107
194
462
113*
296
125** 253
70** 237
40**
83
99** 320
473** 1813
53*
186
226*
110**
73**
25**
94**
567**
122 81 166 94
472 222 553 254
117 96 123 62
91 69 111 61
140 62 170 56
49 25
57 19
187 73 223 73
992 395 1177 436
*P 0.01; **P 0.001 signi®cant difference between older and younger
groups (Mann Whitney U test).
(r 0.27, P 0.05). In younger men and women, the only
signi®cant association between FFQ and plasma carotenoids was observed for b-cryptoxanthin and this correlation
was evident in males (r 0.68, P < 0.0001) and females
(r 0.53, P 0.0025). In the group of older men, positive
correlations were observed for several carotenoids comparing FFQ and plasma carotenoid concentrations. In the
group of older women, the only positive correlation
between FFQ and plasma carotenoids occurred for bcryptoxanthin (r 0.65, P 0.0001). More younger (36 ±
73%) than older volunteers (20 ± 60%) were correctly
classi®ed by estimated records into plasma tertiles.
Within the younger groups and within the older groups,
there was no signi®cant difference between estimated
records and FFQ in their ability to correctly classify
volunteers into the same tertiles of the plasma carotenoid
distribution. Similarly, within the younger and within the
older groups, the percentage of volunteers misclassi®ed by
estimated records into opposite tertiles of the plasma
carotenoid distributions, did not differ signi®cantly from
the percentage misclassi®ed by FFQ. In the younger
groups, a mean of 46 d elapsed between collection of
screening and baseline plasma samples, with a minimum
interval of 13 d and a maximum interval of 57 d. 85% of
screening and baseline samples were collected within 40 ±
57d of one another in the younger age groups, with a
median interval of 51 d. In the older groups, a mean of 38 d
elapsed between collection of screening and baseline
plasma samples, with a minimum interval of 19 d and a
maximum interval of 56d. The median interval was 39 d in
the older groups. The within-person coef®cient of variation
was consistently lower than the between-person coef®cient
of variation in individual carotenoids, in both plasma and
estimated records, as shown in Table 9. Within- and
between-person variability in dietary carotenoids assessed
by estimated records, exceeded the variability in plasma
carotenoid concentrations. In all groups, the ratio of withinperson:between-person variability in estimated records,
was lowest for b-cryptoxanthin.
Discussion
Data on the consumption and plasma concentrations of
individual carotenoids and the associations between these
Carotenoids in diet and plasma
YL Carroll et al
Table 7 Spearman's rank order correlation coef®cients and percentage of men correctly classi®ed in same tertile and misclassi®ed
in opposite tertile between average plasma and estimated records or FFQ carotenoid concentrations in groups of men aged 24 ± 45y
and 65 y
Younger males
Spearman
correlation
coef®cients
r
Estimated records
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanathin
Total carotenoids
Food frequency questionnaire
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanathin
Total carotenoids
Older males
% of classi®cation
Same
tertiles
Opposite
tertile
0.60*
0.05
0.66***
0.52*
0.44*
0.07
68
36
59
55
55
36
5
27
14
14
9
23
0.31
7 0.09
0.68***
0.26
0.27
7 0.16
45
32
68
50
45
23
18
36
5
18
23
36
Spearman
correlation
coef®cients
r
% of classi®cation
Same
tertiles
Opposite
tertile
0.32
0.04
0.46*
0.14
0.07
0.11
44
31
50
32
31
50
19
25
13
38
25
19
0.70***
0.34
0.54**
0.47*
0.39
0.55*
63
50
50
50
50
44
6
19
13
13
13
6
*P 0.05; **P 0.01; *** P 0.001 signi®cant correlation between carotenoid concentrations in plasma and diet assessment
method.
Table 8 Spearman's rank order correlation coef®cients and percentage of women correctly classi®ed in same tertile and
misclassi®ed in opposite tertile between average plasma and estimated records or FFQ carotenoid concentrations in groups of
men aged 24 ± 45y and 65 y
Younger females
Spearman
correlation
coef®cients
r
Estimated records
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanathin
Total carotenoids
Food frequency questionnaire
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanathin
Total carotenoids
0.42**
0.29
0.74***
0.43**
0.32
0.41*
0.24
0.11
0.53**
0.50
7 0.02
0.23
Older females
% of classi®cation
Same
tertiles
Opposite
tertile
55
50
73
59
50
45
18
27
5
14
27
23
45
32
59
59
36
45
23
41
14
9
32
27
Spearman
correlation
coef®cients
r
% of classi®cation
Same
tertiles
Opposite
tertile
0.11
7 0.09
0.52
0.32
0.14
0.27*
45
20
60
40
40
45
35
45
10
30
25
25
7 0.14
0.12
0.65***
0.44
0.10
0.34
30
40
75
60
35
55
35
25
0
10
25
20
*P 0.05; **P 0.01; ***P 0.001 signi®cant correlation between carotenoid concentrations in plasma and diet assessment
method.
variables, are not well documented in European populations. The primary purpose of the present study was to
assess plasma carotenoid concentrations, to assess dietary
intakes of individual carotenoids using an established dietary method, and to examine the relationship between these
dietary and plasma variables in groups of younger and older
volunteers.
In agreement with other studies, the predominant dietary
carotenoids reported by estimated records in both the
younger and older groups are b-carotene and lycopene
(Forman et al, 1993; Yong et al, 1994; Scott et al, 1996).
The concentrations of total carotenoids reported by estimated records in both age groups are similar to those
reported in the USA (Forman et al, 1993; Yong et al,
1994). However, the intake of b-carotene assessed by
estimated records was 1.5 ± 4-times higher than the levels
reported in older women in the UK, but it should be noted
that the discrepancy between Irish and UK data is smaller
than the discrepancies within UK data (Maisey et al, 1995;
Scott et al, 1996). These differences between the various
studies may be attributable to the use of different food
composition databases, different dietary assessment methods and population differences. In this present study, a
modi®ed version of the carotenoid food composition database developed by Scott et al (1996) was used. Weighed
records, which are known to be associated with underreporting of food intakes (Black et al, 1993) and analysis of
only fruit and vegetable sources of carotenoids (Scott et al,
1996), may also account for these differences in carotenoid
intakes between Ireland and the UK. The estimated record
data in the present study shows that composite dishes, for
example, soups and pizza are signi®cant sources of carotenoids. In this present study, some carotenoids were also
partly derived from animal foods with butter, dairy
649
Carotenoids in diet and plasma
YL Carroll et al
650
Table 9 Within-(CWw) and between-subject (CVb) coef®cient of variation in plasma and estimated records of men and women aged
24 ± 45 y and 65y
Younger males (n 32)
Plasma
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanthin
Total carotenoids
Estimated Records
a-carotene
b-carotene
b-cryptoxanthin
Lycopene
Lutein zeaxanathin
Total carotenoids
Younger females (n 32)
Older males (n 25)
Older females (n 29)
CVw
CVb
CVw
CVb
CVw
CVb
CVw
CVb
27.03
29.44
31.02
28.02
16.52
17.63
66.66
69.61
83.69
59.35
45.88
39.49
33.39
25.21
46.66
25.99
14.50
15.74
70.42
56.92
107.88
61.51
41.58
44.20
25.06
30.02
74.16
33.24
19.26
26.18
94.09
66.52
115.85
106.32
55.55
56.44
24.14
25.82
29.24
32.82
11.24
18.03
80.30
65.06
72.18
77.97
46.18
52.40
162.47
114.26
137.44
175.88
84.63
90.87
224.21
162.77
404.17
341.64
177.47
163.62
151.57
104.78
116.00
182.39
107.19
95.87
204.98
142.89
251.99
189.99
108.15
104.60
118.33
84.44
110.50
99.01
54.94
68.11
212.05
175.90
348.07
228.81
108.79
177.34
121.87
90.27
139.60
224.12
93.31
98.64
144.44
114.02
393.11
274.10
120.60
110.95
products and eggs and egg dishes identi®ed as signi®cant
sources of lutein and b-carotene. This agrees with a report
from the USA, where dairy products contribute approximately 7% of the total pro-vitamin A carotenoid intake
(Block, 1994). Similarly, data from Finland indicate that
margarines, oils, butter, milk products and eggs provide
24 ± 25% of b-carotene and lutein intakes in men (Jarvinen,
1995). In this present study, the inter- and intra-individual
coef®cients of variation in estimated record carotenoid
intakes are high in all age groups, but variation in carotenoid intakes was always greater between individuals than
within individuals. In estimated records, b-cryptoxanthin
tended to show that lowest ratio of within-person:betweenperson variability in carotenoid intakes and this may
account for its stronger associations with plasma b-cryptoxanthin concentrations.
b-Carotene was the predominant plasma carotenoid in
all groups in this present study. Plasma carotenoid concentrations were ranked in the order: b-carotene > lutein > a-carotene > b-cryptoxanthin > lycopene >
zeaxanthin in older groups. This contrasts with the pro®le
of the younger groups in which plasma lycopene concentrations were considerably higher and ranked second or
third to b-carotene concentrations. Others have shown that
lycopene and b-carotene were the major plasma carotenoids in younger and older subjects respectively (Yeum et
al, 1996). In this present study, all individual plasma
carotenoid concentrations, with the exception of a- and bcarotene, were higher in younger groups than older groups.
Plasma a-carotene concentrations were higher in older than
younger volunteers. It has been shown elsewhere that age is
inversely related to plasma lycopene concentrations (Brady
et al, 1996). Others have shown that age is directly
associated with serum b-carotene concentrations, although
an age effect on plasma b-carotene has not always been
reported (Hallfrisch et al, 1994; Brady et al, 1996; Santos et
al, 1996). Whether these effects of age on plasma carotenoid concentrations are due to physiological mechanisms,
or are merely attributable to different dietary patterns in
younger and older groups, has not yet been established. The
relative order of plasma carotenoid concentrations appears
to be population speci®c. b-Cryptoxanthin is the predominant plasma carotenoid in Spanish women, whereas data
from the US indicate that lycopene is the predominant
plasma carotenoid (Micozzi et al, 1992; Olmedilla et al,
1994). Plasma concentrations of individuals carotenoids are
moderately stable, as shown by correlations in the range
r 0.63 ± 0.91, between repeat plasma samples and withinperson coef®cients of variation generally less than 30% in
this present study.
In the younger group, there were positive associations
between most plasma and estimated record concentrations
of carotenoids, except b-carotene. Although moderate, the
magnitude of the correlations between estimated records
and individual plasma carotenoid concentrations observed
in the younger groups compare well with those reported
elsewhere, by estimated records, weighed intakes and diet
histories (Forman et al, 1993; van Staveren et al, 1994;
Yong et al, 1994; Scott et al, 1996). In the present study,
good reproducibility of plasma carotenoids was observed as
shown by correlations in the range r 0.65 ± 0.85, and
coef®cients of variation generally ranging from 20 ± 30%.
This level of reproducibility is similar to that observed by
others for plasma carotenoids (Campbell et al 1994, Yong
et al, 1994, Apgar et al, 1996, Scott et al, 1996). Therefore,
the interval between screening and baseline plasma samples
is unlikely to account for the observation of only moderate
associations between estimated record and plasma carotenoids. In the younger groups, the association between
estimated record and plasma carotenoid concentrations
was strongest for b-cryptoxanthin, and was stronger than
that reported elsewhere (Forman et al, 1993; van Staveren
et al, 1994; Yong et al, 1994; Scott et al, 1996). No
association between estimated record and plasma b-carotene concentrations was evident in any of the age groups in
the present study. Others report signi®cant, but moderate,
correlations for b-carotene in the range r 0.27 ± 0.52 (van
Staveren et al, 1994; Yong et al, 1994; Scott et al, 1996),
but not all studies have observed signi®cant correlations
between plasma and estimated record b-carotene concentrations (Forman et al, 1993). Within- and between-person
variation in estimated record and plasma b-carotene concentrations was similar to that observed for other carotenoids and may not explain the lack of association between
estimated record and plasma b-carotene concentrations. A
possible explanation for the poor association between
estimated record and plasma b-carotene concentrations,
may be the wide range of foods in which it is distributed.
Data from the present study indicate that approximately 10
foods account for 90% of b-carotene consumption compared to approximately 4 foods accounting for 90% of
lycopene and b-cryptoxanthin intakes. Other studies also
Carotenoids in diet and plasma
YL Carroll et al
show that the number of foods contributing to b-carotene
intake is considerably greater than that of lycopene and bcryptoxanthin (Granado et al, 1996). This extended number
of sources of b-carotene has implications for absorption,
matrix composition and quanti®cation by the dietary assessment tool, and may thereby affect the relationship between
dietary and plasma b-carotene. The food matrix in which
the carotenoids are provided may affect the absorption and
physical inaccessibility of carotenoids in plant tissues, for
example in pigment protein, complexes may reduce their
bioavailability (Brown et al, 1989; de Pee et al, 1995).
By contrast with the many positive correlations observed
in the younger groups, only b-cryptoxanthin in men and
total carotenoids in women showed signi®cant associations
between plasma and estimated record carotenoid concentrations, in the older groups. The lack of association
between estimated record and plasma carotenoid distributions in the older groups was also re¯ected in the poor
ability of estimated records to correctly classify individuals
into extremes of the plasma carotenoid distributions, with
as many as 45% being misclassi®ed into opposite tertiles.
This low level of association between plasma and estimated
records in the older groups, does not agree with the trends
of signi®cant associations observed for several carotenoids
in the younger groups, in this present study and in other
studies (Ascherio et al, 1992; Forman et al, 1993; Yong et
al, 1994). The poor agreement between estimated record
and plasma carotenoid concentrations in the older group
was unanticipated and possible explanations may include
physiological differences, differences in validity of estimated records in younger and older volunteers, and seasonal differences in consumption of carotenoids. An alteration
in gastric acid secretion with age could be complicating the
relationship between dietary and plasma carotenoid concentrations (Hartz et al, 1992; Tang et al, 1996). However,
a study of patients positive for Helicobacter pylori, (a
condition associated with atrophic gastritis and hypochlorhydria) has shown that these patients do not have low
concentrations of a-carotene, b-carotene or lycopene (Sanderson et al, 1997). Furthermore, in this present study,
screening excluded volunteers with gastrointestinal disorders, so it is unlikely that this is an adequate explanation.
Female gender and age over 45y have been shown to be
predictors of underreporting of food consumption (Hirvonen et al, 1997) and may be another reason why the
associations between estimated record and plasma carotenoids were poor in the older groups. Underreporting, as
de®ned by energy intakes less than 1.1 times the basal
metabolic rate (Goldberg et al, 1991), was evident in the
present study. However, similar percentages of volunteers
in both age groups (16% of men and 9 ± 10% of women in
both age groups) underreported energy intakes in the present study and this degree of underreporting is not unusual
in dietary studies (Black et al, 1991). If underreporting was
distorting the diet-plasma relationship, this bias should also
have in¯uenced the associations between plasma and estimated record carotenoid concentrations in the younger
groups. Spanish data revealed that marked seasonality in
some food items, caused differences in the dietary supply of
b-cryptoxanthin and lycopene (Granado et al, 1996). This
group also reported signi®cant seasonal variation in some,
but not all, serum carotenoid concentrations of Spanish men
and women (Olinedilla et al, 1994). It remains to be
determined whether seasonal effects are profound in the
Irish population. In the UK, no seasonal difference was
found in the intake of b-carotene (Scott et al, 1996).
However, this UK study did note that the strength of the
association between dietary and plasma b-carotene concentrations varied according to season, with no signi®cant
association observed in winter, compared to a signi®cant
association in spring (Scott et al, 1996). Dietary data were
recorded in November in the younger groups and in January
in the older groups, and in the context of the ®ndings in the
UK study, this may help to explain why no positive
associations were observed for b-carotene with any of the
dietary methods in the present study. As part of a multicentre study the carotenoid food composition database used
in the present study was compiled from published analysis
of foods sourced mainly in Europe. This could in¯uence the
diet-plasma relationships observed in the present study
which was con®ned to Irish population groups. A carotenoid food composition database, based on analysis of foods
sourced in Ireland, is not available. Many carotenoid food
composition databases are compiled from published data
relating to foods sourced in several countries (Mangels et
al, 1993; West & Poortvliet, 1993). Comparison of carotenoid intakes estimated using several food composition
databases has shown that the use of a single database may
give misleading carotenoid intake values (Granado et al,
1997). Analysis of dietary data by reference to two different
carotenoid composition databases, indicated that although
estimates of carotenoid intake differed signi®cantly, only
minor differences in carotenoid rankings and diet-serum
correlations were observed using either data source (Vandenlangenberg et al, 1996).
A secondary purpose of this present study was to assess
the validity of a FFQ developed for assessing dietary
carotenoid intakes in several European countries. Validity
was assessed by comparison of mean intakes with estimated records, by examining correlations with estimated
records, by observing the extent of correct classi®cation
and gross misclassi®cation into tertiles of estimated records
carotenoid concentrations, by examining correlations with
plasma and by observing the extent of correct classi®cation
and gross misclassi®cation into tertiles of plasma carotenoid concentrations. The FFQ concentrations of dietary
carotenoids were approximately 2 ± 3-fold higher than estimated records in the present study. Furthermore, the FFQ
total carotenoid and b-carotene intakes in both age groups,
in this present study, are at least 2-fold higher than those
reported by FFQ in other studies (Forman et al, 1993;
Mares-Perlman et al, 1993; Vandenlangenberg et al, 1996;
OckeÂ et al, 1997). Overestimation of carotenoid intakes by
FFQ by 10 ± 30% of estimated records and by 38 ± 50% of
weighed record concentrations have been observed (Yong
et al, 1994; Bingham et al, 1994). This is attributed to a
greater reported frequency of consumption in the questionnaire methods than actually measured by the weighed
records (Bingham et al, 1994). In this present study,
correlations between dietary intakes of most carotenoids
assessed by estimated records and FFQ, were poor in most
groups except younger men. In contrast to this present
study, modest, but signi®cant correlations between estimated record and FFQ have been observed for several
carotenoids in young men and women (Rimm et al, 1992;
Forman et al, 1993; Yong et al, 1994). Misclassi®cation by
FFQ in opposite tertiles of the estimated record carotenoid
distributions ranged from 19 ± 36%, and is much greater
than that reported elsewhere (Bingham et al, 1994; Bonifacj et al, 1997). The only group in which several
651
Carotenoids in diet and plasma
YL Carroll et al
652
signi®cant associations between FFQ and plasma carotenoids were observed was in older men. Other studies have
reported signi®cant associations between several plasma
and dietary carotenoids, estimated by FFQ (Coates et al,
1991; Ascheno et al, 1992; Vandenlangenberg et al, 1996).
Conversely, several studies failed to note a positive relationship between plasma and lycopene or b-carotene concentrations assessed by FFQ (Coates et al, 1991; Ascherio
et al, 1992; Forman et al, 1993; Kardinaal et al, 1995; OckeÂ
et al, 1997). b-Cryptoxanthin was the only carotenoid for
which signi®cant correlations were observed between
plasma and FFQ in both age groups. Other studies have
also shown that correlations between plasma and FFQ were
stronger for b-cryptoxanthin than other carotenoids
(Forman et al, 1993; Vandenlangenberg et al, 1996).
There was no statistical evidence, in the present study,
that FFQ were better than estimated records in correctly
classifying individuals into extremes of the plasma carotenoid distribution.
The 110 item FFQ administered in these studies
included only foods high in carotenoids, and this emphasis
combined with the lack of representation of other foods,
may have accounted for its poor performance. It has been
shown in another study that adding a list of carotenoid-rich
foods to a standard FFQ, did not improve the validity of the
questionnaire (Enger et al, 1995). The presence of irrelevant nutrient sources on a questionnaire may contribute to
increased misclassi®cation rather than to increased precision (Block, 1994). It has also been shown that fruit and
vegetables, which are perceived as healthy foods, are most
often overreported by FFQ, while meats and dairy products,
which are considered to be less healthy are most often
underreported (Feskanich et al, 1993). Further development
is required to establish a valid FFQ suitable for use in
several European countries.
Conclusions
Estimated records indicate that b-carotene and lycopene are
the major dietary carotenoids. The pro®le of plasma carotenoids show that b-carotene is the major carotenoid in
both age groups. Younger groups have higher plasma
concentrations of lycopene, b-cryptoxanthin, lutein zeaxanthin and total carotenoids than older groups. Moderate
positive associations, similar to those observed in other
countries, exist between several plasma and estimated
record dietary carotenoid concentrations in younger, but
not older groups. Plasma b-cryptoxanthin concentrations
were strongly associated with both estimated record and
FFQ concentrations in both age groups. b-Carotene in
plasma is not associated with estimated record concentrations in any age group. The data imply that plasma
carotenoid concentrations may be a useful biomarker of
several carotenoids, excluding b-carotene, in groups aged
24 ± 45 y. Further work is required to determine if plasma
carotenoids can be a useful biomarker of dietary carotenoid
concentrations in older populations.
Acknowledgements ÐThis work has been carried out with ®nancial support
from the Commission of the European Communities (AIR2 CT93-0888
DG XII SSMA), `Increased fruit and vegetable consumption within the
EC: potential health bene®ts'. b-Cryptoxanthin and zeaxanthin standards
for HPLC analysis were provided free of charge by Hoffman La Roche,
Switzerland. The technical assistance of SineÂad McCarthy and SiobhaÂn
Higgins are gratefully acknowledged.
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