A Single Consumption of High Amounts of the Brazil Nuts Improves Lipid Profile of Healthy Volunteers

Abstract

Background. This study investigates the effects of Brazil nut ingestion on serum lipid profile in healthy volunteers. Methods. Ten healthy subjects were enrolled in the study. Each subject was tested 4 times in a randomized crossover in relation to the ingestion of different serving sizes of the Brazil nut: 0, 5, 20, or 50 g. At each treatment point, peripheral blood was drawn before and at 1, 3, 6, 9, 24, and 48 hours and 5 and 30 days. Blood samples were tested for total cholesterol, high- and low-density lipoprotein cholesterol (HDL-c and LDL-c, resp.), triglycerides, selenium, aspartate and alanine aminotransferases, albumin, total protein, alkaline phosphatase, gamma GT, urea, creatinine, and C-reactive protein. Results. A significant increase of the plasma selenium levels was observed at 6 hours within the groups receiving the nuts. Serum LDL-c was significantly lower, whereas HDL-c was significantly higher 9 hours after the ingestion of 20 or 50 g of nuts. The biochemical parameters of liver and kidney function were not modified by ingestion of nuts. Conclusions. This study shows that the ingestion of a single serving of Brazil nut can acutely improve the serum lipid profile of healthy volunteers.

Full text

Hindawi Publishing Corporation
Journal of Nutrition and Metabolism
Volume , Article ID , pages
http://dx.doi.org/.//
Clinical Study
A Single Consumption of High Amounts of the Brazil Nuts
Improves Lipid Profile of Healthy Volunteers
Elisângela Colpo,1,2 Carlos Dalton de Avila Vilanova,1Luiz Gustavo Brenner Reetz,3
Marta Maria Medeiros Frescura Duarte,1,4 Iria Luiza Gomes Farias,3Edson Irineu Muller,1
Aline Lima Hermes Muller,1Erico Marlon Moraes Flores,1
Roger Wagner,5and João Batista Teixeira da Rocha1
1Department of Chemistry, Natural and Exact Sciences Centers, Federal University of Santa Maria (UFSM),
97105900SantaMaria,RS,Brazil
2Department of Nutrition, Center Franciscan University (UNIFRA), Santa Maria, RS, Brazil
3Clinical Laboratory Analysis, University Hospital, Santa Maria, RS, Brazil
4Lutheran University of Brazil (ULBRA), Santa Maria, RS, Brazil
5Department of Technology and Food and Science, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil
Correspondence should be addressed to Jo˜
ao Batista Teixeira da Rocha; jbtrocha@yahoo.com.br
Received  April ; Revised  May ; Accepted  May 
Academic Editor: Cindy Davis
Copyright ©  Elisˆ
angela Colpo et al. is is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Background. is study investigates the eects of Brazil nut ingestion on serum lipid prole in healthy volunteers. Methods.Ten
healthy subjects were enrolled in the study. Each subject was tested  times in a randomized crossover in relation to the ingestion
of dierent serving sizes of the Brazil nut: , , , or g. At each treatment point, peripheral blood was drawn before and at
, , , , , and  hours and  and  days. Blood samples were tested for total cholesterol, high- and low-density lipoprotein
cholesterol (HDL-c and LDL-c, resp.), triglycerides, selenium, aspartate and alanine aminotransferases, albumin, total protein,
alkaline phosphatase, gamma GT, urea, creatinine, and C-reactive protein. Results. A signicant increase of the plasma selenium
levels was observed at  hours within the groups receiving the nuts. Serum LDL-c was signicantly lower, whereas HDL-c was
signicantly higher  hours aer the ingestion of  or  g of nuts. e biochemical parameters of liver and kidney function were
not modied by ingestion of nuts. Conclusions. is study shows that the ingestion of a single serving of Brazil nut can acutely
improve the serum lipid prole of healthy volunteers.
1. Background
Selenium is an essential nutrient for human health [], and its
biological functions are mediated by the expression of about
 selenoproteins which have selenocysteine at their active
centers [–]. Some selenoproteins, for example, glutathione
peroxidase (GPx) and thioredoxin reductase (TrxR), are im-
portant antioxidant enzymes [,–]. However, high acute
selenium ingestion can be toxic to mammals, and epidemio-
logical observations have suggested that dietary overexposure
to selenium increases the prevalence of chronic degenerative
diseases such as type  diabetes, a myotrophic lateral sclerosis,
and neoplasias [,,].
Selenoproteins can promote cardiovascular benets pos-
sibly via their antioxidant properties. Some isoforms of GPx
are known for being able to prevent the oxidative modi-
cation of lipids (including those found in lipoproteins),
inhibit platelet aggregation, and modulate inammation by
reducing the peroxide tonus [,,–]. Additionally, some
animals as well as epidemiological studies in humans have
identied a putative protective role of some GPx isoforms
against cardiovascular damage [,,]. However, some large
randomized trials investigating the eects of the adminis-
tration of selenium containing supplements have failed to
show a signicant protective eect on cardiovascular disease
and mortality [–]. On the other hand, a meta-analysis

Journal of Nutrition and Metabolism
T : Anthropometric and biochemical variables baselines of subjects.
Characteristic Men (𝑛=6)Women(𝑛=4) Reference
Weight (Kg)  ±. . ±.
BMI (Kg/m) . ±. . ±. .–.
Plasma selenium (𝜇g⋅L−).±. . ±.  ±.– ±
Leucocytes (/mm).±. . ±. .–
Hematocrit (%) . ±. . ±. §: –
|:–
Hemoglobin (g/dL) . ±. . ±§: .–.
|: .–.
Fasting glucose (mg/dL) . ±.    .  ±.    –  
Albumin (g/dL) . ±. . ±. .–.
Total protein (g/dL) . ±. . ±. –
Cholesterol total (mg/dL)  ±.  ±. <
HDL-c (mg/dL) . ±. . ±. ≥
LDL-c (mg/dL) . ±. . ±. <
Triglycerides (mg/dL) . ±. . ± <
Results are expressed as mean ±S.D. §: masculine; |: females.
of  observational studies showed a signicant inverse
association between selenium status with the risk of coronary
heart disease (CHD), particularly within populations with
low selenium intake or status []. A positive association
between plasma selenium levels with lower atherogenic index
(a reliable indicator of predisposition to heart diseases [])
has been suggested in nutritional surveys among Japanese
[], Indians [], and Koreans [].
Cereals,nuts,meats,andseafoodarethemajorsources
ofhumandietarySe.eSecontentinvegetablesvaries
depending on several factors such as the soil in which they
aregrown,theSeconcentrationintheirrigatingwater,
and the usage of Se-containing fertilizers []. Selenium
concentration in Brazil nut varies between  and  𝜇g/g
andisamongthehighestfoundwithinfoodsconsumedby
humans [–].Brazilnutisalsoagoodsourceofother
nutrients, including unsaturated fatty acids, proteins, ber,
magnesium, phosphorus, thiamin, niacin, vitamin E, vitamin
B6,calcium,iron,potassium,zinc,andcopper.Moreover,the
oily endosperm contains about % monounsaturated fatty
acids (MUFA) [].
As pointed out above, Se consumption and selenoen-
zymes (particularly GPx) have been associated with cardio-
vascular protection in rodents and humans [,,,].
Brazil nut has a high content of selenium and could, therefore,
have cardioprotective eects. In addition, dierent types of
nuts such as peanuts, almonds, walnuts, and macadamia nuts,
among others, have been shown to modulate the lipid prole
in both unhealthy as well as healthy subjects [–]. is
benecial eect has been attributed to the high levels of
MUFA and polyunsaturated fatty acids (PUFA) found in nuts
[].
Fatty acids from nuts are important contributors to the
benecial health eects which protect from the development
of CHD []. Willett et al. [] reported that high MUFA
diets are associated with a reduced cardiovascular disease-
associated mortality. Recently, a few studies have indicated
a benecial eect of long-term Brazil nut intake on serum
cholesterol among obese and nonobese subjects [,,].
However, the acute eects of the ingestion of Brazil nut on
the atherogenic index of healthy subjects have not yet been
evaluated. In this study, we investigate the eects of moderate
to high amount Brazil nut ingestion on lipid prole, hepatic
and kidney biochemical parameters in healthy volunteers
to determine either benecial or potentially toxic eect of
selenium.
2. Methods
2.1. Study Subjects. Fieen healthy subjects ( men and 
women) were initially recruited at the Universidade Fed-
eral de Santa Maria, Brazil. Study candidates (– years
old) were evaluated based on their self-reported medical
history and laboratory tests. Early in the study, two male
and one female subjects were excluded due to high acute
alcohol intake. Two female subjects were diagnosed with
hypothyroidism and were, therefore, excluded. Body weight
was measured to the nearest . kg using a digital scale,
and height was measured to the nearest . cm using a
wall-mounted stadiometer. e body mass index (BMI)
(kilograms per square meter) was calculated, and the subjects
were classied according to the World Health Organization
guidelines []. e demographics and baseline test results of
the  selected participants ( men and  women) are shown
in Table . is study has been reviewed and approved by the
Universidade Federal de Santa Maria’s Internal Review Board
(no. ...-), and informed consent was obtained
from all participants.
2.2. Experimental Design. Each subject was tested  times
following a randomized crossover regarding the administra-
tion of the dierent amounts of Brazil nut: , , , and  g.
Two L a t in squar es of  × for the  treatments were used to
randomize participants into  orders of treatment. Prior to

Journal of Nutrition and Metabolism 
each treatment, the volunteers underwent a -day washout
period.
2.3. Brazil Nut Diet. e volunteers were given instructions
by a nutritionist to exclude Se-rich foods from their diets
(eggs, egg yolks, garlic, Brazil nut, whole wheat cereal, viscera,
etc.) throughout the blood sampling period.
e volunteers were given a balanced diet with daily
energy requirement of  kcal/kg/day, a diet normocaloric.
We applied -hour dietary recall ( hDR) and food fre-
quency questionnaires (FFQ) aer the last blood sampling to
verify the types of foods consumed during the study period.
According to the United States Department of Agriculture—
USDA, Brazil nut contains (per  g) . g of protein, . g
of carbohydrates, . g of total fat (. g SFA, . g MUFA,
and  g PUFA), and . g of dietary ber, for a total of , kJ
[].
2.4. Se Determination in Brazil Nut. Samples with mass up to
 was weighed, transferred to quartz vessels together with
 mL of concentrated nitric acid. e vessels were heated in a
microwave oven with maximum temperature and pressure of
∘Candbar,respectively.
2.5. Lipid Determination in Brazil Nut. e extraction of
Brazil nut was performed according to the method described
by Bligh and Dyer [], grinding a known amount of Brazil
nuts in the presence of a methanol/chloroform ( :  v/v) mix-
ture at  mL/g of fresh weight. e fatty acid methyl esters
were analyzed by a gas chromatograph using a procedure
described by Christie []. e results were expressed as
relative percent of total fatty acids according to Visentainer
[].
2.6. Blood Samples Collection. Blood samples were collected
by venous puncture prior to and at , , , , , and 
hours and  and  days aer the ingestion of nuts. Except
for the - and -hour time points, all volunteers were at
a -hour fasting period for the collection of blood. Blood
samples were collected by venous puncture into Vacutainer
(BD Diagnostics, Plymouth, UK) tubes with no anticoagulant
and EDTA anticoagulant. Blood samples stored in ice were
routinely centrifuged within h aer collection at  ×g
formin.Aliquotsofserumsampleswereimmediatelyused
to assess fasting glucose, total cholesterol (TC), high-density
lipoprotein cholesterol (HDL-c), triglycerides, aspartate and
alanine aminotransferases (AST and ALT, resp.), albumin,
total protein, alkaline phosphatase, gamma GT, urea, cre-
atinine, and C-reactive protein (CRP). Aliquots of plasma
wereusedforseleniummeasurements.Serumandplasma
samples were then stored at −∘Cforuptoweeksbefore
the analyses.
2.7. Blood Tests. Hemoglobin levels and hematocrit were
determined in a Cobas Micros system (Hematology Analyzer,
Roche Diagnostics). Fasting glucose, TC, HDL-c, triglyc-
erides, AST, ALT, albumin, total protein, alkaline phos-
phatase, gamma-GT, urea, creatinine, and CRP measure-
ments were performed using Ortho-Clinical Diagnostics
reagents on a fully automated analyzer (Vitros  dry chem-
istry system, Johnson & Johnson, Rochester, NY, USA). Low-
density lipoprotein cholesterol (LDL-c) was calculated using
theFriedewaldequation[].
2.8. Atherogenic Index (AI) Determination. e atherogenic
index was calculated as the ratio between total cholesterol
and HDL-c or as the ratio between LDL-c and HDL-c
concentrations according to Kinosian et al. []andLemieux
et al. [].
2.9. Se Concentration in Plasma. e plasma Se concentra-
tion was determined using atomic absorption spectrometry
with graphite furnace atomizer (GFAAS) and Zeeman Eect
background correction. Samples were diluted with Triton
X-. Palladium chemical modier, wavelength . nm,
pyrolysis temperature ∘C, and atomization temperature
∘Cwereused.
2.10. Statistical Analysis. Data are expressed as mean ±Stan-
dard Deviation (SD). e statistical analysis was performed
using analysis of variance with measure repeated (ANOVA)
and nonparametric tests (Wilcoxon). Descriptive statistics
was performed for all baseline characteristics. Dierences
were considered signicant when 𝑃 < 0.05.
3. Results
e volunteers included in the study were . ±. years old
(range – years old). Demographic, anthropometric, and
laboratory characteristics are listed in Table .
e average Se concentration in Brazil nut was .
±. 𝜇g/g. erefore, the net Se intake was about  𝜇g,
 𝜇g, and 𝜇g for the groups ingesting , , and  g of
nuts, respectively. e estimated fat intake from nuts is shown
in Table .
e biochemical parameters of liver and kidney function
in he a l thy v ol u nt e ers, su c h a s AS T, A LT, a l k alin e p h o sp ha t as e,
Gama GT, urea, and creatinine, were not modied by inges-
tion of nuts, indicating an absence of hepatic and renal
toxicity of high amounts of Brazil nuts intake. PCR was also
evaluated, and there was no change in its levels aer ingestion
of Brazil nuts (data not shown).
Plasma selenium levels were signicantly increased in all
groups  hours aer the ingestion of Brazil nut. Moreover, at
the highest dose ( g) the Se increase was evident starting
at as early as  h and remained above baseline levels for up to
 h (Figure ). At  hours, the plasma Se levels did not dier
from its baseline concentration (Figure ).
Serum LDL-c levels were signicantly lower starting at 
hours aer the ingestion of nuts within the groups receiving
 or  g and reached a steady level at  hours (Figure ).
Subjects that consumed higher amounts of Brazil nut exhib-
ited an increase in HDL-c starting at  hours aer the intake
which reached a stable level at  days (Figure ,𝑃 < 0.05).
Interestingly, the ingestion of  g of Brazil nut deter-
mined a more pronounced decrease in LDL-c levels as well
as a higher increase in HDL-c than did  g. ese results

Journal of Nutrition and Metabolism
T : Fatty acids composition of the Brazil nut.
Fatty acids g/ g SD
AGS
C: . .
C: . .
C: . .
C: . .
C: . .
Total . .
MUFA
C: . .
C:n cis . .
C: . .
Total . .
PUFA
C:n cis . .
C:n . .
C:n . .
Total . .
MUFA: monounsaturated fatty acids; PUFA: polyunsaturated fatty acids;
SFA: saturated fatty acids.
0g Brazil nut
5g Brazil nut
20 g Brazil nut
50 g Brazil nut
Time
Plasma selenium
100
80
60
40
20
0
Basal 1h3h6h9h24 h48 h5days 30 days
Plasma (𝜇g/L)
F : Plasma levels of selenium in healthy volunteers aer
consumption of the Brazil nut. Measures repeated—ANOVA and
Wilcoxon tests.
suggest that eating an average of  nuts might be enough to
improve the levels of LDL-c and HDL-c for up to  days.
Accordingly, the AI (TC/HDL-c and LDL-c/HDL-c ratio)
was decreased in subjects that consumed  and  g of Brazil
nut (𝑃 < 0.05, data not shown). Serum triglycerides and total
cholesterol did not signicantly vary (𝑃 > 0.05)withinthe
study time frame (data not shown).
Even though the measured plasma Se concentrations did
not signicantly vary following the ingestion of , , or  g
of nuts, changes in LDL-c and HDL-c were only observed
with the ingestion of  or  g which persisted for up to 
days. ese results raise the question of whether the benecial
eects of Brazil nut on the atherogenic index may be due
to factors other than selenium (MUFA and PUFA perhaps),
(mg/dL)
LDL-c
0g Brazil nut
5g Brazil nut
20 g Brazil nut
50 g Brazil nut
Time
100
80
60
Basal 1h3h6h9h24 h48 h5days 30 days
90
70
F:SericlevelsofLDL-cinhealthyvolunteersaerconsump-
tion of the Brazil nut. Measure repeated—ANOVA and Wilcoxon
tests.
70
65
60
55
50
45
40
(mg/dL)
HDL-c
0g Brazil nut
5g Brazil nut
20 g Brazil nut
50 g Brazil nut
Time
Basal 1h3h6h9h24 h48 h5days 30 days
F:SericlevelsofHDL-cinhealthyvolunteersaerconsump-
tion of the Brazil nut. Measure repeated—ANOVA and Wilcoxon
tests.
highlighting the importance of studying the separate and
combined eect of selenium and fatty acids on atherogenic
indexes.
4. Discussion
Regular nut intake has been associated with many health
benets in adults [,,].eresultsofthisstudysupport
the notion that the consumption of a single serving of nuts
can acutely benecially modify serum lipids.
Contrasting with diets rich in SFA, MUFA- and PUFA-
rich foods are potentially benecial for health []. Nuts are
generally low in saturated fatty acids and high in unsatu-
rated fatty acids []. Unsaturated fatty acids (both mono-
and polyunsaturated) have been shown to reduce serum
TC zand LDL-c. Brazil nut is a good source of unsaturated fat
(∼% MUFA). However, despite knowing that the Brazil
nut has high concentrations of unsaturated fatty acids when
compared with other nuts such as macadamias, almonds,

Journal of Nutrition and Metabolism 
walnuts, pecans, pistachios, and peanuts, the Brazil nut has
a relatively higher content of SFAs.
erefore, the increase in HDL-c observed in this present
study may be attributed to the higher MUFA and SFA content
in Brazil nut []. According to Riccardi et al. [], SFA
and MUFA increase HDL-c, whereas high intakes of PUFA
decrease HDL-c. Unsaturated fatty acids have been shown to
increaseHDL-clessthanSFAsdo[]. Furthermore, while
the unsaturated fatty acid prole of nuts (high MUFA and
PUFA) is thought to mediate the majority of the benecial
eects of nuts on serum lipids, other components such as ber
and selenium might contribute to these eects [,,,].
Many studies have shown that chronic intake of varying
amountsofnutsiseectivetoincreasethebloodconcen-
trations of Se and improve lipid prole [–,,–].
A meta-analysis by Flores-Mateo et al. []basedonsev-
eral observational studies pointed to an inverse correlation
between plasma selenium concentrations and coronary heart
disease incidence. But the validity of such correlations needs
further conrmation. Stranges et al. []concludedthat
an increase in plasma selenium in adult population was
associated with increased total and non-HDL cholesterol
levels but not with HDL-c. Moreover, evidence showing that
low selenium status is a cardiovascular risk factor must still
be considered provisional.
In conclusion, the results obtained here suggest that the
consumption of a single serving of Brazil nut is sucient to
improve the lipid prole of healthy volunteers (lowered LDL-
c and raised HDL-c), without producing hepatic and renal
toxicity of high amounts of Brazil nuts intake. However, fur-
ther investigation is needed to validate the benecial eects
of Brazil nut because here we have used a small number
of subjects. In addition, it is also important to evaluate the
isolated and combined eects of selenium and/or unsaturated
fatty acids found in Brazil nuts on atherogenic parameters
in order to better understand their mechanistic role in
modulating cardiac indexes in healthy and dyslipidemic
subjects. In addition, the evaluation of the eects of chronic
consumption of Brazil nuts and the inclusion of dyslipidemic
patients are paths to be followed.
Abbreviations
GPx: Glutathione peroxidase
TrxR: ioredoxin reductase
CHD: Coronary heart disease
MUFA: Monounsaturated fatty acids
PUFA: Polyunsaturated fatty acids
SFA: Saturated fatty acids
BMI: Body mass index
 hDR: -hour dietary recall ( hDR)
FFQ: Food frequency questionnaires
TC: Total cholesterol
HDL-c: High-density lipoprotein cholesterol
LDL-c: Low-density lipoprotein cholesterol
AI: Atherogenic index
AST: Aspartate aminotransferases
ALT: Alanine aminotransferases
CRP: C-reactive protein.
Conflict of Interests
On behalf of all authors, the corresponding author states that
thereisnoconictofinterests.
Authors’ Contribution
Jo˜
ao Batista Teixeira da Rocha designed the research, ana-
lyzed and interpreted data and wrote the paper; Elisˆ
angela
Colpo, Carlos Dalton de Avila Vilanova, Luiz Gustavo Bren-
ner Reetz, Marta Maria Medeiros Frescura Duarte, Iria Luiza
Gomes Farias, Edson Irineu Muller, Aline Lima Hermes
Muller, Erico Marlon Moraes Flores, and Roger Wagner
conducted the research, compiled and interpreted the data,
andeditedthepaper.Allauthorsreadandapprovedthenal
paper.
Acknowledgment
is work was nanced by grants received from the Na-
tional Counsel of Technological and Scientic Development
(CNPq).
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