Natural Folates from Biofortified Tomato and Synth

Plant Foods Hum Nutr
DOI 10.1007/s11130-013-0402-9
ORIGINAL PAPER
Natural Folates from Biofortified Tomato and Synthetic
5-methyl-tetrahydrofolate Display Equivalent Bioavailability
in a Murine Model
Fabiola Castorena-Torres & Perla A. Ramos-Parra &
Rogelio V. Hernández-Méndez & Andrés Vargas-García &
Gerardo García-Rivas & Rocío I. Díaz de la Garza
# Springer Science+Business Media New York 2014
Abstract Folate deficiency is a global health problem related
to neural tube defects, cardiovascular disease, dementia, and
cancer. Considering that folic acid (FA) supply through industrialized foods is the most successful intervention, limitations
exist for its complete implementation worldwide.
Biofortification of plant foods, on the other hand, could be
implemented in poor areas as a complementary alternative. A
biofortified tomato fruit that accumulates high levels of folates
was previously developed. In this study, we evaluated shortterm folate bioavailability in rats infused with this folatebiofortified fruit. Fruit from tomato segregants
hyperaccumulated folates during an extended ripening period,
ultimately containing 3.7-fold the recommended dietary allowance in a 100-g portion. Folate-depleted Wistar rats separated in three groups received a single dose of 1 nmol of folate/
F. Castorena-Torres : P. A. Ramos-Parra :
R. V. Hernández-Méndez : A. Vargas-García :
R. I. Díaz de la Garza (*)
Escuela de Biotecnología y Alimentos, Centro de
Biotecnología-FEMSA, Tecnológico de Monterrey,
Campus-Monterrey, Eugenio Garza Sada 2501, Monterrey,
NL 64849, México
e-mail: [email protected]
F. Castorena-Torres : R. V. Hernández-Méndez : A. Vargas-García :
G. García-Rivas
Cátedra de Cardiología y Medicina Vascular, Escuela de Medicina,
Tecnológico de Monterrey, Monterrey, Nuevo León, México
G. García-Rivas
Centro de Investigación Básica y Transferencia, Instituto de
Cardiología y Medicina Vascular, Tec Salud, San Pedro Garza
García, Nuevo León, México
g body weight in the form of lyophilized biofortified tomato
fruit, FA, or synthetic 5-CH3-THF. Folate bioavailability from
the biofortified tomato was comparable to that of synthetic 5CH3-THF, with areas under the curve (AUC0–∞) of 2,080±
420 and 2,700± 220 pmol ·h/mL, respectively (P=0.12).
Whereas, FA was less bioavailable with an AUC0–∞of 750±
10 pmol·h/mL. Fruit-supplemented animals reached maximum levels of circulating folate in plasma at 2 h after administration with a subsequent steady decline, while animals
treated with FA and synthetic 5-CH3-THF reached maximum
levels at 1 h. Pharmacokinetic parameters revealed that
biofortified tomato had slower intestinal absorption than synthetic folate forms. This is the first study that demonstrates the
bioavailability of folates from a biofortified plant food, showing its potential to improve folate deficiency.
Keywords Biofortified tomato . Folate bioavailability . Rat
model . Biofortification . Vitamin
Abbreviations
ADCS
AUC
Cmax
DHFR
FA
GGH
GCHI
MTHFR
MG
Aminodeoxychorismate synthase
Area under the curve
Maximum concentration
Dihydrofolate reductase
Folic acid
γ-glutamyl hydrolase
GTPcyclohydrolase I
Methylenetetrahydrofolate reductase
Monoglutamylated
Plant Foods Hum Nutr
NTD
PG
RDA
THF
Tmax
t1/2
5-CHO-THF
5-CH3-THF
5,10-CH = THF
5,10-CH2-THF
Neural tube defects
Polyglutamylated
Recommended dietary allowance
Tetrahydrofolate
Maximum concentration time
Half-time
5-formyl-THF
5-methyl-THF
5,10-methenyl-THF
5,10-methylene-THF
Introduction
Folates are water-soluble compounds that are essential for
humans and other vertebrates; they belong to the group B of
vitamins (B9) and participate as one-carbon donors in several
anabolic reactions, such as methionine and nucleic acid biosynthesis. In public health it is well-recognized the role of folate
in reducing the risk of neural tube birth defects (NTD) [1], and
its deficiency is a cause of megaloblastic anemia, which is
highly prevalent among pregnant women and young children
[2]. Folate malnutrition has also been found to be a risk factor
for cardiovascular disease [3], and there is growing evidence
that suggests a role in dementia and some types of cancer [4, 5].
Plants are the primary source of folates for humans. Certain
plants foods have a higher content of folates, such as green
leafy vegetables, legumes, and a few fruits. However, the main
source of calories in developing countries have low folate
levels (e.g., roots and cereals) [6]. Furthermore, folates are
labile compounds that can partially degrade during food processing [7–9]. Thus, it is difficult to consume the recommended
dietary allowance (RDA). To provide a continuous source of
folates, folic acid (FA), a synthetic fully-oxidized folate form
(Fig. 1a), has been successfully used in dietary supplements
and in food fortification programs for the last 15 years [1].
However, to implement fortification through processed foods
in poor and rural areas represents a challenge [10]. In addition,
some developed countries do not mandate that foods be fortified with FA due to concerns about the risk of masking the
symptoms of vitamin B12 deficiency and the potential adverse
effects of chronic intake of synthetic folate [11]. An appealing
alternative to increase folate availability for the global population is through biofortified staple crops. Biofortification is the
process of increasing micronutrient levels through plant
breeding or genetic engineering [10]. Folate-biofortified foods
produce and accumulate natural folates, and their production
has the potential to be sustainable. Naturally occurring folates
exist in food as tetrahydrofolate (THF) derivatives, with the
one-carbon group attached to the nitrogen 5- and/or 10positions in the molecule at different reduction levels. In
addition, contrary to synthetic forms that are exclusively
monoglutamylated (MG), natural folates accumulate in tissues as a mixture of MG and polyglutamylated (PG) forms
(Fig. 1c). The polyglutamyl tail is needed for intracellular
retention and possibly has an impact on folate bioavailability
[12, 13].
Folate biofortification of a plant food was first accomplished in tomato via the overexpression of the GTP
cyclohydrolase I (GCHI) and aminodeoxychorismate synthase (ADCS), which catalyze the first steps in folate
biosynthesis. This strategy increased the folate level in
ripe tomato fruits by 25-fold. The predominant folate
class produced was 5-methyl-THF (5-CH3-THF), and the
amount of folates accumulated in the fruit tissue was
enough to meet the RDA in less than one portion [14].
Moreover, a synthetic 5-CH3-THF (Fig. 1b) has recently
become available as a dietary supplement; it has comparable absorption, bioavailability, and physiological activity to FA at equimolar doses [15]. Thus, the objective of
this study was to evaluate the absorption and disposition
of folates from a biofortified tomato in a murine model.
We found that the relative bioavailability of folates from
the engineered tomato fruit was comparable to that of the
synthetic 5-CH3-THF in rats.
Fig. 1 Chemical structure of synthetic and natural folates. a Folic acid, b
synthetic 5-CH3-THF, and c natural folates. Tomato biofortified folates
have γ-linked polyglutamyl tails of up to seven residues attached to the
first glutamate. C1 units at various levels of oxidation can be linked to
nitrogen 5 and/or 10, as indicated by R and R′
Plant Foods Hum Nutr
Materials and Methods
Plant Material T3 progenies from a transgenic tomato
(Lycopersicon esculentum. Mill., cv MicroTom) overexpressing GCHI [E.C. 3.5.4.16] and ADCS [E.C. 2.6.1.85] were
kindly shared by Dr. Andrew Hanson (University of Florida).
Tomato plants segregants were screened using PCR for both
GCHI and ADCS, as previously described [14]. Plants containing both transgenes were allowed to set fruit in a greenhouse. Tomato fruit that ripened on the vine were harvested at
7, 15, 30, and 45 days after the breaker stage. All samples
were frozen in liquid N2 and stored at −80 °C until they were
analyzed.
Animals Experimental procedures were performed in accordance with the Guide for the Care and Use of Laboratory
Animals published by the U.S. National Institutes of Health
(NIH Publication No. 85-23, revised 1996). All procedures
were approved by the Animal Use and Care Committee of the
School of Medicine at the Tecnológico de Monterrey (Project
2011-010). After weaning, 36 male Wistar rats (300±30 g)
were fed a control diet (CD) for six weeks and then changed to
an FA-deficient diet (FADD); both diets were Purina Rodent
Chow (Purina Mills, Richmond, IN, USA). The CD contained
the recommended amount of FA for rodents (7.1 mg/kg diet),
while the FADD contained 0.2 mg/kg diet. A 28-day folate
depletion protocol was employed; through this time, the rats
were housed in clean wire mesh cages with controlled temperature (23±1 °C) and humidity (45 % to 55 %) and a 12 h
dark and light cycle. Before the experiment, the rats were
randomized in three groups (n=12). The animals were starved
overnight (12 h) and to guarantee consumption of equivalent
folate doses, a single intragastric bolus of an equimolar concentration (1 nmol/g body weight) of FA, synthetic 5-CH3THF pulverized tablets, or lyophilized biofortified tomato fruit
(all dissolved in a 2 mL saline solution) was infused in the
animals. Rats were exposed to 2 to 5 % isoflurane, and blood
samples (approximately 400 μL) were collected from the tails
of three animals at different time points after folate administration and placed in EDTA tubes. At the end of the experiment, all rats were sacrificed with an intraperitoneal injection
of 60 mg/kg of sodium pentobarbital (CDMV, Calgary, AB,
Canada). Plasma was obtained by centrifugation at 1,500 g for
10 min and was aliquoted in vials with a folate extraction
buffer (50 mM Na-HEPES, 50 mM CHES, 10 mM 2mercaptoethanol, and 2 % Na-ascorbate; pH=7.9). Oxygen
was removed from the samples by flushing them with N2 gas.
Samples were stored at −80 °C until analysis.
Folate Analysis Folates from tomato fruit were extracted and
purified according to the method described by Ramos-Parra
et al. [16]. Briefly, folates were extracted from the frozen
samples by boiling in the extraction buffer, and then folates
were deglutamylated to MG forms by a plant conjugase (for
PG profiles this step was omitted). Folates were purified by
affinity chromatography and analyzed using an HPLCelectrochemical detector, which can separate, detect, and
quantify individual folate derivatives. Plasma folates were
determined using the same method, starting with 250 μL of
homogenized plasma in a 5-mL folate extraction buffer. The
FA and 5-CH3-THF supplements were quantified in a solution
using spectrophotometry (λmax =282 and 292 nm, respectively).
Chemicals Folates were purchased from Schircks
Laboratories (Jona, Switzerland) and other chemicals used in
the study from Sigma-Aldrich (St. Louis, MO, USA). The FA
and 5-CH3-THF tablets were commercial supplements:
400 μg FA (Vitae Laboratorios, Guadalajara, Jalisco,
México) and 800 μg Solgar Folate (as Metafolin®; Leonia,
NJ, USA).
Statistical Analysis Values were expressed as the mean ±
standard error of the mean (SEM). The area under the
plasma concentration time curve from 0 to 12 (AUC 0–12)
was calculated using the trapezoidal method for 5-CH3-THF.
Both the maximum concentration (Cmax) and maximum
concentration time (Tmax) values were obtained directly
from the plasma concentration data. The area under the
plasma concentration time curve was extrapolated from
12 h to infinity (AUC0–∞) using log-linear regression analysis, and half-time (t1/2) was calculated using the pkexamine
function in Stata software (Stata version 10.0, College
Station, TX, USA). Differences among treatments were
evaluated using ANOVA and, when significant (P <0.05),
individual post hoc tests were performed using Tukey’s
range statistic for pair-wise comparisons.
Results and Discussion
Characterization of Natural Folates in Fully Ripe Biofortified
Tomato Fruit The synthetic and natural folate derivatives that
were used in this study are shown in Fig. 1. In a previous
work, folates were characterized in the fruit of parental plants
(T1) at 12 days after the onset of ripening (the breaker stage)
[14]. To confirm phenotype maintenance, in this study folates
were analyzed in fruit from T3 progenies containing both
GCHI and ADC transgenes. At days 7 and 15 after the breaker
stage, the fruit hyperaccumulated folates similar to what was
previous reports, meeting the RDA in less than one 100-g
portion (Fig. 2a) [14]. However, since higher folate concentrations were needed for this single-dose experiment and
considering that both transgenes are under the control of the
E8 promoter (fruit specific and ethylene responsive), the fruits
were allowed to ripen for a longer period of time assuming
Plant Foods Hum Nutr
a
Folate content
(nmol g -1 fresh weight)
50
5-CHO-THF
5,10-CH=THF + 10-CHO-THF
5-CH3-THF
THF + 5,10-CH 2-THF
40
30
20
10
0
7
14
30
45
b
5-CH3-THF Polyglutamylation
(nmol g -1 fresh weight)
30
Glu1
20
10
3
Glu5
Glu6
2
1
Glu4
Glu2
Glu7
Glu3
0
7
14
30
45
Ripening time (days after breaker stage)
Fig. 2 Folate derivatives and 5-CH3-THF polyglutamyl tail length in
biofortified tomato fruit during ripening. a Accumulation of folate derivatives in biofortified ripening fruit. b Polyglutamyl tail lengths of 5-CH3THF. GLU1-7 corresponds to the polyglutamyl tail lengths. Data are
mean ± SEM (n=3)
further folate accumulation. The biofortified tomato fruits
were harvested at days 30 and 45 after the breaker stage, and
their folate levels showed a progressive increase of up to 39.7
±1.8 nmol/g of fresh weight at day 45 after the breaker
(Fig. 2b); this represents an almost 40-fold increase from
wild-type tomato levels. These results confirm that under
longer periods of ripening, higher folate concentrations are
achieved, which demonstrates the capacity of aged fruit tissues to accumulate folates. Fruit allowed to ripen for this
unusual longer period usually starts to senesce; these observations also suggest that the endogenous enzymes that participate in folate biosynthesis remain expressed and active during
this extended ripening period, although only two biosynthetic
genes were overexpressed. This is consistent with the feedforward control in folate biosynthesis gene expression shown
previously in engineered fruit [17]. The majority of the increase in the folate pools was due to higher levels of 5-CH3THF; this derivate was the main folate class in the tomato fruit
(76 to 85 % of total folate content) during the evaluated
periods of time (Fig. 2a). Moreover, since PG folate forms
might be less bioavailable than MG [13], we characterized the
5-CH3-THF PG levels in ripe tomato fruit harvested at day 30
after the breaker stage (which was the stage chosen for animal
treatment). Similar to the fruit in the previous study, 5-CH3THF MG was the predominant folate form, reaching levels of
26.6 nmol/g of fresh weight at day 30 after the breaker stage,
representing 80 % of the total 5-CH3-THF pool (Fig. 2b).
Moreover, the 5-CH3-THF PG forms had tails of up to 7
glutamates (Glu7), but the Glu5 and Glu6 were the most
prevalent (12 % of the 5-CH3-THF pool), these increased
steadily as the fruit ripened (Fig. 2b). The rest of the 5-CH3THF PG forms accumulated at relatively lower levels, and did
not change significantly with time. Regarding the other folate
species, 54 % of the THF pool was in the MG form, while
67 % of 5-CHO-THF was MG at day 30 after the breaker
stage (not shown); however, the 5,10-CH = THF MG contribution could not be assessed. Based on these proportions, we
estimated that at least 71 % of the folates in the tomato fruit
were in the MG form. Overall, these results show that this
engineered tomato fruit (even at early ripening stages) could
be an excellent folate source with expected high absorption,
since PG folates only accumulated in minor proportions.
Bioavailability of Natural Folates in Biofortified Tomato versus Synthetic Folates This single-dose study was designed to
assess relative bioavailability under standardized conditions;
lyophilized ripe fruit at day 30 after the breaker stage was
resuspended in saline solution and administered to folatedepleted rats in puree form. To properly compare the pharmacokinetic parameters of folates from the biofortified tomato
fruit, FA and synthetic 5-CH3-THF pulverized tablets were
also administered in a solution in equimolar doses in parallel
experiments. Bioavailability was evaluated by analyzing folates in plasma because they show an immediate response to a
single oral dose. Folates are absorbed in the jejenum cell and
are metabolized into 5-CH3-THF MG, which is the folate
derivative that is transported into the blood stream [18].
Except for the FA group (see below), 5-CH3-THF was the
only folate detected in the plasma. To assure that rats depleted
their folate reserves, rats were fed a FADD for four weeks. The
mean baseline folate level of the CD group was 209±36
pmol/mL, while that from FADD rats was less than 28
pmol/mL. This level of folate depletion was comparable to
other studies, in which the plasma folate concentration from
depleted rats ranged from 37 to 60 pmol/mL [19, 20]. Next,
we evaluated plasma folate levels in FADD rats at different
time points during the first 12 h after treatment (Fig. 3). At
time zero, 5-CH3-THF MG levels were not different among
the three groups. After ingestion of both the FA and synthetic
5-CH3-THF, plasma folate peaked at 1 h and remained higher
than baseline for up to 12 h after bolus infusion. Conversely, in
Plant Foods Hum Nutr
a
500
5-CH3-THF (pmol mL -1)
Folic acid
400
a
Synthetic 5-CH3-THF
300
b
a
a
200
a
b b
100
c
0
a
a
a
ab
a
0 b
b
Biofortified tomato
a
b
a
b
a
b
c
b
b
b
c
2
4
6
8
10
12
6
8
10
12
35
Folic acid (pmol mL
-1
)
30
25
20
15
10
5
0
0
2
4
Time (h )
Fig. 3 Time-course response to synthetic and natural folates from
biofortified tomato fruit. a Mean plasma levels of 5-CH3-THF response
in rats after treatment with equimolar folate doses. b Unmetabolized folic
acid in plasma after treatment. Data are mean ± SEM (n=3). Means with
different letters at a given time point are significantly different (P≤0.05,
Tukey’s post hoc test)
animals treated with biofortified tomato, maximum 5-CH3THF levels were reached at 2 h with a subsequent steady
decline. A delay can be expected as folates accumulate within
plant tissues and need to be extracted during digestion prior to
absorption. In addition, folate bioavailability is known to be
affected by the food matrix [21]. These results thus suggest
that natural folates present in biofortified tomato have a slower
intestinal absorption than synthetic preparations.
In addition, when folates were analyzed from the FAtreated rats, we detected unmetabolized FA along with 5CH3-THF in plasma (Fig 3b). The FA concentration also
peaked at 1 h (23±6 pmol FA/mL of plasma) as 5-CH3-THF
did (Fig 3a). This finding suggests an enzymatic system
overload. After ingestion, FA is mainly absorbed via carriermediated transport involving the reduced folate carrier and
proton-coupled folate transporter [22]. At high doses, FA is
also absorbed through passive diffusion, increasing the unmetabolized FA concentration. Additionally, FA undergoes a
two-step reduction by dihydrofolate reductase (DHFR) [E.C.
1.5.1.3] mainly in intestinal epithelial cells to become the
metabolically active THF (Fig. 4). At high FA doses, DHFR
activity may become a limiting step in the bioconversion of
FA to 5-CH3-THF [22], maintaining a non-reduced FA pool
that can pass throughout the circulation system.
The pharmacokinetics parameters following the treatments
are presented in Table 1. Surprisingly, all parameters showed
that, under the conditions tested, the bioavailability of synthetic 5-CH3-THF was higher than the FA. The Cmax of
synthetic 5-CH3-THF was 6-fold higher than the FA Cmax.
These data are consistent with a previous study that evaluated
the effect of high doses of synthetic folates in humans [23].
However, at lower doses, results from other studies have
shown that the bioavailability of synthetic 5-CH3-THF is at
least as high as that of FA after a single dose of both compounds in humans [15, 24]. This dissimilarity among previous
reports could be due to the different doses used and the
preceding folate saturation regimen of the subjects. In our
study, as well as in reports performed in murine models [19,
25], a folate-depleted rat model was used to minimize interindividual differences in baseline plasma folate content before
treatment. Consequently, all rats started the treatment with a
similar folate regimen, and recovery of folate plasma concentration was readily observed and comparable among groups.
Under these conditions, the AUC and Cmax levels of the
natural folates from the biofortified tomato fruit were slightly
lower than the levels of the synthetic 5-CH3-THF (Table 1).
This difference could be due to a food matrix effect (folate
interactions with tomato fruit components that can affect
bioavailability) in addition to the different stability of the other
folate species during digestion (15 % of the folates present in
the fruit were not 5-CH3-THF; Fig. 2a). In fact, bioavailabilities of folates from foods differ when compared to synthetic
folates in rats and humans (usually less than 80 %) [26, 27].
Another consideration is the amount of PG folates in the
biofortified tomato; based on our calculation, PG folate probably represented less than 25 % of the total folates infused into
the animals. PG folate forms first need to be deglutamylated
by intestinal γ-glutamyl hydrolase (conjugase) prior to being
absorbed by the small intestine; however, the
polyglutamylation effect on the rate of intestinal absorption
of folates is still controversial. There are several studies in
humans that show different degrees of bioavailability when
natural PG folates were compared to MG folates, while others
have not found differences [28]. Another pertinent consideration is the limitations of using a rat model for folate bioavailability studies. Folate deconjugation in rats is different than in
humans; they have low intestinal conjugase activity, while
their pancreatic juice is a rich source of conjugases [29, 30].
Thus, there is a possibility that the relative bioavailability
values found in this animal model would change for humans
if the natural PG folates were a limiting factor in this study.
Plant Foods Hum Nutr
BIOFORTIFIED TOMATO
SYNTHETIC 5-CH3-THF
GGH
JEJUNUM CELLS
5-CH3-THF (Glu)n
FOLIC ACID
5-CH3-THF MG
FOLIC ACID
DHFR
DHF
a
b
5-CH3-THF
c
5-CH3-THF
DHFR
THF
5-10-methylene-THF
MTHFR
5-CH3-THF
BLOOD STREAM
5-CH3-THF
FOLIC ACID
Fig. 4 Digestion and absorption of synthetic and natural folates. a
Polyglutamylated natural folates (mainly 5-CH3-THF) from biofortified
tomato are hydrolyzed by γ-glutamyl hydrolase (GGH, conjugase) in the
intestinal lumen or at the brush border. Monoglutamyl folates are
transported into the intestinal cell, appearing in the circulation as 5-
CH3-THF. b Synthetic 5-CH3-THF is transported directly to the bloodstream. c FA is transported into the intestinal cell, where it is reduced and
methylated, appearing in the circulation as 5-CH3-THF. Unmetabolized
FA was observed in mesenteric circulation
Nevertheless, considering that this biofortified fruit accumulated around 1.5 mg of folate in a 100-g portion (3.7-fold the
RDA), a slightly reduction in bioavailability would not diminish its potential to improve folate status in individuals.
with FA has been shown to be effective, and epidemiological
data show that it lowers NTDs among certain populations
[31]. However, there are concerns surrounding FA consumption by certain individuals and potential negative effects of
unmetabolized FA in the circulation [11]. FA bioavailability
depends on the reduction capacity of DHFR (Fig. 4); this
capacity could be surpassed by high doses (as shown in our
data when unmetabolized FA was detected in the rat plasma)
or altered by polymorphisms or pathologies. Folates from
biofortified food matrices would not cause these concerns,
since all folates are in their reduced forms, and additionally,
have to be subjected to a number of enzymatic steps in order to
be absorbed, transported, and accumulated within tissue. In
this study, 5-CH3-THF levels in plasma were significantly
raised after tomato fruit consumption with no detection of
FA, as expected.
On the other hand, FA-fortified food has been successfully
implemented in over 50 countries [1], but implementation in
developing countries and rural areas is difficult due to a lack of
industrialized food systems. We consider that generation of
biofortified staple crops will lead to improved nutrition in
these target populations, particularly because it has the potential to be sustainable. There are ongoing efforts to biofortify
staple crops with folate, particularly rice, which has been
engineered with very similar results to tomato fruit [32], and
corn, with a 2-fold increase in folate, along with important
increases in pro-vitamin A and vitamin C [33]. However, this
is the first study that demonstrates folate bioavailability from a
biofortified plant organ similar to that of synthetic 5-CH3THF, when administered in a single high dose. In contrast,
FA at this dose probably saturated the rat reduction system.
Folates from Biofortified Plant Foods as an Alternative to
Improve Human Nutrition Results from this work constitute
the first step towards in vivo assessment of biofortified plant
foods with folates. Folates accumulated within ripe tomato
fruit primarily in the most common form of reduced folate,
namely 5-CH3-THF, which has been proven to be as effective
as FA when administered as a supplement [15]. Food fortified
Table 1 Pharmacokinetic parameters for 5-CH3-THF after administration of either synthetic or natural folates from biofortifed tomato fruit in
rats
Cmax (pmol/mL)
Tmax (h)
T½ (h)
AUC (0–12)
(pmol·h/mL)
AUC (0–∞)
(pmol·h/mL)
Folic
acid
Synthetic
5-CH3-THF
Biofortified
tomato
60±10a
1a
6±2a
500±20a
380±70b
1a
4.2±0.4a
2,250±90b
270±20b
2b
6.4±2a
1,590±330b
750±10a
2,700±220b
2,080±420b
Cmax maximum concentration, Tmax maximum concentration time, T½
half-life, AUC area under the curve
All values are reported as means ± SEM (n=12)
Differences among groups were evaluated by using one-way ANOVA.
Means with different letters are significantly different. (P≤0.05, Tukey’s
post hoc test)
Plant Foods Hum Nutr
Results from this work demonstrate the potential of folatebiofortified plant foods to improve folate deficiency. Further
long-term preclinical studies that focus on physiological doses
can provide more evidence of the capability of these foods to
improve folate status and will evaluate toxic effects prior to be
tested in humans. In response to the global population’s increasing demand for food that can provide necessary nutrients
in smaller portions, the biofortification of food plants has been
shown to increase accumulation of micronutrients [10]. Future
efforts need to focus on advancing these crops toward sustainable human consumption that can help relieve global micronutrient deficiencies.
Conclusion
The short-term bioavailability of folates from biofortified
tomato fruit is comparable to synthetic 5-CH3-THF preparations in a rat model. We suggest additional long-term studies
to evaluate its bioequivalence and safety.
Acknowledgments The authors thank Dr. Andrew Hanson at the University of Florida, for generously sharing the biofortified tomato lines. We
are grateful to Dr. Adriana Pacheco for critically reading the manuscript
and for her insightful comments. This research was supported by the
FEMSA Nutrigenomics Fund, and by Endowed Chairs of the
Tecnológico de Monterrey in Cardiology 0020CAT131 and
Micronutrients 0020CAT198. RVHM was supported by CONACyT
M.Sc. scholarship 39354.
Conflict of Interest All authors declare not having conflict of interest.
All animal procedures received prior approval by the Tecnológico de
Monterrey Animal Care and Use Committee.
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