Efeitos da Lactoferrina no Verão

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Journal of Microbiology, Immunology and Infection (2021) 54, 566e574
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Original Article
Effects of lactoferrin on infectious diseases
in Japanese summer: A randomized, double-
blinded, placebo-controlled trial
Hirotsugu Oda a,*, Hiroyuki Wakabayashi a, Miyuki Tanaka a,
Koji Yamauchi a, Chihiro Sugita b, Hiroki Yoshida b,
Fumiaki Abe a, Tohru Sonoda c, Masahiko Kurokawa b
a Food Ingredients and Technology Institute, Morinaga Milk Industry Co., Ltd., 5-1-83, Zama,
Kanagawa, 252-8583, Japan
b Department of Biochemistry, Graduate School of Clinical Pharmacy, Kyushu University of Health and
Welfare, 1714-1, Nobeoka, Miyazaki, 882-8508, Japan
c Department of Occupational Therapy, School of Health and Science, Kyushu University of Health and
Welfare, 1714-1, Nobeoka, Miyazaki, 882-8508, Japan
Received 2 April 2019; received in revised form 12 February 2020; accepted 17 February 2020
Available online 26 February 2020
KEYWORDS
Lactoferrin;
Summer cold;
Vigor/Activity;
Cortisol
* Corresponding author. Fax: þ81 46
E-mail address: h-oda@morinagam
https://doi.org/10.1016/j.jmii.2020.0
1684-1182/Copyright ª 2020, Taiwan
BY-NC-ND license (http://creativecom
Abstract Purpose: To investigate the effects of lactoferrin (LF) on infectious diseases in Jap-
anese summer.
Methods: An intake of placebo, 200 mg, or 600 mg of LF were administered to healthy adults in
Kyushu University of Health and Welfare for 12 weeks in a randomized, double-blinded, pla-
cebo-controlled parallel-group comparative trial. The primary endpoints were the prevalence
and duration of infectious diseases and changes in immune parameters.
Results: Three hundred and ten subjects were randomized (placebo, n Z 104; 200 mg,
n Z 103; 600 mg, n Z 103). Twenty subjects were lost to the follow-up, leaving 290 for a full
analysis set (nZ 99; nZ 95; nZ 96). The duration (day) of total infectious diseases was short-
er in the 200 mg group (2.0, p Z 0.045) and 600 mg group (2.0, p Z 0.010) than in the placebo
group (3.0). The duration of summer colds was shorter in the 600 mg group (2.0, p Z 0.036)
than in the placebo group (3.0). No significant differences were observed in the prevalence
of infectious diseases or changes in immune parameters. In exploratory investigations, changes
in the neutrophil phagocytic capacity, cortisol concentrations, and T score of “Vigor/Activity”
in the Profile of Mood States 2 were greater in the 600 mg group than in the placebo group,
when analysis was done on the lower half groups at the baseline. Adverse events were similar
in each group and none had a causal relationship with the intake of the test foods.
Conclusions: In summer, the intake of LF attenuates infectious diseases, including summer
colds.
252 3017.
ilk.co.jp (H. Oda).
2.010
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Effects of Lactoferrin on Infectious Diseases in Summer 567
Copyright ª 2020, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC. This is an
open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-
nc-nd/4.0/).
Introduction
Infectious diseases that are unique to hot seasons are
prevalent in summer and present public health issues in
Japan.1e3 Respiratory illnesses prevalent in summer are
called summer colds, mainly attributed to viruses.1e3 Cur-
rent protective measures are insufficient and thus desired.
The innate immune system is important for the sup-
pression of infectious diseases but may be impaired by heat
stress, which affects the autonomic nervous and endocrine
systems. Heat stress activates the sympathetic nervous
system,4 suppresses the innate immune system,5,6 in-
creases cortisol levels, and reduces vigor.7
Lactoferrin (LF) is an iron-binding glycoprotein found in
the milk of most mammals.8 It is known to have some anti-
viral properties9e12 and immunostimulatory effects such as
enhancing the cytotoxicity of natural killer (NK) cells,13 the
phagocytic capacity of neutrophils,14 and the production of
secretory immunoglobulin A (sIgA).13 LF also modulates the
autonomic neuron balance and cortisol levels.15,16 As LF in
commercial dairy products is denatured during the process
of sterilization, LF derived from natural bovine milk is used
to fortify food products.17 In previous trials, the intake of LF
suppressed infectious diseases in winter.18e20 However,
pathogens in summer may differ from those in win-
ter,1e3,21,22 and the effects of LF on infectious diseases
prevalent in summer have not yet been examined.
Based on this background, we investigated whether the
intake of LF suppresses infectious diseases in the Japanese
summer season, in conjunction with changes in immune
parameters, cortisol levels, the autonomic neuron balance,
and vigor/activity.
Material and methods
Trial design and ethical approval
A randomized (1:1:1), double-blinded, placebo-controlled,
parallel-group comparative trial was conducted at Kyushu
University of Health and Welfare between June and
September 2017. The design and trial implementation were
conformant to the current revision of the Declaration of
Helsinki (2013),23 and Ethical Guidelines for Medical and
Health Research Involving Human Subjects (2015).24 The
protocol and informed consent form were approved by the
Institutional Review Board (IRB) at the university on May 16,
2017 (approval number: 17e003).
Subjects, eligibility, and exclusion criteria
Eligible subjects were all healthy adults aged between 20
and 65 years from the university. Exclusion criteria were
chronic diseases, pregnancy, breast-feeding, a milk allergy,
the habitual consumption of lactoferrin, a history of serious
disorders in the liver, kidneys, heart, lungs, gastrointestinal
tract, blood, endocrine system, or metabolic system, and
being judged as inappropriate to participate in this trial by
the principal investigator.
Intervention
After IRB approval, investigators explained the details of
the trial in accordance with the informed consent form,
and written informed consent, then background informa-
tion were obtained from subjects. Blood was collected in
citrate phosphate dextrose (CPD) tubes (7.5 mL) during the
morning, and NK cell cytotoxicity was investigated on the
same day in LSI Medience (Japan) using the 51Cr release
assay as described previously.25,26 The target cells were
human chronic myelogenous leukemia K-562 cells, with an
effector-to-target [E/T] ratio of 50:1. One hundred and
twenty subjects were selected from those with NK cell
cytotoxicity close to 50%, excluding smokers, subjects with
bleeding in the mouth, and subjects taking medicine. Due
to the limited testing capacity of the institute, clinical
examinations were only performed on these 120 subjects.
These 120 subjects and the remainder were respectively
allocated into three groups. The test food and a diary were
issued before the start of the intervention. Subjects in each
group were instructed to swallow six tablets per day (pla-
cebo, 200 mg, or 600 mg of LF) with water at bedtime
during the intervention period (12 weeks), and to record
the intake. All subjects started and finished the intake, as
well as the diary records, on the same day. Investigators
met the subjects every 4 weeks to check the intake and
diary records. Since past clinical trials on similar contexts
were carried out for three months27; we used an inter-
vention period of 12 weeks during summer in Japan, be-
tween June and September. The efficacy of LF in treating
infectious diseases using a doseof less than 600 mg/day 27
has been demonstrated in the past.27 A previous study from
our group (not yet published) found ingestion of 200 mg and
600 mg/day of LF to suppress infectious gastroenteritis in a
dose-dependent manner. Therefore, we decided on LF
doses of 200 mg or 600 mg/day.
Primary, secondary, and exploratory endpoints
The primary endpoints were the prevalence and duration of
infectious diseases, and changes in immune parameters (NK
cell cytotoxicity, the neutrophil phagocytic capacity, and
concentration of salivary sIgA).
Prevalence and duration of infectious diseases
Following previous studies,28,29 subjects were instructed to
record the presence of infectious diseases, summer cold
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http://creativecommons.org/licenses/by-nc-nd/4.0/
568 H. Oda et al.
symptoms based on diagnosis in medical institutes and
subjective symptoms, medication, and other physical
changes in their diary. A sore throat, cough, nasal secre-
tion, nasal congestion, headache, chills, and fatigue were
recorded as summer cold symptoms. The principal investi-
gator met subjects every 4 weeks for follow up, checked
their diary records, and distinguished symptoms other than
infectious diseases, such as allergic symptoms, from those
being studied. Prevalence was calculated as the number of
subjects with onset of infectious diseases among the total
subjects, or the number of subjects with onset of symptoms
among subjects with each infectious disease, while episode
was calculated as the number of blocks of consecutive days
of infectious diseases or their symptoms, and duration as
the mean consecutive days of total episodes. The interval
between episodes was at least one day.
Immune parameters
All clinical examinations and questionnaires were con-
ducted in the 4 days before and the last 4 days of the
intervention period. Clinicians collected saliva and blood
samples from one hundred and twenty subjects (30 sub-
jects/day) in the morning. Sublingual rest saliva was
collected for 2 min using Salisoft (Sarstedt, Germany),
frozen, and then the concentration of salivary sIgA was
measured with a YK280 Human s-IgA (saliva) ELISA kit
(Yanaihara Institute, Japan), as previously described30,31 in
Yanaihara Institute (Japan). Blood was collected in CPD
tubes (7.5 mL) and Heparin-Na tubes (4 mL), while NK cell
cytotoxicity and the neutrophil phagocytic capacity were
examined on the same day in LSI Medience (Japan). To
investigate the neutrophil phagocytic capacity, the granu-
locytic phagocytosis of Fluoresbrite plain YG-2.0-mm mi-
crospheres 2.5% solid-latex (Polysciences Inc., PA) was
evaluated using a flow cytometer, as previously
described.32
The secondary endpoints were changes in the autonomic
neuron balance (LF/HF ratio) and the concentration of
cortisol.
One hundred and twenty subjects also underwent clin-
ical examinations of their autonomic neuron balance (Low
Frequency/High Frequency [LF/HF] ratio) during the
morning using the measurement sensor VM302 (Fatigue
Science Laboratory, Japan). Blood was also collected in
EDTA-2Na tubes (5.5 mL), and concentrations of cortisol
were examined on the same day in LSI Medience (Japan)
and measured with the chemiluminescent immunoassay,
Architect Cortisol (Abbott Japan, Japan), as previously
described.33
Table 1 Baseline demographic and clinical characteristics.
Total Pl
Subjects1 310 10
Female1 187 64
Age2 23.7 � 6.6 23
NK cell cytotoxicity (%)2 61.2 � 18.2 60
1, number; 2, mean � standard deviation.
Exploratory endpoints were changes in the T scores of
“Vigor/Activity” in the Profile of Mood States 2 (POMS2),
and subgroup analyses.
All subjects answered questionnaires for “Vigor/Activ-
ity” in the POMS2.
Any unfavorable and unintended signs, symptoms, or
diseases temporally associated with the intake of the test
foods were defined as an adverse event and evaluated with
Revised National Cancer Institute - Common Toxicity
Criteria (NCI-CTCAE) Version 4.0. Any adverse event with a
probable causal relationship to the intake of the test foods
was defined as an adverse drug reaction.
Sample size
We estimated the prevalence of infectious diseases to be
20%, the expected intake of LF to reduce it to 6.7% (one-
third) with a type 1 error of 0.05 and a power of 80%,
calculated a sample size of 306 (102 in each group), and set
a target sample size of 310 (103e104 in each group)
including dropouts. Regarding immune parameters, previ-
ous trials were performed using a sample size of 30e40 in
each group,34 and, thus, we set a target sample size of 120
(40 in each group) including dropouts.
Randomization, allocation, and blinding
The allocation manager, a researcher unrelated to this trial
in a different department in the university, used computer-
generated lists of block-randomized numbers with a block
size of 3 (1:1:1 ratio), prepared allocation tables for de-
partments, and numbered test foods consecutively in
accordance with the lists. He concealed allocation tables
from investigators, by sealing them in an opaque envelope,
and kept them until code breaking. Both the investigators
and subjects were blinded during this period. Investigators
enrolled subjects, stratified them by departments, assigned
order numbers, and gave test foods with the corresponding
numbers to them. Test foods were presented in round
tablets with a red-orange color, weighing 250 mg, with a
diameter of 9.1 mm, and thickness of 4.8 mm. The 600 mg
group received six tablets of 100 mg of bovine LF (purity
[�96%] by a HPLC method and iron saturation [10.4%] by an
ICP-MS method) derived from cheese whey (identical to the
commercial supplement “Lactoferrin Original”, Morinaga
Milk Industry, Japan). The tablets for the 200 mg group and
placebo group contained 33.3 mg (200 mg/6 tablets) and
0 mg of LF, respectively. The tablet for the 600 mg group
consisted of maltitol, indigestible dextrin, dextrin, hydro-
genated rapeseed oil, LF, and guar gum, while in the 200 mg
acebo 200 mg 600 mg
4 103 103
63 60
.3 � 6.3 23.7 � 6.1 24.0 � 7.5
.5 � 18.8 60.9 � 18.3 62.3 � 17.4
Figure 1. Flow diagram of subjects.
Effects of Lactoferrin on Infectious Diseases in Summer 569
group and placebo group, LF was replaced with dextrin, and
the color tone was adjusted with pigment. The allocation
manager evaluated the appearance, solidness, smell, and
taste, as well as the packages of the 3 types of test foods at
both allocation and code breaking, and confirmed them to
be indistinguishable. Code breaking was performed after
locking the database and statistical analysis plan.
Statistical analysis
A chi-squared test was used to analyze the prevalence of
infectious diseases and their symptoms, and the
ManneWhitney U test was used to analyze the duration of
infectious diseases and their symptoms as well as changes
in the concentrations of salivary sIgA and cortisol. An
analysis of covariance (ANCOVA) adjusted for values at
Figure 2. Prevalence o
0 weeks was used to analyze changes in NK cell cytotox-
icity, the neutrophil phagocytic capacity, T scores in
POMS2, and the natural logarithm of the autonomic
neuron balance based on the close testing procedure. The
chi-squared test for trends and the Jonckheere-Terpstra
trend test were used to analyze the doseeresponse rela-
tionship. Statistical analyses were performed with EZR
software (Saitama Medical Center, Jichi Medical Univer-
sity, Saitama, Japan).35 P values0.011
Medication1 13 11 10 0.561 0.910 0.873
Duration of medication
(day)2
4.0 (2.0
e8.0)
2.0 (1.3
e4.0)
1.5 (0.8
e3.0)
0.352 0.120 0.085
1, number; 2, median (interquartile range [25th percentile - 75th percentile]); 3, placebo vs 200 mg; 4, placebo vs 600 mg; RD, risk
difference; CI, confidence interval.
570 H. Oda et al.
intervention period was between June and September
2017, and was completed as scheduled.
Three hundred and ten subjects provided informed
consent and were enrolled (placebo n Z 104; low LF
n Z 103; high LF n Z 103) (Table 1). After randomization,
5, 8, and 7 subjects were lost to the follow-up in each
group. We used a full analysis set (FAS) of data (n Z 99;
n Z 95; n Z 96) for the primary analysis (Fig. 1).
The mean � SD intake rates (%) of the test foods were
92.2 ± 10.7, 90.8 ± 13.3, and 89.0 ± 15.9 in each group, and
were not significantly different (P Z 0.68). The number of
subjects with various infectious diseases were as follows:
total, 76; summer colds, 66; cold sores, 9; gastroenteritis, 5;
styes, 2. As a primary endpoint, the prevalence of infectious
diseases was not significantly different (Fig. 2). The duration
of total infectious diseases showed significant trend and was
significantly shorter in the 600 and 200 mg groups than in the
placebo group (Table 2). The duration of summer colds was
significantly shorter in the 600 mg group than in the placebo
group (Table 3). No significant differences were observed in
the prevalence or duration of summer cold symptoms (Table
4). No significant differences were observed in the durations
of other infectious diseases (Fig. 3).
Table 3 Prevalence and duration of summer colds.
Placebo 200 mg 600 mg RD
Prevalence1 25 20 21 0.0
0.1
Episode2 1.0 (1.0
e2.0)
1.0 (1.0
e2.3)
1.0 (1.0
e3.0)
Duration (day)2 3.0 (2.0
e6.0)
2.0 (1.0
e4.0)
2.0 (1.3
e2.3)
Medication1 10 9 8
Duration of medication
(day)2
3.5 (2.0
e6.1)
1.7 (1.2
e5.0)
1.0 (0.6
e2.3)
1, number; 2, median (interquartile range [25th percentile - 75th pe
difference; CI, confidence interval.
No significant changes were observed in NK cell cytotox-
icity, the neutrophil phagocytic capacity, or concentration of
salivary sIgA. As secondary endpoints, changes in the auto-
nomic neuron balance and the concentration of cortisol were
not significantly different (Table 5).
As exploratory endpoints, no significant changes were
noted in the T scores of “Vigor/Activity” in POMS2. How-
ever, in the analysis of the lower half group at the baseline,
changes were significantly greater in the 600 mg group than
in the placebo group (Table 6). In the analysis of the
neutrophil phagocytic capacity in the lower half group at
the baseline, changes were greater in the 600 mg group
than in the placebo group, whereas no significant differ-
ence was observed in the analysis of the higher half group
(Table 5). In the analysis of cortisol concentrations in the
lower half group, concentrations showed significant trend
(p Z 0.037), being higher in the 600 mg group than in the
placebo group, while in the analysis of the higher half
group, they were slightly lower in the 600 mg group than in
the placebo group (Table 5).
The numbers of subjects with adverse events were 44,
48, and 38 in the placebo group, 200 mg group, and 600 mg
group, respectively. No significant differences were
(95% CI) P
value3
RD (95% CI) P
value4
P for
trend
42 (�0.077,
61)
0.488 0.034 (�0.085,
0.153)
0.579 0.571
0.857 0.804 0.832
0.204 0.036 0.060
0.736 0.895 0.913
0.460 0.082 0.053
rcentile]); 3, placebo vs 200 mg; 4, placebo vs 600 mg; RD, risk
Table 4 Prevalence and duration of each symptom of
summer colds.
Placebo 200 mg 600 mg P
value3
P
value4
Sore throat
Prevalence1 18 11 11 0.236 0.170
Duration (day)2 2.8 (1.8
e4.8)
2.7 (1.5
e3.0)
1.5 (1.0
e2.3)
0.715 0.096
Cough
Prevalence1 10 9 5 0.736 0.243
Duration (day)2 5.5 (2.3
e7.0)
2.0 (1.0
e3.5)
1.5 (1.0
e4.0)
0.175 0.196
Nasal secretion
Prevalence1 15 14 13 0.486 0.895
Duration (day)2 2.5 (1.8
e3.5)
1.9 (1.0
e3.0)
2.0 (1.0
e3.0)
0.321 0.283
Nasal congestion
Prevalence1 10 7 11 0.731 0.401
Duration (day)2 2.0 (1.7
e2.4)
2.0 (1.2
e4.0)
2.0 (1.0
e2.8)
0.960 0.884
Headache
Prevalence1 11 6 8 0.336 0.685
Duration (day)2 2.0 (1.0
e3.0)
1.0 (1.0
e1.8)
1.5 (1.0
e2.0)
0.381 0.657
Chills
Prevalence1 5 4 7 1.000 0.305
Duration (day)2 2.0 (1.0
e2.0)
1.0 (1.0
e1.3)
1.5 (1.0
e2.0)
0.338 0.599
Fatigue
Prevalence1 11 5 11 0.186 0.571
Duration (day)2 2.0 (1.3
e3.0)
1.0 (1.0
e1.0)
1.0 (1.0
e2.0)
0.235 0.095
1, number; 2, median (interquartile range [25th percentile -
75th percentile]); 3, placebo vs 200 mg; 4, placebo vs 600 mg.
Effects of Lactoferrin on Infectious Diseases in Summer 571
observed between groups (P Z 0.37). None had a causal
relationship with the intake of the test foods.
Discussion
We investigated whether the intake of LF exerts suppres-
sive effects on infectious diseases in Japanese summer. In
Table 5 Changes in immune parameters.
Placebo 20
NK cell cytotoxicity (%) 1 �3.9 � 9.8 �7
Neutrophil phagocytic capacity (%) 1 1.2 � 7.5 1.
Lower half group3 3.5 ± 7.5 5.
Higher half group4 �3.2 ± 5.0 �2
Salivary sIgA concentration (mg/mL) 2 34.4 (15.9e73.2) 21
Natural logarithm of LF/HF 1 0.0 � 3.2 0.
Cortisol concentration (mg/dL) 2 �0.2 (�2.1 - 1.7) �0
Lower half group5 �0.6 (�1.6e1.9) 1.
Higher half group6 0.2 (�2.8e1.7) �1
1, mean� standard deviation; 2, median (interquartile range [25th per
median of the neutrophil phagocytic capacity or the cortisol concent
group. 7, placebo vs 200 mg; 8, placebo vs 600 mg.
the FAS of data, the duration of total infectious diseases
showed a significant trend, and was significantly shorter in
the 600 and 200 mg groups than in the placebo group. The
most common infectious diseases observed were summer
colds whereby the duration was significantly shorter in the
600 mg group than in the placebo group. The prevalence of
adverse events was similar between groups, and none had a
causal relationship with the intake of the test foods. These
results suggest that the intake of 200e600 mg/day of LF is
safe and efficacious for ameliorating infectious diseases in
summer, including summer colds, in a dose-responsive
manner. Previous studies reported the suppressive effects
of LF with other components on respiratory illnesses in
adults18,19,29; however, the effects of LF alone remain un-
clear. This is the first study to show the suppressive effects
of LF alone on respiratory illnesses in adults.
The immunomodulatory effects of LF were expected to
contribute to the suppression of these infectious diseases.
However, we did not confirm the effects of LF on immune
parameters. It is not preferable for immune parameters to
merely be enhanced; being in appropriate ranges is bene-
ficial. The subjects were all healthy adults, and their im-
mune parameters appeared to be within appropriate
ranges. In the analysis of the neutrophil phagocytic ca-
pacity in the lower half group at the baseline, the change
observed was significantly greater in the 600 mg group than
in the placebo group. If the baseline immune parameters of
subjects are relatively low, the enhancing effects of LF may
be observed. The autonomic neuron balance and cortisol
concentrations are often adopted to evaluate stress levels,
and we expected negative effects due to heat stress in
summer, and LF to improve them. However, LF did not
exert any effects on these stress parameters. The tem-
perature in September was slightly lower than that in June
in 2017. In the university, they had finished term exami-
nations and six weeks of summer vacation during the
intervention period. Therefore, participants may have been
more relaxed at the end of the intervention period, which
potentially masked the effects of LF. Regarding the auto-
nomic neuron balance, the values measured varied widely,
even in measurements with 5-min intervals during the
preliminary investigation. Therefore, it remainsunclear
whether we accurately evaluated the autonomic neuron
balance using the measurement sensor. Regarding cortisol
concentrations, in the analysis of the higher half group at
0 mg 600 mg P value7 P value8
.3 � 13.2 �6.3 � 10.5 0.235 0.520
1 � 7.3 2.0 � 8.6 0.103 0.070
3 ± 6.7 7.4 ± 8.5 0.185 0.049
.1 ± 6.0 �1.7 ± 6.3 0.368 0.537
.5 (6.9e53.4) 19.8 (3.9e35.6) 0.282 0.060
0 � 0.3 0.0 � 0.3 0.919 0.385
.1 (�1.9e2.6) 0.2 (�2.2 - 3.7) 0.667 0.525
7 (0.2e4.6) 2.0 (0.1e4.6) 0.150 0.029
.1 (�2.5e4.6) �2.4 (�4.2e0.1) 0.415 0.088
centile - 75th percentile]); 3, 4, 5, 6, Subjects were divided at the
rations at the baseline into the lower half group and higher half
Figure 3. Duration of infectious diseases. The horizontal line indicates the median, the box covers the 25e75th percentiles, and
the maximum length of each whisker is 1.5-fold that of the interquartile range. Points outside this are outliers.
572 H. Oda et al.
the baseline, the changes observed were slightly lower in
the 600 mg group than in the placebo group (p Z 0.09).
Therefore, if the baseline cortisol concentration of subjects
is relatively high, the suppressive effects of LF may be
observed. On the other hand, cortisol concentrations in the
lower half group at the baseline were significantly greater
in the 600 mg group than in the placebo group. Subjects
woke at approximately 7 am on average, and blood was
collected between 8 and 9 am. Cortisol concentrations are
low at night, increase in the early hours before waking, and
continue to increase after waking up.36 Low cortisol con-
centrations in the morning are associated with high levels
of sleepiness at awakening, and anxiety and exhaustion the
day before, and predict higher levels of fatigue later that
day.37,38 Therefore, a certain concentration of cortisol in
the morning appears to be necessary for stress tolerance,
and the ingestion of LF may modulate levels within an
appropriate range, thereby supporting stress tolerance.
Since heat stress lowers vigor,7 we were concerned that the
results obtained showed no significant changes in the T
scores of “Vigor/Activity”, whereas they were significantly
higher in the 600 mg group than in the placebo group in the
lower half group at the baseline. These results suggest that
the intake of 600 mg/day of LF improves “Vigor/Activity” in
summer. The modulation of cortisol concentrations may
also have contributed to improved “Vigor/Activity”.
Table 6 Changes in T scores of “Vigor/Activity” in POMS2.
Placebo 200 mg
Total 1 0.1 � 6.9 0.8 � 8.4
Lower half group2 0.7 � 6.5 3.0 � 7.6
Higher half group3 �0.5 � 7.2 �1.5 � 8.6
1, mean � standard deviation; 2, 3, Subjects were divided at the medi
the lower half group and higher half group. 4, placebo vs 200 mg; 5,
In the present study, the prevalence of infectious dis-
eases other than summer colds was low and evaluating the
suppressive effects of LF on them proved challenging. A
larger sample size or higher prevalence may be needed to
investigate these effects. Subjects were healthy adults
(mean age 23.7 years) and may have been immunocompe-
tent and tolerant to infectious diseases. The effects of LF
may be more significant in individuals at high risk of in-
fections, such as the elderly or immunosuppressed in-
dividuals; however, neither of these were subjects.
Different settings or age of subjects may have changed the
prevalence of infectious diseases. The pathogens of infec-
tious diseases are rarely identified in medical institutions in
Japan. Therefore, the prevalence of infectious diseases
was mainly recorded based on the inquiries of doctors, and,
thus, it remains unclear whether LF suppressed infections
by specific pathogens. Furthermore, the results obtained in
exploratory investigations need to be assessed again in
other studies as primary endpoints. Further studies that
consider the limitations above are required to normalize
and confirm the reliability of the outcomes obtained
herein.
This study was registered at the University Hospital
Medical Information Network Clinical Trials Registry in
Japan on May 19, 2017 under the registration number
UMIN000027405. Full details on the protocol (in Japanese)
600 mg P value4 P value5
1.5 � 8.8 0.420 0.074
4.9 � 8.7 0.225 0.037
�1.4 � 7.8 0.902 0.985
an of the T scores of “Vigor/Activity” in POMS2 at the baseline into
placebo vs 600 mg.
Effects of Lactoferrin on Infectious Diseases in Summer 573
are available from the corresponding author on reasonable
request.
Declaration of Competing Interest
HO, HW, MT, KY, and FA are employees of Morinaga Milk
Industry. CS, HY, TS, and MK declare no conflicts of interest.
Acknowledgments
The authors thank all subjects, those in charge of clinical
examinations, and the allocation manager for their contri-
butions to the present study. Morinaga Milk Industry pro-
vided research funds and the test foods.
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	Effects of lactoferrin on infectious diseases in Japanese summer: A randomized, double-blinded, placebo-controlled trial
	Introduction
	Material and methods
	Trial design and ethical approval
	Subjects, eligibility, and exclusion criteria
	Intervention
	Primary, secondary, and exploratory endpoints
	Prevalence and duration of infectious diseases
	Immune parameters
	Sample size
	Randomization, allocation, and blinding
	Statistical analysis
	Results
	Discussion
	Declaration of Competing Interest
	Declaration of Competing Interest
	Acknowledgments
	References