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Photoprotection and skin whitening effect of dietary soy milk in healthy young female adults

Authors:
  • The National University of Malaysia, Kuala Lumpur, Malaysia
  • University Kebangsaan Malaysia Medical Center

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Journal of Pakistan Association of Dermatologists. 2020; 30(3): 412-417.
412
Address for correspondence
Dr. Adawiyah Jamil,
Department of Medicine,
University Kebangsaan Malaysia Medical Center,
Bandar Tun Razak, Cheras, 56000 Kuala Lumpur,
Malaysia.
PH: +060391456074
Email: adda_jamil@yahoo.com
Original Article
Photoprotection and skin whitening effect of dietary
soy milk in healthy young female adults
Introduction
Ultraviolet (UV) radiation from the sun has
multiple potentially detrimental effects on the
skin including skin cancers, photodermatoses,
photoaggravated diseases, photodamage and
photoaging. Photoprotective measures are
required for prevention and treatment of these
conditions. Midday sun avoidance, seeking
shade, topical sunscreens, protective clothing
and headgears are recommended sun protection
measures.1 However, sun-protective practices
are still largely inadequate2-4 despite sun safety
education due to the inconvenience of these
measures.3 A safe and effective oral sunscreen
would be ideal.
Soy (Glycemic max) is a legume that is high in
protein and fiber. Soy milk contains 3.5%
protein, 2.0% fat, 0.5% ash, 2.9%
carbohydrates5 and a high amount of isoflavone
that scavenger free radicals released by UV
exposure to prevent skin aging and protect
against UV induced skin damage.6 Genistein,
daidzein and glycitein are 3 major types of
isoflavone, soy milk contain mostly genistein. In
addition to UV protection, genistein lightens the
skin as it interferes with melanin synthesis
pathway by inhibiting melanin production.7-9
H Haron, A Jamil*, NA Awang Besar
Nutritional Sciences Programme, School of Healthcare Sciences, Faculty of Health Sciences
Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.
* Department of Medicine, University Kebangsaan Malaysia Medical Center, Bandar Tun Razak,
Cheras, Kuala Lumpur, Malaysia.
Abstract
Background Topical soy formulations improve signs of aging and protects against ultraviolet light.
We aimed to determine photoprotective and whitening effects of oral soy.
Methods Healthy volunteers drank commercial soy milk containing 20mg isoflavones twice daily
for 8 weeks, and avoided consumption of isoflavone-rich food, sunscreen and lightening products.
Phototest and skin colour measurement was performed at baseline and at the end of study.
Results Thirty healthy females aged 21(19-22) years with Fitzpatrick skin type III and IV
participated. Soy milk significantly increased whiteness at the cheek and gluteal regions. Minimal
erythema dose (MED) to UVA increased in 60% subjects, MED to UVB increased in 87%.
Significant reduction in UVB induced erythema was observed with all UVB doses, UVA induced
erythema decreased with higher doses.
Conclusion Short term regular consumption of soymilk showed photoprotection and skin whitening
effects.
Key words
Soy milk, photoprotection, whitening, minimal erythema dose, ultraviolet light.
Journal of Pakistan Association of Dermatologists. 2020; 30(3): 412-417.
413
Oral genistein has been shown to protect mice’s
skin from UV10 but its effect on human’s skin
has not been investigated. We conducted a study
to determine the effect of dietary soy milk in UV
protection and skin whitening in healthy young
females.
Methods
This was a prospective, open label interventional
cohort study performed over 8 weeks at the
Faculty of Health Science, Universiti
Kebangsaan Malaysia (UKM). Subjects were
recruited by convenience sampling among
students of the faculty. Inclusion criteria were
females aged 18-35 years old with no chronic
disease such as hypertension and diabetes,
individuals who like soy products and able to
fulfil the study requirements. Exclusion criteria
were known allergy to soy products,
photosensitivity or having skin that is sensitive
to sunlight, routine excessive exposure to the
sun (e.g. athletes), on any medicine or
supplements, and smokers.
Informed consent was obtained from volunteers
who fulfilled the inclusion and exclusion
criteria. Subjects completed a food frequent
questionnaire (FFQ)11 to determine their usual
dietary intake of soy products in the last 1
month. The FFQ consisted of 24 types of foods,
portions were determined using standard
measurements from Atlas of Food Exchange and
Portion Size.12 Subjects then underwent a 2
weeks washout period where they were asked to
avoid soy products, other photoprotective foods
and use of sunscreens. Baseline phototest and
skin colour assessments were then performed.
Subjects were instructed to consume 250mls of a
commercial soy milk in the morning with
breakfast (between 7-9am) and at noon with
lunch (between 12noon to 2pm) and to continue
avoiding other soy products, photoprotective
foods and use of sunscreens for the next 6
weeks. At the end of the study, phototest and
skin colour assessments were repeated.
The isofalvone dose required for its
photoprotective effect was estimated based on
an animal study performed by Wei et al.10 About
40mg of isoflavone per day was given to our
subjects by consuming a commercial soy milk
containing 6g of protein/ 250mls. The estimation
of isoflavone content in soy milk was based on
protein calculation proposed by Nagata et al.13
Photoprotective effects were measured by
phototest with UVB and UVA to determine the
degree of erythema induced on the skin by
multiple doses of UV. The minimal erythema
dose (MED) which is the lowest dose of UV
required to induce erythema were also
documented. Lower values of the degree of
erythema and higher MED indicates
photoprotective effects. The degree of erythema
was objectively measured using a mexameter.
Skin color was assessed at the right cheek to
represent a sun exposed area and the right
gluteal region to represent a covered area.
Chromameter measured the lightness or
whiteness of the skin while mexameter
measured melanin or darkness.
Calculated sample size was 30, based on results
from Heinrich et al.13 and adjusted for 10%
missing data. Ethical approval was obtained
from the UKM Research Ethics Committee
(UKMREC).
Results
Thirty healthy female subjects with median age
of 21 (19-22) years and Fitzpatrick skin type III
and IV participated in the study. The average
soy products intake based on FFQ was
66.66±111.50 g/day, while the average intake of
isoflavone was 22.82±39.40 mg/day. The most
common types of dietary soy products and the
amount consumed were commercial soy milk,
Journal of Pakistan Association of Dermatologists. 2020; 30(3): 412-417.
414
Table 1 The effect of soy milk on skin whiteness and darkness
Site
Whiteness (N=30)
Week 0
Median (IQR)
Week 6
Median (IQR)
p value
Week 0
Median (IQR)
Week 6
Median (Q1,Q3)
p value
Face
30.00
(2.89)
30.80
(3.61)
0.01
42.73
(3.78)
40.41
(4.63)
0.01
Gluteal
28.07
(8.52)
29.93
(8.22)
0.00
44.81
(9.63)
43.53
(9.72)
0.00
Figure 1 Type and amount of dietary soy products
Figure 2 Source and amount of dietary isoflavones
soy bean sprout, soft tofu pudding and fried tofu.
(Figure 1). Soy milk was the most consumed
soy product (30.20 g/day) and the highest source
of dietary isoflavone (7.01mg/day). The source
and amount of dietary isoflavones are
summarised in Figure 2.
Table 2 and 3 show changes in UVA and UVB
induced erythema on the skin before and after
soy milk consumption. Erythema was reduced
with all doses of UVA and UVB. The reductions
were significant with higher doses UVA at 4.5
and 5.0 J/cm2. Erythema with all doses of UVB
ranging from 32 to 130 mJ/cm2 were
significantly reduced.
1.73
2.26
2.62
3.98
5.77
6.1
6.32
30.2
0 5 10 15 20 25 30 35
Sambal Jawa
Sambal tempe
Japanese tofu
Fried tempe
Fried tofu
Soft tofu pudding
Soybean sprouts
Soy milk
Intake of soy products (g/day)
Type of soy products
0.74
1.65
1.89
2.17
2.48
3.58
7.01
012345678
Samabal Jawa
Soft tofu pudding
Sambal tempe
Soybean sprouts
Fried tofu
Fried tempe
Soy milk
Intake of isoflavones mg/day
Source of isoflavones
Journal of Pakistan Association of Dermatologists. 2020; 30(3): 412-417.
415
Table 2 Erythema induced by phototest with multiple
doses of UVA before and after soy milk consumption
UVA
dose
(J/cm2)
Erythema N=30
Week 0
Median (IQR)
Week 6
Median (IQR)
p
value
2.0
14.10(2.65)
13.43 (2.61)
0.09
2.8
14.99 (3.35)
14.15 ( 3.20)
0.05
3.5
14.88 (3.81)
14.35 (3.71)
0.74
4.3
14.77 (3.43)
14.30 (2.34)
0.02
5.0
15.91 (3.74)
14.07 (2.18)
0.00
Table 3 Erythema induced by phototest with multiple
doses of UVB before and after soy milk consumption
UVB
dose
(mJ/cm2)
Erythema (N=30)
Week 0
Median (IQR)
Week 6
Median (IQR)
p
value
32
14.92(3.81)
14.41(3.76)
0.03
44
15.45(3.15)
14.40(2.24)
0.03
56
15.66(3.33)
14.47(3.30)
0.05
68
15.87(3.42)
15.03(2.32)
0.01
80
16.51(3.68)
14.99(3.09)
0.00
52
15.81(4.71)
14.42(3.44)
0.01
72
16.41(4.92)
15.43(2.40)
0.04
91
16.85(4.22)
15.63(3.18)
0.00
111
17.55(3.47)
15.20(2.75)
0.00
130
17.63(3.54)
16.19(2.27)
0.00
The MED to UVA increased in 18(60%) of
subjects, while the MED to UVB increased in 26
(87%). Skin color measurements on the cheek
and gluteal region showed a significant increase
in whitening and reduction in darkness at both
sun exposed and covered areas. Whiteness of
face increased from 30.00 to 30.80 unit, p=0.01
while at the gluteal region, increment from 28.07
to 29.93 unit, (p=0.00) was observed (Table 1).
Synchronously, the measurement of skin
darkness/ melanin on the face decreased from
42.73 to 40.41 unit, p=0.0. The gluteal region
showed a decline in the melanin measurement
from 44.81 to 43.53 unit, p= 0.00 (Table 2).
There were no adverse effects reported
throughout the study.
Discussion
The amount of soy isoflavone intake in our
study population was slightly lower to that
reported in Japan,15,16 Hong Kong, Singapore,15
China17 and Korea.18 Asian diets in general are
richer in isoflavones compared to Western diet
and the sources of isoflavones differ as well.19-21
Isoflvones are mainly derived from peas, beans,
coffee, tea, nuts and grains in the west while soy
is the major source of isoflavones in Asia.19 Soy
milk was by far the most favoured product by
our subjects compared to soy prepared by
fermentation or traditional recipes. Most reports
on isoflavone intake in Asia were on middle
aged population that consumed more
concentrated forms of soy like tofu, paste and
curd,16,22,23 this explains the lower value seen in
our younger population that consumed soy
mainly as a drink.
Genistein and daidzein in soy have both
antioxidant and anti- inflammatory effect against
UV induced cell damage that results in skin
aging and predisposes to skin cancer.10,24,25
Genistein inhibits mitogen-activated protein
kinases in keratinocytes and fibroblasts which is
responsible for stimulation of matrix
metalloproteinases to produce collagenase,
gelatinase and stromelysin-1. These enzymes
break down collagen, elastin and other
components of the dermal matrix that results in
skin aging.26-28 Soybean trypsin inhibitor (STI)
and Bowman-Birk protease inhibitor (BBI) are
soy proteins that inhibit activation of
keratinocytes’ protease-activated receptor 2
(PAR-2).8,9 Activation of this receptor will
initiate transfer of melanosomes from
melanocytes to keratinocytes by phagocytosis.
In addition, soy isoflavones are potent inhibitors
of tyrosinase, the crucial enzyme in melanin
synthesis.29 Lightening of skin color occurs due
to reduced melanin production and reduction in
the number of melanosomes in keratinocytes.
Topical soy formulations has been shown to
reduce pigmentation, improve signs of aging like
wrinkling and elasticity of the skin and protects
against UVA and UVB.7,10,27,30,31 Oral
Journal of Pakistan Association of Dermatologists. 2020; 30(3): 412-417.
416
formulations produces the same pigmentary and
aging effects.10,30 The benefit of oral forms of
soy genistein and daidzein against UVA and
UVB have been demonstrated in vivo and in
vitro in mice and human skin cell
culture.10,24,25,30 It has not been documented in
humans to the best of our knowledge. Our
results revealed the photoprotective effect of
dietary soy against UV in healthy young adults.
Better protection was achieved against UVB as
significant reduction in UVB induced erythema
was observed from low doses. Protection against
UVA was observed only at higher doses. Skin
whitening was another effect seen at both sun
exposed and covered areas. A limitation of our
study is, quantity of isoflavone in soy milk was
estimated based on its protein content, it was not
objectively measured. However, our results
illustrate soy isoflavone‘s potential as oral
sunscreen with added benefits of skin lightening
and reduction in skin aging. The optimal dose of
isoflavone or genistein and daidzein, and a
detailed side effect profile in long term use need
to be further determined. In conclusion, dietary
soy milk is protective against UVA and UVB
and whitens the skin. Its potential as oral
sunscreen and skin whitening agent needs to be
further evaluated.
Acknowledgements
The authors would like to thank Pn. Julianah
Ramli and Pn. Nur Arifah Muhd Rafiee for their
technical assistance in performing the
phototests.
References
1. Sun protection.
http://www.who.int/uv/sun_protection/en/
(accessed on 4 May 2018).
2. Reinau D, Weiss M, Meier CR et al.
Outdoor workers’ sun-related knowledge,
attitudes and protective behaviours: a
systemic review of cross-sectional and
interventional studies. Br J Dermatol.
2013;168(5): 928-40.
3. Reinau D, Melier C, Gerber N et al. Sun
protective behavior of primary and
secondary school students in North-Western
Switzrland. Swiss Med Wkly 2012; 142:
w13520.
4. Shirley Y, Yang BS, Bernstein I et al.
Photoprotective habits of cutaneous lupus
erythematosus patients. J Am Acad
Dermatol 2013; 68: 944-51.
5. Ikya J, Gernah D, Ojobo H et al. Effect of
cooking temperature on some quality
characteristics of soy milk. Adv J Food Sci
Technol 2013; 5(5): 543-6.
6. Iovine, B, Iannella ML, Gasparri F et al.
Synergic effect of genistein and daidzein on
UVB-induced DNA damage: an effective
photoprotective combination. J Biomed
Biotechnol 2011; 2011: 692846.
7. Huang ZR, Hung CF, Lin YK et al. In vitro
and in vivo evaluation of topical delivery
and potential dermal use of soy isoflavones
genistein and daidzein. Int J Pharm 2008;
364(1): 36-44.
8. Seiberg M, Paine C, Sharlow E et al.
Inhibition of melanosome transfer results in
skin lightening. J Invest Dermatol 2000;
115(2):1627.
9. Paine C, Sharlow E, Liebel F et al. An
alternative approach to depigmentation by
soybean extracts via inhibition of the PAR-2
pathway. J Invest Dermatol 2001:116(4):
58795.
10. Wei H, Saladi R, Lu Y et al. Isoflavone
genistein: photoprotection and clinical
implications in dermatology. J Nutr 2003;
133: 3811S-19S.
11. Haron H. Calcium absorption and
bioavailability of isoflavones from tempeh
compared to milk among postmenopausal
Malay women. Kuala Lumpur: Universiti
Putra Malaysia, 2009.
12. Shahar S, Safii NS, Abdul Manaf Z et al.
Atlas of Food Exchange and Portion Size.
Third edition. Kuala Lumpur: MDC
Publishers, 2015.
13. Nagata C, Takatsuka N, Kurisu Y et al.
Decreased serum total cholesterol
concentration is associated with high intake
of soy products in Japanese men and
women. J Nutr 1998; 128(2): 209-13.
14. Heinrich U, Neukam K, Tronnier H et al.
Long-term ingestion of high flavanol cocoa
provides photoprotection against UV-
induced erythema and improves skin
Journal of Pakistan Association of Dermatologists. 2020; 30(3): 412-417.
417
condition in women. J. Nutr 2006; 136(6):
156569.
15. Messina M, Nagata C, Wu AH. Estimated
Asian adult soy protein and isoflavone
intakes. Nutrition and Cancer 2006; 55(1):
1-12.
16. Arai Y, Watanabe S, Kimira M et al.
Dietary intakes of flavonols, flavones and
isoflavones by Japanese women and the
inverse correlation between quercetin intake
and plasma LDL cholesterol concentration. J
Nutr 2000; 130(9): 224350.
17. Lee SA, Wen W, Xiang YB et al.
Assessment of dietary isoflavone intake
among middle-aged chinese men. J Nutr.
2007; 137(4): 101116.
18. Surh J, Kim MJ, Koh E et al. Estimated
intakes of isoflavones and coumestrol in
Korean population. Int J Food Sci Nutr
2006; 57(5-6):325-44.
19. Boker LK, Van Der Schouw YT, De Kleijn
MJ et al. Intake of dietary phytoestrogens
by Dutch women. J Nutr 2002; 132(6):
1319-28.
20. Horn-Ross PL, Lee M, John EM et al.
Sources of phytoestrogen exposure among
non-Asian women in California, USA.
Cancer Causes Control 2000; 11(4): 299
302.
21. De Kleijn MJJ, Van der Schouw YT, Wilson
PWF et al. Intake of dietary phytoestrogens
is low in postmenopausal women in the
United States: the Framnigham study. J Nutr
2001; 131(6): 182632.
22. Chan SG, Ho SC, Kreiger N et al. Dietary
sources and determinants of soy isoflavone
intake among midlife Chinese women in
Hong Kong. J Nutr 2007;137(11): 245155.
23. Surh J, Kim MJ, Koh E et al. Estimated
intakes of isoflavones and coumestrol in
Korean population. Int J Food Sci Nutr
2006; 57(5-6):325-44.
24. Iovine B, Iannella ML, Gasparri F et al. A
comparative analysis of the photo-protective
effects of soy isoflavones in their aglycone
and glucoside forms. Int J Mol Sci 2012;
13(12): 16444-56.
25. Moore JO, Wang Y, Stebbins WG et al.
Photoprotective effect of isoflavone
genistein on ultraviolet B-induced
pyrimidine dimer formation and PCNA
expression in human reconstituted skin and
its implications in dermatology and
prevention of cutaneous carcinogenesis.
Carcinogenesis 2006; 27(8):1627-35.
26. Fisher GJ, Datta SC,Talwar HS et al.
Molecular basis of sun-induced premature
skin aging and retinoid antagonism. Nature
1996; 379(6563) :335-39.
27. Fisher GJ, Wang ZQ, Datta SC et al.
Pathophysiology of premature skin aging
induced by ultraviolet light. N Engl J Med
1997; 337(20):1419-28.
28. Kang S, Chung JH, Lee JH et al. Topical N-
acetyl cysteine and genistein prevent
ultraviolet-light-induced signaling that leads
to photoaging in human skin in vivo. J
Invest Dermatol 2003; 120(5): 835-41.
29. Chang TS, Ding HY, Lin HC. Identifying
6,7,4′-trihydroxyisoflavone as a potent
tyrosinase inhibitor. Biosci Biotechnol
Biochem 2005; 69(10);1999-2001.
30. Izumi T, Saito M, Obata A et al. Oral intake
of soy isoflavone aglycone improves the
aged skin of adult women. J Nutr Sci
Vitaminol 2007; 53(1): 57-62.
31. Miyazaki K, Hanamizu T, Iizuka R et al.
Bifidobacterium-fermented soy milk extract
stimulates hyaluronic acid production in
human skin cells and hairless mouse skin.
Skin Pharmacol Appl Skin Physiol 2003;
16(2): 108-16.
32. Kim SY, Kim SJ, Lee JY et al. Protective
Effects of dietary soy isoflavones against
UV-induced skin-aging in hairless mouse
model. J Am Coll Nutr 2004; 23(2): 157-62.
... (Heinrich et al., 2011) Daidzein Daidzein-containing soy products were consumed orally by thirty healthy women over eight weeks, and the results demonstrated significant photoprotection with minimum erythema dosage to UVA increased by 60% and to UVB increased by 87%. (Haron et al., 2020) Glycitein Over eight weeks, thirty healthy women consumed soy products containing glycitein orally, and the results showed considerable photoprotection with minimum erythema dosage to UVA increased by 60% and to UVB increased by 87%. (Haron et al., 2020) Hesperetin Hesperetin formulations with enhancers (D-limonene and lecithin) were effective as topical photoprotective agents on six volunteers (25-35 years old). ...
... (Haron et al., 2020) Glycitein Over eight weeks, thirty healthy women consumed soy products containing glycitein orally, and the results showed considerable photoprotection with minimum erythema dosage to UVA increased by 60% and to UVB increased by 87%. (Haron et al., 2020) Hesperetin Hesperetin formulations with enhancers (D-limonene and lecithin) were effective as topical photoprotective agents on six volunteers (25-35 years old). (Saija et al., 1998) Naringenin As topical photoprotective agents in six participants (25-35 years old), naringenin formulations with enhancers (D-limonene and lecithin) proved successful. ...
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Background:  Sun protection is a major concern for outdoor workers as they are particularly exposed to solar ultraviolet radiation and therefore at increased risk of developing some forms of skin cancer, cataract, and ocular neoplasm. Objectives:  First: to provide an overview of outdoor workers' sun-related knowledge, attitudes, and protective behaviours as reported in the literature. Second: to evaluate the effectiveness of sun safety education programmes in outdoor occupational settings. Methods:  We conducted a systematic review of the literature by searching three electronic databases (PubMed, Embase, PsycINFO) from their inception up to 25 April 2012. An extensive hand search complemented the database searches. Results:  We identified 34 relevant articles on descriptive studies and 18 articles on interventional studies. Considerable numbers of outdoor workers were found to have sun sensitive skin types; sunburn rates per season ranged from 50% to 80%. Data concerning outdoor workers' sun-related knowledge and attitudes were scarce and controversial. The reported sun protective behaviours were largely inadequate, with many workers stating that they never or only rarely wore a long-sleeved shirt (50-80%), sun protective headgear (30-80%), and sunscreen (30-100%) while working in the sun. However, there is growing evidence that occupational sun safety education is effective in increasing outdoor workers' sun protection habits and presumably in decreasing sunburn rates. Conclusions:  Occupational sun safety education programmes offer great potentials for improving outdoor workers' largely insufficient sun protective behaviours. It is hoped that in the future committed support from the Healthcare Authorities, cancer foundations, employers and dermatologists open the way for rapid and uncomplicated implementation of sun safety education programmes.
Article
The chemical basis of melanogenesis is well documented, but the mechanism of melanosome transfer and the regulation of pigmentation by keratinocyte–melanocyte interactions are not well understood. Therefore we examined the effects of serine protease inhibitors on skin pigmentation and found that the protease-activated receptor 2, expressed on keratinocytes, may regulate pigmentation via keratinocyte–melanocyte interactions. Here we show that modulation of protease-activated receptor 2 activation affects melanosome transfer into keratinocytes, resulting in changes in pigment production and deposition. SLIGRL, the protease-activated receptor 2 activating peptide, enhanced melanosome ingestion by keratinocytes, thus increasing pigment deposition. RWJ-50353, a serine protease inhibitor, led to reduced pigment deposition in melanocytes and depigmentation. Electron microscopy studies illustrated an accumulation of immature melanosomes inside melanocytes and abnormal dendrite dynamics in RWJ-50353-treated epidermal equivalents. RWJ-50353 induced a visible and dose-dependent skin lightening effect in the dark-skinned Yucatan swine. Examinations by electron microscopy indicated that the in vivo transfer of melanosomes from melanocytes to keratinocytes was affected. Our data suggest that modulation of keratinocyte–melanocyte interactions via the protease-activated receptor 2 pathway affects melanosome transfer. The use of RWJ-50353 to modulate protease-activated receptor 2 activation could lead to a new class of depigmenting agents.Keywords: PAR-2, RWJ-50353
Article
Higher consumption of phytoestrogens might be protective against certain chronic diseases. Accurate quantification of habitual phytoestrogen intake is important for assessing associations between phytoestrogens and risk for certain diseases. The aim of this study was to estimate dietary intake of phytoestrogens in Dutch middle-aged and elderly women and to describe their main sources. Women were recruited between 1993 and 1997 and aged 50-69 y at enrollment (Prospect-EPIC; n = 17,357). A detailed food frequency questionnaire referring to the preceding year was filled in at recruitment. A literature search was conducted to obtain data regarding content of the isoflavones daidzein, genistein, formononetin, biochanin A, the coumestan coumesterol and the lignans matairesinol and secoisolariciresinol in relevant food items. Concentrations of each phytoestrogen in each food item were subsequently grouped by seven categories; group scores were multiplied by daily intakes of food items and then summed across food items to produce for each participant a total daily intake score for each phytoestrogen. Approximately 75% of participants were postmenopausal at recruitment. The mean age was 57 y. Geometric means of daily intake of daidzein, genistein, formononetin, biochanin A, coumesterol, matairesinol and secoisolariciresinol were 0.15, 0.16, 0.08, 0.001, <0.001, 0.07 and 0.93 mg, respectively. The main sources for isoflavones were peas and beans, nuts, grain products, coffee, tea and soy products. The main sources for coumestans were peas, beans and other vegetables. The main sources of lignans were grain products, fruit and alcoholic beverages (red and white wines). We conclude that intake levels of phytoestrogen in our study population are low; however, they are comparable with intake levels previously reported for other Western cohorts. In this population, phytoestrogen intake consisted largely of lignans.
Article
Genistein, daidzein, and glycitein are soy isoflavones. These compounds can be used to protect the skin from oxidative stress induced by UVB radiation. To this end, the feasibility of skin absorption of soy isoflavones was evaluated in the present study. As assayed by flow cytometry, UVB-induced H(2)O(2) production in keratinocytes was inhibited by genistein and daidzein, confirming that these two compounds can act as free radical scavengers when keratinocytes are photodamaged. Glycitein showed no protective activity against photodamage. The effects of vehicles on the in vitro topical delivery from saturated solutions such as aqueous buffers and soybean oil were investigated. The isoflavones in a non-ionized form (pH 6) showed higher skin deposition compared to the ionized form (pH 10.8). Soybean oil reduced the isoflavone amount retained in the skin, especially for genistein. Genistein generally exhibited greater skin absorption than did daidzein. However, daidzein permeation was enhanced when an aglycone mixture was used as the active ingredient. An eutectic effect was proposed as the enhancing mechanism. In vivo skin deposition showed a linear correlation with the in vitro results. The safety profiles suggested no or only negligible stratum corneum disruption and skin erythema by topical application of soy isoflavones. It was concluded that topical delivery may serve as a potent route for soy isoflavones against photoaging and photodamage.