Soy
products and their health-giving properties.
Possibly
the best known effect of soy products is their ability to help women during pre-menstrual tension and the menopause. For
more information on this you can contact the Women’s Nutritional Advisory
Service (http://www.wnas.org.uk) and see
one of many scientific papers I’ve found on use of estrogenic
plant extracts for the treatment of menopausal symptoms (N.B. an underlined
section constitutes a direct hyperlink to a summary of the publication referred
to). Latest discoveries show that it isn’t only women that benefit from
including regular soy products in their diet – men are protected from prostate
cancer and heart disease by a regular intake of soy, not to mention evidence
that they can help osteoporosis, and diabetes. In this newsletter I’ll concentrate on
cancer prevention and particularly findings on breast and prostate
cancer.
Why
do soy products help?
Like
some other plants, the soya bean contains isoflavones or phytoestrogens
which are chemically similar to estrogen and to artificial xenoestrogens,
which are increasingly finding their way into the environment. Because of this similarity,
phytoestrogens are able to block the absorption of excessive amounts of estrogen
by certain cells in the body.
Excessive stimulation by high levels of estrogen and estrogen-like
compounds is believed to precipitate certain forms of cancer, mainly in the
reproductive organs.
Breast
cancer:
Soy phytoestrogens have been to have a
preventative effect. Asian women
eating an Asian diet have a 10-20 fold lower risk of dying of breast cancer than
Western women; this effect seems to be strongest if soy
products are eaten from adolescence or even earlier. However, there is also evidence that
phytoestrogens
protect from post menopausal breast cancer
.
Prostate
cancer:
Some
years ago, a series of post mortems carried out on Japanese men who had died of
causes other than prostate cancer found that prostate cancer was actually
present in about the same proportion of them as in western men. This field is
reviewed by Dr Adlercreutz in Phytoestrogens
and western disease. The
interesting thing was that these cancers had not grown, but remained so small
that they presented no danger. This
was related to a high consumption of tofu (eating it every day); see below for
hints on how to get soy products into a western diet. Among the interesting papers I have
found on this subject are one on nutrition
and prostate cancer and another more specifically on soy,
disease prevention and prostate cancer .
A complete list
of scientific paper on this subject is available by
contacting me, drmcelroy@collectiveability.co.uk
.
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Getting
soy products into your diet:
The
problem for westerners is that of finding a way of including it in our diet that
is easy and fits in with our ordinary dietary style. I happen to love Japanese
and Chinese food, so stir-fry tofu (soy-bean curd) very happily, but not
everyone can tolerate a non-western diet.
Here
are a few ideas if you want to have a go at adding a bit of soya protection to
your diet:
·
Use
Soya “milk” in baking, making scrambled eggs, pancakes, omelettes. Not sauces,
unless you are very confident, because soya milk tends to
separate.
·
Add
a little soya flour whenever you use flour – you won’t notice the
taste.
·
Use
soya margarine and soya oil
·
Sorry
– soy sauce doesn’t have the goodies in it. It does brighten up stir-fried tofu,
though.
·
If
you like beany things (Chile con Carne?) have some soy beans soaked and cooked
in the freezer to add to the haricot beans or whatever you are using. Again, the
taste of the beans is pretty bland and they can make themselves invisible in a
full-flavoured dish – but still be useful!
·
A
useful thing is that flavourings such as grated ginger, crushed garlic,
turmeric, bay leaves, and of course onions, peppers and celery, are all healthy
ingredients in an Eat Yourself Well diet.
Most
of the ingredients I’ve mentioned are available in Sainsbury’s and
any good quality supermarket, or (in Beeston, Nottinghamshire, our home town) in
Out Of This World – the wholefood shop opposite the Sainsbury’s
car park, or your own local wholefood shop.
More tofu recipes can be found by
entering "tofu" in the search engine of Recipes4us, including some
submitted by Maggi. See our Links page for
details.
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Information:
– We have a growing list of information leaflets available from Collective
Ability, printed in the same format as this newsletter. Just give us a ring if
you would like some or all of them.
As of this date they include :
·
Antioxidants
– what exactly are they?
·
Growing
Healthy Humans
·
Hints
for Intimate Hygiene
·
Smokers
·
Nutrition
and cancer
We
are researching the research all the time, so if you want to know about
something that you haven’t seen covered, let us know and we will do our best to
get you up-to-date information. We would also very much appreciate comments
about what you’d find useful to have in the newsletter, and anything that you’d
like to contribute yourself.
APPENDIX
References from May/June 2001 Collective Ability
newsletter (in the order in which they appear).
J Agric Food Chem 2001 May;49(5):2472-9
Evaluation
of estrogenic activity of plant extracts for the potential treatment of
menopausal symptoms.
Liu J, Burdette JE, Xu H, Gu C, van Breemen RB, Bhat KP, Booth N,
Constantinou AI, Pezzuto JM, Fong HH, Farnsworth NR, Bolton JL.
Department of Medicinal Chemistry and Pharmacognosy, UIC/NIH Center for
Botanical Dietary Supplements Research, College of Pharmacy, M/C 781, University
of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612, USA.
Eight botanical preparations that are commonly used for the treatment of
menopausal symptoms were tested for estrogenic activity. Methanol extracts of
red clover (Trifolium pratense L.), chasteberry (Vitex agnus-castus L.), and
hops (Humulus lupulus L.) showed significant competitive binding to estrogen
receptors alpha (ER alpha) and beta (ER beta). With cultured Ishikawa (endometrial)
cells, red clover and hops exhibited estrogenic activity as indicated by
induction of alkaline phosphatase (AP) activity and up-regulation of
progesterone receptor (PR) mRNA. Chasteberry also stimulated PR expression, but
no induction of AP activity was observed. In S30 breast cancer cells, pS2
(presenelin-2), another estrogen-inducible gene, was up-regulated in the
presence of red clover, hops, and chasteberry. Interestingly, extracts of Asian
ginseng (Panax ginseng C.A. Meyer) and North American ginseng (Panax
quinquefolius L.) induced pS2 mRNA expression in S30 cells, but no significant
ER binding affinity, AP induction, or PR expression was noted in Ishikawa cells.
Dong quai [Angelica sinensis (Oliv.) Diels] and licorice (Glycyrrhiza glabra L.)
showed only weak ER binding and PR and pS2 mRNA induction. Black cohosh [Cimicifuga
racemosa (L.) Nutt.] showed no activity in any of the above in vitro assays.
Bioassay-guided isolation utilizing ER competitive binding as a monitor and
screening using ultrafiltration LC-MS revealed that genistein was the most
active component of red clover. Consistent with this observation, genistein was
found to be the most effective of four red clover isoflavones tested in the
above in vitro assays. Therefore, estrogenic components of plant extracts can be
identified using assays for estrogenic activity along with screening and
identification of the active components using ultrafiltration LC-MS. These data
suggest a potential use for some dietary supplements, ingested by human beings,
in the treatment of menopausal symptoms.
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Cancer Epidemiol Biomarkers Prev 2001 May;10(5):483-8
Soyfood
intake during adolescence and subsequent risk of breast cancer among Chinese
women.
Shu XO, Jin F, Dai Q, Wen W, Potter JD, Kushi LH, Ruan Z, Gao YT, Zheng W.
Vanderbilt University School of Medicine, Center for Health Service Research,
Nashville, Tennessee 37232, USA. Xiao-Ou.Shu@mcmail.vanderbilt.edu
Many experimental but few epidemiological studies have suggested that soyfoods
and their constituents have cancer-inhibitory effects on breast cancer. No
epidemiological study has evaluated the association of adolescent soyfood intake
with the risk of breast cancer. To evaluate the effect of soyfood intake during
adolescence, one of the periods that breast tissue is most sensitive to
environmental stimuli, on subsequent risk of breast cancer, we analyzed data
from a population-based case-control of 1459 breast cancer cases and 1556
age-matched controls (respective response rates were 91.1% and 90.3%).
Information on dietary intake from ages 13-15 years was obtained by interview
from all study participants and, in addition, from mothers of subjects less than
45 years of age (296 cases and 359 controls). Odds ratios (ORs) and 95%
confidence intervals (CIs) derived from unconditional logistic models were used
to measure soyfood intake and breast cancer risk. After adjustment for a variety
of other risk factors, adolescent soyfood intake was inversely associated with
risk, with ORs of 1.0 (reference), 0.75 (95% CI, 0.60-0.93), 0.69 (95% CI,
0.55-0.87), 0.69 (95% CI, 0.55-0.86), and 0.51 (95% CI, 0.40-0.65),
respectively, for the lowest to highest quintiles of total soyfood intake (trend
test, P < 0.001). The inverse association was observed for each of the
soyfoods examined and existed for both pre- and postmenopausal women. Adolescent
soyfood intakes reported by participants' mothers were also inversely associated
with breast cancer risk (P for trend < 0.001), with an OR of 0.35 (95% CI,
0.21-0.60) for women in the highest soyfood intake group. Adjustment for rice
and wheat products, the major energy source in the study population, and usual
adult soyfood intake did not change the soyfood associations. Our study suggests
that high soy intake during adolescence may reduce the risk of breast cancer in
later life.
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Menopause 2000 Sep-Oct;7(5):289-96
Comment in: Menopause. 2000 Sep-Oct;7(5):283-5
Phytoestrogens
and breast cancer in postmenopausal women: a case control study.
Murkies A, Dalais FS, Briganti EM, Burger HG, Healy DL, Wahlqvist ML, Davis
SR.
Jean Hailes Foundation, Clayton, Victoria, Australia.
OBJECTIVE: To examine the association between isoflavones, androgens, and
dietary composition and the risk of breast cancer in Australian postmenopausal
women. DESIGN: Eighteen women with recently diagnosed breast cancer before
surgery and 20 controls were recruited over a 12-month period. Both cases and
controls were similarly assessed for urinary isoflavones, serum and urinary
sex steroids, and dietary intake. RESULTS: Women with breast cancer had lower
24-h urinary daidzein compared with controls (cases: 31 [95% CI: 4, 234] nmol/day;
controls: 427 [95% CI: 4, 234] nmol/day; p = 0.03), and there was a trend to
lower urinary genistein excretion (cases: 25 [95% CI: 5, 132] nmol/day;
controls: 155 [95% CI: 43, 550] nmol/day; p = 0.08). Total testosterone was
higher in women with breast cancer compared with controls (cases: 1.3 [95% CI:
1.1, 1.5] nmol/L; controls: 1.0 [95% CI: 0.8, 1.11 nmol/L; p = 0.05). No
significant differences were found for serum sex hormone binding globulin,
free androgen index, dehydroepiandrosterone sulphate, estradiol and
progesterone, or in urinary androgen metabolites, or in dietary intake with
regard to fat, carbohydrate, protein, or fiber consumption between cases and
controls. CONCLUSIONS: This preliminary study is the first report of low
urinary daidzein and genistein in postmenopausal women with breast cancer.
These findings are in keeping with the increasing observational data
demonstrating a protective effect from phytoestrogens on breast cancer risk.
Ann Med 1997 Apr;29(2):95-120
Phyto-oestrogens
and Western diseases.
Adlercreutz H, Mazur W.
Department of Clinical Chemistry, University of Helsinki, Meilahti Hospital,
Finland. herman.adlercreutz@helsinki.fi
Incidences of breast, colorectal and prostate cancer are high in the Western
world compared to countries in Asia. We have postulated that the Western diet
compared to the semivegetarian diet in some Asian countries may alter hormone
production, metabolism or action at the cellular level by some biochemical
mechanisms. Our interest has been focused on two groups of hormone-like
diphenolic phyto-oestrogens of dietary origin, the lignans and isoflavonoids
abundant in plasma of subjects living in areas with low cancer incidence. The
precursors of the biologically active compounds detected in man are found in
soybean products, whole-grain cereal food, seeds, and berries. The plant lignan
and isoflavonoid glycosides are converted by intestinal bacteria to hormone-like
compounds. The weakly oestrogenic diphenols formed influence sex-hormone
production, metabolism and biological activity, intracellular enzymes, protein
synthesis, growth factor action, malignant cell proliferation, differentiation,
cell adhesion and angiogenesis in such a way as to make them strong candidates
for a role as natural cancer-protective compounds. Their effect on some of the
most important steroid biosynthetic enzymes may result in beneficial modulation
of hormone concentrations and action in the cells preventing development of
cancer. Owing to their oestrogenic activity they reduce hot flushes and vaginal
dryness in postmenopausal women and may to some degree inhibit osteoporosis, but
alone they may be insufficient for complete protection. Soy intake prevents
oxidation of the low-density lipoproteins in vitro when isolated from
soy-treated individuals and affect favourably plasma lipid concentrations.
Animal experiments provide evidence suggesting that both lignans and
isoflavonoids may prevent the development of cancer as well as atherosclerosis.
However, in some of these experiments it has not been possible to separate the
phyto-oestrogen effect from the effect of other components in the food. The
isoflavonoids and lignans may play a significant inhibitory role in cancer
development particularly in the promotional phase of the disease, but recent
evidence points also to a role in the initiation stage of carcinogenesis. At
present, however, no definite recommendations can be made as to the dietary
amounts needed for prevention of disease. This review deals with all the
above-mentioned aspects of phyto-oestrogens.
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Nutr Cancer 1994;22(1):1-10
Nutrition
and prostate cancer: a proposal for dietary intervention.
Wynder EL, Rose DP, Cohen LA.
Division of Epidemiology, American Health Foundation, New York, NY 10017, USA.
In this review, we consider the evidence from geographic and metabolic
epidemiology and laboratory studies with human prostate cancer cell lines and
animal models that emphasizes the need for the development and implementation of
a dietary intervention trial in prostate cancer patients. It is concluded that
such a trial should include a reduction in total fat consumption to 15% of total
calories and supplementation of the diet with selenium, vitamin E, and a soya
product. The low-fat intervention would provide an appropriate reduction in the
intake of any specifically targeted dietary fatty acid, such as linoleic acid or
alpha-linolenic acid.
Semin Urol Oncol 1999 May;17(2):97-102
Soy,
disease prevention, and prostate cancer.
Moyad MA.
Section of Urology, University of Michigan, Ann Arbor 48109-0330, USA.
Population-based studies from around the world support the theory that soy
products and their constituents, primarily the isoflavones or phytoestrogens,
are partly responsible for the lower rates of certain chronic diseases in
different areas of the world. Cardiovascular disease and hormonally induced
cancers are just a few of the conditions lower in Asian countries that consume
large quantities of soy per average person. Genistein, one of soy's individual
phytoestrogens, has been found to inhibit numerous breast and prostate cancer
cell lines. A limited amount of clinical evidence also points to a beneficial
role of soy in reducing hormonal levels and exhibiting weak estrogen and
antiestrogen-like qualities. Other phytoestrogens found in nature, such as
lignans, may also have a future role in cancer. Collectively, these
phytoestrogens, like genistein, have enough evidence to warrant their use in a
number of clinical trials as a potential chemopreventive agent or adjunct to
prostate cancer treatment.
