Ideal diet

The ideal diet is high in fibre, vegetables, fish protein, unprocessed cereals and grains, and mono-unsaturated fat, not saturated (animal) fat.

'Colourful' fruit and vegetables are the most nutritious in terms of vitamins and minerals. High fibre diets protect against high cholesterol and heart disease, colon cancer and possibly other cancers. 

Fish contains omega - 3 fatty acids which can reduce blood fats and blood clotting, and fish bones (sardines and tinned salmon) are a rich source of calcium. What about phytoestrogens? 

What are phytoestrogens?

Phytoestrogens are compounds that occur naturally in plants (phyto) and under certain circumstances can have actions like human oestrogen. When eaten they bind to oestrogen receptors and may act in a similar way to oestrogen. However, phytoestrogens are much weaker, so their effects are different from those of hormones found in Hormone Therapy, (HT). 

The consumption of a phytoestrogen-rich diet has been linked to reduced rates of heart disease and cancer. However, the populations known to have a high phytoestrogen intake also consume predominantly fruit and vegetables and have little animal fat. Hence it is not yet known whether the lower disease rates in these communities is due to the overall healthy diet and lifestyle or is linked to the specific effects of phytoestrogens. 

It is essential that a distinction be made between nutrients consumed in food and as supplements taken as powders or pills. We need to understand that the latter are not "natural" therapy, but rather pharmacotherapy, which can have adverse effects and should be evaluated with the same rigour as conventional pharmaceuticals. Phytoestrogens fall into this category, and taking phytoestrogen supplements as milk concentrate, flour or in tablet form can not be justified at this stage. There is no evidence that phytoestrogen supplements are more effective than placebo for relieving menopausal symptoms. Further, safety, particularly in terms of oestrogenic effects on the breast, has yet to be established. Of specific concern is the use of phytoestrogen supplements in women who have had breast cancer, and potential interference with the therapeutic effects of tamoxifen.

Phytoestrogens are classified according to their chemical structure. The two groups which have been most researched are 

• the isoflavones, such as soy and 
• the lignans which occur in linseed, grains and vegetables. 

There is much interest on the effects of these compounds on menopausal symptoms, heart disease, bone and cancer. 

Phytoestrogens containing foods have been found to have 

• heart disease prevention action; 
• possible anti-cancer properties - but more research is needed; and 
• possible role in the prevention of osteoporosis although more research is needed

Phytoestrogens and heart disease 

Consuming a diet high in soy may lower total and LDL cholesterol in men and women. Animal studies also indicate components of soy protein may have beneficial effects on blood vessel function. The observed benefits are greater for natural soy protein (tofu or soy flour) than for the extracted phytoestrogens alone. 

Cancer

There is some evidence to suggest that phytoestrogens may protect against cancer of the breast and uterus. The anti-cancer effects may be because phytoestrogens compete with the oestrogen made by our bodies. Phytoestrogens also have anti-cancer effects which are unrelated to their oestrogen actions which appear to be important. 

• A high phytoestrogen diet in early life may be important for the anti-cancer effects of phytoestrogens in later life. 
• Phytoestrogens may compete with the oestrogen in our bodies and this may help prevent cancer before menopause, but it is not certain that this effect persists after menopause. 

Further study is needed into the effects, as safety of high doses of phytoestrogens after menopause is needed before a very high intake of these compounds can be recommended for postmenopausal women. 

Phytoestrogens and women's health 

When phytoestrogens act as oestrogens they are much much weaker than the oestrogen produced in humans. Published studies mostly indicate that increased consumption of phytoestrogens (soy/linseed) by postmenopausal women is no more effective than placebo (wheat diet) on reducing hot flushes. 

There is no evidence that either soy or linseed alleviate other common menopausal symptoms. 

General recommendations

Multiple lifestyle factors including the food we eat are related to good health and protect against disease. Improving diet at any stage of life will result in health benefits, but it may be that phytoestrogen intake needs to be life-long and in the context of a healthy diet and lifestyle for the protective effects to be significant.

Food sources

So far, we know that legumes particularly soybeans, whole grain cereals, and seeds are high in phytoestrogen. Research into the content in Australian food is continuing.

The content varies in different foods with some foods exerting a stronger effect than others. The content varies within the same group of foods eg soy beverages depending on processing and type of soy bean used.

Foods containing Phytoestrogens

• soy beans  
• dried beans
• tofu 
• lentils
• tempeh 
• rice
• soy beverages 
• alfalfa
• linseed 
• mung beans
• sesame seeds 
• apples
• wheat 
• carrots
• berries 
• wheat germ
• oats 
• ricebran
• barley 
• soy linseed bread

There are a variety of soy products now readily available. Make sure you buy ‘calcium’ enriched soy milk for your bone health.

How much each day?

Many foods such as soy foods are not a regular part of the Australian diet. We need to make changes to the way we eat to get the benefits of these foods. Try including at least one serve of these foods daily:

• 2-4 slices soy and linseed bread, or multi-grain (for lignans)
• 1-2 cups soy milk
• 150 grams tofu
• 30-40g linseed
• 1 cup soy beans or other legumes

Try to have a wide variety of plant foods every day, including some of the above.

How to include these foods in your diet 

• Replace some meat meals with cooked dried beans
• Add linseed to breakfast cereal
• Make a fruit smoothie with soy milk or half cow’s milk, half soy
• Add firm tofu to stir fries
• Make your own muesli with rolled oats, wheatgerm, linseed, sesame seeds, dried fruit and nuts.

Useful Resources Books

Available from the Jean Hailes Foundation for Women's Health Shop. 

Nutrition for Life By Catherine Saxelby (2005) An excellent family reference book on all matters related to nutrition and is highly recommended. Calm Eating By Dr Rick Kausman (2001)           Anyone who's ever felt out of control around food will recognise that to relax and enjoy food. Color Me Healthy By Rita Erlich & Dr Alice Murkies (2001) Its message is simple and positive: eat (almost) everything. If Not Dieting, Then What? By Dr Rick Kausman (1998) Is a straightforward, no-nonsense guide to weight management.

  Content updated August 14, 2006