Men's Health - Practitioner Review 2

Men's Health - What evidence is there that diet can influence the health of the prostate gland?

Prostate disease is one of the most common health problems Men may have to face at some time in their lives. This article takes a look at what evidence there is that dietary factors may be behind the growing incidence of prostate problems and how increasing phytosterol intakes could help men to keep their prostate healthy!

If any of your clients are male and over 30, the chances are you might wish to talk to them about a subject that is often avoided or overlooked - helping them to keep their prostate healthy.

While there is high level of public attention and awareness of health issues like obesity, heart disease and breast cancer, for a variety of reasons the male problems of prostate cancer and Benign Prostatic Hypertrophy (BPH) are not commonly publicised, and awareness amongst many people is low.   However, when you look at the statistics for incidence of these male health problems they are a major cause for concern.  

How common are prostate problems?

It is estimated from studies that 15% of men aged 50 in the UK have microscopic prostate cancer, rising to 40% in men aged 75 or over. Fortunately most cases of microscopic prostate cancer remain undetected and dormant: in other words they do not go on to cause life threatening disease - but an unacceptably high number of cases do go on to cause problems and require treatment.

The condition of Benign Prostatic Hyperplasia or BPH is not life-threatening, but is a troublesome condition where the prostate gland becomes enlarged.   The enlargement of the gland can cause an obstruction of the urethra leading to urinary frequency problems, urinary tract infections and discomfort.   Most often a diagnosis is made when patients go to visit their doctor complaining about the need to get up several times a night or more to go to the toilet. Benign Prostatic Hypertrophy is exceptionally common in men over the age of 40, and affects between 50 - 60% of men between the ages of 40 - 59, rising to 80% in men aged 80.   In severe cases surgery can be needed and whilst there is no proven link at the moment between the incidence of BPH and prostate cancer, there are many researchers who believe that BPH could lead an increased risk of developing prostate cancer.  

Because there is always a risk that someone who complains of problems like this may have prostate cancer, they should always be referred to their doctor so that they can rule out any possibility of serious disease.

The Mechanism of Prostate Enlargement

As men reach middle age, usually about 40, the prostate gland tends to accelerate the rate at which it converts testosterone to dihydrotestosterone (DHT).   The accumulation of DHT in the prostate stimulates the cells to divide and multiply at a faster rate increasing the total number of prostate cells and causing the prostate gland to enlarge.   The paradox is that as men age their bodies produce less total testosterone, but the prostate gland converts available testosterone into DHT more aggressively.   This increased conversion rate is due to an increase in activity of the enzyme responsible:- 5- a -reductase.    Researchers believe that the increased rate of cell division in BPH may increase the chances of cancerous cells forming.

A higher risk if you live in the west

When epidemiologists looked at the incidence of active prostate cancer across the globe they found marked differences between countries in the West and other parts of the world, noticeably Asia.   The incidence of active prostate cancer is relatively low in Asian populations compared to those of the United States and the UK.   In the US, 137 men per 100,000 will develop prostate cancer compared with 2 per 100,000 in China.   One clue lies in the observation that when men emigrate from a country of low prostate disease incidence to the US, their risk of developing prostate problems changes to that of the resident population within a generation.   When the incidence of latent microscopic cancer is examined, it is similar for all populations in all countries - therefore some factor is present in the Western lifestyle which increases the risks of microscopic prostate cancer cells being triggered to grow and metastasise into the full blown disease.

The Links between Prostate Disease and Diet & Lifestyle

This epidemiological evidence strongly implicates an environmental factor such as diet or lifestyle in the incidence of prostate disease - so considerable amounts of research and study are ongoing to try to find out what aspect of dietary practice or lifestyle might be responsible.

So what has been found out so far?   One of the largest dietary intervention studies ever carried out is the Health Professionals Follow Up Study, which reported its first results in 2002.   This study was conducted in the United States and involved over 51,000 men.   One key finding showed that total fat consumption, particularly animal fat consumption, was directly related to the risk of advanced prostate cancer.   When the data was analysed for BPH incidence, people with a high animal fat intake were found to have 1.5 times the risk of developing BPH compared to people with a low animal fat intake.  

These findings confirmed results from other smaller clinical studies carried out in the US and Europe over the last ten years.   However, fat intake alone is unlikely to be the whole story.   Whilst some Asian diets have a lower intake of animal fats in their diets compared with the West, many do not - yet these populations still have a lower incidence and risk of prostate disease than Western people following a low fat diet.   So what other differences are there in diets or lifestyle that might account for this?

Different diets

One key area of dietary difference between Western and Asian diets is that Asian populations eat a substantially higher intake of foods such as soy, rice, some herbs, unprocessed nuts, seeds and whole grains.   So how could these foods be responsible for helping to protect people from prostate disease and help them stay healthy? One noticeable difference is that all these foods are particularly high in plant phytosterol content. The average Western Diet currently contains about 80mg of phytosterol per day, compared with 345mg per day in a vegetarian diet and 400mg day in an average Japanese diet.

Phytosterols are a 'non-nutritive' food component found only in plants, and they are nearly completely removed from foods if they are refined or processed.   The high consumption of   refined and processed foods along with differences in dietary balance probably explains why the phytosterol content of the Western diet is so much lower than that of Asia.

How might Phytosterols help maintain a healthy prostate?

While most of the phytosterols eaten in the diet are unabsorbed and pass through the intestines undigested, a very small amount - about 3% - are absorbed.   Phytosterols, and specifically beta-sitosterol in the blood appear to have an affinity for prostate and liver cell membranes. Studies have shown that increasing levels of phytosterols in the diet by relatively small amounts reduces the activity of 5- a -reductase in the prostate gland (the enzyme responsible for converting testosterone into the growth promoting dihydrotestosterone) by over 30%.

The other way increased phytosterols in the diet may help maintain a healthy prostate result from their effects in maintaining healthy cholesterol levels.   Plant phytosterols, and particularly beta-sitosterol, are the plant version of animal cholesterol and are known to have a beneficial effect on blood cholesterol levels when dietary amounts are increased.   The 97% of phytosterols that are not absorbed by the intestines occupy and temporarily block cholesterol absorption sites in the intestines, and in effect reduce the amount of cholesterol that can be absorbed.   This leads to a reduction in the amount of absorbed LDL or 'bad' cholesterol and a consequent reduction in the total blood cholesterol.   This is important as high cholesterol levels are known to stimulate testosterone production which can lead to increased DHT production, and lower levels of dietary cholesterol have been shown to reduce the risk of prostate disease.

Either or both of these effects on health may explain why increasing the daily intake of phytosterols could help men to maintain a healthy prostate. Problems associated with BPH have long been treated in Europe with the herbal supplement Saw Palmetto.   It is estimated that about a third of saw palmetto is made up of phytosterols, and herbal extracts have been shown to reduce the severity of some symptoms commonly associated with BPH, such as reduced frequency of night time urination.   Saw Palmetto is a good source of phytosterols, which are thought to be its principle active ingredient, and similar beneficial results on prostate health have been found in people taking phytosterol concentrates.

Increasing phytosterol intake for prostate health

One approach to increasing phytosterol intake is dietary: - adoption of a low fat, organic diet high in fresh unrefined peanuts, whole grains, rice and soy will increase an individuals phytosterol intake significantly. Alternatively a number of supplements are available that are rich in phytosterols - Vibrant Life's Beta-ST is a beta-sitosterol and citrus pectin concentrate that contains 300 mg of phytosterol complex in every tablet, extracted from soy and rice.   Other supplements containing phytosterols include supplements with Saw Palmetto; It is difficult to make a direct assessment of the phytosterol content of Saw Palmetto supplements as this is affected by the level of standardisation and amount of the herbal extract, but generally about one third of the herbal content is made up by phytosterols.

Summary

Whilst phytosterol intake is certainly not the whole story in keeping the prostate healthy, there is a growing body of evidence that suggests that low levels of phytosterols in the western diet might be a significant contributory factor to the high levels of prostate disease seen in the past few decades, either through the specific action of phytosterols on the prostate gland cell membrane, or through the effect of phytosterols in reducing cholesterol uptake and absorption.

Increasing daily phytosterol intakes to the levels found in an Asian diet is a relatively easy step   that men can take to look after their prostate gland and heart;   increasing dietary phytosterols also have proven benefits in helping the body to maintain healthy cholesterol levels.

Phytosterols and Prostate Health - Key Reference List 

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