Where's your prostate?
Last week, I started writing a blog on prostate cancer. As it’s November, and because most of us know and care for men who have a prostate, I thought the timing was good. I had no idea how many paths this would take me down, from learning why my grandmother told me “you must eat cream with your strawberries,” to my memories of working in New Zealand and the forgotten brazil nut.
We will begin with the signs and symptoms, the blood test that can detect prostate cancer, and discuss the foods that can reduce your risk of getting it. If you’re a man be prepared to hear (in your head) the names of those male body parts that are absent from every day conversation.
I have written a more comprehensive article on my website, which I invite you to read and share with your family.
Prostate cancer is the most common cancer in men. It grows slowly over 10 to 20 years, mostly affects men over the age of 50 and it is 2.4 times more common in men of African-Caribbean heritage. If you have an uncle, father, or brother with prostate cancer your chances of getting it are increased 2 to 4 fold; this depends on which relative is affected and how old they were when they were diagnosed. Most men with prostate cancer will lead a normal life and are more likely to die from heart disease that the cancer itself.
A few brave men have asked me “where is the prostate?” The question is always welcome. The prostate gland is the size of a walnut, it sits at the opening of the bladder, can be felt via the rectum, and produces a substance to form semen. As well as being a gland that produces semen, it is also made up of muscle which contracts to cause ejaculation.
How do you know the prostate is not working properly?
The most common symptoms are: passing urine more frequently at night, difficulty passing urine or having an erection, blood in the urine or semen, constipation, or pain in the rectum. Even if you are under 50 years old, these symptoms warrant a digital rectal examination (DRE) to feel the prostate, and a blood test called the PSA (prostate specific antigen).
This part can be confusing. PSA is a protein produced by both normal prostate cells and prostate cancer cells. When PSA levels are high, cancer is often suspected. However like most tests the PSA is not perfect; it can be normal when a small cancer is present or it can be raised where there is no cancer. A 'falsely raised PSA' means that the level is high but there is no cancer. There are a number of things that can cause this, the unlikely sport of cycling being one of them. The release of PSA is thought to be due to the saddle pressing on the skin behind the genitals, causing the prostate to become irritated and inflamed; in response the prostate gland produces more PSA. It does not cause prostate cancer but it does result in an increased PSA level. Most Urology doctors recommend repeating the PSA test one week after abstaining from cycling, following which exercise can be resumed. (See main article on website)
Cycling increases your PSA level, but can it reduce the risk of cancer?
The answer is yes. Men who do regular moderate exercise have a decreased risk of prostate cancer. Moderate exercise means walking, running or cycling to an intensity that causes you to break a sweat and feel out of breath. The amount of exercise needed depends on how active you are. Research has shown that if you are usually inactive (you take the car, watch a lot of TV and do no exercise), then just 10 minutes of moderate exercise a day will reduce your risk of heart disease. You can find exercise recommendations at NHS choices, where you will see that two resistance training sessions a week are also recommended for the health of your heart and bones.
Seeing the forest for the trees: Can your diet really reduce the risk of prostate cancer and are supplements always good for you?
Before discussing the super-foods and supplements (the trees), which could help prevent cancer, I want to emphasise the importance of the forest. That forest is the whole body we take care of by eating a healthy diet, exercising, reducing alcohol intake and maintaining a normal body weight. Looking after the forest alone, reduces the risk of developing prostate cancer.
So why was I reading about Arsenic? Arsenic, as most people know is poisonous. However, despite this, it has had an important role to play within medicine. Just beside Arsenic in the periodic table, sits selenium. Selenium is an element found naturally in the earth’s soil. It is referred to as ‘an essential element’, because like iron and zinc, it is essential for the DNA in our cells to work normally.
My interest in selenium began in 2005 when I was working as a doctor in the North Island of New Zealand. I was seeing public health adverts advising men to eat brazil nuts and tomatoes to reduce their risk of prostate cancer; I wondered why we didn’t have the same adverts at home in Northern Ireland. A colleague of mine was eager to explain. He was diagnosed with prostate cancer in his mid 40’s, just when it had been discovered that the soil in New Zealand contained low levels of selenium. This soil produced vegetables low in selenium and because the animals were fed these same vegetables, the meat they produced was also affected; next in line were humans. As a result men in who consumed these vegetables and meat as part of their daily diet became low in selenium; the most important consequence was a higher associated rate of prostate cancer. While munching on some brazil nuts, my colleague explained that Brazil nuts contained more Selenium than any other food and were his snack of choice.
Since the 1960’s many studies have shown a strong association between low levels of selenium and high rates of cancer. However research using selenium supplements (tablets containing selenium) demonstrates mixed results. A large review of these studies, in 2014, concluded that recommending selenium supplements in the form of tablets, to prevent cancer, was not supported. This review also warned that if blood levels of selenium are normal, taking a supplement tablet could actually increase the risk of prostate Cancer. Although very different to arsenic, this is an important reminder that selenium may be dangerous at high levels.
The conclusion: eat enough foods to provide 70mg of selenium each day. In brazil nuts this is 1-2 nuts a day. There is no evidence that selenium supplements reduce the risk of cancer. (See website for other food sources of selenium)
So what about tomatoes?
Tomatoes contain high amounts of a substance called lycopene, which is thought to be an anti-oxidant. It is also found in strawberries, pink grapefruit, and papaya, but in much lower concentrations. My grandmother always told me, “You must eat cream or yogurt with your strawberries if you want to absorb the nutrients”; this nutrient was probably lycopene, which we now know is absorbed from the gut with the help of fat. lycopene is released from the tomato by heating, so its concentration is much higher in cooked tomatoes, tomato pastes and pizza sauces. In-order to ingest approximately 10mg of lycopene (the recommended daily dose) you have to eat 2 cooked tomatoes mixed with some olive oil or a fat of your choice. A medical review in 2011, by a well-known group, stated it was unable to refute or support lycopene’s role in prostate cancer. However, the majority of studies before and after this review have shown that higher dietary intakes of lycopene are associated with a 20-25% reduction in prostate cancer. In some cases patients have also had a reduction in prostate cancer growth.
Conclusion: Despite mixed messages cooked tomatoes should remain a daily food for men wanting to stay healthy. There is no evidence that lycopene supplements reduce the risk of prostate cancer.
What other foods could help?
I mentioned fish as a source of selenium. Consumption of oily fish increases your intake of omega-3 fatty acids, which has been linked to lower rates of prostate cancer; it also improves your cholesterol profile which in turn reduces your risk of heart disease. Other sources of omega- 3 which do not affect the ocean's marine life include flax seeds, nuts, and chia seeds. Find out which fish in your area come from sustainable sources before you go shopping.
Why might foods, vitamins and omega-3 fatty acids reduce cancer rates?
We are unsure if the substances in food are acting on the DNA in our genes to produce anti-cancer affects or if there is some other mechanism involved. Which ever it is, a good diet and staying active are crucial to getting the most out of the genes we already have.
I hope you’ve learned about the signs of prostate cancer, what the prostate does, how your doctor might examine it and what you can do to increase your chances of keeping it healthy. If you would like to learn more you can sign up for my prostate newsletter which contains information on other food, drinks, and recipes that could help keep your prostate healthy.