Western-style diets are a major risk factor for prostate cancer, says New Zealand medical doctor Mandy Bergstrom. Speaking at a one-night Evidence Based Eating symposium in Auckland in 2022, she said the incidence of prostate cancer was much higher in Western nations than in Asian countries.

“It is the most commonly diagnosed cancer, apart from skin cancer, in Kiwi men. Every year, more than 4000 men are diagnosed, and over 700 die from the disease. It is the third highest cause of death after lung and bowel cancers.”

She said prostate cancer first develops in patients in their 50s. “It’s a slow-growing tumour.”

Several factors affect the development and progression of prostate cancer. These factors include your genetic background, testosterone, exercise, diet and obesity. Another interesting feature, however, was the way in which it affected migrants moving from low to high-risk areas.

“International variation in vascular prostate cancer is profound as in the frequency which migrants from low to high-risk areas adopt the risk pattern of the host country. Japanese Americans have an incidence rate 43 times higher than their counterparts in Japan, and there is data indicating that migrants develop these patterns within one generation.”

She said some of the main dietary risk factors for prostate cancer included high saturated fat, particularly from animal sources, and high red meat intake, “partly due to the lack of anti-carcinogenic phytochemicals in high meat diets and the potentially carcinogenic effect of compounds generated during high-temperature meat cooking.

“There are more than 20 epidemiological studies that have examined the role of dairy foods in prostate cancer. These studies are consistent with a positive association independent of the association of the contribution of dairy foods to total and saturated fat intake.

“And the evidence regarding the impact of selenium, vitamin E and lycopene, which comes from tomatoes, plus other evidence on oxidant damage in the prostate, supports the concept that oxidant and antioxidant balance is crucial,” she said.

In a prospective cohort study involving 47,239 men in a Health Professionals follow-up study from 1986 to 2014 plant-based diets were calculated from food frequency questionnaires. In follow-up, 6655 men were diagnosed with prostate cancer.

“Greater overall plant-based consumption was associated with a significantly lower risk of fatal prostate cancer. This prospective study provides supportive evidence that greater consumption of healthful plant-based foods is associated with a lower risk of aggressive forms of prostate cancer with stronger benefits among men aged less than 65.

“It is important to note that fewer than one per cent of participants followed a strict vegetarian or vegan diet.

“High fat diets consisting of a large amount of animal fat are linked to an increased risk of prostate cancer, an association attributed, in part, to the ability of excess fat to induce inflammation in the prostate’s immune cells.”

She said a study had revealed novel links between fat intake and inflammation in cancer.