Weekly blog: What's for dinner?

03 May 2022

By Tim Baker

I love food. I love eating it. I love cooking it. I love shopping for it. I love planning a meal or discovering a new restaurant.

So, since I was diagnosed, on July 7, 2015, with metastatic prostate cancer, one of the most vexed questions I’ve faced is a remarkably basic one. What should I eat?

I’ve been told everything from, “Eat whatever you want. It makes no difference,” by my oncologist, to recommendations for vegetarian, vegan, ketogenic, Mediterranean and pescatarian diets. Well-meaning friends and family have suggested apricot kernels (high in cyanide, not a great idea), custard apple leaf tea, pomegranate seeds, broccoli sprouts, exotic mushroom varieties like turkey tail. Does any of it make any difference? I’m still not entirely sure and unqualified to judge. What I do know is that when I eat a sensible diet of clean, whole foods, combined with regular exercise and good quality sleep, I just feel a whole better, able to ride the bumps of hormone therapy, ward off some of the moodiness and fatigue which otherwise dogs me. Fortunately, there is a growing body of evidence to guide the dietary choices of men with prostate cancer.

Few oncologists make any specific recommendations around diet, perhaps because the typical medical degree devotes little time to nutrition. I was told, “It doesn’t matter if you eat organic fruit and vegetables, Hungry Jacks or cardboard, your body just turns it all into glucose anyway,” by my original oncologist, who is no longer my oncologist. This confusion and lack of clear messaging is particularly perplexing given that there is ample evidence for a predominantly plant-based diet, with lots of fresh fruit and vegetables, nuts, seeds and berries, while reducing red meat, alcohol, sugar, wheat and dairy.              

There’s abundant evidence that prostate cancer rates are lower in parts of the world where traditional diets have not been subsumed by the deleterious effects of the modern western diet of highly processed foods, high in sugar, salt and fat. Consulting a qualified nutritionist with some experience in cancer care, in collaboration with your oncologist, is the most prudent means to arrive at an optimal dietary plan,

The danger in not giving clear dietary advice is that men with prostate cancer (and cancer patients in general) might be moved to take matters into their own hands and try all kinds of extreme diets, which could have adverse outcomes and provide inadequate nutrition. I’d include myself in that category. Unconvinced by my oncologist’s arguments in favour of eating hamburgers or cardboard, I road tested a variety of dietary approaches, from juicing carrots by the truckload, going hard core vegan, trying a ketogenic diet low in carbs, and intermittent fasting. I lost 15 kg in the first month after my diagnosis which is a dangerous amount of weight to drop so suddenly, particularly when going through chemo.

Happily, sanity prevailed, and I eventually saw a nutritionist and settled on a more moderate diet. I no longer describe myself as vegan, vegetarian or even pescatarian (adding fish to a vegetarian diet), but rather a “flexitarian,” trying to make sensible food choices as my own tastes and circumstances allow. The dietary term I’ve become most comfortable with is a “plant-based” diet. This is a somewhat fluid concept that defies a hard definition, but it does mean placing fresh fruit and vegetables at the centre of your diet and giving less “plate-space” to animal proteins and highly processed foods.

And growing evidence is adding weight to the virtues of a plant-based diet in managing a cancer diagnosis and for general health. I receive a monthly newsletter as part of the GAP4 Interval study into the role of exercise in managing prostate cancer and was delighted when the latest instalment focussed on diet, providing some much-needed clarity for men with prostate cancer.  It stated very clearly:

“Plant-based diets are linked with better heart health, lower risk of diabetes, healthier body weight, and lower risk of death. Emerging science shows that a lifelong commitment to a plant-based diet may also lower a man’s risk of developing prostate cancer and, after prostate cancer diagnosis, reduce the risk of cancer recurrence or progression.”

It recommends a healthy dinner plate should compromise half or more fresh vegetables and fruit, a quarter lean protein, and a quarter starchy vegetables like sweet potato, squash, corn or whole grains. They identify healthy sources of lean protein as ocean-caught fish, tofu, tempe, nuts, and unprocessed and ideally organic poultry without the skin.

There is also particularly compelling evidence for the virtues of specific foods such as green tea, cruciferous vegetables (leafy greens like kale, spinach, brussel sprouts), cooked tomato (high in lycopene), mushrooms and oily fish like sardines, herring, trout and salmon, rich in Omega 3 fatty acids.

The two most common dietary traditions highlighted as helpful in managing prostate cancer are the traditional Japanese diet and the Mediterranean diet. They provide a reasonable framework for a healthy approach to food, with their emphasis on fresh fruit and vegetables, seasonal and local whole foods, healthy fats like olive oil. The Japanese diet includes plenty of green tea, soy products like tofu, tempe and soy milk and fresh fish. Significantly, prostate cancer rates are lower in Japan than most western countries.

In his book, In Defence of Food – an eater’s manifesto, author Michael Pollan offers some succinct and persuasive, general dietary advice. He says everything he learnt in researching the book can be summarised in seven words: “Eat food, mainly plants, not too much.” And when Pollan says, “eat food,” he later elaborates: “Don’t eat anything that your great grandmother wouldn’t recognise as food,” which means avoiding what he calls “edible food-like substances”. These are highly processed foods with long lists of unpronounceable ingredients.

Other handy food rules:

• Stop eating when 80% full to avoid over-eating. Hormone therapy slows metabolism and promotes weight gain so it’s important to avoid over-eating.
• Eat a rainbow. Consuming a wide variety of fresh fruit and vegetables of diverse colours help ensure you are getting an adequate range of nutrients.
• Pollan says, “It’s not food if it arrived through the window of your car.” Ie. Avoid drive through junk food.
• Importantly, he also adds the qualifier, “Break the rules occasionally.”

I realised a few years ago, this whole healthy eating business is a marathon not a sprint. You can go out too hard, too fast, and find your new dietary zeal unsustainable, as I did. And you don’t want to deprive yourself of all the joy of eating well. There was a meme doing the rounds on the internet recently that said, “Replacing your morning coffee with green tea can help eliminate 80% of the joy in life.” That might be overstating things a little, but it also makes a valid point. A healthy diet should be enjoyable and sustainable.

I made a little deal with myself on a family holiday on a live-aboard boat to the Great Barrier Reef a few years back, where food options were limited and I found myself succumbing the decadent temptations of a ham and salad sandwich, a pizza or even (gasp) a cleansing ale at the end of the day to complement another psychedelic, Pacific sunset. That deal was, when I was on holidays, I’d give myself a little holiday from the super strict diet too. Sometimes the stress of trying to source the right foods and forgo the temptations right under your nose might be worse for you than just having the damn sandwich or pizza or occasional beer.

But there should no longer be any doubt that a sensible, plant-based diet can deliver real benefits to men with prostate cancer in managing cancer-related fatigue, withstanding the rigours of treatment, and for general well-being. A 2020 literature review, Diet and lifestyle considerations for patients with prostate cancer, offered a simple and compelling conclusion: “The best recommendation for patients with prostate cancer is to form a habit of wellness through healthy eating, aerobic and resistance exercise, and psychological well-being.”

They are, quite literally, words to live by.

References

^{GAP4 Interval Study, Year 2, Issue 21, April 2022.}

^{Pollan, M. In Defence of Food: An eater’s manifesto, Penguin, 2009.}

^{Kyle B. Zuniga, June M. Chan, Charles J. Ryan, Stacey A. Kenfield, Diet and lifestyle considerations for patients with prostate cancer, Urologic Oncology: Seminars and Original Investigations, Volume 38, Issue 3, 2020, Pages 105-117, ISSN 1078-1439.
https://doi.org/10.1016/j.urolonc.2019.06.018.}

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