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Active Surveillance, Exercise, Vegan Diets and Healthy Fat: Your Questions Answered (Part 2)

Dr. Stacey Kenfield, Associate Professor in the Departments of Urology and Epidemiology & Biostatistics at UCSF, was a guest on PCF’s monthly webinar series hosted by CEO Dr. Charles J. Ryan. She discussed her research on Prostate 8, a collection of lifestyle changes that have been shown to reduce a patient’s risk of prostate cancer recurrence or death from prostate cancer.

Dr. Kenfield has followed up with her answers to common questions posed before and during the webinar, covering recommendations for active surveillance, the role of alcohol drinking, resistance training, and healthy fats. Read more in Part 1 here on eggs, dairy, and supplements, and view the full webinar here.

Are there differences in the exercise and diet recommendations for men with early prostate cancer diagnosis on active surveillance than for those with more advanced disease?

Most of the studies to date examining post-diagnostic diet and clinical outcomes have focused on men diagnosed with localized prostate cancer, including those who receive primary treatment (e.g., radical prostatectomy, radiation, androgen deprivation therapy) and those on active surveillance. The studies we mentioned during the webinar included both of these groups and did not separate out men on active surveillance from the group receiving primary treatment. Since men on active surveillance were included in these studies, we would recommend the same guidance. There are limited studies to date in men with more advanced disease examining the diet and clinical outcomes.

What is the relationship between alcohol drinking and prostate cancer?

Specifically for prostate cancer, some research shows that modest alcohol intake after a diagnosis of prostate cancer (1 drink on 3-5 days per week) – may be beneficial. A U-shaped relationship was observed in that study, with most benefit at modest level (vs. no alcohol intake or heavier intake). Note that this is actually less than the general recommendation in the Dietary Guidelines for Americans for men limiting intake to 2 or fewer drinks per day.

Of note, if you are a non-drinker, it is not recommended to start drinking alcohol to prevent prostate cancer. Please discuss with your doctor based on your personal health situation.

How is a plant-based diet beneficial?

A plant-based diet is associated with better heart health (lower risk of type 2 diabetes and cardiovascular disease), healthier body weight, and lower risk of death (overall death and death from cardiovascular disease). This means that the bulk of what you eat comes from plant foods, but that meat, dairy, eggs, fish, and other seafood makes up a smaller proportion of total food. Research also shows benefits of certain plant-based diets specifically on prostate cancer outcomes, such as a 19% lower risk of fatal prostate cancer. Read more here.

If a person is on a vegan diet (no fish), how can they get the recommended amounts of omega-3 fatty acids?

The recommended adequate intake (AI) for alpha-linolenic acid (ALA), a type of omega-3 essential fatty acid from plant-based sources, is 1,600 mg/day for men. Plant-based sources include: vegetable oils (especially high in flaxseed oil, walnut oil, canola oil, and soybean oil), nuts (especially walnuts), flax seeds, chia seeds, hemp seeds, and pumpkin seeds. For example, one serving of walnuts can fulfill an entire day’s requirement with 1 ounce (14 walnut halves) containing 2,570 mg of ALA. One ounce of chia seeds contains 5,060 mg of ALA. One tablespoon of flaxseed oil contains 7,260 mg of ALA. Aim for at least one rich source of omega-3 fatty acids in your diet every day. Add a tablespoon of canola or soybean oil in salad dressing or in cooking, eat a handful of walnuts, or add ground flaxseed mixed into oatmeal.

Keep in mind that long-chain omega-3 fatty acids called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) consumed directly from eating fish are thought to have more significant health benefits than ALA from plant-based foods. It’s estimated that up to 10% of ALAs are converted to EPA/DHA, so a tablespoon of flaxseed oil is worth about 700 mg of EPA and DHA. For reference, the 2020-2025 Dietary Guidelines for Americans recommend 8-10 ounces of seafood per week; 8 ounces of fatty fish is equivalent to 250-500 mg combined of EPA and DHA per day. If you are getting this equivalency level from plant-based ALA sources, we wouldn’t recommend a supplement. If you have trouble incorporating a rich omega-3 plant-based food source daily, adding a high-quality algae (plant-based) or fish oil supplement may be recommended. Consult with your doctor first before adding an omega-3 supplement. Read more here and here.

What is the guidance on amount and intensity of resistance training?

Perform muscle strengthening exercises at least 2 days per week. Choose 8-10 different exercises that work major muscle groups (legs, hips/glutes, chest, arms, core). Aim for 2-3 sets of 8-12 repetitions for each exercise. Choose a weight or resistance that allows you to perform the 8-12 repetitions, but not more, with proper form. When you first increase the weight, you may only be able to do 6-10 repetitions with proper form. Work up to 8-12 repetitions. When you start to exceed that range, increase the weight again, so that you can continue to progress. Separate sessions by at least 24 hours to allow your muscles time to recover. Note: consult your doctor before beginning any new exercise routine to understand what types of exercise can be done safely. 

Additional resources:

UCSF’s Department of Urology Resources for Healthy Living.

Global Action Plan (GAP-4) trial of exercise in patients with metastatic prostate cancer

PCF’s wellness guide, The Science of Living Well, Beyond Cancer