Health Concerns on Supplements and Blood Tests
Dear Doctor: I’m a 68-year-old man, weighing 130 pounds and standing 5 feet, 7 inches tall. Generally, I’m in good shape and work out regularly. After about six years of monitoring, I had my prostate removed in 2023 and just completed radiation treatment.
I’ve been taking vitamins for as long as I can remember. My regimen includes Centrum Silver, fish oil, calcium, and vitamin D for osteoporosis. Recently, I came across information suggesting that selenium and vitamin E, both present in Centrum Silver, are not advisable for those with prostate cancer. There’s also mixed info about fish oil—some sources say it’s beneficial, while others claim it could be harmful if you have prostate cancer.
Should I keep taking these vitamins, or is it better to stop? Could they have worsened my cancer? If I do decide to stop, is it smart to wean off them or just stop completely? I’d really hate to think I might be doing more harm than good. My diet is pretty solid—I eat a lot of fruits and vegetables, along with chicken, fish, and lean red meat. I also try to stay hydrated with green tea and plenty of water.
— Anonymous
Dear Anonymous: There are indeed several supplements linked with a higher risk of prostate cancer. The evidence against vitamin E is particularly compelling; a significant study looking for benefits had to be terminated due to safety concerns, showing a 17% increase in prostate cancer risk with vitamin E use.
Some studies suggest fish oil may increase prostate cancer risk, while others do not find that correlation. Personally, I would advise men with prostate cancer—or those at high risk—not to take vitamin E. Unless fish oil is specifically recommended based on your triglyceride levels or another clinical need, I’d steer clear of that too.
Since your multivitamin contains both vitamin E and selenium, which may elevate the risk of prostate cancer, I’d recommend not continuing it. There’s no need to gradually taper off; you can stop it outright.
In terms of diet, a more plant-based pattern that prioritizes fruits, vegetables, whole grains, and healthy fats, while limiting animal fats, processed meats, and refined carbs, has been shown to yield better outcomes for prostate cancer survivors. While lean meats are preferable, focus more on plant-based foods. Green tea has been suggested to have potential benefits, though that hasn’t been conclusively proven.
Dear Doctor: At 78, I’m in reasonably good health. Due to some symptoms—foamy urine and a prior eGFR of 55—my nephrologist has advised me to undergo a metabolic blood test. He mentioned that fasting isn’t necessary for this test, which is unusual for me as I’ve always fasted beforehand.
According to my research, fasting usually provides more accurate results. However, it also seems that not fasting might not significantly alter the creatinine levels. So, what’s the best course of action? Should I fast or not?
— B.E.
Dear B.E.: It’s important to follow your nephrologist’s guidance. Non-fasting blood tests reflect what your body is like under normal conditions. You’re correct that creatinine levels aren’t heavily influenced by diet, though high meat intake can marginally raise those levels.
Fasting tends to most affect blood sugar and lipid levels. While lipid tests are often standardized for fasting, blood sugar readings require context about whether fasting occurred. Measuring blood sugar after eating a specified amount of sugar is the most effective method for diagnosing diabetes.
