Prostate-specific antigen (PSA) is a protein made by the prostate gland. A high
PSA level could be a sign of an enlarged prostate, inflammation called prostatitis, or prostate cancer.
The PSA test checks for levels of this protein.
After a prostate cancer diagnosis, a rising PSA level can mean that the cancer has progressed or returned following treatment. “As cancer progresses, the PSA progresses,” says Hope Barkoukis, PhD, RDN, chair of the nutrition department at Case Western Reserve University School of Medicine in Cleveland.
Eating nutrient-rich foods could help you stay healthy during treatment and possibly reduce the risk of a recurrence.
But are there any specific foods that lower PSA levels? Recent studies are scant and the evidence is very limited, because nutrition studies generally look at the effects of dietary patterns on cancer progression, rather than the effects of one specific food, says
June M. Chan, ScD, Steven and Christine Burd-Safeway Distinguished Professor of Urology at UCSF in San Francisco.
Diet also isn't a replacement for the medicines your healthcare team prescribes. Instead, it should work along with your treatment. “Integrating nutrients with traditional medicine is the best option. We call that the field of integrated medicine,” says Nagi Kumar, PhD, RD, a senior member in the department of cancer epidemiology at Moffitt Cancer Center in Tampa, Florida.
Here are a few foods you may want to include in — or leave out of — your diet during prostate cancer treatment because of their potential effects on PSA levels and prostate cancer.
Cruciferous vegetables like broccoli may stop cancer cells from growing and dividing, and speed up their death.
Cauliflower, kale, mustard greens, and Brussels sprouts are also part of this healthy vegetable group, and worthy of including in your diet. One older study found that men who ate the most cruciferous vegetables had a 59 percent lower risk of prostate cancer progression compared with those with the lowest intake.
This vegetable group might also protect men who haven't been diagnosed. “Cruciferous veggies contain certain compounds such as glucosinolates and isothiocyanates, which are known to reduce risks of a multiplicity of human cancers, including prostate,” says Dr. Barkoukis. A systematic review and meta-analysis found that men who had a higher intake of cruciferous vegetables had a lower risk of prostate cancer.
Fatty fish like salmon, sardines, mackerel, and herring are rich sources of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Although these fatty acids don't seem to affect PSA concentration, a recent study found that they may slow prostate cancer cell growth.
There may also be an association between higher omega-3 intake from fish and a reduced risk of death from prostate cancer.
Green tea contains healthful plant compounds called catechins, most notably epigallocatechin-3-gallate (EGCG). Early studies have shown that green tea catechins may block cancer cell growth. People who drink large amounts of green tea may be at lower risk for cancer, but the evidence is limited and more research is necessary.
“EGCG can significantly reduce PSA in men who are at high risk for prostate cancer,” says Dr. Kumar. In her own research of catechins for prostate cancer prevention, giving men 200-milligram (mg) capsules of EGCG for one year led to a drop in PSA level.
But she cautions that to drink the amount of green tea needed to produce that effect, “You have to literally stand near a bathroom because it's a
diuretic.”
These red fruits are rich in the antioxidant lycopene, which may slow the growth and spread of prostate cancer. Cooking tomatoes in oil before eating them improves lycopene absorption.
Studies have linked tomatoes with a reduced risk of developing prostate cancer, and especially late-stage prostate cancer. But the evidence of its effects on PSA levels is limited. A review of studies showed that lycopene supplements, not tomatoes, did lower PSA levels in men with early-stage prostate cancer, but only in those whose PSA levels were high to begin with.
Because tomatoes are healthy in general, they're worth eating. Kumar suggests consuming them in the form of tomato soup or sauce for the greatest benefit.
Coffee contains compounds with anti-inflammatory and antioxidant effects that might stop cancer cell growth and encourage programmed cell death, called apoptosis. One study found that in men at risk for prostate cancer, those with a higher PSA level had consumed less caffeine than those with a normal PSA level. However, that association didn't stand after the researchers adjusted for other factors that might affect PSA levels.
Better evidence exists showing that drinking coffee might lower the risk for prostate cancer, and positively affect outcomes in men who've been diagnosed.
In one older study, men who drank four or more cups of coffee a day had a 59 percent lower risk of prostate cancer recurrence or progression compared with those who drank one or fewer cups a week. The researchers didn't find that coffee drinkers faced lower odds of dying from their cancer, but it was hard for them to confirm that finding, since very few men died during the study period.
The evidence on nuts and prostate cancer is mixed, but studies have shown that more frequent nut consumption is associated with a significantly lower risk of developing this cancer.
One older study showed a 34 percent lower rate of death in people who ate nuts five or more times a week after their prostate cancer diagnosis, compared with those who ate nuts less than once a month.
Because nuts are a good source of healthy unsaturated fat and fiber, they're worth adding to your diet.
Grains are high in fiber, as well as vitamins and minerals that have anti-cancer properties. An analysis of 15 studies found that high consumption of fiber from grains was associated with a lower risk of progression to advanced prostate cancer and death from prostate cancer.
Rye bread in particular may be beneficial. In an older study, men with prostate cancer who ate whole grain and bran from rye had significantly lower PSA levels compared with those who ate refined wheat.
Eggs (along with red meat and dairy products) contain large amounts of the nutrient choline, which is also in prostate cancer cells. In one study, men who ate the most choline (around 500 mg per day) had a 70 percent increased risk of metastatic or fatal prostate cancer compared with men who ate around 300 mg per day.
Experts say there's no need to cut eggs, or other choline sources, completely from your diet, since it's a required nutrient. Just limit eggs to two or less per week.
Eating a lot of processed meats like bacon, sausage, hot dogs, and bologna is linked to an increased risk for prostate cancer.
In men who are already diagnosed, cutting out meat doesn't affect PSA concentrations.
But because processed red meat increases the risk of dying overall, it's worth avoiding.
“In general, we recommend eating more healthy
plant-based fats instead of saturated fat [from red or processed meat], things that would overlap with a general healthy diet or a heart-healthy diet,” says Dr. Chan.
