Carotenoids are micronutrient antioxidants found in orange or yellow fruits and vegetables. The most common dietary carotenoids include beta-carotene, alpha-carotene, beta-cryptoxanthin, lutein, zeaxanthin, and lycopene. Lycopene is the most efficient antioxidant in this group and is the predominant carotenoid in the plasma and in various tissues, including the prostate. It is found in watermelon, tomato, and all tomato-based products, pink grapefruit, apricots, papaya, guava and persimmons. Carrots contain high levels of carotene, but contain little lycopene. Some studies have shown a decreased risk of developing advanced prostate cancer with a high intake of tomato products (> 10 serving per week). Cooked tomato products seem to have a greater effect than raw tomato products.

Broccoli, cauliflower, Brussel sprouts, bok choy, cabbage and kale contain high levels of sulforaphane and indole-3 carbinol, which possess anticarcinogenic properties. These nutrients can induce the production of antioxidant enzymes that can protect cells from oxidative damage. They have also been shown to induce apoptosis in damaged cells as well as exhibiting antiproliferative and antimetastatic properties.

Some early studies suggested a benefit to Vitamin E, is a lipid-soluble antioxidant, and Selenium, is a trace element that is a component of multiple antioxidant enzymes in the prevention of prostate cancer. The SELECT trial, was a large randomized placebo-controlled trial involving over 35,000 men in which subjects were given high dose vitamin E and/or selenium to study the effects of these supplements on the risk of developing of prostate cancer. Recently reported results of this trial showed no beneficial effect of either vitamin E or selenium and in fact, in certain subgroups of patients, there was an increased risk of developing prostate cancer. Vitamin D deficiency has also been correlated with increased risk of cancer incidence and mortality. The major and most important source of vitamin D is sunlight but is also contained in dairy products, eggs, vitamin D–fortified cereals, and fatty fish such as salmon and tuna. Many men are vitamin D deficient, and this substance can readily be measured in the serum.

Soy is a rich source for the isoflavones genistein, daidzein, and equol, which have been shown to affect cell-growth pathways and angiogenesis. Isoflavones have also been shown to affect the production and metabolism of androgen and estrogens, which play an important role in the development and progression of prostate cancer. The traditional Western diet entails minimal soy consumption, and few epidemiologic studies that provide useful recommendations have been performed as a result. Isoflavones studied in animal studies indicate a beneficial effect in the prevention and reduction in the growth rate of prostate cancer.

Polyphenols are found in varying amounts in most fruits and vegetables, as well as green tea and red wine. These agents act via antioxidant, antiproliferative, and antiangiogenesis pathways. Some of the more popular polyphenols have been the catechins in green tea, which have been shown to inhibit cancer-cell growth in both animal and epidemiologic studies.