Several studies were done on different diets which all have proved to benefit cancer patients. These studies appear to be conflicting, but if you study them closely, you find that they had some things in common:
i. No processed, prepackaged and preserved foods
ii. Lots of fruit and vegetables of which the more colorful ones are the best
iii. The inclusion of whole grains
iv. Healthy fats from nuts, seeds, olives, avocados and cold water fish.
v. Avoid unhealthy fats such as trans fats and saturated fats from animal products
vi. Avoid the consumption of meat and milk from cattle treated with high dosages of hormones and antibiotics
vii. Eat as organic as possible to reduce the toxic effect of pesticides
Specific diets shown in the literature to benefit the health of prostate cancer patients were:
a) Mediterranean-style diet : This diet is full of anti-oxidants found in fruit and vegetables, healthy fats found in nuts, seeds, olives and fish. It is also high in lignans found in legumes such as chickpeas and lentils. These nutrients fight cancer in several ways. It does not only protect against DNA damage (the root of cancer) but also help repair already damaged DNA. Furthermore, the anti-oxidants prevent free radicals or oxidants to damage the DNA in the first place. Healthy fats have an anti-inflammatory effect which also protects against the initial development of cancer.
b) A strict vegan diet is also associated with protection against prostate cancer . This diet has a lot in common with the Mediterranean-style diet but excludes all kinds of animal products such as diary, meat and even fish.
c) A third study from Japan  found that there was a significant correlation between lower fish consumption and the number of deaths from prostate cancer.
d) Although the concept of the ketogenic diet is still new and the use of it to combat modern disease is not well researched, one study  did find that this diet shows potential to slow down tumor growth. Cancer cells only thrive in the presence of sugar. The low carbohydrate diet with plenty beneficial fats make this a logic choice for people who want to fight cancer.
Specific nutrients shown in the literature to benefit prostate cancer patients were:
a) Lycopene found in tomatoes has long been known to fight prostate cancer [6-11].
b) Broccoli [12, 13].
c) Polyphenol-rich foods such as pomegranate, green tea, broccoli and turmeric 
d) Lots of fruit and vegetables  witch is rich in vitamin C specifically .
e) Coffee consumption may be associated with a reduced risk of prostate cancer as well as limited progression of the disease .
f) Curcumin found in turmeric has been shown to fight cancer in general as well as prostate cancer in a number of ways [18-21]. It also protects against some side effects of traditional cancer therapies.
g) Mammalian phytoestrogens were shown to protect against prostate cancer as an anti-oxidant as well as on a hormonal level. These compounds are formed from the bacteria in the gut after consumption of flaxseeds, sesame seeds, brassica vegetables, whole grains and red wine.
h) Resveratrol in red grapes, pomegranate, raw cacao and red berries kills cancer cells through a few mechanisms in the body .
Lifestyle habits which have proven to help fight prostate cancer were:
a) A low-fat diet together with a strenuous exercise regime  as well as a regular exercise regime  had a positive outcome on prostate cancer.
b) Vitamin D and sunlight are proven fighters against cancer in general as well as prostate cancer in particular .
c) Yoga, qigong as well as tai chi are meditative forms of exercise which improves sleep. During sleep a lot of healing takes place in the body and it could be the reason why this kinds of exercise is helpful when fighting against cancer .
It is important to remember that developing any cancer is a process which happens over a period of time. It is becoming increasingly apparent that this process could possibly be reversed at any time, and definitely more easily in the beginning stages. It is also a process which depends on many factors, some favorable to the development of cancer and some less favorable.
The following factors have shown to aid in the development of prostate cancer:
a) The consumption of meat and milk , specifically from cattle treated with high dosages of hormones and antibiotics.
b) Use of nonsteroidal anti-inflammatories  and statin drugs .
c) Exposure to pesticides [29-31].
 B.C. Melnik, S.M. John, P. Carrera-Bastos, L. Cordain, The impact of cow's milk-mediated mTORC1-signaling in the initiation and progression of prostate cancer, Nutr Metab (Lond) 9 (2012) 74.
 S. Erdrich, K.S. Bishop, N. Karunasinghe, D.Y. Han, L.R. Ferguson, A pilot study to investigate if New Zealand men with prostate cancer benefit from a Mediterranean-style diet., PeerJ 3:e (2015).
 Y. Tantamango-Bartley, S.F. Knutsen, R. Knutsen, B.K. Jacobsen, J. Fan, W.L. Beeson, J. Sabate, D. Hadley, K. Jaceldo-Siegl, J. Penniecook, P. Herring, T. Butler, H. Bennett, G. Fraser, Are strict vegetarians protected against prostate cancer?, Am J Clin Nutr 103 (2016) 153-160.
 T.M. Pham, Y. Fujino, T. Kubo, R. Ide, N. Tokui, T. Mizoue, I. Ogimoto, S. Matsuda, T. Yoshimura, Fish intake and the risk of fatal prostate cancer: findings from a cohort study in Japan, Public Health Nutr 12 (2009) 609-613.
 H.S. Kim, E.M. Masko, S.L. Poulton, K.M. Kennedy, S.V. Pizzo, M.W. Dewhirst, S.J. Freedland, Carbohydrate restriction and lactate transporter inhibition in a mouse xenograft model of human prostate cancer, BJU Int 110 (2012) 1062-1069.
 L. Wan, H.L. Tan, J.M. Thomas-Ahner, D.K. Pearl, J.W. Erdman, Jr., N.E. Moran, S.K. Clinton, Dietary tomato and lycopene impact androgen signaling- and carcinogenesis-related gene expression during early TRAMP prostate carcinogenesis, Cancer Prev Res (Phila) 7 (2014) 1228-1239.
 L. Jian, C.-J. Du, A.H. Lee, C.W. Binns, Do dietary lycopene and other carotenoids protect against prostate cancer?, Int J Cancer. 2005 Mar 1;113(6):1010-4. PMID: 15514967 113 (2005) 1010-1014.
 A. Wang, L. Zhang, [Effect of lycopene on proliferation and cell cycle of hormone refractory prostate cancer PC-3 cell line], Wei Sheng Yan Jiu 36 (2007) 575-578.
 P. Chen, W. Zhang, X. Wang, K. Zhao, D.S. Negi, L. Zhuo, M. Qi, X. Wang, X. Zhang, Lycopene and Risk of Prostate Cancer: A Systematic Review and Meta-Analysis., Medicine (Baltimore) 94 ( 2015) 1260.
 F.H. Schroder, M.J. Roobol, E.R. Boeve, R. de Mutsert, S.D. Zuijdgeest-van Leeuwen, I. Kersten, M.F. Wildhagen, A. van Helvoort, Randomized, double-blind, placebo-controlled crossover study in men with prostate cancer and rising PSA: effectiveness of a dietary supplement, Eur Urol 48 (2005) 922-930; discussion 930-921.
 I. Paur, W. Lilleby, S.K. Bohn, E. Hulander, W. Klein, L. Vlatkovic, K. Axcrona, N. Bolstad, T. Bjoro, P. Laake, K.A. Tasken, A. Svindland, L.M. Eri, B. Brennhovd, M.H. Carlsen, S.D. Fossa, S.S. Smeland, A.S. Karlsen, R. Blomhoff, Tomato-based randomized controlled trial in prostate cancer patients: Effect on PSA, Clin Nutr (2016).
 M. Traka, A.V. Gasper, A. Melchini, J.R. Bacon, P.W. Needs, V. Frost, A. Chantry, A.M. Jones, C.A. Ortori, D.A. Barrett, R.Y. Ball, R.D. Mills, R.F. Mithen, Broccoli consumption interacts with GSTM1 to perturb oncogenic signalling pathways in the prostate, PLoS One 3 (2008) e2568.
 A.I. Amjad, R.A. Parikh, L.J. Appleman, E.R. Hahm, K. Singh, S.V. Singh, Broccoli-Derived Sulforaphane and Chemoprevention of Prostate Cancer: From Bench to Bedside, Curr Pharmacol Rep 1 (2015) 382-390.
 R. Thomas, M. Williams, H. Sharma, A. Chaudry, P. Bellamy, A double-blind, placebo-controlled randomised trial evaluating the effect of a polyphenol-rich whole food supplement on PSA progression in men with prostate cancer-the UK NCRN Pomi-T study, Prostate Cancer Prostatic Dis (2014).
 P.-H. Lin, W. Aronson, S.J. Freedland, Nutrition, dietary interventions and prostate
cancer: the latest evidence, BMC Medicine 13 (2015).
 X.-Y. Bai, X. Qu, X. Jiang, Z. Xu, Y. Yang, Q. Su, M. Wang, H. Wu, Association between Dietary Vitamin C Intake and Risk of Prostate Cancer: A Meta-analysis Involving 103,658 Subjects., J. cANCER 6 (2015) 913-921.
 H. Liu, G.-H. Hu, X.-C. Wang, T.-B. Huang, L. Xu, P. Lai, Z.-F. Guo, Y.-F. Xu, Coffee consumption and prostate cancer risk: a meta-analysis of cohort studies, Nutr Cancer 67 (2015) 392-400.
 D. Perrone, F. Ardito, G. Giannatempo, M. Dioguardi, G. Troiano, L. Lo Russo, D.E.L. A, L. Laino, L. Lo Muzio, Biological and therapeutic activities, and anticancer properties of curcumin, Exp Ther Med 10 (2015) 1615-1623.
 M.H. Teiten, F. Gaascht, S. Eifes, M. Dicato, M. Diederich, Chemopreventive potential of curcumin in prostate cancer, Genes Nutr 5 (2010) 61-74.
 Q.H. Chen, Curcumin-based anti-prostate cancer agents, Anticancer Agents Med Chem 15 (2015) 138-156.
 H. Mahammedi, E. Planchat, M. Pouget, X. Durando, H. Cure, L. Guy, I. Van-Praagh, L. Savareux, M. Atger, M. Bayet-Robert, E. Gadea, C. Abrial, E. Thivat, P. Chollet, J.C. Eymard, The New Combination Docetaxel, Prednisone and Curcumin in Patients with Castration-Resistant Prostate Cancer: A Pilot Phase II Study, Oncology 90 (2016) 69-78.
 D. Delmas, E. Solary, N. Latruffe, Resveratrol, a phytochemical inducer of multiple cell death pathways: apoptosis, autophagy and mitotic catastrophe, Curr Med Chem 18 (2011) 1100-1121.
 R.J. Barnard, T.H. Ngo, P.-S. Leung, W.J. Aronson, L.A. Golding, A low-fat diet and/or strenuous exercise alters the IGF axis in vivo and reduces prostate tumor cell growth in vitro, Prostate 56 (2003) 201-206.
 R.J. Barnard, P.S. Leung, W.J. Aronson, P. Cohen, L.A. Golding, A mechanism to explain how regular exercise might reduce the risk for clinical prostate cancer, Eur J Cancer Prev. 16 (2007 ) 415-421.
 R. Gilbert, C. Metcalfe, S.E. Oliver, D.C. Whiteman, C. Bain, A. Ness, J. Donovan, F. Hamdy, D.E. Neal, J.A. Lane, R.M. Martin, Life course sun exposure and risk of prostate cancer: population-based nested case-control study and meta-analysis, Int J Cancer 125 (2009) 1414-1423.
 J.L. McQuade, S. Prinsloo, D.Z. Chang, A. Spelman, Q. Wei, K. Basen-Engquist, C. Harrison, Z. Zhang, D. Kuban, A. Lee, L. Cohen, Qigong/tai chi for sleep and fatigue in prostate cancer patients undergoing radiotherapy: a randomized controlled trial, Psychooncology (2016).
 X. Wang, Y.W. Lin, J. Wu, Y. Zhu, X.L. Xu, X. Xu, Z. Liang, Z.H. Hu, S.Q. Li, X.Y. Zheng, L.P. Xie, Meta-analysis of nonsteroidal anti-inflammatory drug intake and prostate cancer risk, World J Surg Oncol 12 (2014) 304.
 C.C. Chang, S.C. Ho, H.F. Chiu, C.Y. Yang, Statins increase the risk of prostate cancer: a population-based case-control study, Prostate 71 (2011) 1818-1824.
 X. Xu, A.B. Dailey, E.O. Talbott, V.A. Ilacqua, G. Kearney, N.R. Asal, Associations of serum concentrations of organochlorine pesticides with breast cancer and prostate cancer in U.S. adults, Environ Health Perspect 118 (2010) 60-66.
 P.R. Band, Z. Abanto, J. Bert, B. Lang, R. Fang, R.P. Gallagher, N.D. Le, Prostate cancer risk and exposure to pesticides in British Columbia farmers, Prostate 71 (2011) 168-183.
 S. St-Hilaire, S. Mannel, A. Commendador, R. Mandal, D. Derryberry, Correlations between meteorological parameters and prostate cancer, Int J Health Geogr. 9 (2010).