madman
Super Moderator
Dietary Factors and Supplements Influencing Prostate Specific-Antigen (PSA) Concentrations in Men with Prostate Cancer and Increased Cancer Risk: An Evidence Analysis Review Based on Randomized Controlled Trials
Abstract: The quest for dietary patterns and supplements efficient in down-regulating prostate-specific antigen (PSA) concentrations among men with prostate cancer (PCa) or increased PCa risk has been long. Several antioxidants, including lycopene, selenium, curcumin, coenzyme Q10, phytoestrogens (including isoflavones and flavonoids), green tea catechins, cernitin, vitamins (C, E, D) and multivitamins, medicinal mushrooms (Ganoderma lucidum), fruit extracts (saw palmetto, cranberries, pomegranate), walnuts and fatty acids, as well as combined supplementations of all, have been examined in randomized controlled trials (RCTs) in humans, on the primary, secondary, and tertiary PCa prevention level. Despite the plethora of trials and the variety of examined interventions, the evidence supporting the efficacy of most dietary factors appears inadequate to recommend their use.
2. Obesity and Serum PSA Concentrations
3. Antioxidants and PSA Kinetics
3.1. Lycopene
3.2. Selenium
3.3. Curcumin
3.4. Phytoestrogens
3.5. Green Tea Catechins
3.6. Fruit (Cranberries, Pomegranate, Saw Palmetto, and Grapes) and Fruit Extracts
3.7. Vitamin D
3.8. Ascorbic Acid and A-Tocopherol
3.9. Combined Antioxidant Therapy
4. Fatty Acids (FA) and Foods Rich in Fatty Acids
5. Dietary Interventions
6. Lack of Efficacy, Drawbacks in the Amount of PSA Considered as “Elevated”, and Food for Thought
Considering that the prostate gland has a very efficient blood supply [6], amounts of PSA are constantly entering the bloodstream, elevating circulating concentrations. This often produces concentrations exceeding the 3 ng/mL, which is considered the cutoff for PCa risk, developing a grey area in what is considered as “normal” and what is thought to be “elevated” [6]. Elevated PSA concentrations might well be the epiphenomenon of urinary tract infections, prostatitis, indirect pressure on the prostate gland, or BPH. Therefore, these factors, alongside age, ethnicity, and BMI, might account for the reported inconsistency in the findings of all aforementioned trials and should all be considered as confounders when relevant RCTs are designed.
7. Conclusions
In the phytotherapeutic field, it appears that high-quality studies are lacking, with the majority of RCTs being underpowered [229]. In parallel, as already mentioned by others, PCa chemoprevention by natural agents is not supported by the available evidence [230]. Therefore, the need for well-designed trials to expand the existing knowledge, replicate the findings, and aggregate the results is necessitated [231]. Moreover, the efficacy of supplements and, in particular, antioxidants, in tampering down PSA concentrations is questionable and a “first do no harm” concept must prevail before the formulation of any recommendations [232]. Given that the majority of evidence outlined in the present review revealed little or no effect, it can be assumed that nutrition-wise, PSA is not as sensitive as we might think, whereas the role of nutrition in down-regulating PSA concentrations appears to be minimal.
Abstract: The quest for dietary patterns and supplements efficient in down-regulating prostate-specific antigen (PSA) concentrations among men with prostate cancer (PCa) or increased PCa risk has been long. Several antioxidants, including lycopene, selenium, curcumin, coenzyme Q10, phytoestrogens (including isoflavones and flavonoids), green tea catechins, cernitin, vitamins (C, E, D) and multivitamins, medicinal mushrooms (Ganoderma lucidum), fruit extracts (saw palmetto, cranberries, pomegranate), walnuts and fatty acids, as well as combined supplementations of all, have been examined in randomized controlled trials (RCTs) in humans, on the primary, secondary, and tertiary PCa prevention level. Despite the plethora of trials and the variety of examined interventions, the evidence supporting the efficacy of most dietary factors appears inadequate to recommend their use.
2. Obesity and Serum PSA Concentrations
3. Antioxidants and PSA Kinetics
3.1. Lycopene
3.2. Selenium
3.3. Curcumin
3.4. Phytoestrogens
3.5. Green Tea Catechins
3.6. Fruit (Cranberries, Pomegranate, Saw Palmetto, and Grapes) and Fruit Extracts
3.7. Vitamin D
3.8. Ascorbic Acid and A-Tocopherol
3.9. Combined Antioxidant Therapy
4. Fatty Acids (FA) and Foods Rich in Fatty Acids
5. Dietary Interventions
6. Lack of Efficacy, Drawbacks in the Amount of PSA Considered as “Elevated”, and Food for Thought
Considering that the prostate gland has a very efficient blood supply [6], amounts of PSA are constantly entering the bloodstream, elevating circulating concentrations. This often produces concentrations exceeding the 3 ng/mL, which is considered the cutoff for PCa risk, developing a grey area in what is considered as “normal” and what is thought to be “elevated” [6]. Elevated PSA concentrations might well be the epiphenomenon of urinary tract infections, prostatitis, indirect pressure on the prostate gland, or BPH. Therefore, these factors, alongside age, ethnicity, and BMI, might account for the reported inconsistency in the findings of all aforementioned trials and should all be considered as confounders when relevant RCTs are designed.
7. Conclusions
In the phytotherapeutic field, it appears that high-quality studies are lacking, with the majority of RCTs being underpowered [229]. In parallel, as already mentioned by others, PCa chemoprevention by natural agents is not supported by the available evidence [230]. Therefore, the need for well-designed trials to expand the existing knowledge, replicate the findings, and aggregate the results is necessitated [231]. Moreover, the efficacy of supplements and, in particular, antioxidants, in tampering down PSA concentrations is questionable and a “first do no harm” concept must prevail before the formulation of any recommendations [232]. Given that the majority of evidence outlined in the present review revealed little or no effect, it can be assumed that nutrition-wise, PSA is not as sensitive as we might think, whereas the role of nutrition in down-regulating PSA concentrations appears to be minimal.
