Long-chain (n-3) fatty acid intake and risk of cancers of the breast and the prostate: recent epidemiological studies, biological mechanisms, and directions for future research

Role of vitamins, minerals and supplements in the prevention and management of prostate cancer

The authors review the current literature on the complementary and alternative medicines most frequently utilized by prostate cancer patients and those at risk for the disease. Products covered are vitamin E, vitamin A, selenium, zinc, soy, lycopene, pomegranate juice, green tea and omega-3 fatty acids. There is no definitive proof that any of the nutritional supplements discussed can impact the course of prostate cancer or its development. The authors believe that simply taking a standard daily multivitamin should be sufficient to ensure that patients have the appropriate levels of vitamins and minerals without risking the over utilization of vitamins, minerals, and supplements which can lead to numerous negative side effects.

Association of frequent consumption of fatty fish with prostate cancer risk is modified by COX-2 polymorphism

Dietary intake of marine fatty acids from fish may protect against prostate cancer development. We studied this association and whether it is modified by genetic variation in cyclooxygenase (COX)-2, a key enzyme in fatty acid metabolism and inflammation. We assessed dietary intake of fish among 1,499 incident prostate cancer cases and 1,130 population controls in Sweden. Five single nucleotide polymorphisms (SNPs) were identified and genotyped in available blood samples for 1,378 cases and 782 controls. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by multivariate logistic regression. Multiplicative and additive interactions between fish intake and COX-2 SNPs on prostate cancer risk were evaluated. Eating fatty fish (e.g., salmon-type fish) once or more per week, compared to never, was associated with reduced risk of prostate cancer (OR: 0.57, 95% CI: 0.43-0.76). The OR comparing the highest to the lowest quartile of marine fatty acids intake was 0.70 (95% CI: 0.51-0.97). We found a significant interaction (p < 0.001) between salmon-type fish intake and a SNP in the COX-2 gene (rs5275: +6365 T/C), but not with the 4 other SNPs examined. We found strong inverse associations with increasing intake of salmon-type fish among carriers of the variant allele (OR for once per week or more vs. never = 0.28, 95% CI: 0.18-0.45; p(trend) < 0.01), but no association among carriers of the more common allele. Frequent consumption of fatty fish and marine fatty acids appears to reduce the risk of prostate cancer, and this association is modified by genetic variation in the COX-2 gene.

Androgen receptor CAG and GGC polymorphisms in Mediterraneans: repeat dynamics and population relationships

Microsatellite variation (CAG and GGC repeats) of the androgen receptor (AR) gene shows remarkable differences among African and non-African populations. In vitro studies have demonstrated an inverse relationship between the length of both microsatellites and AR activity. This fact may explain the observed association of the AR gene with prostate cancer and the strong ethnic differences in the incidence of this cancer. CAG and GGC genetic variation has been tested in a large set of populations from the Ivory Coast as well as 12 Mediterranean samples whose variation is described for the first time. The pattern of frequencies observed in the Ivory Coast agrees with data previously reported for other Sub-Saharan populations. Concerning the Mediterranean variation, Sardinian samples are characterised by low genetic diversities, and Egyptian Siwa Berbers by a particular pattern of GGC frequencies. High and Middle Atlas Moroccan Berbers are the most closely related to the Sub-Saharan variation. For both the CAG and GGC repeats, the Ivory Coast and some Moroccan samples exhibit high frequencies of low size alleles (CAG under 18 repeats, and GGC under 15 repeats) that have been associated with prostate cancer.

Quantitative analysis of the benefits and risks of consuming farmed and wild salmon

Contaminants in farmed Atlantic and wild Pacific salmon raise important questions about the competing health benefits and risks of fish consumption. A benefit-risk analysis was conducted to compare quantitatively the cancer and noncancer risks of exposure to organic contaminants in salmon with the (n-3) fatty acid-associated health benefits of salmon consumption. Recommended levels of (n-3) fatty acid intake, as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may be achieved by consuming farmed or wild salmon while maintaining an acceptable level of noncarcinogenic risk. However, the recommended level of EPA+DHA intake cannot be achieved solely from farmed or wild salmon while maintaining an acceptable level of carcinogenic risk. Although the benefit-risk ratio for carcinogens and noncarcinogens is significantly greater for wild Pacific salmon than for farmed Atlantic salmon as a group, the ratio for some subgroups of farmed salmon is on par with the ratio for wild salmon. This analysis suggests that risk of exposure to contaminants in farmed and wild salmon is partially offset by the fatty acid-associated health benefits. However, young children, women of child-bearing age, pregnant women, and nursing mothers not at significant risk for sudden cardiac death associated with CHD but concerned with health impairments such as reduction in IQ and other cognitive and behavioral effects, can minimize contaminant exposure by choosing the least contaminated wild salmon or by selecting other sources of (n-3) fatty acids.

Human CYP1A1 variants lead to differential eicosapentaenoic acid metabolite patterns

To answer the question whether the most common allelic variants of human CYP1A1, namely CYP1A1.1 (wild type), CYP1A1.2 (Ile462Val), and CYP1A1.4 (Thr461Asn), differ in their catalytic activity towards eicosapentaenoic acid (EPA), in vitro enzymatic assays were performed in reconstituted CYP1A1 systems. All CYP1A1 variants catalyzed EPA epoxygenation and hydroxylation to 17(R),18(S)-epoxyeicosatetraenoic acid (17(R),18(S)-EETeTr) and 19-OH-EPA, yet with varying catalytic efficiency and distinct regiospecificity. CYP1A1.1 and CYP1A1.4 formed 17(R),18(S)-EETeTr as main product (K(m)=53 and 50 microM; V(max)=0.60 and 0.50 pmol/min/pmol; V(max)/K(m)=0.11 and 0.10 microM(-1)min(-1), respectively), followed by 19-OH-EPA (K(m)=76 and 93 microM; V(max)=0.37 and 0.37 pmol/min/pmol; V(max)/K(m)=0.005 and 0.004 microM(-1)min(-1), respectively). The variant CYP1A1.2 produced almost equal amounts of both metabolites, but its catalytic efficiency for hydroxylation was five times higher (K(m)=66 microM; V(max)=1.7 pmol/min/pmol; V(max)/K(m)=0.026 microM(-1)min(-1)) and that for epoxygenation was twice higher (K(m)=66 microM; V(max)=1.5 pmol/min/pmol; V(max)/K(m)=0.023 microM(-1)min(-1)) than those of the wild-type enzyme. Thus, the Ile462Val polymorphism in human CYP1A1 affects EPA metabolism and may contribute to interindividual variance in the local production of physiologically active fatty acid metabolites in the cardiovascular system and other extrahepatic tissues, where CYP1A1 is expressed or induced by polycyclic aromatic hydrocarbons and other xenobiotics.

Arachidonic acid and long-chain n-3 polyunsaturated fatty acid contents in meat of selected poultry and fish species in relation to dietary fat sources

Arachidonic acid (AA) content, long-chain n-3 polyunsaturated fatty acid (PUFA) equivalent [LCE; calculated as 0.15 x linolenic acid (LA) + eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA)], and PUFA n-6/PUFA n-3 ratio were determined in meat [breast meat (BM), thigh meat (TM), and fillets (F), respectively] within four sets of chickens, five sets of turkeys, one set of common carp, and four sets of rainbow trout, fed either commercial diet or diets with manipulated PUFA n-3 and PUFA n-6 contents. AA content was within the range of 20 mg/100 g (F of rainbow trout fed the diet with linseed oil, LO) to 138 mg/100 g (TM of chickens fed restrictively the diet based on maize to the age of 90 days). AA content in BM of turkeys fed the diet with LO or fish oil (FO) did not differ (P > 0.05) from that of rainbow trout F. LCE was in the range of 16 mg/100 g (BM of turkeys fed a commercial feed mixture) to 681 mg/100 g (F of rainbow trout fed a commercial feed mixture). With regard to BM, only turkeys fed the diet with LO deposited more (P < 0.01) LCE (71 mg/100 g) as compared to all other poultry sets except turkeys fed the diet with FO (123 mg/100 g). Apart from all fish samples, also both BM and TM of turkeys fed the diet with either LO or FO met the recommended value of the PUFA n-6/PUFA n-3 ratio (<4). AA content in the tissue increased significantly (P < 0.001) with increasing dietary LA in both all chicken tissues and all turkey tissues, which is contrary to the suggested strong metabolic regulation of the AA formation. When all tissues within all animal species were taken as a one set, both AA percentage and EPA + DHA percentage in the tissue (Y, %) decreased (P < 0.001) with increasing fat content in the tissue (X, %), according to the equation Y = 4.7 - 0.54X (R (2) = 0.41) and Y = 6.0 - 0.33X (R (2) = 0.35), respectively. AA content in chicken BM, chicken TM, and turkey BM, respectively, decreased linearly (P < 0.01) with increasing live weight reached at the slaughter age.

An unexpected wide population variation of the G1733A polymorphism of the androgen receptor gene: Data on the Mediterranean region

The androgen receptor (AR) has been proposed as a candidate gene for several cancers (breast, prostate, uterine endometrium, colon, and esophagus). Ethnicity is considered an associated risk factor for some of these cancers. Several case-control genetic studies have been focused in samples of the main ethnic groups, but little is known about the distribution of risk polymorphisms in current populations with accurate ethnic and/or geographic origins. The A allele of the G1733A polymorphism of the AR gene has been associated with increased risk of prostate cancer. We provide data from this marker in 12 samples from 7 Mediterranean countries such as Spain, Italy (Sardinia), Greece, Turkey, Morocco, Algeria, and Egypt. A sample from Ivory Coast has also been analyzed. The A allele distribution shows a frequency in the Ivory Coast population (65.17%) that contrasts with the low values found in Northern Mediterraneans (mean average value of 13.98%). North African populations present two-times higher frequencies (average value of 27.19%) than Europeans. The wide population variation range found for the A allele strengthens the potential interest of further screening as a baseline to the design of future preventive and population health programs.