Protective effects of diets supplemented with omega-3 polyunsaturated fatty acids and calcium against colorectal tumor formation

Zinc, ω-3 polyunsaturated fatty acids and vitamin D: An essential combination for prevention and treatment of cancers

Zinc, ω-3 polyunsaturated fatty acids (PUFAs) and vitamin D are essential nutrients for health, maturation and general wellbeing. Extensive literature searches have revealed the widespread similarity in molecular biological properties of zinc, ω-3 PUFAs and vitamin D, and their similar anti-cancer properties, even though they have different modes of action. These three nutrients are separately essential for good health, especially in the aged. Zinc, ω-3 PUFAs and vitamin D are inexpensive and safe as they are fundamentally natural and have the properties of correcting and inhibiting undesirable actions without disturbing the normal functions of cells or their extracellular environment. This review of the anticancer properties of zinc, ω-3 PUFAs and vitamin D is made in the context of the hallmarks of cancer. The anticancer properties of zinc, ω-3 PUFAs and vitamin D can therefore be used beneficially through combined treatment or supplementation. It is proposed that sufficiency of zinc, ω-3 PUFAs and vitamin D is a necessary requirement during chemotherapy treatment and that clinical trials can have questionable integrity if this sufficiency is not checked and maintained during efficacy trials.

Omega-3 Polyunsaturated Fatty Acids and Their Bioactive Metabolites in Gastrointestinal Malignancies Related to Unresolved Inflammation. A Review

Chronic inflammation takes part in the pathogenesis of some malignancies of the gastrointestinal tract including colorectal (CRC), gastric, and esophageal cancers. The use of ω3 polyunsaturated fatty acid (ω3-PUFA) supplements for chemoprevention or adjuvant therapy of gastrointestinal cancers is being investigated in recent years. Most evidence has been reported in CRC, although their protective role has also been reported for Helicobacter pylori-induced gastric cancer or Barrett’s esophagus-derived adenocarcinoma. Studies based on ω3-PUFA supplementation in animal models of familial adenomatous polyposis (FAP) and CRC revealed positive effects on cancer prevention, reducing the number and size of tumors, down-regulating arachidonic acid-derived eicosanoids, upregulating anti-oxidant enzymes, and reducing lipid peroxidation, whereas contradictory results have been found in induced colitis and colitis-associated cancer. Beneficial effects have also been found in FAP and ulcerative colitis patients. Of special interest is their positive effect as adjuvants on radio- and chemo-sensitivity, specificity, and prevention of treatment complications. Some controversial results obtained in CRC might be justified by different dietary sources, extraction and preparation procedures of ω3-PUFAs, difficulties on filling out food questionnaires, daily dose and type of PUFAs, adenoma subtype, location of CRC, sex differences, and genetic factors. Studies using animal models of inflammatory bowel disease have confirmed that exogenous administration of active metabolites derived from PUFAs called pro-resolving mediators like lipoxin A4, arachidonic acid-derived, resolvins derived from eicosapentaenoic (EPA), docosahexaenoic (DHA), and docosapentaenoic (DPA) acids as well as maresin 1 and protectins DHA- and DPA-derived improve disease and inflammatory outcomes without causing immunosuppression or other side effects.

The anticancer and antiobesity effects of Mediterranean diet

Cancers have been the leading cause of death worldwide and the prevalence of obesity is also increasing in these few decades. Interestingly, there is a direct association between cancer and obesity. Each year, more than 90,000 cancer deaths are caused by obesity or overweight. The dietary pattern in Crete, referred as the traditional Mediterranean diet, is believed to confer Crete people the low mortality rates from cancers. Nevertheless, the antiobesity effect of the Mediterranean diet is less studied. Given the causal relationship between obesity and cancer, the antiobesity effect of traditional Mediterranean diet might contribute to its anticancer effects. In this regard, we will critically review the anticancer and antiobesity effects of this diet and its dietary factors. The possible mechanisms underlying these effects will also be discussed.

SUPLEMENTAÇÃO COM ÔMEGA-3 PÓS-RECONSTRUÇÃO DO LIGAMENTO CRUZADO ANTERIOR

Introdução: As lesões do ligamento cruzado anterior (LCA) contribuem para a formação de radicais livres de oxigênio que, em excesso, podem desencadear dano oxidativo na articulação do joelho. Objetivo: Avaliar os efeitos da suplementação oral com ômega-3 sobre marcadores de estresse oxidativo em indivíduos submetidos à reconstrução do LCA. Métodos: Este estudo é um ensaio clínico prospectivo, randomizado, controlado e simples cego, com amostra de 25 indivíduos submetidos à reconstrução do LCA, separados aleatoriamente em: grupo ômega-3 (GO), suplementado diariamente com 2 g de ômega-3 durante 15 dias pós-reconstrução do LCA e grupo controle (GC), não suplementado. Foi realizada coleta de sangue e de líquido sinovial imediatamente antes do procedimento cirúrgico e 15 dias pós-reconstrução do LCA. As análises bioquímicas avaliaram os níveis de produtos de lipoperoxidação (MDA); atividade da catalase; grupos sulfidrílicos totais e polifenóis e proteína C reativa (PCR). Resultados: Observou-se diminuição significativa nos níveis de MDA no GO em comparação ao GC (p < 0,05), da mesma forma que a atividade da enzima antioxidante catalase foi significativamente menor no GO quando comparado ao GC (p < 0,001). Também foram observados níveis significativamente elevados de grupos sulfidrílicos totais no plasma dos indivíduos suplementados quando comparados aos do GC (p < 0,001). Além disso, foram observados níveis significativamente maiores de polifenóis (p < 0,05) tanto no plasma quanto no líquido sinovial dos indivíduos que receberam ômega-3 no período pós-cirúrgico comparado ao pré-cirúrgico. Entretanto, não foi observado um efeito protetor da administração do ômega-3 sobre a função anti-inflamatória. Conclusão: Verificamos um efeito protetor do ômega-3 na modulação dos marcadores de estresse oxidativo em indivíduos submetidos à reconstrução do LCA.

Colorectal carcinogenesis: a cellular response to sustained risk environment

The current models for colorectal cancer (CRC) are essentially linear in nature with a sequential progression from adenoma through to carcinoma. However, these views of CRC development do not explain the full body of published knowledge and tend to discount environmental influences. This paper proposes that CRC is a cellular response to prolonged exposure to cytotoxic agents (e.g., free ammonia) as key events within a sustained high-risk colonic luminal environment. This environment is low in substrate for the colonocytes (short chain fatty acids, SCFA) and consequently of higher pH with higher levels of free ammonia and decreased mucosal oxygen supply as a result of lower visceral blood flow. All of these lead to greater and prolonged exposure of the colonic epithelium to a cytotoxic agent with diminished aerobic energy availability. Normal colonocytes faced with this unfavourable environment can transform into CRC cells for survival through epigenetic reprogramming to express genes which increase mobility to allow migration and proliferation. Recent data with high protein diets confirm that genetic damage can be increased, consistent with greater CRC risk. However, this damage can be reversed by increasing SCFA supply by feeding fermentable fibre as resistant starch or arabinoxylan. High protein, low carbohydrate diets have been shown to alter the colonic environment with lower butyrate levels and apparently greater mucosal exposure to ammonia, consistent with our hypothesis. Evidence is drawn from in vivo and in vitro genomic and biochemical studies to frame experiments to test this proposition.

Bile composition, plasma lipids and oxidative hepatic damage induced by calcium supplementation; effects of goat or cow milk consumption

Calcium-fortified foods, especially milk and dairy products are recommended to be consumed daily for groups in risk of nutritional deficiency, including children, young adults, menopausal women, pregnant women and the elderly, however Ca-supplementation promotes gallstone formation because Ca is a nucleating factor. The objective of the current study was to assess the influence of cow or goat milk-based diets, either normal or Ca-supplemented, on bile composition, biochemical parameters and hepatic antioxidant status. Weanling male rats were randomly divided into six groups, fed standard, goat or cow milk-based diets, either with normal Ca content (5·0 g/kg), or Ca-supplemented (10·0 g/kg), for 2 weeks. Bile cholesterol concentration and output was higher in rats fed goat milk in comparison with those fed with standard and cow-milk-based diet. Ca-supplementation increased lithogenic index with the standard and cow-milk based diets, this change was not observed with the goat milk diet. Activities of plasma transaminases were also lower in the animals fed Ca-supplemented goat milk, in comparison with the other diets assayed. In general, Ca-supplement in the diet led to an increase in the hepatic oxidative damage, with an increase in the activities of all the antioxidant enzymes studied in the standard and cow milk diet, but not with goat milk. The habitual consumption of goat milk has positive effects on the plasma lipid profile, biliary composition and hepatic antioxidant defence. In addition, under our experimental conditions, Ca-supplementation of this type of milk does not increase the lithogenic index, or hepatic oxidative damage.

Fatty acids in habitual diet, plasma phospholipids, and tumour and normal colonic biopsies in young colorectal cancer patients

Fatty acid metabolism is altered in colorectal cancer (CRC). We aimed to investigate incorporation of dietary n-6 and n-3 polyunsaturated fatty acids (PUFAs) into plasma phospholipids (PLs), tumour tissue, and normal mucosa in young CRC patients. We also aimed to study differences in PUFA composition between tumour and normal mucosa, and PUFA status associated with cancer stage. Sixty-five CRC patients younger than 55 years were included in a multicenter study. We assessed dietary fatty acid composition by food-frequency questionnaire. Fatty acid composition in plasma PL (n = 65) and tumour and normal colonic biopsies (n = 32) were analysed by gas chromatography. We observed a significant correlation for docosahexaenoic acid (DHA) between dietary intake and concentration in plasma PL (weight%) (r = 0.42; P = 0.001), but not for any n-6 PUFA. Tissue concentrations of arachidonic acid, eicosapentaenoic acid, and DHA (weight%) were 1.7–2.5 times higher in tumour than normal mucosa (P ≤ 0.001). Concentrations of n-3 and n-6 PUFA in plasma PL and tissues were not related to Duke's stage, although patients with more severe cancer stage reported higher intake of n-3 PUFA. In conclusion, we found accumulation of the long-chained n-3 and n-6 PUFA in tumour tissue in young CRC patients.

Inhibitory effects of calcium against intestinal cancer in human colon cancer cells and Apc(Min/+) mice

The aim of the study was to investigate the inhibitory effects of calcium against intestinal cancer in vitro and in vivo. We first investigated the effects of calcium treatment in HCT116 and HT29 human colon cancer cells. At the concentration range of 0.8-2.4 mM, calcium significantly inhibited cell growth (by 9-29%), attachment (by 12-26%), invasion (by 15-31%), and migration (by 19-61%). An immunofluorescence microscope analysis showed that the treatment with calcium (1.6 mM) for 24 h increased plasma membrane β-catenin but decreased nuclear β-catenin levels in HT29 cells. We then investigated the effect of dietary calcium on intestinal tumorigenesis in Apc^Min/+ mice. Mice received dietary treatment starting at 6 weeks of age for the consecutive 8 weeks. The basal control diet contained high-fat (20% mixed lipids by weight) and low-calcium (1.4 mg/g diet) to mimic the average Western diet, while the treatment diet contained an enriched level of calcium (5.2 mg calcium/g diet). The dietary calcium treatment decreased the total number of small intestinal tumors (by 31.4%; P < 0.05). The largest decrease was in tumors which were ≥ 2 mm in diameter, showing a 75.6% inhibition in the small intestinal tumor multiplicity (P < 0.001). Immunohistochemical analysis showed significantly reduced nuclear staining of β-catenin (expressed as nuclear positivity), but increased plasma membrane staining of β-catenin, in the adenomas from the calcium-treated groups in comparison to those from the control group (P < 0.001). These results demonstrate intestinal cancer inhibitory effects of calcium both in human colon cancer cells and Apc^Min/+ mice. The decreased β-catenin nuclear localization caused by the calcium treatment may contribute to the inhibitory action.

The protective effect of the Mediterranean diet: focus on cancer and cardiovascular risk

The lower occurrence of cancer and cardiovascular disease in the population around the Mediterranean basin has been linked to the dietary habits of the region. Indeed, this so-called Mediterranean diet is essentially different from the diets consumed in Western and Northern European countries and is rich in nuts, fruits, vegetables, legumes, whole-wheat bread, fish, and olive oil, with moderate amounts of red wine, which is mainly consumed during meals. Although a variety of cultural and religious traditions exist among the peoples of the Mediterranean area, olive oil, fish, and red wine hold a traditional and central position in the culinary routines of the region. The components of the diet contain an ample source of molecules with antioxidant and anti-inflammatory actions, among which omega-3 fatty acids, oleic acid, and phenolic compounds hold a prominent place. This review will summarize the results of important epidemiological studies that have investigated the protective effect of fish and olive oil on the risk of breast, prostate, and colorectal cancer and of wine on the risk of cardiovascular disease. The present review also aims to elucidate the various mechanisms by which various dietary components exhibit their beneficial action. In this respect, emphasis will be placed on the properties of omega-3 fatty acids from fish, oleic acid from olive oil, and phenolic compounds from olive oil and red wine.

Associations of red meat, fat, and protein intake with distal colorectal cancer risk

Studies have suggested that red and processed meat consumption elevate the risk of colon cancer; however, the relationship between red meat, as well as fat and protein, and distal colorectal cancer (CRC) specifically is not clear. We determined the risk of distal CRC associated with red and processed meat, fat, and protein intakes in Whites and African Americans. There were 945 cases (720 White, 225 African American) of distal CRC and 959 controls (800 White, 159 African American). We assessed dietary intake in the previous 12 mo. Multivariate logistic regression analyses were used to obtain odds ratios (OR) and 95% confidence intervals (95% CI). There was no association between total, saturated, or monounsaturated fat and distal CRC risk. In African Americans, the OR of distal CRC for the highest category of polyunsaturated fat intake was 0.28 (95% CI = 0.08-0.96). The percent of energy from protein was associated with a 47% risk reduction in Whites (Q4 OR = 0.53, 95% CI = 0.37-0.77). Red meat consumption in Whites was associated with a marginally significant risk reduction (Q4 OR = 0.66, 95% CI = 0.43-1.00). Our results do not support the hypotheses that fat, protein, and red meat increase the risk of distal CRC.