Trans-fatty acids and colon cancer.

Trans-fatty acids have been hypothesized to be carcinogenic, although there are limited data in humans testing this hypothesis. In this study, we examine the association between trans-fatty acids and colon cancer using data from a case (n = 1,993)-control (n = 2,410) study conducted in Utah, Northern California, and Minnesota. Dietary data were collected using a detailed diet history questionnaire, and nutrient values were generated from the Nutrition Coordinating Center nutrient database. After adjustment for other variables, including age at diagnosis, body size, physical activity, aspirin and/or nonsteroidal anti-inflammatory drug (referred to collectively as NSAIDs) use, energy intake, and dietary fiber and calcium, we found a weak association in women [odds ratio (OR) = 1.5, 95% confidence interval (CI) = 1.1-2.0] but not in men (OR = 1.2, 95% CI = 0.9-1.7); no increased risk was observed for the cis form of the fatty acids. For men and women, slightly stronger associations were observed in those > or = 67 years of age (OR = 1.4, 95% CI = 0.9-2.1 for men; OR = 1.6, 95% CI = 1.0-2.4 for women). Those who did not use NSAIDs were at a 50% greater risk of developing colon cancer when they consumed high levels of trans-fatty acids. Women who were estrogen negative, i.e., postmenopausal not taking hormone replace therapy, had a twofold increase in risk from high levels of trans-fatty acids in the diet, while women who were estrogen positive did not experience an increased risk of colon cancer, regardless of level of trans-fatty acids consumed. We believe that these data have important public health implications. It seems prudent to avoid consuming partially hydrogenated fats, since no increased risk was observed for the cis form of fatty acids, while suggestions of increased risk from trans-fatty acids exist for subsets of the population.     

The role of breakfast in diet adequacy of the U.S. adult population

Breakfast consumption patterns of the U.S. adult population were examined by using the U.S.D.A. Nationwide Food Consumption Survey. Results indicated that approximately one-quarter of the adult population skipped breakfast regularly. For those adults who consumed breakfast, the four most commonly consumed breakfasts were eggs, bread, and coffee; ready-to-eat cereal with milk; coffee and bread; and eggs, bread, and milk. The sample was partitioned by six age/sex classes and by four breakfast consumption patterns. Assessments of average intakes of seven frequently underconsumed nutrients showed that omission of the breakfast meal had a significant negative impact, particularly among adult females, on the diet quality. Findings indicated that for all age/sex classes, consumption of ready-to-eat cereal at breakfast, whether frequently or on a more limited basis, increased the average daily intake levels of the underconsumed nutrients. Further, groups of adults who regularly consumed ready-to-eat cereal at breakfast had, on average, lower average daily intakes of fat and cholesterol. It was concluded that regular breakfast consumption greatly enhanced the overall diet quality of the U.S. adult population.     

The role of breakfast in diet adequacy of the U.S. adult population.

Breakfast consumption patterns of the U.S. adult population were examined by using the U.S.D.A. Nationwide Food Consumption Survey. Results indicated that approximately one-quarter of the adult population skipped breakfast regularly. For those adults who consumed breakfast, the four most commonly consumed breakfasts were eggs, bread, and coffee; ready-to-eat cereal with milk; coffee and bread; and eggs, bread, and milk. The sample was partitioned by six age/sex classes and by four breakfast consumption patterns. Assessments of average intakes of seven frequently underconsumed nutrients showed that omission of the breakfast meal had a significant negative impact, particularly among adult females, on the diet quality. Findings indicated that for all age/sex classes, consumption of ready-to-eat cereal at breakfast, whether frequently or on a more limited basis, increased the average daily intake levels of the underconsumed nutrients. Further, groups of adults who regularly consumed ready-to-eat cereal at breakfast had, on average, lower average daily intakes of fat and cholesterol. It was concluded that regular breakfast consumption greatly enhanced the overall diet quality of the U.S. adult population.     

The effect of age, sex, and education on food consumption of a middle-aged English cohort-EPIC in East Anglia

BACKGROUND: Different dietary patterns are associated with differing risks of chronic disease. Yet independent relationships between diet and demographic variables, such as age, sex, and education, are poorly described. METHODS: The first 1968 subjects enrolled to the European Prospective Investigation of Cancer (EPIC) cohort from general practices in East Anglia, UK, provided food frequency and demographic data. RESULTS: Men ate meat, eggs, milk, and sugary foods more frequently, but fruit and vegetables less frequently than women. Older subjects ate red meats and saturated bread spreads more frequently but consumed less poultry and drank less coffee than younger subjects. Better educated subjects ate less meat, more salads, and fewer cakes and sweet foods than those less educated. Five clusters representing different dietary patterns were readily identified. These were (a) younger well-educated, probably containing many vegetarians; (b) "low calorie," two-thirds female; (c) high alcohol, nuts, meat, largely male; (d) preferring fruits, vegetables, unsaturated fats, poultry, and fish, 71% female; (e) preferring meat, potatoes, sweet foods, saturated fats, less well-educated older men. CONCLUSIONS: The reported consumption of many foods varies by age, gender, and education. A pattern of eating that is generally considered less healthful was particularly seen in older men, placing them at increased risk of chronic disease.     

Association between serum trans-monounsaturated fatty acids and breast cancer risk in the E3N-EPIC Study

The authors assessed the association between serum phospholipid fatty acids as biomarkers of fatty acid intake and breast cancer risk among women in the E3N Study (1989-2002), the French component of the European Prospective Investigation into Cancer and Nutrition. During an average of 7 years of follow-up, 363 cases of incident invasive breast cancer were documented among 19,934 women who, at baseline (1995-1998), had completed a diet history questionnaire and provided serum samples. Controls were randomly matched to cases by age, menopausal status at blood collection, fasting status at blood collection, date, and collection center. Serum phospholipid fatty acid composition was assessed by gas chromatography. Adjusted odds ratios for risk of breast cancer with increasing levels of fatty acids were calculated using conditional logistic regression. An increased risk of breast cancer was associated with increasing levels of the trans-monounsaturated fatty acids palmitoleic acid and elaidic acid (highest quintile vs. lowest: odds ratio = 1.75, 95% confidence interval: 1.08, 2.83; p-trend = 0.018). cis-Monounsaturated fatty acids were unrelated to breast cancer risk. A high serum level of trans-monounsaturated fatty acids, presumably reflecting a high intake of industrially processed foods, is probably one factor contributing to increased risk of invasive breast cancer in women.     

Fat intake, diet variety and health promotion

Different epidemiological studies indicated that the optimization of diet and nutrition combined with healthy life style can decrease the risk and even lead to amelioration of various noncommunicable diseases. Promising food-based dietary guidelines have been recommended in order to improve the nutritional and health status. One of the most popular recommendations is related to the amount (less fat and fat-rich foods) and type of the dietary fat component (less saturated, more polyunsaturated fatty acids, lower n-6:n-3 ratio). An overview on the nutrient intake among different age groups in Austria shows that the general consumption of some food groups--especially those rich in carbohydrates--is too low and that the intake of fat is far beyond the recommended amount of 30% of total energy (E%). The results of the 24-hour recall made among Austrian adults (n = 2,585) showed that about 18% of this population group had a fat intake of 30-35 E%, whereas 60% had an intake higher than 35 E%. Only 24% of the female and male adults had a fat intake lower than 30 E%. A result of this high proportion of fat--in the form of foods rich in fat--in the average total energy consumption is a too low intake of carbohydrates, and foods rich in carbohydrates, respectively. An increasing fat intake is associated with an increasing intake of some nutrients such as vitamin A, E, calcium and zinc, but a decreasing intake of other nutrients like vitamin C, folate, carotenoids and others. The diversity of foods consumed during a day increases with decreasing amount of fat in the diet of adults. People with a high amount of fat in their daily diet show a lower intake of vegetables and fruit, cereal products, carotenoids, folates and dietary fibers, but a higher intake of meat and meat products, milk and milk products, sweets and flummeries as well as saturated fatty acids (SFA) and cholesterol. Of course, a higher variety of food items in the daily diet should not be associated with a higher energy intake. Thus, foods with a high nutrient density (vegetables, fruits, low-fat milk products, whole grain cereals, legumes etc.) are recommended. Finally, it has to be annotated that a high diversity in the daily diet with reduced fat and SFA intake allows a sufficient nutrient intake and is an important approach for health promotion.     

Individual saturated fatty acids and nonfatal acute myocardial infarction in Costa Rica

BACKGROUND: Epidemiological studies on the effect of individual saturated fatty acids (SFAs) on cardiovascular disease, especially in developing countries with different dietary patterns, are scarce. OBJECTIVE: To determine the risk of nonfatal acute myocardial infarction (MI) associated with consumption of individual SFAs and their food sources in Costa Rica. DESIGN: The cases (n=485) were survivors of a first acute MI and were matched by age, sex and area of residence to population controls (n=508). Data on anthropometrical measurements, lifestyle and diet were collected using interviewer-administered questionnaires. RESULTS: In analyses adjusted for confounders, consumption of total and individual SFAs was associated with an increased risk of MI. The odds ratio (OR) (95% confidence intervals) for 1% increase in energy from total saturated fat was 1.12 (1.03-1.21) while it was 1.51 (1.03-2.22) for lauric acid+myristic acid, 1.14 (1.01-1.30) for palmitic acid and 2.00 (1.34-3.00) for stearic acid. Although lauric and myristic acids were associated with increased risk of MI, they were consumed in small amounts and most of the saturated fat (87%) came from palmitic and stearic acids, which derived mainly from red meat and fried foods. Consumption of cheese (1-2 vs 0 servings/day) was associated with increased risk of MI (OR=3.07; 95% confidence interval: 1.74-5.39; P for trend <0.0001), while consumption of low-fat milk was not. CONCLUSION: Increased consumption of total and individual SFAs is associated with increased risk of MI. Lauric, myristic and stearic acids were more potent than palmitic acid.     

Serum phospholipid fatty acids and prostate cancer risk: results from the prostate cancer prevention trial

Inflammation may be involved in prostate cancer development and progression. This study examined the associations between inflammation-related phospholipid fatty acids and the 7-year-period prevalence of prostate cancer in a nested case-control analysis of participants, aged 55-84 years, in the Prostate Cancer Prevention Trial during 1994-2003. Cases (n = 1,658) were frequency matched to controls (n = 1,803) on age, treatment, and prostate cancer family history. Phospholipid fatty acids were extracted from serum, and concentrations of ω-3, ω-6, and trans-fatty acids (TFAs) were expressed as proportions of the total. Logistic regression models estimated odds ratios and 95% confidence intervals of associations of fatty acids with prostate cancer by grade. No fatty acids were associated with low-grade prostate cancer risk. Docosahexaenoic acid was positively associated with high-grade disease (quartile 4 vs. 1: odds ratio (OR) = 2.50, 95% confidence interval (CI): 1.34, 4.65); TFA 18:1 and TFA 18:2 were linearly and inversely associated with risk of high-grade prostate cancer (quartile 4 vs. 1: TFA 18:1, OR = 0.55, 95% CI: 0.30, 0.98; TFA 18:2, OR = 0.48, 95% CI: 0.27, 0.84). The study findings are contrary to those expected from the pro- and antiinflammatory effects of these fatty acids and suggest a greater complexity of effects of these nutrients with regard to prostate cancer risk.     

Alcohol use and the risk of prostate cancer: results from the VITAL cohort study

An association between alcohol consumption and prostate cancer risk remains uncertain. Although some studies have found that heavy alcohol consumption is associated with increased risk, a recent study reported that red wine consumption is associated with reduced risk. We examined the association between alcohol use and prostate cancer among 34,565 men, 50-76 yr old, in the Vitamins and Lifestyle (VITAL) cohort in Washington State. Alcohol consumption was ascertained by baseline questionnaire between October 2000 and December 2002. Incident prostate cancers (n = 816) as of December 31, 2004, were identified through the Surveillance, Epidemiology, and End Results cancer registry. Men who consumed more than one drink per month had a small increased risk of prostate cancer (hazard ratio, HR = 1.20; 95% confidence interval, CI = 1.02-1.40) compared with men who drank no alcohol or less than one drink per month. White wine consumption was associated with increased risk (HR for any vs. no white wine consumption = 1.27; CI = 1.08-1.49). Red wine, liquor, and beer were not associated with prostate cancer nor was total alcohol consumed at ages 18, 30, and 45. Associations of alcohol use with prostate cancer are modest and complex. More detailed assessment of specific alcoholic beverages is warranted in future studies.     

Trans fatty acids– Metabolic and nutritional significance

'Trans' fatty acids are unsaturated acids with special structural features that occur naturally in dietary fats from animal and plant sources and in fats processed by catalytic hydrogenation. They are readily metabolized by the human body. Thus, although when consumed in the diet they are incorporated into body fat (including depot and milk fats), they are subject to rapid 'turnover'. In physical properties, trans monounsaturatedfatty acids are intermediate between cis-monounsaturated and saturated acids, and they tend to be treated either as saturated or cis-monounsaturated acids in metabolic pathways. The author argues in this article that any adverse effects on health or metabolism that may have been observed can be ascribed to an imbalance between the intake of trans and essential fatty acids. Such imbalances, could also occur with non-essential fatty acids other than trans fats. Normally, the amounts eaten in average diets would not pose serious problems and only when products have excessively high trans contents and make a significant contribution to the diet need trans acids be highlighted on labels.     

Fat and protein composition of mature milk in adolescents.

The levels of certain components, notably total protein, total fat, energy, and fatty acids, of mature milk from 48 adolescent and 44 adult mothers was studied. These two groups were subdivided into high and low socioeconomic level (SEL). All mothers were primiparous, eutrophic, and with term pregnancy; and their newborns weighted over 2500 g at birth. The age factor appeared to have significant influence on the concentration of total protein, with higher levels in the group of adolescent mothers possibly as a compensatory mechanism to maintain the caloric value of the milk. The fatty acid content was altered significantly by the SEL probably due to the direct effect of maternal diet. The milk in adolescent mothers of low SEL demonstrated higher concentration of lauric and myristic acids, while the milk in low SEL adults contained higher proportions of linoleic and linolenic acids. The milk in adult mothers of high SEL demonstrated higher concentrations of palmitic, palmitoleic, and oleic acids. The different feeding habits of two socioeconomic groups may explain these results. The regular intake of soya oil, corn oil, and margarine by the urban population in general resulted in higher levels of linoleic acid in the milk of all groups studied.     

Dietary habits and prostate cancer prevention: a review of observational studies by focusing on South America

There exist several works considering the association between diet and prostate cancer (PC) risk, but the issue is largely unsettled. This article systematically reviews the epidemiological studies on diet and risk of PC focusing on those carried out in countries of South America. There is some suggestion that dairy products, red meat, processed meat, α-linolenic fatty acids, as well as dietary patterns characterized by higher intakes of red and processed meat, eggs, and grains may play some role in the development of PC. There is no clear association with the intake of vegetables and fruits, lycopene, fats, and different types of fatty acids. The evidence on diet and PC is therefore inconclusive in general and specifically in South America. Particular attention must be paid to the study of cancer risk in some countries of South America because of the singularly risky dietary pattern consumed by its population.     

A high ratio of dietary n-6/n-3 polyunsaturated fatty acids is associated with increased risk of prostate cancer

Experimental studies suggest omega-3 (n-3) polyunsaturated fatty acids (PUFA) suppress and n-6 PUFA promote prostate tumor carcinogenesis. Epidemiologic evidence remains inconclusive. The objectives of this study were to examine the association between n-3 and n-6 PUFA and prostate cancer risk and determine if these associations differ by race or disease aggressiveness. We hypothesize that high intakes of n-3 and n-6 PUFA will be associated with lower and higher prostate cancer risk, respectively. A case-control study comprising 79 prostate cancer cases and 187 controls was conducted at the Durham VA Medical Center. Diet was assessed using a food frequency questionnaire. Logistic regression analyses were used to obtain odds ratios (ORs) and 95% confidence intervals (95% CI) for the associations between n-3 and n-6 PUFA intakes, the dietary ratio of n-6/n-3 fatty acids, and prostate cancer risk. Our results showed no significant associations between specific n-3 or n-6 PUFA intakes and prostate cancer risk. The highest dietary ratio of n-6/n-3 was significantly associated with elevated risk of high-grade (OR, 3.55; 95% CI, 1.18-10.69; P_trend = 0.03), but not low-grade prostate cancer (OR, 0.95; 95% CI, 0.43-2.17). In race-specific analyses, an increasing dietary ratio of n-6/n-3 fatty acids correlated with higher prostate cancer risk among white men (P_trend = 0.05), but not black men. In conclusion, our findings suggest that a high dietary ratio of n-6/n-3 fatty acids may increase the risk of overall prostate cancer among white men and possibly increase the risk of high-grade prostate cancer among all men.     

Fatty acid composition of human milk from South African black mothers consuming a traditional maize diet

Fatty acid composition of mature human milk of rural and urban black South African mothers was determined by gas-liquid chromatography. Rural mothers consumed traditional diets low in animal protein and fat, and high in carbohydrate and fibre. Urban mothers consumed more varied, partially westernized diets, and two-thirds were overweight. Plasma cholesterol concentrations were significantly lower in the rural group (3.64 vs 4.75 mmol/l, P less than 0.01). Milk of rural mothers contained significantly higher percentages of C10:0, C12:0, and total saturated fatty acids. Fatty acids C8:0-C14:0 synthesized de novo in the mammary gland were substantially higher in the milk of the rural mothers (24.7 vs 15.9 per cent). Conversely, the milk of the urban group contained higher percentages of monounsaturated fatty acids, 18:3 omega 3 and 20:2 omega 6. The ratio of polyunsaturated to saturated fatty acids in rural samples was 0.36 +/- 0.13 compared to 0.41 +/- 0.15 in urban samples (P greater than 0.1). It is concluded that maternal dietary intake significantly affects milk composition, as demonstrated by the high percentages of fatty acids synthesized de novo in the mammary gland of rural mothers habituated to low-fat, high-carbohydrate intakes.     

Nutrition of preschool age children. General considerations and assessment of child nutrition

Results of the study performed between June 1999 and January 2000 on dietary assessment of 822 pre-school children (age 3-7) showed that majority of children regularly consumed the main meals: breakfast, dinner and supper. The habit of snacks eating between the meals was observed in 91% of children. The presence and structure basic products in analysed children diets (milk, fermented milk products, fats, fish, whole grain bread, juices) was different. About 87% reported drinking of milk, 75%--yoghurt or other fermented milk products, 97%--fruit juices including nectar, water--42%. The main fat used to spreading on bread was butter. Fish products recommended as a source of n-3 polyunsaturated fatty acids were still not eaten by 23% of children. Whole grain bread was consumed daily only in 8% children. The study also showed that the diets included products being the source of unfavourable fatty acids (chips, sweet bars, cookies, hard margarine) and excess of saccharose (sweets, lollipops, chewing gum). The results of the study showed the permanent need of the dissemination of dietary recommendations for children at pre-school age.     

The serum LDL/HDL cholesterol ratio is influenced more favorably by exchanging saturated with unsaturated fat than by reducing saturated fat in the diet of women

We compared the effects of a high fat diet [38.4% of energy (E%) from fat; HSAFA diet, polyunsaturated/saturated fatty acid (P/S) ratio = 0.14], a low fat diet (19.7 E% from fat; LSAFA diet, P/S = 0.17), both based on coconut oil, and a diet with a high content of mono- and polyunsaturated fatty acids (PUFA; 38.2 E% from fat; HUFA diet, P/S = 1.9) on serum lipoproteins. The 25 women studied consumed each diet for 3-wk periods in a crossover design. The two high fat diets were identical except for the quality of the test fat. The LSAFA diet was identical to the HSAFA diet except that half the fat was replaced by carbohydrates. Serum total cholesterol, LDL cholesterol and apoB concentrations did not differ between the HSAFA and the LSAFA diet periods. Total cholesterol, LDL cholesterol and apoB were lower when women consumed the HUFA diet than when they consumed the other two diets. HDL cholesterol and apoA-I were 15 and 11%, respectively, higher when women consumed the HSAFA diet than when they consumed the LSAFA diet; HDL cholesterol and apoA-I were lower when women consumed the HUFA diet than when they consumed the HSAFA diet, but not the LSAFA diet. The LDL cholesterol/HDL cholesterol and apoB/apoA-I ratios were higher when women consumed the LSAFA diet than when they consumed the HSAFA diet. The LDL/HDL cholesterol ratio was higher when women consumed either the LSAFA or the HSAFA diet than when they consumed the HUFA diet, whereas apoB/apoA-I was higher when women consumed the LSAFA diet than when they consumed the HUFA diet. Triacylglycerol and VLDL cholesterol were higher when women consumed the LSAFA diet than when they consumed either the HSAFA or the HUFA diet. We conclude that, to influence the LDL/HDL cholesterol ratio, changing the proportions of dietary fatty acids may be more important than restricting the percentage of total or saturated fat energy, at least when derived mainly from lauric and myristic acids, both of which increase HDL cholesterol.     

Fat content, energy value and fatty acid profile of donkey milk during lactation and implications for human nutrition

ABSTRACT: Background and AimsMilk contains numerous nutrients. The content of n-3 fatty acids, the n-6/n-3 ratio, and short- and medium-chain fatty acids may promote positive health effects. In Western societies, cow's milk fat is perceived as a risk factor for health because it is a source of a high fraction of saturated fatty acids. Recently, there has been increasing interest in donkey's milk. In this work, the fat and energetic value and acidic composition of donkey's milk, with reference to human nutrition, and their variations during lactation, were investigated. We also discuss the implications of the acidic profile of donkey's milk on human nutrition. METHODS: Individual milk samples from lactating jennies were collected 15, 30, 45, 60, 90, 120, 150, 180 and 210days after foaling, for the analysis of fat, proteins and lactose, which was achieved using an infrared milk analyser, and fatty acids composition by gas chromatography. RESULTS: The donkey's milk was characterised by low fat and energetic (1719.2kJ.kg-1) values, a high polyunsaturated fatty acids (PUFA) content of mainly alpha-linolenic acid (ALA) and linoleic acid (LA), a low n-6 to n-3 FA ratio or LA/ALA ratio, and advantageous values of atherogenic and thrombogenic indices. Among the minor PUFA, docosahesaenoic (DHA), eicosapentanoic (EPA), and arachidonic (AA) acids were present in very small amounts (<1%). In addition, the AA/EPA ratio was low (0.18). The fat and energetic values decreased (P<0.01) during lactation.The fatty acid patterns were affected by the lactation stage and showed a decrease (P<0.01) in saturated fatty acids content and an increase (P<0.01) in the unsaturated fatty acids content. The n-6 to n-3 ratio and the LA/ALA ratio were approximately 2:1, with values <1 during the last period of lactation, suggesting the more optimal use of milk during this period. CONCLUSIONS: The high level of unsaturated/saturated fatty acids and PUFA-n3 content and the low n-6/n-3 ratio suggest the use of donkey's milk as a functional food for human nutrition and its potential utilisation for infant nutrition as well as adult diets, particular for the elderly.     

A Milk-Fat Based Diet Increases Metastasis in the MMTV-PyMT Mouse Model of Breast Cancer

A high-fat diet (HFD) and obesity are risk factors for many diseases including breast cancer. This is particularly important with close to 40% of the current adult population being overweight or obese. Previous studies have implicated that Mediterranean diets (MDs) partially protect against breast cancer. However, to date, the links between diet and breast cancer progression are not well defined. Therefore, to begin to define and assess this, we used an isocaloric control diet (CD) and two HFDs enriched with either olive oil (OOBD, high in oleate, and unsaturated fatty acid in MDs) or a milk fat-based diet (MFBD, high in palmitate and myristate, saturated fatty acids in Western diets) in a mammary polyomavirus middle T antigen mouse model (MMTV-PyMT) of breast cancer. Our data demonstrate that neither MFBD or OOBD altered the growth of primary tumors in the MMTV-PyMT mice. The examination of lung metastases revealed that OOBD mice exhibited fewer surface nodules and smaller metastases when compared to MFBD and CD mice. These data suggest that different fatty acids found in different sources of HFDs may alter breast cancer metastasis.     

Effects of low fat diets varying in P/S ratio on nutrient intakes, fecal excretion, blood chemistry profiles, and fatty acids of adult men

Twenty-three apparently healthy volunteers aged 35 to 60 years consumed closely monitored self-selected (SS) diets for five weeks followed by two low fat controlled diets (25% energy) for two six-week periods followed by another five-week SS diet. The two low fat diets, fed in a crossover design to one-half of the subjects per controlled diet period, had a polyunsaturated/saturated (P/S) fat ratio of either 0.3 or 1.0. Results are reported for bi-weekly measurements of energy and nutrients; blood profiles and plasma fatty acids; and for end-of-period values for stool characteristics. Blood chemistry profiles differed in the two groups. The low P/S diet produced significant increases not only in cholesterol, but in 16:0, 16:1, and percent saturated fatty acids and decreases in 18:2 and omega 6 fatty acids. The reverse was seen with the high P/S diet. The essential fatty acid (EFA) linoleic acid returned in the poststudy period to prestudy levels (all subjects), but arachidonic acid did not. The explanation for negative correlation between magnesium intake or excretion and percent plasma linoleic acid must await further research.     

Nutrition and immunity in cancer

The purpose of this article is to give a general overview of the effects of nutrition on the development of cancer as well as part of a therapeutic approach. There is much evidence that diet and lifestyle can alter the risk of cancer development as is the case for many other chronic diseases. This may be through a direct action on the immune system, either by enhancing or suppressing it, as well as on the development of the tumour itself, by modulating gene expression or by antioxidant activity. Protective effects can be achieved by adequate intakes of vitamins A and C, beta-carotene, selenium and n-3 fatty acids among others, while negative effects are found mainly with high intakes of n-6 and saturated fatty acids. Weight gain, obesity and lack of regular physical activity have also been associated with an increased risk of cancer. The protective effects are best observed when adequate diet and lifestyle are present together. With respect to the therapeutic role of nutrition in cancer, it has been observed that the use of pre- or post-operative enteral or parenteral nutrition may improve patients' survival rates and quality of life; however, more research is needed in this particular area. Breast, colon, rectum, prostate, stomach and lung are the types of cancer most commonly associated with diet or dietary components.