Conjugated linoleic acid intake and breast cancer risk in a prospective cohort of Swedish women

Dietary Phospholipid-Bound Conjugated Linoleic Acid and Docosahexaenoic Acid Incorporation Into Fetal Liver and Brain Modulates Fatty Acid and N-Acylethanolamine Profiles

We evaluated whether maternal intake of conjugated linoleic acid (CLA) and docosahexaenoic acid (DHA) in the phospholipid (PL) form (CLA-DHA PL) affects maternal and fetal brain and liver fatty acids (FAs) profile and the biosynthesis of FA-derived bioactive lipid mediators N-acylethanolamines (NAEs) involved in several neurophysiological functions. We fed rat dams during the first 2/3 of their pregnancy a CLA-DHA PL diet containing PL-bound 0.5% CLA and 0.2% DHA. FA and NAE profiles were analyzed in maternal and fetal liver and brain by Liquid Chromatography diode array detector (LC-DAD) and MS/MS in line. We found that CLA and DHA crossed the placenta and were readily incorporated into the fetal liver and brain. CLA metabolites were also found abundantly in fetal tissues. Changes in the FA profile induced by the CLA-DHA PL diet influenced the biosynthesis of NAE derived from arachidonic acid (ARA; N-arachidonoylethanolamine, AEA) and from DHA (N-docosahexaenoylethanolamine, DHEA). The latter has been previously shown to promote synaptogenesis and neuritogenesis. The reduced tissue n6/n3 ratio was associated to a significant decrease of AEA levels in the fetal and maternal liver and an increase of DHEA in the fetal and maternal liver and in the fetal brain. Maternal dietary CLA-DHA PL by promptly modifying fetal brain FA metabolism, and thereby, increasing DHEA, might represent an effective nutritional strategy to promote neurite growth and synaptogenesis and protect the offspring from neurological and psychiatric disorders with neuroinflammatory and neurodegenerative basis during the critical prenatal period.

Dietary intake of trans fatty acids and breast cancer risk in 9 European countries

BACKGROUND

Trans fatty acids (TFAs) have been hypothesised to influence breast cancer risk. However, relatively few prospective studies have examined this relationship, and well-powered analyses according to hormone receptor-defined molecular subtypes, menopausal status, and body size have rarely been conducted.

METHODS

In the European Prospective Investigation into Cancer and Nutrition (EPIC), we investigated the associations between dietary intakes of TFAs (industrial trans fatty acids [ITFAs] and ruminant trans fatty acids [RTFAs]) and breast cancer risk among 318,607 women. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models, adjusted for other breast cancer risk factors.

RESULTS

After a median follow-up of 8.1 years, 13,241 breast cancer cases occurred. In the multivariable-adjusted model, higher total ITFA intake was associated with elevated breast cancer risk (HR for highest vs lowest quintile, 1.14, 95% CI 1.06-1.23; P trend = 0.001). A similar positive association was found between intake of elaidic acid, the predominant ITFA, and breast cancer risk (HR for highest vs lowest quintile, 1.14, 95% CI 1.06-1.23; P trend = 0.001). Intake of total RTFAs was also associated with higher breast cancer risk (HR for highest vs lowest quintile, 1.09, 95% CI 1.01-1.17; P trend = 0.015). For individual RTFAs, we found positive associations with breast cancer risk for dietary intakes of two strongly correlated fatty acids (Spearman correlation r = 0.77), conjugated linoleic acid (HR for highest vs lowest quintile, 1.11, 95% CI 1.03-1.20; P trend = 0.001) and palmitelaidic acid (HR for highest vs lowest quintile, 1.08, 95% CI 1.01-1.16; P trend = 0.028). Similar associations were found for total ITFAs and RTFAs with breast cancer risk according to menopausal status, body mass index, and breast cancer subtypes.

CONCLUSIONS

These results support the hypothesis that higher dietary intakes of ITFAs, in particular elaidic acid, are associated with elevated breast cancer risk. Due to the high correlation between conjugated linoleic acid and palmitelaidic acid, we were unable to disentangle the positive associations found for these fatty acids with breast cancer risk. Further mechanistic studies are needed to identify biological pathways that may underlie these associations.

Dietary intake and serum levels of trans fatty acids and risk of breast cancer: A systematic review and dose-response meta-analysis of prospective studies

BACKGROUND & AIMS

Although the relationship between dietary intake and serum levels of trans fatty acids and risk of breast cancer has been investigated extensively, findings are inconsistent. To summarize earlier findings on the association of dietary intake and serum levels of trans fatty acids with risk of breast cancer through a dose-response meta-analysis.

METHODS

The online databases of PubMed, ISI Web of Science, Scopus, ProQuest, Science Direct and Embase were searched for relevant publications up to June 2018, using MeSH and non-MeSH keywords. In total, 7 prospective studies [6 cohort studies and one nested case-control study] were included on total dietary trans fat intake, and five studies [1 cohort study and 4 nested case-control studies] were included about serum trans fatty acids. Assessment of study quality was conducted using the Newcastle-Ottawa scale. Study-specific RRs were combined via fixed-effects model to compute overall RRs.

RESULTS

Participants were apparently healthy aged 26 years or older. We observed no significant relationship between dietary intake of total trans fatty acids and risk of breast cancer (pooled effect size: 1.02, 95% CI: 0.95-1.10, P = 0.403). Combining 3 effect sizes from 2 prospective and one nested case-control study, no significant relation was seen between dietary intake of CLA and risk of breast cancer (pooled effect size: 1.05, 95% CI: 0.95-1.17, P = 0.513). Based on 5 effect sizes, each additional 1 g/day dietary intake of total trans fats was not significantly associated with risk of breast cancer (RR = 1.00; 95% CI = 0.99-1.01). In addition, it seems that serum levels of trans fats might be associated with an increased risk of breast cancer only among postmenopausal women (Pooled effect size: 1.37, 95% CI: 1.04-1.81, P = 0.02).

CONCLUSIONS

In conclusion, dietary intake of trans fatty acids was not associated with risk of breast cancer; however, a significant positive association was seen between serum trans fats and risk of breast cancer in postmenopausal women.

Meat, eggs, full-fat dairy, and nutritional boogeymen: Does the way in which animals are raised affect health differently in humans?

Background: Food recommendations to improve cancer prevention are generally based on epidemiologic data and remain inconsistent. These epidemiologic studies, while controversial, have generally produced results that caution against the consumption of high-fat foods, including eggs, red meat, and full-fat dairy, such as butter and cheese. Yet, limited data exist assessing the quality of individual sources of these foods and the effect each has after its consumption. This study set out to assess the impact sources of food within the same groups from animals raised differently on variables associated with health in human studies. Methods and Materials: A search was conducted through MEDLINE, Embase, and PubMed. In total, twenty-nine studies met inclusion criteria, measuring physiologic changes in humans after consuming animal products following animal diet manipulation. A meta-analysis was attempted to assess the differences between the cohorts in these studies, but was aborted due to poor study quality, vast differences in study design, and a limited number of studies. Results: Studies varied by animal, animal diet manipulation, food product, and overall design. Significant differences were present between groups eating the same food (cheese, beef, eggs, and butter) from animals raised differently, including levels of: conjugated linoleic acid, omega-3 fatty acids (alpha linoleic acid [ALA], docosahexaenoic acid [DHA], and eicosapentaenoic acid [EPA]), and inflammatory factors (triacyl glycerol [TAG], interleukin-6 [IL-6], interleukin-8 [IL-8], tumor necrosis factor [TNF], and C-reactive protein [CRP]). Lipid levels were minimally affected. Conclusions: This work highlights differences in human health markers after consumption of the same foods from animals raised differently. Overall, lipid levels remained relatively neutral, but significant changes in inflammatory and other serum markers and phospholipids were present. Future studies and dietary recommendations should consider how animals are raised, as this can produce different effects on health markers.

The effects of conjugated linoleic acids on breast cancer: A systematic review

Recently prevention strategies for breast cancer are focused on lifestyle modification such as diet. Some dietary factors such as Conjugated linoleic acid (CLA) can lower the risk of breast cancer, metastasis and some factors concerning this malignancy. Many studies have been established in this field, but their results are inconsistent. Therefore, we evaluated this association based on systematic review among published scientific literature. We performed an electronic search using PubMed, Cochrane, Scopus, Google Scholar and Persian database (Iran Medex, magiran) to identify relevant studies. We summarized the findings of 8 papers in this review. Although, three cohort studies were not overall identified a protective effect of CLA dietary intake or CLA content in breast tissue on breast cancer incidence, metastasis and death, one of them showed an inverse association after adjusting for age. Also, among case-control studies a weak inverse association between breast cancer risk and CLA dietary intake and serum levels among post-menopausal women was reported. Besides, a clinical trial showed that some indicator of breast tumor decreased after CLA administration among women with breast adenocarcinoma. Lacking published evidence suggested inconsistent results. So, further well-designed studies are required, particularly in considering the main breast cancer risk factors.

Pros and cons of CLA consumption: an insight from clinical evidences

This comprehensive review critically evaluates whether supposed health benefits propounded upon human consumption of conjugated linoleic acids (CLAs) are clinically proven or not. With a general introduction on the chemistry of CLA, major clinical evidences pertaining to intervention strategies, body composition, cardio-vascular health, immunity, asthma, cancer and diabetes are evaluated. Supposed adverse effects such as oxidative stress, insulin resistance, irritation of intestinal tract and milk fat depression are also examined. It seems that no consistent result was observed even in similar studies conducted at different laboratories, this may be due to variations in age, gender, racial and geographical disparities, coupled with type and dose of CLA supplemented. Thus, supposed promising results reported in mechanistic and pre-clinical studies cannot be extrapolated with humans, mainly due to the lack of inconsistency in analyses, prolonged intervention studies, follow-up studies and international co-ordination of concerted studies. Briefly, clinical evidences accumulated thus far show that CLA is not eliciting significantly promising and consistent health effects so as to uphold it as neither a functional nor a medical food.

Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study

OBJECTIVE

To investigate the association between long term intake of dietary and supplemental calcium and death from all causes and cardiovascular disease.

DESIGN

Prospective longitudinal cohort study.

SETTING

Swedish mammography cohort, a population based cohort established in 1987-90.

PARTICIPANTS

61 433 women (born between 1914 and 1948) followed-up for a median of 19 years.

MAIN OUTCOME MEASURES

Primary outcome measures, identified from registry data, were time to death from all causes (n=11 944) and cause specific cardiovascular disease (n=3862), ischaemic heart disease (n=1932), and stroke (n=1100). Diet was assessed by food frequency questionnaires at baseline and in 1997 for 38 984 women, and intakes of calcium were estimated. Total calcium intake was the sum of dietary and supplemental calcium.

RESULTS

The risk patterns with dietary calcium intake were non-linear, with higher rates concentrated around the highest intakes (≥1400 mg/day). Compared with intakes between 600 and 1000 mg/day, intakes above 1400 mg/day were associated with higher death rates from all causes (hazard ratio 1.40, 95% confidence interval 1.17 to 1.67), cardiovascular disease (1 49, 1.09 to 2.02), and ischaemic heart disease (2.14, 1.48 to 3.09) but not from stroke (0.73, 0.33 to 1.65). After sensitivity analysis including marginal structural models, the higher death rate with low dietary calcium intake (<600 mg/day) or with low and high total calcium intake was no longer apparent. Use of calcium tablets (6% users; 500 mg calcium per tablet) was not on average associated with all cause or cause specific mortality but among calcium tablet users with a dietary calcium intake above 1400 mg/day the hazard ratio for all cause mortality was 2.57 (95% confidence interval 1.19 to 5.55).

CONCLUSION

High intakes of calcium in women are associated with higher death rates from all causes and cardiovascular disease but not from stroke.

Human health effects of conjugated linoleic acid from milk and supplements

The primary purpose of the present review was to determine if the scientific evidence available for potential human health benefits of conjugated linoleic acid (CLA) is sufficient to support health claims on foods based on milk naturally enriched with cis-9, trans-11-CLA (c9, t11-CLA). A search of the scientific literature was conducted and showed that almost all the promising research results that have emerged in relation to cancer, heart health, obesity, diabetes and bone health have been in animal models or in vitro. Most human intervention studies have utilised synthetic CLA supplements, usually a 50:50 blend of c9, t11-CLA and trans-10, cis-12-CLA (t10, c12-CLA). Of these studies, the only evidence that is broadly consistent is an effect on body fat and weight reduction. A previous review of the relevant studies found that 3.2 g CLA/d resulted in a modest body fat loss in human subjects of about 0.09 kg/week, but this effect was attributed to the t10, c12-CLA isomer. There is no evidence of a consistent benefit of c9, t11-CLA on any health conditions; and in fact both synthetic isomers, particularly t10, c12-CLA, have been suspected of having pro-diabetic effects in individuals who are already at risk of developing diabetes. Four published intervention studies using naturally enriched CLA products were identified; however, the results were inconclusive. This may be partly due to the differences in the concentration of CLA administered in animal and human studies. In conclusion, further substantiation of the scientific evidence relating to CLA and human health benefits are required before health claims can be confirmed.

Influence of in vitro supplementation with lipids from conventional and Alpine milk on fatty acid distribution and cell growth of HT-29 cells

Background

To date, the influence of milk and dairy products on carcinogenesis remains controversial. However, lipids of ruminant origin such as conjugated linoleic acids (CLA) are known to exhibit beneficial effects in vitro and in vivo. The aim of the present study was to determine the influence of milk lipids of different origin and varying quality presenting as free fatty acid (FFA) solutions on cellular fatty acid distribution, cellular viability, and growth of human colon adenocarcinoma cells (HT-29).

Methods

FAME of conventional and Alpine milk lipids (ML_con, ML_alp) and cells treated with FFA derivatives of milk lipids were analyzed by means of GC-FID and Ag⁺-HPLC. Cellular viability and growth of the cells were determined by means of CellTiter-Blue^®-assay and DAPI-assay (4',6-diamidino-2-phenylindole dihydrochloride), respectively.

Results

Supplementation with milk lipids significantly decreased viability and growth of HT-29 cells in a dose- and time-dependent manner. ML_alp showed a lower SFA/MUFA ratio, a 8 fold increased CLA content, and different CLA profile compared to ML_con but did not demonstrate additional growth-inhibitory effects. In addition, total concentration and fatty acid distribution of cellular lipids were altered. In particular, treatment of the cells yielded highest amounts of two types of milk specific major fatty acids (μg FA/mg cellular protein) after 8 h of incubation compared to 24 h; 200 μM of ML_con (C16:0, 206 ± 43), 200 μM of ML_alp (C18:1 c9, (223 ± 19). Vaccenic acid (C18:1 t11) contained in milk lipids was converted to c9,t11-CLA in HT-29 cells. Notably, the ratio of t11,c13-CLA/t7,c9-CLA, a criterion for pasture feeding of the cows, was significantly changed after incubation for 8 h with lipids from ML_alp (3.6 - 4.8), compared to lipids from ML_con (0.3 - 0.6).

Conclusions

Natural lipids from conventional and Alpine milk showed similar growth inhibitory effects. However, different changes in cellular lipid composition suggested a milk lipid-depending influence on cell sensitivity. It is expected that similar changes may also be evident in other cell lines. To our knowledge, this is the first study showing a varied impact of complex milk lipids on fatty acid distribution in a colon cancer cell line.

Dietary conjugated linoleic acid and long-chain n-3 fatty acids in mammary and prostate cancer protection: a review

The role of dietary fatty acids on cancer is still controversial. To examine the current literature on the protective role of conjugated linoleic acid (CLA) and marine long-chain fatty acids [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] and the risk of breast and prostate cancer, data from 41 case-control and cohort studies and relevant in vitro and animal experiments were included in this 2000-2010 revision. Epidemiological studies on CLA intake or its tissue concentration related to breast and prostate tumorigenesis are not conclusive; EPA and DHA intake have shown important inverse associations just in some studies. Additional research on the analysed association is required.

Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study

OBJECTIVE

To investigate associations between long term dietary intake of calcium and risk of fracture of any type, hip fractures, and osteoporosis.

DESIGN

A longitudinal and prospective cohort study, based on the Swedish Mammography Cohort, including a subcohort, the Swedish Mammography Cohort Clinical.

SETTING

A population based cohort in Sweden established in 1987.

PARTICIPANTS

61,433 women (born between 1914 and 1948) were followed up for 19 years. 5022 of these women participated in the subcohort.

MAIN OUTCOME MEASURES

Primary outcome measures were incident fractures of any type and hip fractures, which were identified from registry data. Secondary outcome was osteoporosis diagnosed by dual energy x ray absorptiometry in the subcohort. Diet was assessed by repeated food frequency questionnaires.

RESULTS

During follow-up, 14,738 women (24%) experienced a first fracture of any type and among them 3871 (6%) a first hip fracture. Of the 5022 women in the subcohort, 1012 (20%) were measured as osteoporotic. The risk patterns with dietary calcium were non-linear. The crude rate of a first fracture of any type was 17.2/1000 person years at risk in the lowest quintile of calcium intake, and 14.0/1000 person years at risk in the third quintile, corresponding to a multivariable adjusted hazard ratio of 1.18 (95% confidence interval 1.12 to 1.25). The hazard ratio for a first hip fracture was 1.29 (1.17 to 1.43) and the odds ratio for osteoporosis was 1.47 (1.09 to 2.00). With a low vitamin D intake, the rate of fracture in the first calcium quintile was more pronounced. The highest quintile of calcium intake did not further reduce the risk of fractures of any type, or of osteoporosis, but was associated with a higher rate of hip fracture, hazard ratio 1.19 (1.06 to 1.32).

CONCLUSION

Gradual increases in dietary calcium intake above the first quintile in our female population were not associated with further reductions in fracture risk or osteoporosis.

An urgent need to include risk-benefit analysis in clinical trials investigating conjugated linoleic acid supplements in cancer patients

Malnutrition and weight loss are common in patients with cancer, both factors could potentially affect the response and tolerance to treatment, decreased quality of life, and thus associate them with poor survival. Conjugated linoleic acid (CLA) is shown to have beneficial health effects in healthy and disease situations including chemoprotective properties in various experimental cancer models. However, the anticarcinogenic property of CLA in animal and tissue culture models could not be confirmed in the Netherlands Cohort Study on Diet and Cancer and a prospective cohort of Swedish women. Cancer patients are already at increased risk of anorexia and there are evidences that CLA suppresses appetite even in healthy individuals. Risk/benefit analysis of CLA supplementation has never been reported before and it is not clear whether any beneficial anti-tumor effect of CLA prevails over its anti-appetite and/or weight lowering side effect in these patients. I suggest that clinical trials investigating CLA supplements in cancer patients, measure appropriate variables such as food intake, weight, and appetite change to yield preliminary data for future trials. I also suggest that data from previous trials that have administered CLA supplements to cancer patients be re-analyzed retrospectively to attempt to find out any effect from routine nutritional measures such as weight, serum albumin and such as those.

Dairy consumption and calcium intake and risk of breast cancer in a prospective cohort: the Norwegian Women and Cancer study

Objective

To study the association between consumption of dairy products and calcium intake and risk of breast cancer risk according to menopausal status.

Methods

In a population-based prospective cohort study of 64,904 Norwegian women followed from 1996/1999 through 2006, we examined total dairy consumption and consumption of various dairy products in relation to pre- and postmenopausal breast cancer risk. We also examined breast cancer in relation to calcium intake and to milk consumption during childhood and performed additional analyses corrected for measurement errors in the dietary data. In total, 218 premenopausal and 1,189 postmenopausal incident breast cancer cases were diagnosed during follow-up.

Results

Total dairy, adult, and childhood milk consumption was not associated with either pre- or postmenopausal breast cancer risk. Premenopausal women with the highest consumption of white cheese had half the risk of breast cancer compared to those with the lowest consumption (hazard rate ratio in the 4th quartile vs. the 1st quartile 0.50, 95% confidence interval 0.29–0.87). Total calcium intake tended to be inversely related to premenopausal (hazard rate ratio in the 4th quartile vs. the 1st quartile 0.65, 95% confidence interval 0.39–1.08) and postmenopausal breast cancer (hazard rate ratio in the 4th quartile vs. the 1st quartile 0.85, 95% confidence interval 0.70–1.04). Correcting for measurement errors did not alter the results substantially, nor did exclusion of early cancer cases.

Conclusion

Dairy consumption is not strongly related to breast cancer risk in this prospective study. A non-significant negative association between calcium intake and breast cancer risk was seen, particularly among premenopausal women.

Healthier meat products as functional foods

A promising approach to improving health care would be to produce a healthier food supply as a preventive health care strategy. The food supply could be improved by producing functional foods that have nutritional profiles that are healthier than conventional products. However, production of functional foods is not always easily accomplished since they must also taste good, be convenient and reasonably priced so that consumers will regularly purchase and use the products. Meats have great potential for delivering important nutrients such as fatty acids, minerals, dietary fiber, antioxidants and bioactive peptides into the diet. However, to produce successful products with these ingredients, technologies must be developed to increase their stability and decrease their flavor impact on muscle foods. In addition, many regulatory hurdles must be overcome for the commercial production of meats with added nutrients. These include redefinition of standard of identities and policies that allow front of the package nutritional claims. Without these regulatory changes, production of healthier meat products won't become a reality since these products would not have a competitive advantage over unfortified meats.

Fatty acids and breast cancer: the role of stem cells

Studies with animal models in vivo as well as with animal and human tumor cells in vitro suggest that specific fatty acids could reduce breast tumorigenesis. The most striking dietary fatty acid studies in animal models that show promise for reduction of breast cancer risk in humans are with conjugated linoleic acids (CLA) and n-3 fatty acids. Although a number of mechanisms have been proposed, the specific target of those fatty acids is not yet known. We sought to determine whether the effects of those fatty acids on terminally differentiated tumor cell seen could be due to alteration of breast cancer stem cells. The isomers, cis9, trans11-CLA and trans10, cis12-CLA, and the n-3 fatty acids, docosahexaenoic and eicosapentaenoic, reduced the proliferation of, and had increased toxicity towards, mammary tumor initiating cells. One mechanism involved in the effect of n-3 fatty acids may be due to alteration of the profile of prostaglandins. These results indicate that select fatty acids may be useful for preventing or reducing the risk of breast cancer as they may target the tumor initiating cell.

Summary and meta-analysis of prospective studies of animal fat intake and breast cancer

The objective of the present review was to examine the potential association between animal fat intake and breast cancer. We conducted a meta-analysis and review of epidemiological cohort studies, including data reported in the Pooling Project publication of Prospective Studies of Diet and Cancer. Random- and fixed-effects models were utilised to generate summary relative risk estimates (SRRE), and sensitivity and influence analyses were conducted. In the meta-analysis that included data reported in the Pooling Project publication of prospective cohorts (n 8) and subsequent publications of cohort studies (n 3), no significant association was observed comparing the highest category of animal fat intake with the lowest (SRRE 1.03; 95 % CI: 0.76, 1.40). Similarly, no significant association between a 5 % increment of energy from animal fat intake and breast cancer (SRRE 1.02; 95 % CI 0.97, 1.07) was observed in the meta-analysis of these studies. In conclusion, the results of the present quantitative assessment are not supportive of a positive independent association between consumption of animal fat and breast cancer, although findings may be sensitive to the type of dietary instrument used in cohort studies.