Modulation of serum and breast ductal fluid lipids by a very-low-fat, high-fiber diet in premenopausal women

Weight loss reduces breast ductal fluid estrogens in obese postmenopausal women: a single arm intervention pilot study

BACKGROUND

Accumulation of excess body fat increases breast cancer risk after menopause. Whether the localized breast is differently influenced by adipose tissue compared to the rest of the body, has not been well studied. Our purpose was to demonstrate feasibility and preliminarily evaluate serum-based and localized breast biomarker changes resulting from a weight loss intervention among obese postmenopausal women.

METHODS

We conducted a 12-week pilot controlled dietary and exercise intervention among healthy obese postmenopausal women, collected serum and breast ductal fluid before and after the intervention, and estimated the association with systemic and localized biomarker changes. We recruited 7 obese (mean body mass index = 33.6 kg/m2) postmenopausal women. We collected samples at baseline and the 12th week for: anthropometry; phlebotomy; dual-energy x-ray absorptiometry (lean and fat mass); exercise fitness (maximum oxygen consumption (VO2Max); 1-repetition strength maximum); and breast ductal lavage.

RESULTS

Changes from baseline occurred in body composition and exercise performance including fat mass loss (14% average drop), VO2Max (+36% increase) and strength improvement (+26%). Breast ductal fluid markers declined from baseline with estradiol showing a 24% reduction and IL-6 a 20% reduction. We also observed serum biomarker reductions from baseline including leptin (36% decline), estrone sulfate (-10%), estradiol (-25%), and Il-6 (-33%).

CONCLUSIONS

Conduct of the diet and exercise intervention, collection of ductal fluid, and measurement of hormones and cytokines contained in the ductal fluid were all feasible. We preliminarily demonstrated estradiol and IL-6 reductions from baseline in both serum and breast ductal fluid among obese postmenopausal women who participated in the 12-week weight loss diet and exercise intervention.

Nutrients and nipple aspirate fluid composition: the breast microenvironment regulates protein expression and cancer aetiology

The aetiology of breast cancer is complex and multifactorial, and may include diet and xenobiotic compounds. A change in diet affects nutrient levels in blood, but to what extent diet can affect micronutrient concentrations in the breast is not yet well established. Breast nipple aspirate fluids (NAF) can be non-invasively obtained from the breast in most women; it represents a biological tool to assess metabolic changes in the breast ductal microenvironment. A wide variation in biomolecular and hormonal composition of NAFs collected from healthy and breast cancer patient may be due to genetic and nutritional factors; however, micro- and macro-nutrients may influence the secretory status of these women, thus NAF composition and risk of breast carcinoma. The aim of this overview is to highlight the detrimental/beneficial role that diet-related compounds in nipple aspirate fluid can have in breast cancer risk.

Effects of High Fruit-Vegetable and/or Low-Fat Intervention on Breast Nipple Aspirate Fluid Micronutrient Levels

BACKGROUND

A change in diet is known to affect micronutrient levels in blood but to what extent diet can affect micronutrient levels in the breast is not yet well established.

METHODS

Healthy, premenopausal women with a family history of breast cancer were randomized across four diet arms for 1 year in a 2 x 2 factorial design study: control, low-fat, high fruit-vegetable, and combination low-fat/high fruit-vegetable diets. Subjects were asked to collect breast nipple aspirate fluid (NAF) at 0, 6, and 12 months, and levels of micronutrients were measured in the fluid.

RESULTS

A total of 122 women were enrolled, 97 were retained for 12 months, and sufficient NAF for analysis was available from 59 women at baseline, 49 at 6 months, and 50 at 12 months. Repeated measures mixed-model ANOVA was used to model the data using cholesterol levels and lactation duration as covariates, where appropriate. The high fruit-vegetable intervention, regardless of fat intake, significantly increased total carotenoid levels in NAF. In the low-fat arm, levels of total carotenoids decreased over time relative to control. Levels of total tocopherols and retinol did not change significantly. Levels of 15-F(2t)-isoprostane, a marker of lipid peroxidation, also did not change significantly over time, although there was a decrease observed in the combination arm.

CONCLUSIONS

These results indicate that total carotenoid levels in NAF can be significantly increased in the breast NAF with a high fruit-vegetable diet. A low-fat diet that was achieved with little increase in fruit and vegetable intake, however, decreased NAF carotenoid levels.

Influence of Lactation History on Breast Nipple Aspirate Fluid Yields and Fluid Composition

Analysis of nipple aspirate fluid (NAF) can be useful for understanding the impact that various lifestyle factors have on the biology of the breast. In this study, breast NAF was obtained at baseline from premenopausal women who volunteered for a dietary intervention trial. The influence of lactation history on both fluid yields and fluid composition was explored. We examined the levels of fat-soluble micronutrients (tocopherols, carotenoids, retinol), one lipid oxidation product (8-isoprostane), cholesterol, and protein in NAF. Roughly half of the women in the trial had never lactated, but this did not affect fluid yields appreciably. Carotenoid and tocopherol levels were significantly higher in NAF from women who lactated 6 months or more versus women who had lactated for shorter periods of time or never, but 8-isoprostane, protein, and cholesterol levels were not affected appreciably by lifetime lactation history. Longer times after weaning were associated with higher cholesterol levels, and there also was a suggestion the fat-soluble micronutrients declined with time after weaning. This is of interest since high cholesterol levels in breast fluid have been associated with an increased breast cancer risk, while carotenoids and tocopherols are thought to be protective. The results of this study provide further evidence of the potential benefits of prolonged lactation via its influence on NAF composition.

Conjugated linoleic acid isomers and trans fatty acids inhibit fatty acid transport in hepatoma 7288CTC and inguinal fat pads in Buffalo rats

Conjugated linoleic acid (CLA) and some trans fatty acids (FA) decrease tumor growth and alter tumor and host lipid uptake and storage. The goal of this study was to test the hypothesis that the acute inhibitory effects of CLA isomers and trans FAs on FA transport in tumors and white adipose tissue are mediated via an inhibitory G-protein coupled (GPC), FFA receptor (FFAR). Experiments were performed in hepatoma 7288CTC and inguinal fat pads in Buffalo rats during perfusion in situ. CLA isomers and trans FAs (0.03-0.4 mmol/L, in plasma) were added to the arterial blood, and FA uptake or release was measured by arterial minus venous difference. In hepatoma 7288CTC, the CLA isomers, t10,c12-CLA > (+/-)-9-HODE [13-(S)-hydroxyoctadecadienoic acid] > t9,t11-CLA, and the trans FAs, linolelaidic = vaccenic > elaidic, decreased cAMP content and inhibited FA uptake, 13(S)-HODE release, extracellular signal-regulated kinase p44/p42 phosphorylation, and [(3)H]thymidine incorporation. Other CLA isomers, c9,t11-CLA, 13-(S)-HODE, c9,c11-CLA, and c11,t13-CLA, had no effect. In inguinal fat pads, FA transport was inhibited by t10,c12-CLA = linolelaidic acid > trans vaccenic acid, whereas c9,t11-CLA had no effect. In both hepatoma 7288CTC and inguinal fat pad, addition of either pertussis toxin or 8-Br-cAMP to the arterial blood reversed the inhibitions of FA transport. These results support the idea that an inhibitory GPC FFAR reduces cAMP and controls FA transport by CLA isomers and trans FAs. Ligand activity is conferred by the presence of a trans double bond proximal to the carboxyl group.

Potential mechanisms of diet therapy for fibrocystic breast conditions show inadequate evidence of effectiveness

Fibrocystic breast conditions, formerly referred to as fibrocystic breast disease, affect about half of all women and typically present as any combination of breast nodularity, swelling, and pain. We reviewed the literature to evaluate evidence supporting nutrition interventions commonly recommended for fibrocystic breast conditions by health care providers. Randomized, controlled studies of the effectiveness of caffeine restriction fail to support any benefit in fibrocystic breast conditions. Similarly, evidence supporting evening primrose oil, vitamin E, or pyridoxine as treatments for the discomforts of fibrocystic breast conditions is insufficient to draw conclusions about effectiveness. Dietary alterations that influence the intermediate markers for fibrocystic breast conditions include low-fat (15% to 20% energy), high-fiber (30 g/day), and soy isoflavone regimens. However, our findings provide no solid evidence for secondary prevention or treatment of fibrocystic breast conditions through a dietary approach. Health care providers should limit recommendations to proven diet therapies supported by randomized, placebo-controlled trials, given the instability inherent in fibrocystic breast conditions and the near 20% placebo effect associated with intervention. Because excessive estrogen or altered sensitivity to estrogen is the dominant theory of etiology, interventions that may modulate endogenous steroid hormones warrant further investigation as potential treatments for symptomatic fibrocystic breast conditions.

Nutritional aspects of breast cancer

Nutrition, in its broadest sense, plays a clear role in breast cancer, identified through its relationship to such known risk factors as rate of growth and development, age at menarche, adult height, postmenopausal body weight, and fat distribution. The relative importance of daily diet is hotly debated. There is no agreement on the relative importance of nutrition's effect, the responsible food groups and nutrients, nor the age or ages at which it can be influential. Evidence linking breast cancer and diet comes from human ecologic and observational studies as well as a body of experimental feeding studies in rats and mice. The population studies, including increasing numbers of migrant studies, and the animal experiments suggest that high-fat diets promote breast cancer, particularly among older women. Studies that compare diets of persons with and without breast cancer and those that record breast cancer incidence among women with different dietary histories have been inconclusive enough as to warrant randomized intervention trials. Recognition of differences between the risk factors for premenopausal and postmenopausal women and increasing insight into the ages at which known risk factors exert their influence have helped in the design of these trials. Human feeding studies and the trials themselves are identifying metabolic changes and their biomarkers as well as biomarkers for changes in fat and nutrient intakes. The Women's Health Initiative Dietary Modification Trial was designed to show whether a sustained (9-year) low-fat, high-fruit-and-vegetable eating pattern will lower the incidence of breast cancer among women who will be between ages 59 and 88 when the trial ends, the time of peak incidence. Meanwhile, the Women's Intervention Nutrition Study will learn in approximately 5 years whether a low-fat, adjuvant eating pattern will improve the prognoses of postmenopausal women with early and moderate stage breast cancer and whether tamoxifen should be used as at least part of their treatment. The results of these trials will have important applications for both public health and the provision of medical care.