Women who developed invasive breast cancer, 350 post-menopausally and 257 pre-menopausally, during 240 959 person-years of follow-up in the UK Women’s Cohort Study (UKWCS) were studied. This cohort has 35 792 subjects with a wide range of exposure to dietary fibre with intakes of total fibre in the lowest quintile of <20 g/day up to >30 g/day in the top quintile. Fibre and breast cancer relationships were explored using Cox regression modelling adjusted for measurement error. Effects of fibre, adjusting for confounders were examined for pre- and post-menopausal women separately.

Results in pre-menopausal, but not post-menopausal women a statistically significant inverse relationship was found between total fibre intake and risk of breast cancer (P for trend = 0.01). The top quintile of fibre intake was associated with a hazard ratio of 0.48 [95% confidence interval (CI) 0.24–0.96] compared with the lowest quintile. Pre-menopausally, fibre from cereals was inversely associated with risk of breast cancer (P for trend = 0.05) and fibre from fruit had a borderline inverse relationship (P for trend = 0.09). A further model including dietary folate strengthened the significance of the inverse relationship between total fibre and pre-menopausal breast cancer.

These findings suggest that in pre-menopausal women, total fibre is protective against breast cancer; in particular, fibre from cereals and possibly fruit.

Janet Elizabeth Cade, Victoria Jane Burley, Darren Charles Greenwood the UK Women’s Cohort Study Steering Group, Centre for Epidemiology and Biostatistics, University of Leeds, 30-32 Hyde Terrace, Leeds LS2 9PL, UK.

International Journal of Epidemiology

Full text 

Stress intensifies release of catecholamines and corticosteroids that increase survival of normal animals when their lives are threatened. When magnesium (Mg) deficiency exists, stress paradoxically increases risk of cardiovascular damage including hypertension, cerebrovascular and coronary constriction and occlusion, arrhythmias and sudden cardiac death (SCD). In affluent societies, severe dietary Mg deficiency is uncommon, but dietary imbalances such as high intakes of fat and/or calcium (Ca) can intensify Mg inadequacy, especially under conditions of stress. Adrenergic stimulation of lipolysis can intensify its deficiency by complexing Mg with liberated fatty acids (FA), A low Mg/Ca ratio increases release of catecholamines, which lowers tissue (i.e. myocardial) Mg levels. It also favors excess release or formation of factors (derived both from FA metabolism and the endothelium), that are vasoconstrictive and platelet aggregating; a high Ca/Mg ratio also directly favors blood coagulation, which is also favored by excess fat and its mobilization during adrenergic lipolysis. Auto-oxidation of catecholamines yields free radicals, which explains the enhancement of the protective effect of Mg by anti-oxidant nutrients against cardiac damage caused by beta-catecholamines. Thus, stress, whether physical (i.e. exertion, heat, cold, trauma–accidental or surgical, burns), or emotional (i.e. pain, anxiety, excitement or depression) and dyspnea as in asthma increases need for Mg. Genetic differences in Mg utilization may account for differences in vulnerability to Mg deficiency and differences in body responses to stress.

Seelig MS.

Department of Nutrition, School of Public Health, University of North Carolina, Chapel Hill.

J Am Coll Nutr. 1994 Oct;13(5):429-46. Links

Both physical activity and exposure to nature are known separately to have positive effects on physical and mental health. We have investigated whether there is a synergistic benefit in adopting physical activities whilst being directly exposed to nature (‘green exercise’). Five groups of 20 subjects were exposed to a sequence of 30 scenes projected on a wall whilst exercising on a treadmill. Four categories of scenes were tested: rural pleasant, rural unpleasant, urban pleasant and urban unpleasant. The control was running without exposure to images. Blood pressure and two psychological measures (self-esteem and mood) were measured before and after the intervention. There was a clear effect of both exercise and different scenes on blood pressure, self-esteem and mood. Exercise alone significantly reduced blood pressure, increased self-esteem, and had a positive significant effect on 4 of 6 mood measures. Both rural and urban pleasant scenes produced a significantly greater positive effect on self-esteem than the exercise-only control. This shows the synergistic effect of green exercise in both rural and urban environments. By contrast, both rural and urban unpleasant scenes reduced the positive effects of exercise on self-esteem. The rural unpleasant scenes had the most dramatic effect, depressing the beneficial effects of exercise on three different measures of mood. It appears that threats to the countryside depicted in rural unpleasant scenes have a greater negative effect on mood than already urban unpleasant scenes. We conclude that green exercise has important public and environmental health consequences.

Pretty J, Peacock J, Sellens M, Griffin M.
Department of Biological Sciences, University of Essex, Colchester, UK. jpretty@essex.ac.uk

The deleterious effect of ultraviolet radiation on humans has increased the need for photoprotection. Sunscreens are widely used as photo protective agents. They are divided into chemical sunscreens which absorb high-energy ultraviolet rays and physical blockers which reflect or scatter light. Effectiveness of sunscreens depends upon sun protection factor and its substantivity. Clothing is also important for sun protection and its effectiveness is measured by Ultraviolet Protection Factor. There are many other agents with photo protective properties, which range from antioxidants to plant extracts to DNA repair enzymes. Usage of wide brimmed hats and sunglasses, avoidance of solar exposure at times of peak intensity, use of cover-up garments and sunscreen lotions are effective for photo protection of the skin.

Rai R, Srinivas CR.

Department of Dermatology, PSG Hospitals, Peelamedu, Coimbatore, India

Indian J Dermatol Venereol Leprol. 2007 Mar-Apr;73(2):73-9.

 

This hypothesis proposes that carcinogens in the breast are generated by the action of superoxide free radicals released when acinal gland distension, under the influence of unopposed prolactin, causes microvessel ischaemia. Inadequate nipple care in the at-risk years leads to ductal obstruction preventing the elimination of carcinogens from the breast. The regular production of oxytocin (OT) from nipple stimulation would cause contraction of the myoepithelial cells, relieving acinal gland distension and aiding the active elimination of carcinogenic fluid from the breast. Mechanical breast pump stimulation causes an increase in plasma OT levels in the luteal but not in the follicular phase of the menstrual cycle. OT production upon nipple stimulation in the luteal phase of premenopausal, non-lactating women may be protective against the high rates of mitotic breast cell division noted at this time via the potential to block the effect of oestrogen. The epidemiology of breast cancer suggests that lengthy lactation time is beneficial. Sexual activity in nulliparous women also protects and OT levels have been shown to rise with orgasm in women and in men. OT systems in the brain are intricately linked to oestrogen and progesterone levels, and it is possible that these hormones may modify the OT secretory response both centrally and through an effect on the sensitivity of the breast. OT production with nipple care and in sex and lactation, and the reduction in cycling ovarian hormones that occurs with pregnancy, may all be important preventative factors in the development of breast cancer both pre- and post-menopausally.

Murrell TG, Department Community Medicine, University of Adelaide, Australia.