Influence of recent altitude exposure on sea level sympathetic neural & hemodynamic responses to orthostasis.

Although it has been shown that muscle sympathetic nerve activity increases during high altitude exposure, mechanisms of sympathoexcitation and blood pressure control after return from altitude are not well described. We hypothesized that: (1) living for 12days at 4300m (Pikes Peak, Colorado) would result in increased muscle sympathetic nerve activity 24h after return to sea level; (2) post-Pikes Peak sympathetic neural and hemodynamic responses to orthostasis would be decreased due to a potential 'ceiling effect' on sympathetic activity; and (3) the magnitude of individual increases in sympathetic nerve activity post-Pikes Peak would be inversely related to baseline sympathetic nerve activity before traveling to altitude. Muscle sympathetic nerve activity, heart rate and blood pressure were measured in 9 healthy individuals (24±8years) in supine, 30° and 45° head-up tilt positions. Measurements were conducted twice at sea level, once before (pre-Pikes Peak) a 12day residence at 4300m, and once within 24h of return (post-Pikes Peak). Supine muscle sympathetic nerve activity was higher (post: 27±5 vs pre: 17±6bursts/min) upon return from altitude (p<0.05). Individual values for pre-Pikes Peak sympathetic activity were inversely related to post-altitude sympathoexcitation (r=-0.69, p<0.05). There were no differences in neural or cardiovascular responses to tilt between pre and post- Pikes Peak (p>0.05). We conclude that 12days' residence at 4300m causes a sustained sympathoexcitation which does not impair the ability of muscle sympathetic nerves to respond appropriately to orthostasis.

Dietary folate intake and breast cancer risk: European prospective investigation into cancer and nutrition.

BACKGROUND: There is limited evidence on the association between dietary folate intake and the risk of breast cancer (BC) by hormone receptor expression in the tumors. We investigated the relationship between dietary folate and BC risk using data from the European Prospective Investigation into Cancer and Nutrition (EPIC). METHODS: A total of 367993 women age 35 to 70 years were recruited in 10 European countries. During a median follow-up of 11.5 years, 11575 women with BC were identified. Dietary folate intake was estimated from country-specific dietary questionnaires. Cox proportional hazards regression models were used to quantify the association between dietary variables and BC risk. BC tumors were classified by receptor status. Subgroup analyses were performed by menopausal status and alcohol intake. Intake of other B vitamins was considered. All statistical tests were two-sided. RESULTS: A borderline inverse association was observed between dietary folate and BC risk (hazard ratio comparing top vs bottom quintile [HRQ5-Q1] = 0.92, 95% CI = 0.83 to 1.01, P trend = .037). In premenopausal women, we observed a statistically significant trend towards lower risk in estrogen receptor-negative BC (HRQ5-Q1 = 0.66, 95% CI = 0.45 to 0.96, P trend = .042) and progesterone receptor-negative BC (HRQ5-Q1 = 0.70, 95% CI = 0.51 to 0.97, P trend = .021). No associations were found in postmenopausal women. A 14% reduction in BC risk was observed when comparing the highest with the lowest dietary folate tertiles in women having a high (>12 alcoholic drinks/week) alcohol intake (HRT3-T1 = 0.86, 95% CI = 0.75 to 0.98, P interaction = .035). CONCLUSIONS: Higher dietary folate intake may be associated with a lower risk of sex hormone receptor-negative BC in premenopausal women.

Organic food consumption and the incidence of cancer in a large prospective study of women in the United Kingdom.

BACKGROUND: Organically produced foods are less likely than conventionally produced foods to contain pesticide residues. METHODS: We examined the hypothesis that eating organic food may reduce the risk of soft tissue sarcoma, breast cancer, non-Hodgkin lymphoma and other common cancers in a large prospective study of 623 080 middle-aged UK women. Women reported their consumption of organic food and were followed for cancer incidence over the next 9.3 years. Cox regression models were used to estimate adjusted relative risks for cancer incidence by the reported frequency of consumption of organic foods. RESULTS: At baseline, 30%, 63% and 7% of women reported never, sometimes, or usually/always eating organic food, respectively. Consumption of organic food was not associated with a reduction in the incidence of all cancer (n=53 769 cases in total) (RR for usually/always vs never=1.03, 95% confidence interval (CI): 0.99-1.07), soft tissue sarcoma (RR=1.37, 95% CI: 0.82-2.27), or breast cancer (RR=1.09, 95% CI: 1.02-1.15), but was associated for non-Hodgkin lymphoma (RR=0.79, 95% CI: 0.65-0.96). CONCLUSIONS: In this large prospective study there was little or no decrease in the incidence of cancer associated with consumption of organic food, except possibly for non-Hodgkin lymphoma.

Serum concentrations of cholesterol, apolipoprotein A-I and apolipoprotein B in a total of 1694 meat-eaters, fish-eaters, vegetarians and vegans.

BACKGROUND/OBJECTIVES: The objective of this study was to describe serum lipid concentrations, including apolipoproteins A-I and B, in different diet groups. SUBJECTS/METHODS: A cross-sectional analysis of a sample of 424 meat-eaters, 425 fish-eaters, 423 vegetarians and 422 vegans, matched on sex and age, from the European Prospective Investigation into Cancer and Nutrition-Oxford cohort. Serum concentrations of total, and high-density lipoprotein (HDL) cholesterol, as well as apolipoproteins A-I and B were measured, and serum non-HDL cholesterol was calculated. RESULTS: Vegans had the lowest body mass index (BMI) and the highest and lowest intakes of polyunsaturated and saturated fat, respectively. After adjustment for age, alcohol and physical activity, compared with meat-eaters, fish-eaters and vegetarians, serum concentrations of total and non-HDL cholesterol and apolipoprotein B were significantly lower in vegans. Serum apolipoprotein A-I concentrations did not differ between the diet groups. In males, the mean serum total cholesterol concentration was 0.87 mmol/l lower in vegans than in meat-eaters; after further adjustment for BMI this difference was 0.76 mmol/l. In females, the difference in total cholesterol between these two groups was 0.6 mmol/l, and after further adjustment for BMI was 0.55 mmol/l. [corrected]. CONCLUSIONS: In this study, which included a large number of vegans, serum total cholesterol and apolipoprotein B concentrations were lower in vegans compared with meat-eaters, fish-eaters and vegetarians. A small proportion of the observed differences in serum lipid concentrations was explained by differences in BMI, but a large proportion is most likely due to diet.