Åke Bruce

Dietary antioxidant vitamins, retinol, and breast cancer incidence in a cohort of Swedish women

Dietary antioxidant vitamins and retinol have been proposed to be protective against breast cancer on the basis of their ability to reduce oxidative DNA damage and their role in cell differentiation. Epidemiologic studies have not been convincing in supporting this hypothesis, but women with high exposure to free radicals and oxidative processes have not been specifically considered. We explored these issues in the Swedish Mammography Screening Cohort, a large population‐based prospective cohort study in Sweden that comprised 59,036 women, 40–76 years of age, who were free of cancer at baseline and who had answered a validated 67‐item food frequency questionnaire. During 508,267 person‐years of follow‐up, 1,271 cases of invasive breast cancer were diagnosed. Cox proportional hazards models were used to obtain hazard ratios (HRs) and 95% confidence intervals (CIs). There was no overall association between intake of ascorbic acid, beta‐carotene, retinol or vitamin E and breast cancer incidence. High intake of ascorbic acid was inversely related to breast cancer incidence among overweight women (HR=0.61; 95% CI 0.45–0.82, for highest quintile of intake among women with body mass index>25 kg/m2) and women with high consumption of linoleic acid (HR=0.72; 95% CI 0.52–1.02, for highest quintile of ascorbic acid intake and average consumption of more than 6 grams of linoleic acid per day). Among women with a body mass index of 25 or below, the hazard ratio for breast cancer incidence was 1.27 (95% CI 0.99–1.63), comparing the highest to the lowest quintile of ascorbic acid intake. Consumption of foods high in ascorbic acid may convey protection from breast cancer among women who are overweight and/or have a high intake of linoleic acid.

Food Habits and Nutrient Intake in Childhood in Relation to Health and Socioeconomic Conditions

In Sweden a multicentre nutritional survey was performed in 1980-81 in four different parts of Sweden. The total number of children investigated was 1109, of whom 92 were two years old, 332 four years, 338 eight years and 347 thirteen years. The 24-hour recall method was used in all children. In addition 7-day record was used in the 2-, 4- and 8-year-olds and the dietary history method in the 13-year-olds. During the weekdays the 2-, 4-, 8- and 13-year-old children had 5.9, 5.8, 5.4 and 5.2 meals and snacks per day, respectively. During weekends these respective numbers decreased to 5.7, 5.6, 5.1 and 5.0. The mean number of light meals and snacks was almost the same on all days and varied between 2.4 and 3.3 in the different age groups. The part of the energy intake deriving from snacks has increased during the last 15 years. The mean daily energy intakes for the 2-, 4-, 8- and 13-year-old boys and girls were 5.8 and 5.6, 6.9 and 6.5, 8.9 and 7.9 and 12.1 and 9.7 MJ respectively. These values are below the recommendations for all age groups except the 2-year-old boys. The mean daily intakes of protein, retinol, ascorbic acid, thiamin, riboflavin, niacin, vitamin B12 and calcium were almost invariably higher or much higher than the recommendations, while those of vitamin D and zinc were below the recommended values. The iron intake fulfilled the recommendations except for the 2-year-olds and the 13-year-old girls. The intake of protein and fat expressed in per cent of the total energy intake was very similar in all age groups, about 14 per cent and 35-37 per cent respectively. The mean ratio between polyunsaturated and saturated fatty acids (P/S ratio) was also the same in all age groups, i.e. 0.22-0.23. This low ratio is explained by a high consumption of dairy products. Furthermore, the nutrient density of the food did not change appreciably with age. The only exception was found for the 2-year-old children, who had slightly higher nutrient density values on account of a relatively high consumption of fortified follow-up formula. In all age groups the mean nutrient densities of vitamins D and B6 and of iron were below the recommendations to varying degrees. No clinical signs of nutritional deficiencies, iron deficiency included, were found in any age group.(ABSTRACT TRUNCATED AT 400 WORDS)

Endurance physical activity, diet and fibrinolysis

The impact of long-term, heavy exercise on recently established cardiovascular/thromboembolic risk factors of the fibrinolytic system, tissue plasminogen activator (tPA) and plasminogen activator inhibitor (PAI-1) in relation to food composition was studied. Twenty healthy men, aged 18-55 years participated in a 14-day skiing tour through the Swedish mountains, carrying a pack load of 30 kg, and spending each night in self-dug igloos (ambient temp -10 degrees to -25 degrees C), and were randomized to 2 food regimens having 30 or 40 energy percent of fat. Individual records were kept of all consumed food. Citrated plasma was obtained before and after 1 and 2 weeks of exercise: tPA release was assessed by a 10 min venous occlusion (VO) test. At baseline, daily dietary fiber intake correlated negatively with PAI-1 activity. Already after the first week of the skiing tour there were significant drops in PAI-1 activities, cholesterol and triglycerides. The tPA mass concentrations also dropped, both before and after VO, but tPA activities were unchanged, as were von Willebrand factor (vWF) levels. These changes were related mainly to the expenditure of energy, calculated from the food consumption, and appeared to be mediated through changed insulin sensitivity and decreased body fat mass. The energy percent of fat in the food had no differential impact. The effects receded a few weeks after cessation of the endurance exercise. Thus, endurance physical activity improves the fibrinolytic risk factor profile by reducing PAI-1 while leaving tPA activity unaffected, independently of food composition. A low dietary fiber intake appears to be associated with higher PAI-1 activities at baseline.

The Effect of Different Dietary Levels of Essential Fatty Acids on Growth of the Rat

Sprague-Dawley rats received three dietary levels of essential fatty acids (EFA) during gestation and the suckling period and up to adult age by raising them on their respective diets for more than two generations. The relative difference in body weight was most pronounced between 13 and 23 days of age, after which it gradually diminished. Between 25 and 60 days of age, rats fed 0.07 cal% EFA had a significantly lower body weight than rats fed 0.75 cal% and the latter had a significantly lower body weight than those fed 3.0 cal%. The difference was slightly more Pronounced for females than for males.

Retention of linoleic acid in carcass lipids of rats fed different levels of essential fatty acids

Rats of an inbred Sprague-Dawley strain were fed purified diets with low (0.3% of total energy), normal (3%) or high (10%) content of essential fatty acids (EFA) for at least three generations. Two 30-days-old rats with similar weights were chosen from one litter. One was killed; weight increase and food consumption of the other rat was measured for 15 days. Total lipid content and fatty acid composition in total lipid and lipid classes were determined in both rats. Seven pairs of rats from each group were treated in the same way. Calculations based an amount of linoleic acid ingested and retained in the carcass lipids showed that 50% of the ingested linoleic acid was retained in the low EFA rats compared to 10–15% in the normal and high EFA rats.

Autoradiographic studies with fatty acids and some other lipids: a review.

In this review, we have mainly included studies in which whole-body autoradiography was used. In lipid research, most studies have been done with fatty acids. These studies showed some common characteristics in the pattern of tissue distribution. A major uptake was seen in the brown fat, liver and adrenal cortex but also to some extent in other tissues with a high metabolic activity or high cell turn-over, e.g. the gastric and intestinal mucosa, diaphragm, kidney cortex and bone marrow. Low levels of radioactivity were generally found in the brain, testes, thymus, white fat, skeletal muscles, lungs and spleen. Most fatty acids showed some specific features, e.g the strong uptake of erucic, arachidonic and docosahexaenoic acid in myocardium and of eicosapentaenoic acid in the adrenal cortex. Studies with PGE1 and LTC3 showed that the liver and kidney and to a lesser degree the lungs were the major sites of metabolism. The distribution of free cholesterol and triolein emulsion labelled in the fatty acid moieties did show some similarities with respect to the general pattern found with most fatty acids. Specific for cholesterol was a very strong uptake in the adrenal cortex. There was also a significant uptake in the spleen whereas the uptake in the brown fat was not as marked as for most fatty acids. Specific for triolein was a marked uptake in the spleen and myocardium, in fed animals also in the white adipose tissue. These studies show that whole-body autoradiography can give much valuable information of the uptake and distribution of lipids that would be rather difficult to obtain with conventional methods. Combined with electron-microscopy, autoradiography can be used to study cellular and even subcellular distribution, and thus given further data on the metabolism of lipids in the body.

Autoradiographic Studies with Albumin-Bound 1–14C-Linoleic Acid in Normal and Essential Fatty Acid-Deficient Rats

Young rats fed a diet providing 0.3, 3 or 10% of the energy as essential fatty acids (EFA) were given a single intravenous dose of albumin-bound 1-14C-linoleic acid. 1 animal from each group was killed at 1 and 18 h, respectively, after the injection and submitted to whole-body autoradiography. In general, the activities in the tissues were higher in the 0.3% group than in the other groups, whereas the differences between the 3% and the 10% group were small. In all groups the highest activity occurred in the brown fat. High activities were also noted in the liver, the adrenal cortex, the diaphragm, and the gastric and intestinal mucosa. The higher activities in the tissues of the rats fed 0.3% than in the tissues of those fed 3% or 10% EFA probably reflect a higher incorporation of fatty acids of the linoleic acid series into structural and other lipids in the former group due to the lack of EFA.

Effect of Different Dietary Levels of Essential Fatty Acids on Liver and Serum Lipids in the Rat

Rats were fed diets with three different levels of essential fatty acids (EFA); 3.0, 0.75 and 0.07 cal·% for more than two generations. The concentrations of serum phospholipids and cholesterol rose during the suckling period and fell rapidly after weaning. In the liver the triglycerides reached their highest value early in the suckling period. The concentration of the triglycerides was the same in the EFA-deficient groups as in the control group. The fatty acid patterns of serum and liver lecithins in the four dietary groups were similar in several respects, but the concentration of the highly unsaturated fatty acids, primarily arachidonic and docosahexaenoic acids, were higher in the liver. The largest deficiency of EFA in serum and in liver was found at birth and during the late suckling and early postsuckling periods. This deficiency was compensated for mainly by an increase in the fatty acid 20:3 (n-9) as well as in the monoenoic acids 16:1 and 18:1. The proportions of fatty acids of the linolenic acid series were reduced more than those of the linoleic acid series at all ages, both in the groups which received 0.75 and in those which received 0.07 cal% EFA.

The Effect of Different Dietary Levels of Essential Fatty Acids on Body Composition of the Rat

Three dietary levels of essential fatty acids (EFA) 3.0, 0.75, and 0.07 cal% were studied for their influence on the concentration of lipids, linoleic and arachidonic acids, water, nitrogen, potassium

Blood Lipids and Diet in Swedish Adolescents Living in Norsjö, an Area with High Incidence of Cardiovascular Diseases and Diabetes

ABSTRACT. In Norsjö in Northern Sweden a cardiovascular intervention programme, for adults is presently tested. The aim of the present study was to investigate the presence of factors related to cardiovascular disease in all 15‐year‐old adolescents living in Norsjö in 1987 and 1988. The total cholesterol concentration in serum, as an average for the test period, was 4.2 mmol/l and 4.7 mmol/l for boys and girls, respectively. Fourteen per cent of the boys and 32% of the girls had a total cholesterol concentration exceeding 5 mmol/l. Twenty‐seven per cent of the adolescents had high values for two or more variables related to risk of developing cardiovascular disease. The evaluation of the dietary registrations showed unsatisfactory values for fibre, P/S ratio and total fat. The dietary habits were better in the 15‐year‐olds in 1988 than in 1987 as judged by significantly higher average daily intake of fibre as well as a higher content of fibre per megajoule in the food.