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Biomedical subjects

A S Truswell

Publications and source records attributed to A S Truswell.

At least 19 recordsLinked to original sources
PubMed1992

Diet and coronary heart disease. The National Heart Foundation of Australia.

Over the last four decades there has been extensive research into the links between diet and coronary heart disease. The most recent literature is reviewed in this position statement. The clinical and public health aspects of the National Heart Foundation's nutrition policy are based on this review. The key points are as follows: 1. Saturated fatty acids A high intake of saturated fatty acids is strongly associated with elevated serum cholesterol and LDL-cholesterol levels and increased risk of coronary heart disease. 2. The n-6 polyunsaturated fatty acids The n-6 polyunsaturated fatty acids (principally linoleic acid) lower serum cholesterol levels when substituted for saturated fats and probably have an independent cholesterol-lowering effect. 3. The n-3 polyunsaturated fatty acids (fish oils) The n-3 polyunsaturated fatty acids reduce serum triglyceride levels, decrease the tendency to thrombosis and may further reduce coronary risk through other mechanisms. 4. Monounsaturated fatty acids Monounsaturated fatty acids reduce serum cholesterol levels when substituted for saturated fatty acids. It is not clear whether this is an independent effect or simply the result of displacement of saturates. 5. Trans fatty acids Trans fatty acids may increase serum cholesterol levels and can be reckoned to be equivalent to saturated fatty acids. 6. Total fat Total fat intake, independent of fatty acid type, is not strongly associated with coronary heart disease but may contribute to obesity. Associations between total fat intake and coronary heart disease are primarily mediated through the saturated fatty acid component. 7. Dietary cholesterol Dietary cholesterol increases serum cholesterol levels in some people and may increase risk of coronary heart disease. 8. Alcohol A high intake of alcohol increases blood pressure and serum triglyceride levels and increases mortality from cardiovascular disease. Light alcohol consumption reduces the risk of coronary heart disease. 9. Sugar The consumption of sugar is not associated with coronary heart disease. 10. Sodium and potassium High salt intake is related to hypertension especially in the subset of "salt-sensitive" people. Potassium intake may be inversely related to hypertension. 11. Overweight and obesity Abdominal obesity increases the risk of coronary heart disease probably by adversely influencing conventional risk factors. 12. Vegetarianism A high intake of plant foods reduces the risk of coronary heart disease through several mechanisms, including lowering serum cholesterol and blood pressure levels.

Alcohol Drinking↗
PubMed1992

Glycaemic index of foods.

From the mid-1970s several groups realized progressively that the same amounts of carbohydrates in different foods produce quite different blood glucose curves after ingestion. The glycaemic index (GI) was introduced by Jenkins to express the rise of blood glucose after eating a food against a standard blood glucose curve after glucose (or white bread) in the same subject. The GI ranges from about 20 for fructose and whole barley to about 100 for glucose and baked potato. A table is given of representative GI values. There appears to be no general correlation between GI and per cent resistant starch in foods. Questions about methodology for GI are discussed and the factors in food that affect glycaemic response are briefly reviewed. The GI is affected by the physical form of a food, by processing and by associated fat in the food, which reduces the GI, presumably by delayed gastric emptying. As a rule the degree of insulin response to carbohydrate-containing foods is similar to the glycaemic response. Most investigators have found that the GI of a meal of mixed foods can be predicted from the (weighted) GI of its constituent foods. The GI concept is proving useful in dietary design for the management of diabetes mellitus, especially the non-insulin-dependent type. It may prove useful for prevention of diabetes and perhaps also in pre-event meals for athletes, as a factor in dental cariogenesis, in determining satiety, and conceivably regular low GI foods could delay ageing by reducing glycosylation of body proteins.

Blood Glucose↗
PubMed1992

Elevated plasma vitamers of vitamin B6 in patients with chronic renal failure on regular haemodialysis.

Plasma pyridoxal-5'-phosphate (PL-5'-P), pyridoxal (PL), pyridoxine (PN), and 4-pyridoxic acid (4-PA) were measured by high-performance liquid chromatography (HPLC) in 39 patients (15 male, 24 female) with chronic fenal failure undergoing regular haemodialysis and 46 healthy controls (28 male, 18 female). All three vitamers of vitamin B6 and the metabolite were significantly elevated in the haemodialysis patients. Mean PL-5'-P and PN concentrations were 20 times the mean in controls. Only one patient took a vitamin B6 supplement. In view of the neurotoxicity of supranutritional intakes of PN in normal humans we suggest that supplements of PN be carefully monitored when administered to patients with chronic renal failure.

Adult↗
PubMed1991

Low-glycemic index foods improve long-term glycemic control in NIDDM.

OBJECTIVE: To compare high- and low-glycemic index (GI) diets in the treatment of non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS: Sixteen subjects with well-controlled NIDDM and normal lipid profile, 10 of whom continued oral hypoglycemic medication, participated in the study. A diet that emphasized low-GI foods (e.g., porridge, pasta) was compared with a high-GI diet (e.g., processed cereals, potatoes). The GI of the low-GI diet was 15% lower than the high-GI diet (77 +/- 3 vs. 91 +/- 1) but otherwise similar in macronutrient composition and fiber, as determined by a 4-day weighed record. The diets were instituted under instruction from a dietitian who visited subjects at home on a weekly basis. Body weight was maintained within 1-2 kg. RESULTS: Glycemic control was improved on the low-GI diet compared with the high-GI diet (statistically significant findings, P less than 0.05). Mean glycosylated hemoglobin at the end of the low-GI diet was 11% lower (7.0 +/- 0.3%) than at the end of the high-GI diet (7.9 +/- 0.5%), and the 8-h plasma glucose profile was lower (area under the curve above fasting 128 +/- 23 vs. 148 +/- 22 mmol.h-1.L-1, respectively). Mean fasting plasma glucose, total cholesterol triglycerides, and lipoproteins did not show important differences. CONCLUSIONS: A low-GI diet gives a modest improvement in long-term glycemic control but not plasma lipids in normolipidemic well-controlled subjects with NIDDM.

Blood Glucose↗
PubMed1990

Thiamin status of a sample of homeless clinic attenders in Sydney.

Thiamin is one of the marginally adequate nutrients in the Australian diet. The incidence and prevalence of Wernicke-Korsakoff syndrome in this country may be the highest in the world. Homeless men could be at risk for low intakes of thiamin in association with irregular high alcohol intakes. A sample of 107 homeless men from two hostels and one clinic for homeless persons in inner Sydney was investigated for nutritional status; their thiamin status is reported here. By means of 24-hour recall methods, their mean dietary thiamin intake--0.76 mg per day--was less than the National Health and Medical Research Council's recommended dietary intake of 1.1 mg per day; at 0.076 mg/MJ it was even less than the minimal requirement of 0.08 mg/MJ. It was much lower than the mean intake of 1.38 mg per day that was found in the 1983 National Dietary Survey of adults and the distribution of thiamin intakes in this study was skewed positively, with the largest intake being in the range of 0-0.1 mg per day. On clinical examination we found a high prevalence of signs that were consistent with thiamin deficiency. Twenty-four per cent of the subjects showed three-or-more of the signs of the Wernicke-Korsakoff syndrome (ophthalmoplegia, nystagmus, ataxia, peripheral neuropathy and global confusion). In assaying for red-cell transketolase levels, this subgroup showed higher thiamin pyrophosphate effects than did the whole sample. Thirty-six per cent of the whole sample showed subnormal thiamin status by the thiamin pyrophosphate effect. Thus, in this sample, homeless men showed a high prevalence of dietary, biochemical and clinical features to indicate subclinical or early clinical thiamin deficiency.

Adult↗
PubMed1990

Mutagenicity of basic fractions derived from lamb and beef cooked by common household methods.

Mutagen production was examined in lamb and beef in relation to certain common household cooking methods. Mutagenicity was assessed, after extraction of the basic fraction of cooked meat samples, using Salmonella typhimurium strain TA1538 with added rat-liver S-9 homogenate. Little or no mutagenicity was found in barbecued lamb chops, in microwave-cooked lamb chops, sirloin steak, leg of lamb, or rolled beef loaf, in roasted leg of lamb or rolled beef loaf, in stewed blade steak or in boiled chuck steak. However, the basic fraction from well-done, edible fried or grilled meat contained mutagenic activity equivalent to approximately 30,000 TA1538 revertants/100 g cooked meat. It was found tht the mutagenic activity of grilled lamb chops, sirloin and rump steaks was directly related to the average surface temperatures attained during cooking. Use of butter as a frying medium was particularly associated with higher mutagenicity in meat samples. Fried meats (rump and fillet steaks) generally yielded higher mutagenic activity than did grilled meats (rump steak, lamb chops) at comparable temperatures of the cooking medium. Using similar cooking procedures, lamb did not differ markedly from beef in mutagenic activity.

Animals↗
PubMed1990

Plasma glucose and insulin responses to traditional Pima Indian meals.

The in vivo glycemic and insulin responses and in vitro starch digestibility were determined for six staple foods (corn, lima beans, white and yellow teparies, mesquite, and acorns) traditionally consumed by Pima Indians. Equivalent carbohydrate portions (25 g) of the foods were fed to eight healthy Caucasian volunteers. The calculated glycemic indices (GIs) (mean +/- SEM with glucose as the standard) were all low, ranging from 16 +/- 2 for acorns to 40 +/- 5 for corn. Insulin responses and in vitro starch digestibilities correlated with the GI. These results provide further support for the hypothesis that the slow digestion and absorption of starch in traditional foods was a factor that helped protect susceptible populations from developing diabetes.

Arizona↗
PubMed1990

Energy supplementation and the nutritional status of hemodialysis patients.

Twenty-one patients undergoing regular hemodialysis completed a trial of energy supplementation. Nine patients added the glucose polymer Polycose to their usual diet and 12 acted as control subjects. The supplemented patients were asked to incorporate 100 or 150 g polymer, equivalent to 1600 or 2400 kJ (400 or 600 kcal) into their usual diet, daily for 6 mo. This resulted in a mean increase in energy intake of 1630 kJ (p less than 0.05) and a mean weight gain of 3.1 kg (p less than 0.005). The addition of glucose polymer to the diet resulted in a mean increase in body fat of 1.8 kg and the lean body mass increased by 1.3 kg. No significant effect on plasma triglycerides, urea, or creatinine was detected. The intake of macro- and micronutrients was not adversely affected and no clinical or psychological side effects were reported. Follow-up of these patients showed that the weight gain was maintained after 6 mo. Glucose polymer was an effective energy supplement that had beneficial effects on the nutritional status of hemodialysis patients.

Adult↗
PubMed1990

A mixed Australian fish diet and fish-oil supplementation: impact on the plasma lipid profile of healthy men.

Twelve healthy men were fed in turn three diets for 6 wk each in a 3 x 3 randomized block design: a control diet (essentially fish free), a fish diet (200 g lean Australian fish flesh/d), and the same fish-based meal but supplemented with 5 g fish oil/d. Dietary eicosapentaenoic acid [EPA, 20: 5n-3 (omega-3)] was strongly associated with erythrocyte membrane EPA (r = 0.908 at 6 wk), strengthening its value as a measure of compliance in fish and fish-oil feeding trials. On the fish diet, subjects had increased incorporation of n-3 polyunsaturated fatty acids (PUFAs) at the expense of n-6 PUFAs in their erythrocyte membranes. When the fish-based diet was supplemented with fish oil (5 g/d), there was a significant lowering of plasma triacylglycerol (-0.16 +/- 0.24 mmol/L; mean +/- SD). No change in plasma total cholesterol was detected although the fish + oil diet produced a reduction in very-low-density-lipoprotein cholesterol (-0.24 +/- 0.26 mmol/L).

Adult↗
PubMed1990

Body protein of patients undergoing haemodialysis.

The total body protein status of 18 patients undergoing regular haemodialysis was assessed by measuring total body nitrogen (TBN) using in vivo neutron activation analysis (NAA). Eighteen healthy controls, who were selected according to their height, age and sex match with the patients were also measured. The male and female patients were both found to have lower mean values for total body protein (P less than 0.01, P less than 0.025 respectively) although they had similar weights compared with their matched controls. Seven patients were measured on further occasions and only two patients showed a change in their body protein. One female showed an increase of 11 per cent in body protein (with an increase of 25 per cent in body weight) after intensive nutritional repletion therapy. In vivo NAA provides a direct means of measuring body protein and is a reliable method to monitor changes with treatment regimes.

Adult↗
PubMed1989

Vitamin supplementation of patients receiving haemodialysis.

In order to assess the necessity of vitamin supplementation for patients who are receiving haemodialysis, measurements of vitamin status were made, and both dietary and supplementary intakes were assessed, in 26 patients who were undergoing haemodialysis. Blood samples were collected from these patients before they underwent haemodialysis, after an overnight fast, for the measurement of plasma retinol, alpha-tocopherol and ascorbate levels. Serum and erythrocyte folate levels were measured also. Thiamin status was assessed by the effect of added thiamin pyrophosphate on erythrocyte transketolase activity and pyridoxine status was assessed by the effect of added pyridoxal-5'-phosphate on erythrocyte aminotransferase activity. All patients had elevated plasma retinol levels; 48% of patients had elevated plasma alpha-tocopherol levels; the plasma ascorbate level was low in 50% of patients but was elevated in 25% of patients; and plasma and erythrocyte folate levels were elevated in 76% and 91% of patients, respectively. Thiamin status was normal in all but one patient and the pyridoxine level appeared to be low in two other patients. Many patients had low dietary intakes of vitamin C, folate and vitamin B6. We conclude that supplements of vitamins A and E are not required and, when dietary intakes of water-soluble vitamins are marginal, these should be supplemented at a dose as near as possible to the recommended dietary intake.

Ascorbic Acid↗
PubMed1989

Reduction of food intake in the ovulatory phase of the menstrual cycle.

Food intake was weighed and recorded daily during one complete menstrual cycle in 18 healthy normally menstruating women. Urinary luteinizing hormone indicated the time of ovulation. Mean daily intakes of energy, macronutrients, and alcohol were calculated for five phases during the menstrual cycle: menses, postmenses, ovulatory, postovulatory, and premenses. Weekly variations were also measured. Energy intake was lowest during the ovulatory phase compared with postovulatory, premenses, and menses phases (p less than 0.05). The maximum difference, 1.36 MJ (324 kcal)/d, occurred between ovulatory and postovulatory phases and was twofold higher than the increase of 0.64 MJ (152 kcal)/d observed at weekends. This reduction of food intake at ovulation has not been previously described in humans. It coincides with the expected peak in circulating estrogen levels and is consistent with the hypothesis in animal models that estrogen is an appetite suppressant.

Adolescent↗
PubMed1989

Maternal weight gain, smoking and other factors in pregnancy as predictors of infant birth-weight in Sydney women.

Two hundred and four (204) women attending a Sydney maternity hospital and their babies were followed throughout pregnancy in a study, which aimed: 1) to describe the distribution of maternal weight gain in present day Australian women and 2) to determine the effect of weight gain and other factors on birth-weight. Maternal weights and skinfold thicknesses were measured serially to give an indication of weight gain. Mean weight gain from conception to term was 14.2kg and mean birth-weight was 3,442g. Maternal predictors of birth-weight such as maternal weight gain, parity, age, education, height, public or private booking status, smoking, prepregnancy weight, and sex of the infant and gestational age were explored using simple and multiple regression analysis. Weight gain was predictive of birth-weight, each kg increase in total weight gain resulting in about a 30g increase in birthweight. Other strong predictors were gestational age, maternal smoking, sex of the infant and maternal parity. Maternal height was less strongly predictive and age and prepregnant weight were not predictive. Smoking mothers had infants who were 268g lighter than those of nonsmoking mothers. However, smokers were also younger, shorter, had less education and were more likely to book as public patients than nonsmokers. After adjusting for all other predictors, the birth-weight of infants whose mothers smoked, was still 224g less than that for nonsmoking mothers.

Adolescent↗