The global prevalence of obesity, characterised by a body mass index (BMI) 30 kg/m2, is high and is increasing. Obesity is associated with a higher risk of developing non-communicable diseases such as cardiovascular disease (CVD) and cancer. In Singapore the prevalence of obesity differs among the three main ethnic groups (Chinese, Malays and Indians) but is relatively low compared to Western societies. Despite the low prevalence of obesity (BMI 30 kg/m2), the morbidity and mortality for CVD are high in Singapore. In this paper, the odds ratio for presence of risk factors for CVD was studied in relation to BMI quintiles and in relation to body fat distribution as measured by waist-to-hip ratio (WHR) quintiles in a representative sample of adult Singaporean Chinese. The lowest quintile was used as the reference category. The boundaries for the BMI quintiles were 18.9, 20.7, 22.6 and 25.0 kg/m2 for females and 20.0, 21.7, 23.5 and 25.6 kg/m2 for males. The boundaries for WHR quintiles were 0.68, 0.71, 0.74 and 0.79 for females and 0.77, 0.82, 0.85 and 0.89 for males. As observed in other studies, the odds ratios for high serum total cholesterol, low HDL cholesterol, high total cholesterol/HDL cholesterol ratio, high serum triglyceride level, high blood pressure and high fasting blood glucose were higher in upper BMI and WHR quintiles. The effects were more pronounced in males compared with females. The odds ratios for having at least one of the mentioned risk factors in the different BMI quintiles for females were 1.3 (not significant (ns)), 1.6, 2.1 and 2.7, while in males they were 2.7, 4.1, 6.2 and 7.3. For the WHR quintiles the odds ratios were 0.9 (ns), 1.3 (ns), 1.9 and 2.1 for females, while for males they were 2.1, 4.7, 6.7 and 12.6. As the elevated risks are already apparent at low levels of BMI and low levels of WHR, it can be queried whether the cut-off points for obesity based on BMI and for abdominal fat distribution based on WHR as suggested by the WHO are applicable to the Singaporean Chinese population. There are indications in the literature that Asian populations have higher body fat percentages at lower BMI. This may explain the high odds ratios for CVD risk factors at low BMI and WHR and the high morbidity and mortality from CVD in Singapore, despite relatively low population mean BMI and obesity rates.
Trials of nutritional intervention in a wide range of health and disease states, preventive and therapeutic, are required. Not only has the emergence of chronic non-communicable disease (CNCD) with acknowledged nutritional pathogenesis created this imperative need, but so also have other conditions which, previously, had not been regarded as nutritionally based. Among the latter are health problems associated with ageing: the menopause, a decline in immune function, and a decline in cognitive function. At the same time, there is a new set of materno-foetal and infant nutrition issues for investigation which relate to new food exposures and the long-term effects of nutritionally mediated gene expression. The emergence of the new food science of phytochemicals with human biological importance also sets the scene for their evaluation in traditional diets and novel foods. Such trials are more complex than comparable pharmacotherapeutic studies because of the complexity of food chemistry, as well as the food behavioural changes which may accompany a nutritional intervention, and the general problem of there not being a 'gold standard' for food intake methodology. Choice of study population is also a key issue in relation to the extrapolation of findings from a particular trial, with population representativeness being an advantage. In order to obtain useful information on manageable sample sizes, either intermediate end-points (short of morbidity and mortality) need to be studied or high-risk groups (such as the aged) need to be recruited. There are some unique ethical issues which must inform clinical nutrition trials. These include certain preventive imperatives like the right to be fed, the risks in disruption of food cultures and the need for food security and sustainability. Rapid changes in the food supply do, however, make such trials more important, while the value of food-health knowledge that cannot be obtained by trial must still be appreciated.
Hypertension, an important risk factor for coronary heart disease (CHD), is often associated with certain dietary habits which can either adversely affect or decrease blood pressure. Several Western studies have documented the role of diet, especially excess energy, both quality and quantity of fat and salt, in the aetiopathogenesis of chronic diseases such as hypertension, diabetes and CHD. Indians are particularly susceptible to these chronic diseases. A study was therefore undertaken to investigate the role of dietary factors in relation to hypertension. A total of 158 newly diagnosed cases were selected from the out-patient department of the 1000-bed Osmania General Hospital along with 172 age and gender-matched controls. A detailed diet history was collected and validated. An energy adjustment method was adopted by transforming the data on a log scale as all the nutrients depended upon the intake of energy. A total of 86 hypertensives and 79 controls participated in the study. Among those classified as hypertensives, men reported higher intakes of dietary fat and salt while women reported higher intakes of dietary protein and salt. Risk calculated by Odds ratio revealed that higher intakes of fat, protein and salt increase the risk for hypertension. Multivariate stepwise logistic regression identified salt as the risk factor in men and protein as the risk factor in women. These results suggest a role for dietary fat, protein and salt in hypertension.
We estimated glycemic and insulinemic responses to short-grain rice (Japonica) and a short-grain rice-mixed meal (i.e. short-grain rice and other ingredients) in three healthy male, and five healthy female subjects aged 22-31 years. A 50 g carbohydrate portion of dry rice was used in this study to estimate the glycemic index (GI) of short-grain rice (Experiment 1). The GI of short-grain rice was 68 (white bread = 100). In Eperiment 2, the subjects took three mixed meals (rice-, bread- and cornflakes-mixed) containing 60 g available carbohydrate, 25-29 g fat, 18-22 g protein, 2331-2486 kJ energy, and 67-123 meal GI in order to detemine whether both the amount and source of carbohydrate consumed determined postprandial glycemic and insulinemic responses of mixed meals. Glycemic response after the rice-mixed meal was significantly lower (P< 0.05) than that after the cereal-mixed meal. The predicted glycemic and insulinemic responses, based on GI and the amount of carbohydrate, were related to the observed mean plasma glucose responses. These results suggest that short-grain rice (Japonica) grown in Japan should not be classified as a high GI food and that, in a mixed meal, it is a lower glycemic and insulinemic responder compared with bread or cereal mixed meals. Moreover, both the amount and source of carbohydrate consumed determine the glycemic and insulinemic responses after different mixed meals with variable GI.
It has been suggested that fish-consuming populations have lower blood pressure levels. The aim of this study was to determine and compare the mean blood pressure levels among fish-consuming populations with those among populations who do not consume fish, as a risk marker for cardiovascular disease. A cross-sectional study was conducted among 1000 healthy Indian adult men and women (aged 20 years) randomly chosen from two representative age and sex-matched samples, one of which was fish-consuming (n = 500) and the other of which was non-fish-consuming (n = 500). The systolic and diastolic blood pressures and pulse rates were studied. The mean systolic and diastolic blood pressures and pulse rates were found to be lower in older men and women who were fish consumers in comparison with those who were non-fish consumers, and the levels increased with advancing age. The population and sex differences were significant for certain age groups. The percentile cut-off values for diagnosis of systolic hypertension showed lower prevalence in fish consumers than in non-fish consumers. The results indicate that people who ate fish regularly appeared to have a better cardiovascular risk profile than did non-fish consumers, which is of public health significance. The relationship between fish consumption and blood pressure deserves further studies in normotensive and hypertensive populations.
The Nutrient and Metabolic Study of Indonesian Elderly (NUMSIE) was conducted in part to identify differences in eating patterns and in food and energy intakes between elderly people residing in urban metropolitan Jakarta (JAK) and in urban non-metropolitan Semarang (SEM) in order to investigate the prevalence of food and energy deficiencies. Data on food intake were collected from 212 JAK elderly and 238 SEM elderly aged 60 years and over using a quantitative food frequency questionnaire (FFQ). Although most of the elderly lived with their families or extended families, a large proportion of the subjects were eating alone, especially in the SEM sample. Jakartan elderly had significantly higher intakes of most food groups, except for added sugar and cow's milk. Total food intake of JAK subjects was also significantly higher (P< 0.0001) than that of SEM subjects. The ratio of plant to animal food was lower among SEM elderly due principally to their higher intake of milk. Thirty percent of both JAK and SEM elderly consumed less than the recommended amounts of cereals, followed by vegetables and fruits (10%, 47% JAK; 22%, 75% SEM, respectively). Finally, it was found that the range of daily energy intakes was higher in JAK (1251-2079 kcal) than in SEM (939-1579 kcal). This suggests that SEM elderly were more likely to be energy deficient than were JAK elderly. While the results of this study indicate that food and energy intakes may be inadequate in Indonesian elderly, especially in non-metropolitan areas, more analyses are required to ascertain the true prevalence of malnutrition in this age group using anthropometric and blood measurements.
Vitamin C may 'spare' vitamin E, but this has not to date been confirmed as occurring in vivo. The aim of this study was to test the effect of dietary supplementation with vitamin C on total and lipid standardised vitamin E concentrations in fasting plasma, the hypothesis being that increased vitamin C intake leads to improved vitamin E levels. In this single-blinded study, 12 apparently healthy adults (seven men, five women) took 1 g/day vitamin C for 28 days, with a 28-day placebo-controlled run-in cycle and a 28-day placebo-controlled washout cycle. Concentrations of ascorbic acid, total vitamin E (as total tocopherols) and lipid standardised vitamin E (Vit ELS, expressed as mol vitamin E/mmol total cholesterol plus triglycerides) were measured in fasting plasma after each cycle. Results showed that vitamin C supplementation led to significant increases in ascorbic acid, total vitamin E and Vit ELS. These findings indicate that, by a combination of a vitamin E 'sparing' effect perhaps via improved redox recycling of vitamin E in vivo and a lipid lowering effect, increased intake of vitamin C could increase plasma vitamin E levels, and possibly vitamin E status. Further study of possible in vivo interrelationships between vitamins C and E, and the role of vitamin C in lipid metabolism, is needed.
Kernels of the plant Santalum acuminatum (quandong) are eaten as Australian 'bush foods'. They are rich in oil and contain relatively large amounts of the acetylenic fatty acid, santalbic acid (trans-11-octadecen-9-ynoic acid), whose chemical structure is unlike that of normal dietary fatty acids. When rats were fed high fat diets in which oil from quandong kernels supplied 50% of dietary energy, the proportion of santalbic acid absorbed was more than 90%. Feeding quandong oil elevated not only total hepatic cytochrome P450 but also the cytochrome P450 4A subgroup of enzymes as shown by a specific immunoblotting technique. A purified methyl santalbate preparation isolated from quandong oil was fed to rats at 9% of dietary energy for 4 days and this also elevated cytochrome P450 4A in both kidney and liver microsomes in comparison with methyl esters from canola oil. Santalbic acid appears to be metabolized differently from the usual dietary fatty acids and the consumption of oil from quandong kernels may cause perturbations in normal fatty acid biochemistry.
A comprehensive definition of successful ageing would combine the elements of survival (longevity), health (lack of disability), and life satisfaction (happiness). Predictors of longevity include being female, being physically active, not smoking, having good cognitive functioning, higher socio-economic status and greater life satisfaction. Predictors of life satisfaction include being healthy (which is in part influenced by nutrition and physical activity), being socially active, having work satisfaction, having a high happiness rating and enjoying sexual activity. To age successfully is therefore the ultimate challenge. This paper cannot address all variables in the equation to successful ageing, but will focus on the value of food and physical activity in later life.
In a number of epidemiological surveys and in two recent intervention trials in cardiac patients, diets rich in marine omega-3 polyunsaturated fatty acids (PUFA), which include both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been found to be beneficial in reducing the susceptibility of developing serious ventricular fibrillation (VF) or malignant cardiac dysrhythmia and mortality from sudden cardiac death (SCD). In addition to this information from human studies, there is strong supporting evidence from laboratory experiments utilizing the small non-human primate marmoset monkey (Callithrix jacchus). For example, a diet enriched with tuna fish oil that is high in both DHA and EPA has been found to increase the electrical threshold current necessary for inducing VF and to reduce mortality to zero in marmoset monkeys with experimentally induced ischaemic cardiac dysrhythmia (ICH). From these and earlier studies in other animals there is also some evidence which suggests that it may be the DHA rather than the EPA component of fish oils which is the biologically active fatty acid responsible for the reduction in susceptibility of developing VF and ICH. If this possibility could be determined with confidence, it would greatly assist in the design of future intervention trials, which are required in order to determine both the nature and amount of dietary omega-3 PUFA that is necessary to achieve these beneficial effects. Any simple dietary strategy that could lead to a substantial decrease in VF and mortality from SCD would be of great medical, social and economic benefit.