Dietary intake and practices in the Hong Kong Chinese population. (1/213)

OBJECTIVES: To examine dietary intake and practices of the adult Hong Kong Chinese population to provide a basis for future public health recommendations with regard to prevention of certain chronic diseases such as cardiovascular disease, hypertension, and osteoporosis. PARTICIPANTS: Age and sex stratified random sample of the Hong Kong Chinese population aged 25 to 74 years (500 men, 510 women). METHOD: A food frequency method over a one week period was used for nutrient quantification, and a separate questionnaire was used for assessment of dietary habits. Information was obtained by interview. RESULTS: Men had higher intakes of energy and higher nutrient density of vitamin D, monounsaturated fatty acids and cholesterol, but lower nutrient density of protein, many vitamins, calcium, iron, copper, and polyunsaturated fatty acids. There was an age related decrease in energy intake and other nutrients except for vitamin C, sodium, potassium, and percentage of total calorie from carbohydrate, which all increased with age. Approximately 50% of the population had a cholesterol intake of < or = 300 mg; 60% had a fat intake < or = 30% of total energy; and 85% had a percentage of energy from saturated fats < or = 10%; criteria considered desirable for cardiovascular health. Seventy eight per cent of the population had sodium intake values in the range shown to be associated with the age related rise in blood pressure with age. Mean calcium intake was lower than the FAO/WHO recommendations. The awareness of the value of wholemeal bread and polyunsaturated fat spreads was lower in this population compared with that in Australia. There was a marked difference in types of cooking oil compared with Singaporeans, the latter using more coconut/palm/mixed vegetable oils. CONCLUSION: Although the current intake pattern for cardiovascular health for fat, saturated fatty acid, and cholesterol fall within the recommended range for over 50% of the population, follow up surveys to monitor the pattern would be needed. Decreasing salt consumption, increasing calcium intake, and increasing the awareness of the health value of fibre may all be beneficial in the context of chronic disease prevention.  (+info)

Lifestyle modifications to prevent and control hypertension. 6. Recommendations on potassium, magnesium and calcium. Canadian Hypertension Society, Canadian Coalition for High Blood Pressure Prevention and Control, Laboratory Centre for Disease Control at Health Canada, Heart and Stroke Foundation of Canada. (2/213)

OBJECTIVE: To provide updated, evidence-based recommendations on the consumption, through diet, and supplementation of the cations potassium, magnesium and calcium for the prevention and treatment of hypertension in otherwise healthy adults (except pregnant women). OPTIONS: Dietary supplementation with cations has been suggested as an alternative or adjunctive therapy to antihypertensive medications. Other options include other nonpharmacologic treatments for hypertension. OUTCOMES: The health outcomes considered were changes in blood pressure and in morbidity and mortality rates. Because of insufficient evidence, no economic outcomes were considered. EVIDENCE: A MEDLINE search was conducted for the period 1966-1996 with the terms hypertension and potassium, magnesium and calcium. Reports of trials, meta-analyses and review articles were obtained. Other relevant evidence was obtained from the reference lists of articles identified, from the personal files of the authors and through contacts with experts. The articles were reviewed, classified according to study design, and graded according to the level of evidence. VALUES: A high value was placed on the avoidance of cardiovascular morbidity and premature death caused by untreated hypertension. BENEFITS, HARMS AND COSTS: The weight of the evidence from randomized controlled trials indicates that increasing intake of or supplementing the diet with potassium, magnesium or calcium is not associated with prevention of hypertension, nor is it effective in reducing high blood pressure. Potassium supplementation may be effective in reducing blood pressure in patients with hypokalemia during diuretic therapy. RECOMMENDATIONS: For the prevention of hypertension, the following recommendations are made: (1) The daily dietary intake of potassium should be 60 mmol or more, because this level of intake has been associated with a reduced risk of stroke-related mortality. (2) For normotensive people obtaining on average 60 mmol of potassium daily through dietary intake, potassium supplementation is not recommended as a means of preventing an increase in blood pressure. (3) For normotensive people, magnesium supplementation is not recommended as a means of preventing an increase in blood pressure. (4) For normotensive people, calcium supplementation above the recommended daily intake is not recommended as a means of preventing an increase in blood pressure. For the treatment of hypertension, the following recommendations are made. (5) Potassium supplementation above the recommended daily dietary intake of 60 mmol is not recommended as a treatment for hypertension. (6) Magnesium supplementation is not recommended as a treatment for hypertension. (7) Calcium supplementation above the recommended daily dietary intake is not recommended as a treatment for hypertension. VALIDATION: These guidelines are consistent with the results of meta-analyses and recommendations made by other organizations. They have not been clinically tested. SPONSORS: The Canadian Hypertension Society, the Canadian Coalition for High Blood Pressure Prevention and Control, the Laboratory Centre for Disease Control at Health Canada, and the Heart and Stroke Foundation of Canada.  (+info)

Cloning of a novel kinase (SIK) of the SNF1/AMPK family from high salt diet-treated rat adrenal. (3/213)

PCR-coupled cDNA subtraction hybridization was adapted to identify the genes expressed in the adrenocortical tissues from high salt diet-treated rat. A novel cDNA clone, termed salt-inducible kinase (SIK), encoding a polypeptide (776 amino acids) with significant similarity to protein serine/ threonine kinases in the SNF1/AMPK family was isolated. An in vitro kinase assay demonstrated that SIK protein had autophosphorylation activity. Northern blot revealed that SIK mRNA levels were markedly augmented by ACTH treatment both in rat adrenal glands and in Y1 cells. SIK may play an important role in the regulation of adrenocortical functions in response to high plasma salt and ACTH stimulation.  (+info)

Nutrient intake and use of beverages and the risk of kidney stones among male smokers. (4/213)

High intakes of calcium, potassium, and fluids have been shown to be associated with lowered risk of kidney stones. The authors studied the associations between diet and risk of kidney stones in a cohort of 27,001 Finnish male smokers aged 50-69 years who were initially free of kidney stones. All men participated in the Alpha-Tocopherol, Beta-Carotene Lung Cancer Prevention Study and completed a validated dietary questionnaire at baseline. After 5 years of follow-up (1985-1988), 329 men had been diagnosed with kidney stones. After data were controlled for possible confounders, the relative risk of kidney stones for men in the highest quartile of magnesium intake was 0.52 (95% confidence interval (CI) 0.32-0.85) as compared with men in the lowest quartile. Intake of fiber was directly associated with risk (relative risk (RR) = 2.06, 95% CI 1.39-3.03). Calcium intake was not associated with the risk of kidney stones. Beer consumption was inversely associated with risk of kidney stones; each bottle of beer consumed per day was estimated to reduce risk by 40% (RR = 0.60, 95% CI 0.47-0.76). In conclusion, the authors observed that magnesium intake and beer consumption were inversely associated and fiber intake was directly associated with risk of kidney stones.  (+info)

Regulation of apical K channels in rat cortical collecting tubule during changes in dietary K intake. (5/213)

Long-term adaptation to a high-K diet is known to increase the density of conducting secretory K (SK) channels in the luminal membrane of the rat cortical collecting tubule (CCT). To examine whether these channels are involved in the short-term, day-to-day regulation of K secretion, we examined the density of K channels in animals fed a high-K diet for 6 or 48 h. CCTs were isolated and split open to provide access to the luminal membrane. Cell-attached patches were formed on principal cells with 140 mM KCl in the patch-clamp pipette. SK channels were recognized from their characteristic single-channel conductance (40-50 pS) and gating patterns. Animals fed a control diet had SK channel densities of 0.40 channels/micrometer(2). When the diet was changed for one containing 10% KCl for 6 h, the channel density increased to 1.51 channels/micrometer(2). Maintaining the animals on a high-K diet for 48 h resulted in a further increase in SK channels to 2.29 channels/micrometer(2). Animals fed a low-K diet for 5 days or longer had SK densities of 0.53 channels/micrometer(2), not significantly different from control values. The presence of conducting Na channels in the luminal membrane will also affect K secretion by the CCT by altering the electrical driving force through the K channels. The density of Na channels, measured with LiCl in the pipette, was 0. 08 for controls and 1.00 and 1.08 channels/micrometer(2) after 6 h and 48 h on a high-K diet. Plasma aldosterone increased from 15 +/- 4 ng/dl (controls ) to 36 +/- 8 and 98 +/- 23 ng/dl after 6 and 48 h of K loading, respectively. The increase in K channel density could not be reproduced by infusion of the animals with aldosterone. We conclude that regulation of the density of conducting Na and K channels may contribute to day-to-day variation in the rate of renal K secretion and to the short-term maintenance of K balance.  (+info)

High dietary potassium chloride intake augments rat renal mineralocorticoid receptor selectivity via 11beta-hydroxysteroid dehydrogenase. (6/213)

Glucocorticoid access to renal corticosteroid receptors is regulated by 11beta-hydroxysteroid dehydrogenases (11beta-HSDs), converting 11beta-hydroxyglucocorticoids into inactive 11-ketones. This mechanism plays a key role in maintaining normal salt-water homeostasis and blood pressure. To study whether renal cortical proximal and distal tubular 11beta-HSDs are modulated, upon shifting the electrolyte status (and may thereby contribute to adjusting the salt-water homeostasis), rats were treated for 14 days with diets with low (0.058 w/w%), normal (0.58%, which is the KCl content of standard European laboratory rat food) or high (5.8%) potassium chloride content. In proximal tubules, dietary KCl had no effect regarding corticosterone 11beta-oxidation in intact cells as well as 11beta-HSD1 and 11beta-HSD2 protein (Western blotting) and mRNA levels (semi-quantitative RT-PCR). In distal tubules, the low KCl diet also had no effect. However, distal tubules of rats fed the high KCl diet showed increased corticosterone 11beta-oxidation rates (1.6-fold, P<0.01) and 11beta-HSD2 protein (4-fold, P<0.01), whereas 11beta-HSD1 protein was decreased (no longer detected, P<0.05). Distal tubular 11beta-HSD mRNA levels were not changed upon dietary treatment. Our results suggest that upon dietary KCl loading distal tubular mineralocorticoid receptor selectivity for aldosterone is increased because of enhanced corticosterone 11beta-oxidation. This may contribute to the fine-tuning of salt-water homeostasis by the kidney.  (+info)

NH4+ secretion in inner medullary collecting duct in potassium deprivation: role of colonic H+-K+-ATPase. (7/213)

NH4+ secretion in inner medullary collecting duct in potassium deprivation: Role of colonic H+-K+-ATPase. BACKGROUND: In K+ deprivation (KD), gastric (g) H+-K+-ATPase (HKA) is suppressed, whereas colonic (c) HKA is induced in the terminal inner medullary collecting duct (IMCD). We hypothesized that in KD, cHKA is induced and can mediate the secretion of NH4+. METHODS: Rats were sacrificed after 2, 3, 6, or 14 days on regular (NML) or K+-free (KD) diet. mRNA expression of HKA isoforms in terminal inner medulla was examined and correlated with NH4+ secretion in perfused IMCD in vitro. RESULTS: Urinary NH4+ excretion increased after K+-free diet for six days. In terminal inner medulla, cHKA expression was strongly induced, whereas gHKA expression was decreased. NH4+ secretion increased by 62% in KD (JtNH4+ 0.57 vs. 0.92 pmol/min/mm tubule length, P < 0.001). Ouabain (1 mM) in perfusate inhibited NH4+ secretion in KD by 45% (P < 0.002) but not in NML. At luminal pH 7.7, which inhibits NH3 diffusion, NH4+ secretion in IMCD was 140% higher in KD (0.36 vs. 0.15, P < 0.03) and was sensitive to ouabain. ROMK-1 mRNA expression was induced in parallel with cHKA in inner medulla. CONCLUSIONS: These data suggest that in KD, cHKA replaces gHKA and mediates enhanced secretion of NH4+ (and H+) into the lumen facilitated by K+ recycling through ROMK-1.  (+info)

Protein tyrosine kinase regulates the number of renal secretory K channels. (8/213)

The apical small conductance (SK) channel plays a key role in K secretion in the cortical collecting duct (CCD). A high-K intake stimulates renal K secretion and involves a significant increase in the number of SK channels in the apical membrane of the CCD. We used the patch-clamp technique to examine the role of protein tyrosine kinase (PTK) in regulating the activity of SK channels in the CCD. The application of 100 microM genistein stimulated SK channels in 11 of 12 patches in CCDs from rats on a K-deficient diet, and the mean increase in NP(o), a product of channel number (N) and open probability (P(o)), was 2.5. In contrast, inhibition of PTK had no effect in tubules from animals on a high-K diet in all 10 experiments. Western blot analysis further shows that the level of cSrc, a nonreceptor type of PTK, is 261% higher in the kidneys from rats on a K-deficient diet than those on a high-K diet. However, the effect of cSrc was not the result of direct inhibition of channel itself, because addition of exogenous cSrc had no effect on SK channels in inside-out patches. In cell-attached patches, application of herbimycin A increased channel activity in 14 of 16 patches, and the mean increase in NP(o) was 2.4 in tubules from rats on a K-deficient diet. In contrast, herbimycin A had no effect on channel activity in any of 15 tubules from rats on a high-K diet. Furthermore, herbimycin A pretreatment increased NP(o) per patch from the control value (0.4) to 2.25 in CCDs from rats on a K-deficient diet, whereas herbimycin failed to increase channel activity (NP(o): control, 3.10; herbimycin A, 3.25) in the CCDs from animals on a high-K diet. We conclude that PTK is involved in regulating the number of apical SK channels in the kidney.  (+info)