Genetic variance of SGK-1 is associated with blood pressure, blood pressure change over time and strength of the insulin-diastolic blood pressure relationship

BACKGROUND

Insulin stimulation of the serum- and glucocorticoid-regulated kinase 1 (SGK-1) prolongs the half-life of the epithelial sodium channel, a protein which is essential for blood pressure regulation. The aim of this study was to investigate if variation in the SGK-1 gene is associated with increased blood pressure and strength of the insulin-blood pressure relationship.

METHODS

A promoter C/T, an intron 6 C/T and an exon 8 C/T polymorphism in the SGK-1 gene were genotyped in 4830 subjects from the Malmö Diet and Cancer (MDC) material of whom 4001 were free from antihypertensive medication. Of these, 2171 subjects had also been investigated 11.2 +/- 4.4 years earlier in the Malmö Preventive Project (MPP).

RESULTS

In untreated MDC subjects, intron 6 CC genotype carriers had higher diastolic blood pressure than carriers of the T allele (P = 0.02) and exon 8 C allele carriers had higher systolic blood pressure than TT genotype carriers (P = 0.05). Subjects simultaneously carrying the intron 6 CC genotype and the exon 8 CC or CT genotype (SGK-1 risk) had higher systolic blood pressure (P = 0.03) and higher diastolic blood pressure (P = 0.009) than noncarriers. From MPP to MDC, the percent change in blood pressure per year was higher for systolic blood pressure (P = 0.002) and diastolic blood pressure (P = 0.001) in SGK-1 risk carriers than noncarriers. The correlation between fasting plasma insulin concentration and diastolic blood pressure was stronger in SGK-1 risk carriers than in non-carriers (P = 0.04).

CONCLUSION

Our data suggest that SGK-1 risk carriers are at increased risk of hypertension and are more sensitive to the blood pressure elevating effects associated with hyperinsulinemia.

Dietary fat intake and early mortality patterns--data from The Malmö Diet and Cancer Study

OBJECTIVES

Most current dietary guidelines encourage limiting relative fat intake to <30% of total daily energy, with saturated and trans fatty acids contributing no more than 10%. We examined whether total fat intake, saturated fat, monounsaturated, or polyunsaturated fat intake are independent risk factors for prospective all-cause, cardiovascular and cancer mortality.

DESIGN

Population-based, prospective cohort study.

SETTING AND SUBJECTS

The Malmö Diet and Cancer Study was set in the city of Malmö, southern Sweden. A total of 28,098 middle-aged individuals participated in the study 1991-1996.

MAIN OUTCOME MEASURES

Subjects were categorized by quartiles of relative fat intake, with the first quartile used as a reference point in estimating multivariate relative risks (RR; 95% CI, Cox's regression model). Adjustments were made for confounding by age and various lifestyle factors.

RESULTS

Women in the fourth quartile of total fat intake had a significantly higher RR of cancer mortality (RR 1.46; CI 1.04-2.04). A significant downwards trend was observed for cardiovascular mortality amongst men from the first to the fourth quartile (P=0.028). No deteriorating effects of high saturated fat intake were observed for either sex for any cause of death. Beneficial effects of a relatively high intake of unsaturated fats were not uniform.

CONCLUSIONS

With the exception of cancer mortality for women, individuals receiving more than 30% of their total daily energy from fat and more than 10% from saturated fat, did not have increased mortality. Current dietary guidelines concerning fat intake are thus generally not supported by our observational results.

The association between total energy intake and early mortality: data from the Malmö Diet and Cancer Study

OBJECTIVES

In animal studies, low energy intake (EI) has been associated with a longer lifespan. We examine whether EI is an independent risk factor for prospective all-cause mortality, cardiovascular and cancer mortality in humans.

DESIGN

Population-based, prospective cohort study.

SETTING AND SUBJECTS

The Malmö Diet and Cancer Study is a population-based prospective cohort study. A total of 28 098 individuals, mean age 58.2 years, completed questionnaires on diet and life-style and attended a physical examination during 1991-96.

MAIN OUTCOME MEASURES

Information on mortality was acquired from national registries during a mean follow-up time of 6.6 years. Subjects were categorized by quartiles of total EI. The first quartile was used as a reference point in estimating multivariate relative risks (RR; 95% CI, Cox's regression model). Adjustments were made for confounding by age and various life-style factors.

RESULTS

The lowest total mortality was observed for women in the third quartile (RR: 0.74; CI: 0.57-0.96) and for men in the second and third quartiles (RR: 0.85; CI: 0.69-1.04 and RR: 0.85; CI: 0.69-1.04 respectively). Similar U-shaped patterns were observed for cardiovascular mortality amongst women and cancer mortality amongst men. A statistically significant trend (P = 0.029) towards lower cardiovascular mortality from the first to the fourth quartile was observed for men.

CONCLUSIONS

Low caloric consumers did, on average, not have lower mortality than average or high caloric consumers. Generally, individuals approximately meeting national recommendations for total EI had the lowest mortality. For men, high caloric intake was associated with lower cardiovascular mortality.