Diet, weight change, coronary heart disease and death : The Hordaland Health Studies

Abstract

Background: While nutritional status is considered important in preventing coronary heart disease (CHD) and early mortality, there are numerous nutritional topics needing closer scrutiny. For example, it is unclear to what degree weight changes in older people are associated with mortality. Further, limiting intake of saturated fatty acids (SFA) often leads to increased intake of carbohydrates, and some types of carbohydrates have been shown to associate with increased risk of CHD. Further, studies suggest that cheese, a large contributor to SFA intake and vitamin K2 in the Nordic countries, associate with decreased risk of CHD.

Objectives: 1) To study the association between weight change and mortality in older individuals; 2) To evaluate the importance of the interplay between SFA and total carbohydrates, including food sources, when evaluating the association between SFA and CHD, and 3) to evaluate the association between dietary vitamin K with CHD in middle-aged adults.

Material and methods: Cohort study with participants from the Hordaland Health Study. In Paper I, 2935 men and women, age 71-74 years with weight measured both in 1992-93 and 1997-99 were followed for mortality through 2012. Multivariable Cox regression estimated Hazard ratios (HRs) and 95% confidence intervals (CIs) comparing individuals who lost (≥5%) or gained (≥5%) weight to those with stable weight (±<5% weight change). Cox regression with penalized spline was also used to evaluate the association between weight change (in kg) and mortality. Analyses adjusted for age, sex, physical activity, smoking, diabetes mellitus, hypertension, and previous myocardial infarction or stroke. Papers II and III included 2995 and 2987 men and women, respectively, age 46-49 years at baseline in 1997-99. Participants were followed through 2009 to evaluate associations between intake of SFA, carbohydrates and vitamin K and incident CHD. Baseline diet was assessed by a past-year food frequency questionnaire. Energy- adjusted nutrient intakes were categorized into quartiles. Information on incident CHD events was obtained from the Cardiovascular Disease in Norway (CVDNOR) Project. Multivariable Cox regression estimated HRs and 95% CIs with test for linear trends across quartiles. Analyses were adjusted for age, sex, energy intake, physical activity, smoking and education. Cox regression with penalized spline was used to evaluate the associations between the dietary predictors and incident CHD.

Results: Paper 1 In the adjusted analyses, participants who lost ≥5% weight had an increased mortality risk (HR 1.59; 95% CI 1.35, 1.89) compared to those with stable weight. In contrast, those with a weight gain of ≥5% had a similar risk of CHD as those with a stable weight (HR 1.07; 95% CI 0.90, 1.28). Penalized spline analyses, however, identified that those who lost more than three kg or gained more than 12 kg had increased mortality risk. Paper II In the adjusted analyses, SFA associated with lower risk of CHD (HRQuartile(Q)4vsQ1 0.ּ44; 95%CI 0.26, 0.76), p-trend 0.002). For carbohydrates, the opposite pattern was observed (HRQ4vsQ1 2.10; 95%CI 1.22, 3.63, p-trend 0.003). SFA from cheese associated with lower CHD risk (HRQ4vsQ1 0.44; 95%CI 0.24, 0.83, p-trend 0.006). A 5 energy percent (E%) substitution of carbohydrates with total fat, associated with lower CHD risk (HR 0.75; 95% CI 0.62, 0.90). Paper III In the adjusted analyses, there was no association between intake of vitamin K1 and CHD (HRQ4vsQ1 0.92; 95%CI 0.54, 1.57, p-trend 0.64), while there was a lower risk of CHD associated with higher intake of vitamin K2 (HRQ4vsQ1 0.52; 95% CI 0.29, 0.94, p-trend 0.03). Further adjustment for potential dietary confounders slightly attenuated the association for K2 (HRQ4vsQ1 0.58; 95% CI 0.28, 1.19).

Conclusions and implications: Even a minor weight loss of ≥5% or >3 kg was associated with increased risk of mortality in older people, whereas a weight gain had to be more substantial to increase mortality risk. Thus, weight should be routinely monitored in older adults. A high intake of carbohydrates, reflecting low-fiber and relatively higher sucrose/fructose dietary sources, and a low intake of SFA were associated with higher CHD risk in the current study population. Substituting carbohydrates with total fat was associated with lower risk. Also, SFA from cheese was associated with lower risk of CHD. There is a need to clarify the relative health trade-offs between replacing carbohydrate intake with fat intake in study populations with diverse dietary habits and a wider range in carbohydrate and SFA intakes. In addition, results of our study suggest that dietary guidelines development and their communication to the public, especially regarding reductions in certain foods and nutrients need to consider the potential health impact of alternative sources of energy. A higher intake of vitamin K2 was associated with lower risk of CHD, while there was no association between intake of vitamin K1 and CHD. Current dietary guidelines are based on insufficient knowledge with regard to vitamin K metabolism and the different characteristics of K1 and K2. Therefore, our results indicate a need for more studies on the association between K2 and CHD. In addition, more knowledge about the absorption, transport and bioactivity of K2 is warranted.