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Dietary exposures and disease risk


We aim to describe prevalence, patterns, and trends in diet in the Norwegian and Sami population. However, most of the research is concentrated on exploring associations between foods, nutrients, and cancer, mortality, or other non-communicable diseases. We are also running some intervention studies. We rely heavily on self-reported information from our large population-based cohorts in many of our analyses, but we also utilize nutritional and other biomarkers. We are increasingly making use of repeated measurements and trajectories to also model how changes in lifestyle influence disease risk. Much of the research that falls in this category is based on the Norwegian Women and Cancer study and our large international collaborations e.g., the European Prospective Investigation into Cancer and Nutrition (EPIC).

In Norway, prevalence of alcohol use among women has risen notably over the past three decades. Alcohol consumption contributed to 2.7% (around 442 cases) of 16 370 new cancer cases among women between 2016 and 2020 in Norway. The goal of this project is to describe the longitudinal patterns of alcohol consumption in Norwegian women and to investigate the impact of alcohol consumption on cancer risk and mortality.  

Specific objectives: 

Ongoing PhD project:

Fjorida Llaha

  • To describe the longitudinal patterns of alcohol consumption during adulthood in a representative sample of Norwegian women. 
  • To test and quantify the associations between alcohol consumption and the risk of common cancer types in Norwegian women.
  • To test and quantify the association between alcohol consumption and the risk of all-cause and cause-specific mortality in Norwegian women.

Other completed projects:

  • Marko Lukic. To calculate the burden of colon cancer attributable to alcohol consumption in Norwegian women. Link to publication.
  • Idlir Licaj. To prospectively investigate the association between time-varying alcohol consumption and overall and cause-specific mortality among middle-aged women. Link to publication.
  • EPIC paper. Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599 912 current drinkers in 83 prospective studies. Link to publication.

This research focuses on evaluating dietary habits within the framework of the Healthy Nordic Food Index, aiming to understand how adherence to this diet correlates with dietary composition and lifestyle factors. It investigates the relationship between the consumption of foods associated with a healthy Nordic diet and their potential non-linear impact on all-cause mortality. Additionally, the study explores the effects of substituting processed meat with options like lean or fatty fish, assessing the implications for overall and cause-specific mortality rates. These objectives are pursued through detailed analysis and are documented in linked publications for further reference.

Specific objectives: 

Ongoing PhD projects:

Torill Miriam Enget Jensen

  • To assess adherence to the Healthy Nordic Food Index and explore dietary composition and lifestyle factors associated with adherence to the index. Link to publication.
  • To evaluate the potential non-linear associations between foods part of a healthy Nordic diet and all-cause mortality. Link to publication. 
  • To examine the impact of replacing processed meat with lean or fatty fish on all-cause and cause specific mortality. Link to publication.
Vitamin D

The activities on vitamin D research spans from topics of regional relevance with a focus on vitamin D sources and security for Arctic populations, to the role of vitamin D for disease risk and disease prevention for the general population. It includes systematic and scoping reviews for Nordic nutrition recommendations and evidence-based discussions on optimal vitamin D levels. Currently, we are advancing this area of study with two specific projects:
Completed projects:

Nutrition and recommendations:

Opinions on vitamin D and health:

Vitamin D and UV radiation:

  • Vitamin D status of middle-aged women at 65-71 degrees N in relation to dietary intake and exposure to ultraviolet radiation. Link to publication.
  • Seasonality of UV radiation and vitamin D status at 68 degrees north. Link to publication.
  • The solar UV radiation level needed for cutaneous production of vitamin D3 in the face. A study conducted among subjects living at a high latitude (68 degrees N). Link to publication.
  • Duration of vitamin D synthesis from weather model data for use in prospective epidemiological studies. Link to publication.
  • Daily duration of vitamin D synthesis in human skin with relation to latitude, total ozone, altitude, ground cover, aerosols and cloud thickness. Link to publication.

Vitamin D status, Intakes, food traditions and Arctic and indigenous populations:

  • Predictors for cod-liver oil supplement use--the Norwegian Women and Cancer Study. Link to publication.
  • Vitamin D status in a rural population with high fish liver consumption. Link to publication.
  • Change in plasma levels of vitamin D after consumption of cod-liver and fresh cod-liver oil as part of the traditional north Norwegian fish dish "Molje". Link to publication.
  • Dietary intakes of retinol, beta-carotene, vitamin D and vitamin E in the European Prospective Investigation into Cancer and Nutrition cohort. Link to publication.
  • Vitamin D status in a multi-ethnic population of northern Norway: the SAMINOR 2 Clinical Survey. Link to publication.
  • No ethnic disparities in nutritional adequacy between the Indigenous Sami and the non-Sami population living in rural Northern Norway-the SAMINOR 2 Clinical Survey. Link to publication.
  • Contribution of highly industrially processed foods to the nutrient intakes and patterns of middle-aged populations in the European Prospective Investigation into Cancer and Nutrition study. Link to publication.

Vitamin D and breast cancer:

  • Dietary intake of vitamin D and calcium and breast cancer risk in the European Prospective Investigation into Cancer and Nutrition. Link to publication.
  • Vitamin D-effective solar UV radiation, dietary vitamin D and breast cancer risk. Link to publication.
  • Plasma 25-hydroxyvitamin D and the risk of breast cancer in the European prospective investigation into cancer and nutrition: a nested case-control study. Link to publication.
  • Vitamin D receptor polymorphisms and breast cancer risk Results from the National Cancer Institute Breast and Prostate Cancer Cohort Consortium. Link to publication.

Vitamin D and colorectal cancer:

  • Prediagnostic 25-hydroxyvitamin D, VDR and CASR polymorphisms, and survival in patients with colorectal cancer in western European populations. Link to publication.
  • Association of Circulating Vitamin D With Colorectal Cancer Depends on Vitamin D–Binding Protein Isoforms: A Pooled, Nested, Case-Control Study. Link to publication.
  • Pre-diagnostic circulating vitamin D concentration and risk of colorectal cancer in European populations: a nested case-control study. Link to publication.
  • Vitamin D receptor and calcium sensing receptor polymorphisms and the risk of colorectal cancer in European Populations. Link to publication.
  • Pre-diagnostic intake of vitamin D and incidence of colorectal cancer by anatomical subsites: the Norwegian Women and Cancer Cohort Study (NOWAC). Link to publication.

Vitamin D and other cancers:

  • Dietary vitamin D intake and the bladder cancer risk : A pooled analysis of prospective cohort studies. Link to publication.
  • Circulating vitamin D in relation to cancer incidence and survival of the head and neck and oesophagus in the EPIC cohort. Link to publication.
  • Prediagnostic circulating vitamin D levels and risk of hepatocellular carcinoma in European populations: A nested case-control study. Link to publication.
  • Plasma 25-hydroxyvitamin D concentration and lymphoma risk: results of the European Prospective Investigation into Cancer and Nutrition. Link to publication.
  • Vitamin D, season, and risk of prostate cancer: a nested case-control study within Norwegian health studies. Link to publication.
  • Circulating concentrations of vitamin D in relation to pancreatic cancer risk in European populations. Link to publication.

Vitamin D and diabetes:

  • Longitudinal changes in vitamin D concentrations and the association with type 2 diabetes mellitus: the Tromsø Study. Link to publication.

Vitamin D and multiple Sclerosis:

  • Vitamin D: a candidate for the environmental effect in multiple sclerosis – observations from Norway. Link to publication.
  • Bone turnover and metabolism in patients with early multiple sclerosisand Prevalent Bone Mass Deficit: A Population-Based Case-Control Study. Link to publication.
  • What is needed to keep persons with multiple sclerosis vitamin D-sufficient throughout the year? Link to publication.
Fish
(on the right:) Cod fish, photo by: Hans-Petter Fjeld

In this research endeavor, we delve into the intricate connection between fish consumption and human health. Our studies encompass various aspects of this relationship, which are highlighted below:

  • We examined the rate of overall mortality, as well as mortality from ischaemic heart disease and cancer in relation to the intake of total fish, lean fish, and fatty fish in a large prospective cohort including ten European countries. Link to publication.
  • We examined the association between fish consumption, dietary and circulating levels of n-3 LC-PUFAs, and ratio of n-6:n-3 LC-PUFA with CRC using data from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Link to publication.
  • We have contributed to a comprehensive risk assessment of fish in the Norwegian diet, through the Norwegian Scientific Committee for Food and Environment. Link to publication.
Potato

Potatoes are (or have been) staple foods in many countries, including the Nordic countries, and among the world's most important food commodities. Yet, remarkably little research is done on potato consumption and health. Potatoes are now being included in dietary recommendations – much due to their low environmental footprint. We aim to look more closely into the health effects of potato consumption.

Specific objectives:

Ongoing Project:

  • To study the associations between potato consumption and prospective weight change in the European Prospective Investigation into Cancer and Nutrition cohort.
Lene Angell Åsli, PhD thesis:
  • To map which factors influence potato consumption among women in the Norwegian Women and Cancer (NOWAC) study. Link to publication.
  • To investigate the association between potato consumption and the risk of colorectal cancer (CRC) among participants in the Norwegian Women and Cancer study. Link to publication.
  • To prospectively investigate the association between potato consumption and pancreatic cancer among 114 240 men and women in the HELGA cohort. Link to publication.
summer stipend:
  • To describe the change in potato consumption over time, and how non-dietary variables influenced that change among participants in the Norwegian Women and Cancer study (NOWAC). Link to publication.

The overall aim of this project is to explore possible relationships between intake of sweet beverages and weight change, mortality and risk of colorectal cancer in a representative cohort of middle-aged Norwegian women. More specifically, the objectives are:

Ongoing PhD project, Marie Hauan:

  • To assess if intake of sugar-sweetened beverages, artificially sweetened beverages or juice are associated with weight gain.
  • To investigate if consumption of sugar-sweetened beverages, artificially sweetened beverages or juice are associated with mortality.
  • To study associations between colorectal cancer risk and the intake of sugar-sweetened beverages, artificially sweetened beverages and juice.

Previous student project based on the Fit Futures study: The objective of this paper was to study the intake of sugar-sweetened beverages (SSB) and characteristics associated with SSB intake in adolescents from Troms, Norway. Link to publication.

EPIC paper: Association Between Soft Drink Consumption and Mortality in 10 European Countries.

Dietary factors can be studied alone, as single foods or nutrients, or collectively, in predefined dietary indices, such as the Healthy Nordic Food Index, the Mediterranean Diet Score, or scores reflecting adherence to e.g. the Nordic Nutrition Recommendations or World Cancer research fund recommendations. Alternatively, statistical techniques such as factor or cluster analyses can be used to elucidate dietary patterns. Here is a selection of our papers since 2012:

Descriptive papers:

  • The present study describes the intake of seven priori defined healthy food items across ten countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) and examines their consumption across Europe. Link to publication.
  • The study objective is to describe and investigate dietary composition, micronutrient density, lifestyle, socioeconomic factors, and adherence to the Nordic Nutrition Recommendations across groups of Swedish women defined by their level of adherence to a healthy Nordic food index (HNFI). Link to publication.
  • The objective of the study was to estimate current food intake in the population of northern Norway and to investigate the impact of self-perceived Sami ethnicity and region of residence on food intake. Link to publication.
  • In this study, we carried out a comprehensive assessment of nutrient intake with a focus on Sami ethnicity and studied ethnic and regional differences in nutrient intake in rural Northern Norway. We also attempted to describe the adequacy of the average daily intake of nutrients according to the Estimated Average Requirements (AR) in the 2012 Nordic Nutrition Recommendations (NNR). Link to publication.
  • In this study, we examined the association between education and intake of total energy and macronutrients in participants in the Tromsø Study by sex, and compared the intake of macronutrients with the Nordic Nutrition Recommendations 2012. Link to publication.

Papers exploring associations with health outcomes:

  • The aim of this cohort study was to determine whether a healthy Nordic food index consisting of fish, cabbage, rye bread, oatmeal, apples, pears and root vegetables was related to CRC incidence in a Danish cohort. Link to publication.
  • The aim of the present study was to examine the association between adherence to a healthy Nordic food index (consisting of wholegrain bread, oatmeal, apples/pears, root vegetables, cabbages and fish/shellfish) and overall mortality, and death by cardiovascular disease, cancer, injuries/suicide and other causes in a cohort of Swedish women. Link to publication.
  • To investigate the relationship between diet and pancreatic cancer, an analysis of dietary patterns in participants from the Norwegian Women and Cancer Study was performed using principal component analysis. Link to publication.
  • Relevant EPIC paper: We aimed to investigate whether adherence to the Mediterranean diet prior to diagnosis is associated with overall and breast cancer-specific mortality in the EPIC study. Link to publication.

Coffee

Completed PhD project: Coffee intake and cancer

Marko Lukic. PhD thesis
Specific objectives: 

  • To quantify the association between filtered, boiled, and total coffee consumption and the risk of bladder, esophageal, kidney, pancreatic, and stomach cancers Link to publication.
  • A dose–response meta-analysis to assess the impact of coffee consumption on the risk of endometrial cancer. Link to publication.
  • to investigate the relationship between coffee consumption and the risk of breast, colorectal, ovarian, and lung cancers, as well as cancer at any site, in the Norwegian Women and Cancer (NOWAC) Study using baseline and follow-up information on total coffee consumption. Link to publication.

Other completed projects: 

  • Marko Lukic. To assess the proportion of colon cancer attributable to established modifiable risk factors among Norwegian women in the last 20 years using the data from the nationally representative Norwegian Women and Cancer (NOWAC) study and accounting for competing risk of death and joint exposure effects. Link to publication
  • Marko Lukic. To investigate the association between total coffee consumption and consumption of filtered, instant, and boiled coffee on the incidence of malignant melanoma in a prospective cohort of Norwegian women. Link to publication.
  • Runa Borgund Barnung. To assess the potential associations between coffee consumption and gene expression profiles and elucidate functional interpretation. Link to publication.
  • Marko Lukic. To calculate hazard ratios and 95% confidence intervals for all-cause, cardiovascular, and cancer mortality by total coffee consumption and brewing methods, and adjusted for smoking status, number of pack-years, age at smoking initiation, alcohol consumption, body mass index, physical activity, and duration of education using flexible parametric survival models. Link to Publication.
  • EPIC paper: to study coffee drinking and all-cause and cause-specific mortality in 10 European countries. Link to publication.

We also contributed to the Nordic Nutrition Recommendations' chapter on Beverages – the paper is published in Food and Nutrition Research.

Compared to many other countries, Norway and the other Scandinavian countries have a high intake on whole grains. However, when the Nordic Centre of Excellence "HELGA – Nordic Health – Wholegrain Food" was initiated, there was little research that could differentiate between refined grains and whole grains. Here we present some of the papers from the HELGA project, and beyond, that has helped us understand the associations between wholegrain consumption and health.

Descriptive papers:

  • To describe the intake of whole grain in Scandinavia: intake, sources and compliance with new national recommendations. Link to publication.
  • The objective of this paper was to identify dietary patterns with whole grains as a main focus to see if there is a similar whole grain pattern in the three Scandinavian countries. Another objective is to see if items suggested for a Nordic Food Index will form a typical Nordic pattern when using factor analysis. Link to publication.
  • The objective of this study was to investigate dietary and non-dietary characteristics of wholegrain bread eaters in the Norwegian Women and Cancer study. Link to publication.
  • In the present study, we analysed the plasma concentrations of five AR homologues in 2845 participants from ten European countries from a nested case-control study in the European Prospective Investigation into Cancer and Nutrition.  Link to publication.

Papers describing associations with health outcomes

  • The purpose of this study was to examine associations between intake of dietary fiber and risk of incident colon (including distal and proximal colon) and rectal cancer in the prospective Scandinavian HELGA cohort and to determine if fiber source (vegetables, fruits, potatoes, cereals) impacted the association.  Link to publication.
  • The objective of this study was to investigate the association between whole-grain intake from different cereal and food sources, and colorectal cancer. Link to publication.
  • We performed a case-only study in the Scandinavian HELGA cohort of pre-diagnosis wholegrain intake (total wholegrain, wholegrain wheat, wholegrain rye, and wholegrain oats) and survival of colorectal cancer. Link to publication.
  • In this paper, the association between alkylresorcinols, biomarkers of whole-grain rye and wheat intake, and colorectal cancer incidence were investigated using prediagnostic plasma samples from colorectal cancer case patients and matched control subjects nested within the European Prospective Investigation into Cancer and Nutrition.  Link to publication.
  • We investigated the association between wholegrain intake and colorectal cancer using intakes of whole grains and whole-grain products measured via FFQs and plasma alkylresorcinol concentrations, a biomarker of whole-grain wheat and rye intake, both separately and in combination. We conducted a nested case-control study in a cohort from a research project on Nordic health and whole-grain consumption (HELGA).  Link to publication.
  •  The aim of this paper was to study the associations between consumption of whole grains, whole-grain products and oesophageal cancer, including its two major histological subtypes. Link to publication.
  • The aim of the present study was to investigate the intake of wholegrain products and wholegrain types in relation to all-cause and cause-specific mortality in a large Scandinavian HELGA cohort. Link to publication.
  • The aim of the present study was to investigate the association between whole-grain bread consumption and colorectal cancer incidence among Norwegian women, using data from a prospective cohort study (the Norwegian Women and Cancer Study). Link to publication.
  • We were also invited to write a book chapter on Wholegrains and mortality (Wholegrains and Health), and the chapter on Cereals for the Nordic Nutrition Recommendations 2023. The full report will be published in 2024, and the paper is also in press in Food and Nutrition Research.
  • Whole grain intake and survival among Scandinavian colorectal cancer patients, both wholegrain wheat, wholegrain rye and wholegrain oats. Link to publication.

Relevant collaborative paper:

  • We aimed to assess associations with bladder cancer risk for intakes of whole grains, refined grains, and dietary fiber. Link to publication.

Milk and dairy products have traditionally been consumed in rather large amounts in the Nordic diet, but the associations between intake and various health outcomes are ambiguous. Here are some of our papers on the topic:

  • The aim of this study was to examine the association between milk intake and risk of CRC, colon cancer and rectal cancer among Norwegian women. Link to publication.
  • The aim of this study was to quantify the association between consumption of brown cheese, a common bread topping in Norway, and colorectal, colon, and rectal cancer in the prospective Norwegian Women and Cancer (NOWAC) Study.  Link to publication.

Selected EPIC publication:

  • In this study, we aimed to explore the association between circulating calcium concentrations and CRC risk using data from 2 large European prospective cohort studies. Link to publication.

Ongoing PhD project Bahar Kucuk:

The overall aim of this PhD project is to assess the environmental sustainability aspects of the northern Norwegian diets specifically focusing on the Tromsø population. It aims to investigate the associations between the environmental impact of the dietary consumption and socio-demographic and health characteristics of the population in depth and identify the beneficial transformations from the consumer side. More specifically, the objectives are:

  1. Quantifying the environmental impact of northern Norwegian diet according to greenhouse gas emissions, acidifying emissions, eutrophication emissions, water footprint, and land use.
  2. Exploring potential associations between the environmental impact and age, sex, education, income, and body mass index.
  3. Exploring the co-benefits of the northern Norwegian diets.
  4. Identifying possible dietary shifts/transitions to reach/achieve a diet with lower negative environmental impact while preserving the health benefits.

Selected EPIC papers:

  • To assess the potential co-benefits from shifting to more sustainable diets, we aimed to investigate the associations of dietary greenhouse gas emissions and land use with all-cause and cause-specific mortality and cancer incidence rates in EPIC. Link to publication.
  • In this paper, we examined the associations between dietary species richness, which is recommended as a crosscutting measure of food biodiversity, and subsequent total and cause-specific mortality among adults enrolled in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Link to publication.

Together with colleagues at the Department of Caring Sciences, we have been working on various aspects of dietary intake and status, and environmental contaminants in the MISA study, a study of pre-pregnant and pregnant women, and their offspring. Here are some of our recent and planned publications.

  • The objective of this study was to assess iodine status in pregnant women from Northern Norway and to investigate the influence of iodine status on maternal and infant thyroid function. Link to publication.
  • In this study, we surveyed midwives and public health nurses' knowledge and clinical practice in securing sufficient iodine status in relation to pregnancy. Link to publication.

Methodological studies

Here we present some of the methodological work that we have been involved in, this spans from traditional dietary assessment methods to e- or mhealth methods, food composition databases and validation or quality assurance studies.

  • The purpose of this study was to describe the development of the Norwegian version of Myfood24, a self-administered digital 24-hour recall programme. Link to publication (in Norwegian).
  •  We aimed to examine the usability of a new web-based dietary assessment tool, myfood24 in older adult Norwegian women and men. Link to publication.
  • We aimed to pilot a smartphone-based information communication technology solution to collect nationally representative data, annually, on 4 modifiable risk factors. Link to publication.
  • The aim of this project was to classify food from the Norwegian Women and Cancer study's food frequency questionnaires based on their degree of processing, according to the NOVA classification. Link to publication (In Norwegian).
Selected EPIC publication:
  • In this paper, we aimed to characterizatize of the degree of food processing in the European Prospective Investigation into Cancer and Nutrition, and to apply the Nova classification and validate it using selected biomarkers of food processing. Link to publication.

Miscellaneous studies

  • In this study, we report the prevalence and correlates of self-reported disordered eating among middle-aged Norwegian women. Link to publication. 
  • In this book chapter, we look at potential safety issues with combined use of dietary supplements and medication, with a focus on interactions. Link to publication.