Effects of a healthy Nordic diet on plasma 25-hydroxyvitamin D concentration in subjects with metabolic syndrome: a randomized, [corrected] controlled trial (SYSDIET)

Eur J Nutr. 2014 Jun;53(4):1123-34. doi: 10.1007/s00394-014-0674-3. Epub 2014 Feb 26.

Abstract

Purpose: At northern latitudes, vitamin D is not synthesized endogenously during winter, causing low plasma 25-hydroxyvitamin D (25(OH)D) concentrations. Therefore, we evaluated the effects of a healthy Nordic diet based on Nordic nutrition recommendations (NNR) on plasma 25(OH)D and explored its dietary predictors.

Methods: In a Nordic multi-centre trial, subjects (n = 213) with metabolic syndrome were randomized to a control or a healthy Nordic diet favouring fish (≥300 g/week, including ≥200 g/week fatty fish), whole-grain products, berries, fruits, vegetables, rapeseed oil and low-fat dairy products. Plasma 25(OH)D and parathyroid hormone were analysed before and after 18- to 24-week intervention.

Results: At baseline, 45 % had vitamin D inadequacy (<50 nmol/l), whereas 8 % had deficiency (<25 nmol/l). Dietary vitamin D intake was increased by the healthy Nordic diet (P < 0.001). The healthy Nordic and the control diet reduced the prevalence of vitamin D inadequacy by 42 % (P < 0.001) and 19 % (P = 0.002), respectively, without between-group difference (P = 0.142). Compared with control, plasma 25(OH)D (P = 0.208) and parathyroid hormone (P = 0.207) were not altered by the healthy Nordic diet. Predictors for 25(OH)D were intake of vitamin D, eicosapentaenoic acids (EPA), docosahexaenoic acids (DHA), vitamin D supplement, plasma EPA and plasma DHA. Nevertheless, only vitamin D intake and season predicted the 25(OH)D changes.

Conclusion: Consuming a healthy Nordic diet based on NNR increased vitamin D intake but not plasma 25(OH)D concentration. The reason why fish consumption did not improve vitamin D status might be that many fish are farmed and might contain little vitamin D or that frying fish may result in vitamin D extraction. Additional ways to improve vitamin D status in Nordic countries may be needed.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Body Mass Index
  • Dairy Products
  • Diet*
  • Dietary Supplements*
  • Docosahexaenoic Acids / administration & dosage
  • Docosahexaenoic Acids / blood
  • Edible Grain
  • Eicosapentaenoic Acid / administration & dosage
  • Eicosapentaenoic Acid / blood
  • Fatty Acids, Monounsaturated
  • Feeding Behavior*
  • Female
  • Fruit
  • Humans
  • Life Style
  • Male
  • Metabolic Syndrome / blood*
  • Metabolic Syndrome / complications
  • Middle Aged
  • Nutrition Assessment
  • Nutritional Status
  • Parathyroid Hormone / blood
  • Plant Oils
  • Rapeseed Oil
  • Recommended Dietary Allowances / legislation & jurisprudence
  • Surveys and Questionnaires
  • Vegetables
  • Vitamin D / administration & dosage
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / complications

Substances

  • Fatty Acids, Monounsaturated
  • Parathyroid Hormone
  • Plant Oils
  • Rapeseed Oil
  • Vitamin D
  • Docosahexaenoic Acids
  • 25-hydroxyvitamin D
  • Eicosapentaenoic Acid