Dietary Intake of Whole Walnuts in Adult Subjects Under Low Cardiovascular Risk
Condition: Cardiovascular Risk Factor; Metabolic Syndrome; Hypertension
MeSH terms: Metabolic Syndrome
Study type: Interventional

Summary: 
      This cross-over study investigates health effects of dietary intake of whole walnuts towards
      cardiovascular risk factors in adults under low cardiovascular risk.

      Investigators hypothesize that daily intake of whole nuts as a replacement meal, would
      improve cardiovascular risk factors, including traditional risk factors and molecular
      biomarkers.

      The participants are randomly assigned to receive either study treatment, or no treatment,
      and are crossed after five weeks.

      The study subjects are instructed to continue with their habitual diet and physical activity.
    

Detailed description: 
      Recent literature data raise important questions on the beneficial effect of dietary fats.
      Dietary intake of nuts, although with high caloric burden, is however characterized with high
      intake of fatty acids with known beneficial health effects. Those fatty acids include mono-
      (MUFA) and polyunsaturated fatty acids (PUFA), to whom beneficial health effects are
      ascribed.

      Among nuts, walnuts are characterized with comparatively high levels of MUFA and PUFA,
      especially content of alpha-linolenic PUFA, considered essential fatty acid, since not
      synthesized endogenously in humans. Dietary intake of alpha-linolenic acid is shown to be
      inversely related with cardiovascular risk factors, both in interventional studies and
      epidemiological cohorts. Molecular background of alpha-linolenic actions is bidirectional,
      and includes the action itself, as well as beneficial endogenous conversion towards
      long-chain fatty acids, including eicosapentaenoic and docosahexaenoic fatty acid.

      Although high caloric intake is indicated with intake of walnuts, literature data suggest
      that consumption of walnuts does not increase body weight.

      Dietary intake of walnuts has been shown to decrease cholesterol fractions, triglycerides and
      apolipoproteins in adult population. Also, consumption of walnuts was associated with
      decrease in blood pressure.

      The study design is cross-over, controlled, randomized nutritional intervention. The
      participants are randomly assigned to receive either study treatment, or no treatment, and
      are crossed after five weeks.

      The study subjects are instructed to continue with their habitual diet and physical activity.
      Additionally, study subjects are instructed to avoid walnuts and nuts other then study
      treatment, during the complete study period of 10 weeks.

      Sample size calculation was conducted by use of online calculators, and was based on the low
      density lipoprotein (LDL) cholesterol. Namely, in order to achieve decrease in 0.5 mmol/L, in
      a sample with projected standard deviation of 0.7 mmol/L, and type I and II errors being 0.2
      and 0.05, respectively, 62 subjects are needed.
    

Intervention name(s): Whole Walnuts
Intervention type(s): Dietary Supplement
Intervention description(s): Intervention arm includes whole walnuts taken as dietary replacement meal during the day, and between breakfast and lunch, and/or lunch and dinner. Importantly, none of the main meals, including breakfast, lunch and dinner are to be replaced by study intervention, and the study subjects are instructed to do so. Walnuts are provided with the same producer at the Belgrade market.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: This study is a randomized, cross-over, controlled, 5-week nutritional intervention, investigating health effects of dietary intake of whole walnuts, as a replacement meal within habitual diet and lifestyle.
At the beginning of the study, half of the study subjects are randomly assigned to a treatment arm with walnut consumption, or control arm without study intervention. Treatment arm considers consumption of pre-packed 56 g of whole walnuts daily, as a replacement meal. After 5 weeks, study subjects are crossed, for additional 5 weeks. At the beginning of the study, all subjects are instructed to continue with their habitual diet and physical activity during the study period of 10 weeks.
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Blood Pressure; Cholesterol; Triglycerides; Walnuts