Salmon Intake and Gut Health in Adults

Not Applicable

Completed

Brief Summary: The overall objective of this project is to determine the interplay of salmon as a whole food and its bioactive compound astaxanthin on gut microbiome, fecal metabolome, and inflammation in obese prediabetic individuals. Our central hypothesis is that dietary bioactive astaxanthin in the form of whole food salmon will effectively reduce inflammation in obese prediabetic individuals, and favorably change the gut microbiota composition and diversity. The investigators anticipate that these changes will result in improved metabolic outcomes in obesity and type 2 diabetes.

The two primary aims include:

Aim 1: Assess the anti-inflammatory effect of the salmon dietary intervention and the underlying mechanisms on the change in plasma levels of inflammatory cytokines important for the host immune response.

Aim 2: Identify whether the relationship between salmon consumption and decreased inflammation is mediated by the gut microbiome.

Detailed Description: The goal of this project is to determine whether increased intake of salmon as a whole food and its bioactive compound astaxanthin has a causal impact on preventing inflammation by promoting human gut microbiome homeostasis. Findings from this study will provide new insights into maintenance of gut microbiome and will inform effective dietary recommendations and interventions, thereby reducing inflammation-associated diseases in humans.

Aim: Evaluate the anti-inflammatory properties of astaxanthin-enriched salmon via re-balancing of human gut microbiome in obese prediabetic human subjects.

The investigators will use a randomized, double-blind, crossover feeding study with 15 obese prediabetic males and 15 obese prediabetic females (n=30) . Participants will consume two servings (3 oz per serving) of wild salmon (intervention 1) and farmed salmon (intervention 2) daily in random orders. Each intervention is 4 weeks long and the washout duration between the two interventions is 5 weeks. Primary outcomes will be determined by measuring the inflammatory response and gut microbiota composition.

Recruitment & Eligibility

Inclusion Criteria

Males and non-pregnant, non-lactating pre-menopausal females
BMI 30-40 kg/m2
Fasting blood glucose (without blood glucose-lowering drug) between 100-125 mg/dL
Plasma total cholesterol ≤ 250 mg/dL, plasma triglyceride level ≤ 250 mg/Dl
Age 30-50 years
Weight stable over the last 3 months (< 2% body weight change)
Sedentary and stable physical activity regimen 3 months prior (≤3 h/wk of moderate or high intensity exercise, resistance or aerobic training)
Medication use stable for 6 months prior, and not include anti-inflammatory drugs (e.g. ibuprofen, aspirin)
Not taking a carotenoid-containing or metabolism-altering supplement for the last 1 month, or have autoimmune diseases, and other malabsorptive disorders (including Crohn's, ileus or ulcerative colitis), liver or kidney insufficiency, allergies to tomatoes
No current special diets or nutrient supplements, pre- or probiotics (~3 months)
No tobacco smoking
Limited consumption of alcoholic beverages ≤ 1/d
No frequent habitual consumption of salmon or other astaxanthin-rich foods.

Exclusion Criteria

Pregnant, lactating, or menopausal females
BMI < 30 or >40 kg/m2
Fasting blood glucose <100 or >125 mg/dL; or taking blood glucose lowering medication
Plasma total cholesterol >250 mg/dL, plasma triglyceride level >250 mg/Dl
Age <30 or >50 years
2% body weight change over the last 3 months
>3 h/wk of moderate or high intensity exercise, resistance or aerobic training for the 3 months prior
Changing medications in the past 6 months
Taking anti-inflammatory drugs (e.g. ibuprofen, aspirin), carotenoid-containing or metabolism-altering supplements (for the last 1 month), or have autoimmune diseases, and other malabsorptive disorders (including Crohn's, ileus or ulcerative colitis), liver or kidney insufficiency, or allergies to tomatoes
Currently on a special diet or taking nutrient supplements, pre- or probiotics (~3 months)
Tobacco smoking
>1/d consumption of alcoholic beverages
Frequent habitual consumption of salmon or other astaxanthin-rich foods.

Arm && Interventions

Group	Intervention	Description
Wild Salmon	Wild Salmon	Wild salmon fillets in a raw form
Farmed Salmon	Farmed Salmon	Farmed salmon fillets in a raw form

Primary Outcome Measures

Name	Time	Method
Fecal metabolomics	Over 32 weeks	Small molecules will be extracted using MTBE-based liquid:liquid extraction which results in lipid and aqueous fractions. Compounds will be "extracted" using commercial software (Mass Hunter, Agilent), quantitated using peak volumes and processed using Mass Profiler Professional (MPP, Agilent) to determine normalized compound intensities
Blood biomarkers/inflammatory cytokines	Over 32 weeks	Blood from patients will be processed via centrifugation to archive plasma. A panel of 48 factors from Bio-Rad (Bio-Plex Pro™ Human Cytokine Screening Panel, 48-Plex #12007283) will be measured in plasma by Bio-Rad Bio-Plex analyzer. Five primary biomarkers (IL-1β, IL-6, IL-10, TNF-α, and MCP-1) will be confirmed by traditional ELISA
Gut Microbiome	Over 32 weeks	Gut microbiota structure by 16S sequencing

Secondary Outcome Measures

Name	Time	Method
Urine Analysis	Over 32 weeks	Urine samples will be collected for future metabolomics analysis. This analysis will generate a metabolomics profile in biospecimens, which will help us identify potential signatures related to salmon intake

Locations (1): University of Colorado Anschutz Medical Campus
🇺🇸
Aurora, Colorado, United States