Diet and Systemic Inflammation (DASI)

People with chronic low-grade inflammation have a higher risk for certain diseases such as cardiovascular disease or type 2 diabetes. While it is known that obese people are more likely to show signs of low-grade inflammation than lean individuals, it is unclear what causes this inflammation. In the proposed study, the investigators will examine whether the sugar fructose, when consumed in a sweetened beverage, triggers low-grade inflammation in healthy men and women compared with other caloric sweeteners.

The objective of this proposal is to investigate whether fructose-sweetened beverages trigger low-grade systemic inflammation in healthy men and women. Low-grade systemic inflammation, specifically elevated plasma concentrations of C-reactive protein (CRP), is a risk factor for cardiovascular disease (CVD). While it is known that obesity is associated with inflammation, the causes of low-grade inflammation in humans are not well understood. In a pilot study, the consumption of large amounts of fructose-, but not glucose- or aspartame-sweetened beverages potently induced low-grade inflammation in healthy, lean, young men and women in as little as 8 days. The investigators propose to extend these findings by (a) enrolling a greater number of subjects, (b) enrolling obese as well as non-obese subjects, and (c) including a beverage that is sweetened with high fructose corn syrup (HFCS). HFCS is one of the primary sugars consumed in the United States, and a major source of dietary fructose. Our primary specific aim is to assess whether the consumption of fructose- or HFCS-sweetened beverages promotes systemic low-grade inflammation, as measured by plasma concentrations of CRP and IL-6. The investigators hypothesize that plasma CRP and IL-6 concentrations will be elevated after consumption of fructose-containing beverages (fructose and HFCS) when compared to a glucose-sweetened beverage. Our secondary specific aim is to assess whether the consumption of fructose- or HFCS-sweetened beverages lowers plasma adiponectin concentrations. Specifically, the investigators hypothesize that total and high molecular weight (HMW)-adiponectin concentrations in fasting plasma will be lower after subjects have consumed the fructose- or HFCS-sweetened beverages, compared to a glucose-sweetened beverage. The investigators will recruit 12 overweight/obese (BMI between 25.0 and 40 kg/m2) and 12 normal weight (BMI between 20 and 24.9 kg/m2) men and women who are free of chronic inflammatory or metabolic disease. In a double-blind, randomized cross-over design, each subject will complete three 8-day standardized dietary periods that will differ only in the type of sweetened beverage administered. Specifically, subjects will be asked to drink four servings of a beverage each day that is sweetened with glucose, fructose, or HFCS (55% fructose, 45% glucose). All solid food will be provided for each of the three 8-day diet periods, and will be consumed ad libitum. Following each dietary period, the investigators will collect fasting blood to measure markers of systemic inflammation and plasma concentrations of total and HMW-adiponectin. We will also assess changes in adipose tissue inflammation and intestinal permeability as potential mechanisms by which fructose-sweetened beverages may trigger systemic inflammation. This study has the potential to identify a dietary trigger of low-grade inflammation, a likely contributor to CVD and metabolic diseases. The public health impact of this project might be considerable given that the consumption of fructose in the population is pervasive, and is modifiable on an individual as well as a population level.

Low-grade Chronic Inflammation, Intestinal Permeability, Type 2 Diabetes Mellitus, Cardiovascular Disease, Obesity

Inflammation, Intestinal permeability, Type 2 diabetes mellitus, Cardiovascular disease, Obesity, Sweetened beverages, Sugar, Fructose, Glucose, High-fructose corn syrup

In addition to consuming a standardized diet, subjects will be asked to consume 4 servings per day of a fructose-sweetened beverage for 8 days.

In addition to consuming a standardized diet, subjects will be asked to consume 4 servings per day of a glucose-sweetened beverage for 8 days.

In addition to consuming a standardized diet, subjects will be asked to consume 4 servings per day of a high-fructose corn syrup-sweetened beverage for 8 days.

In addition to consuming a standardized diet, subjects will be asked to consume 4 servings per day of a fructose-sweetened beverage for 8 days. The amount of fructose consumed will be 25% of the subject's estimated daily calorie requirement.

In addition to consuming a standardized diet, subjects will be asked to consume 4 servings per day of a glucose-sweetened beverage for 8 days. The amount of glucose consumed will be 25% of the subject's estimated daily calorie requirement.

In addition to consuming a standardized diet, subjects will be asked to consume 4 servings per day of a high-fructose corn syrup-sweetened beverage for 8 days. The amount of high-fructose corn syrup consumed will be 25% of the subject's estimated daily calorie requirement.

The concentration of C-reactive protein in fasting plasma will be measured by high-sensitivity assay at the beginning (day 1) and end (day 9) of each 8-day dietary period.

The concentration of interleukin-6 in fasting plasma will be measured by high-sensitivity enzyme-linked immunosorbent assay at the end (day 9) of each 8-day dietary period.

The concentration of adiponectin in fasting plasma will be measured by enzyme-linked immunosorbent assay at the end (day 9) of each 8-day dietary period.

Mean daily calorie intake will be assessed during each of the three 8-day diet periods. All foods will be provided to the subjects in excess of what they are estimated to require, and calorie intake will be assessed by subtracting returned foods from foods administered.

Intestinal permeability will be assessed on day 9 of each diet period by administering a beverage containing 2 g of mannitol and 5 g of lactulose followed by collecting urine for 5 hours afterwards. Recovery of mannitol and lactulose in urine will be measured by gas chromatography, and will be indicative of the degree of intestinal permeability.

Zonulin concentrations will be measured by enzyme-linked immunosorbent assay in fasting plasma collected on day 9 of each diet period. Plasma zonulin is a marker of intestinal permeability.

Lipopolysaccharide-binding protein (LBP) will be measured by enzyme-linked immunosorbent assay in fasting plasma collected on day 9 of each diet period. LBP is an acute phase protein secreted by the liver in response to endotoxin (lipopolysaccharide) exposure.

A subgroup of the study population will be enrolled into an ancillary study that will aim to assess the effects of consuming fructose- vs. high-fructose corn syrup- vs. glucose-sweetened beverages on adipose tissue inflammation. Adipose tissue inflammation will be assessed by whole adipose tissue gene expression analysis of TNF-alpha mRNA. Abdominal subcutaneous adipose tissue samples will be obtained from subjects enrolled into the ancillary study by needle aspiration biopsy on day 9 of each 8-day dietary period.

A subgroup of the study population will be enrolled into an ancillary study that will aim to assess the effects of consuming fructose- vs. high-fructose corn syrup- vs. glucose-sweetened beverages on adipose tissue inflammation. Adipose tissue inflammation will be assessed by whole adipose tissue gene expression analysis of IL-1beta mRNA. Abdominal subcutaneous adipose tissue samples will be obtained from subjects enrolled into the ancillary study by needle aspiration biopsy on day 9 of each 8-day dietary period.

A subgroup of the study population will be enrolled into an ancillary study that will aim to assess the effects of consuming fructose- vs. high-fructose corn syrup- vs. glucose-sweetened beverages on adipose tissue inflammation. Adipose tissue inflammation will be assessed by whole adipose tissue gene expression analysis of IL-6 mRNA. Abdominal subcutaneous adipose tissue samples will be obtained from subjects enrolled into the ancillary study by needle aspiration biopsy on day 9 of each 8-day dietary period.

A subgroup of the study population will be enrolled into an ancillary study that will aim to assess the effects of consuming fructose- vs. high-fructose corn syrup- vs. glucose-sweetened beverages on adipose tissue inflammation. Adipose tissue inflammation will be assessed by whole adipose tissue gene expression analysis of IL-10 mRNA. Abdominal subcutaneous adipose tissue samples will be obtained from subjects enrolled into the ancillary study by needle aspiration biopsy on day 9 of each 8-day dietary period.

A subgroup of the study population will be enrolled into an ancillary study that will aim to assess the effects of consuming fructose- vs. high-fructose corn syrup- vs. glucose-sweetened beverages on adipose tissue inflammation. Adipose tissue inflammation will be assessed by whole adipose tissue gene expression analysis of CCL2 mRNA. Abdominal subcutaneous adipose tissue samples will be obtained from subjects enrolled into the ancillary study by needle aspiration biopsy on day 9 of each 8-day dietary period.

A subgroup of the study population will be enrolled into an ancillary study that will aim to assess the effects of consuming fructose- vs. high-fructose corn syrup- vs. glucose-sweetened beverages on adipose tissue inflammation. Adipose tissue inflammation will be assessed by whole adipose tissue gene expression analysis of IFN-gamma mRNA. Abdominal subcutaneous adipose tissue samples will be obtained from subjects enrolled into the ancillary study by needle aspiration biopsy on day 9 of each 8-day dietary period.

Inclusion Criteria: Age: 18-65 years; BMI 20-40 kg/m2; Weight stable to within 10 pounds for 6 months prior to entering the study, and at their lifetime maximum weight (or within 30 pounds of it; excluding pregnancy); Ability to be admitted for ~30 minutes on three occasions, and ~6 hours on three occasions to the FHCRC Prevention Center; Ability to provide informed written consent; Willingness to consume only food and beverages provided by the Human Nutrition Laboratory of the FHCRC Prevention Center for three periods of 8 days each. Exclusion Criteria: Presence or history of chronic inflammatory, autoimmune or metabolic diseases; Presence of phenylketonuria, hereditary fructose intolerance, fructose malabsorption, or malabsorption syndromes; Abuse of alcohol (>2 drinks per day), smoking, or use of recreational drugs; Current or recent (within three months) intake of medications likely to interfere with study endpoints (insulin, antidiabetics, β-blockers, anabolic steroids, glucocorticosteroids, daily high-dose non-steroidal anti-inflammatory drugs, warfarin, antibiotics, probiotics); Presence of anemia, recent (within 2 months) history of anemia; Anyone not willing or able to eat the provided food; Current or recent (within 12 months) pregnancy or breastfeeding.

Kuzma JN, Cromer G, Hagman DK, Breymeyer KL, Roth CL, Foster-Schubert KE, Holte SE, Callahan HS, Weigle DS, Kratz M. No difference in ad libitum energy intake in healthy men and women consuming beverages sweetened with fructose, glucose, or high-fructose corn syrup: a randomized trial. Am J Clin Nutr. 2015 Dec;102(6):1373-80. doi: 10.3945/ajcn.115.116368. Epub 2015 Nov 4.

Kuzma JN, Cromer G, Hagman DK, Breymeyer KL, Roth CL, Foster-Schubert KE, Holte SE, Weigle DS, Kratz M. No differential effect of beverages sweetened with fructose, high-fructose corn syrup, or glucose on systemic or adipose tissue inflammation in normal-weight to obese adults: a randomized controlled trial. Am J Clin Nutr. 2016 Aug;104(2):306-14. doi: 10.3945/ajcn.115.129650. Epub 2016 Jun 29.