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United States Department of Agriculture

Agricultural Research Service

Completed Studies
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Sterol

Research question 

 

The objective of this study is to identify a genetic basis for heterogeneity in responsiveness of lipids to plant sterol use, and to identify which regulators of cholesterol metabolism associate with the genetic factors identified.

 

Importance of proposed work

 

Numerous studies have shown that consumption of plant sterols and stanols can effectively reduce LDL-C levels. However, growing research has shown that not all individuals respond equally to doses of plant sterols and stanols. Thus, this study will examine the genetic basis for differing responses to plant stanol consumption. The long-term goal is to predetermine who will, and will not, respond to plant sterols as functional food ingredients.

 

 

 

 

 

 


Blackberry

Research Question:

The objective of this study is to investigate whether blackberry consumption causes biomarker and gene expression changes that reflect protection against DNA damage, oxidative stress, or inflammation, all of which are associated with cancer risk.

Importance of Proposed Work:

There is a significant body of epidemiological evidence linking intake of certain fruits and vegetables with decreased risk of several cancers. Consumption of berries or foods high in anthocyanins has been associated with prevention of breast, colorectal, esophageal, skin, lung, and liver cancers. The epidemiological evidence for the cancer preventive properties of berries has been supported by cell and animal studies, but there is a significant need to conduct human studies that investigate the efficacy of berries for cancer prevention. In particular, we propose to investigate whether blackberry consumption causes biomarker and gene expression changes that reflect protection against DNA damage, oxidative stress, or inflammation, all of which are associated with cancer risk.

 


Cranberry

 

Main Study Question

 

The objective of this study is to determine the influence of cranberry juice on risk factors for cardiovascular disease (CVD). 

 

Motivation for Research

 

Previous studies have shown that consumption of a low calorie cranberry beverage imparts a favorable impact on HDL cholesterol, LDL oxidation, and cell adhesion molecules in men. However, these studies were not well controlled.  Thus, it is important to confirm these effects in a blinded, placebo-controlled feeding study.        

 

 

This study is complete and is currently undergoing data analysis.


Anthocyanin

 

Main Study Question

 

Is absorption efficiency of anthocyanins from strawberries and blackberries affected by gastric pH? 

 

Motivation for Research

 

Consumers are increasing consumption of anthocyanin-rich foods, especially berries, as a strategy to prevent chronic diseases including cancer, heart disease and diminished brain function.  In order for anthocyanins to reach internal tissues and provide purported protection, they must be absorbed from the gastrointestinal tract.  This research is aimed at identifying the site of anthocyanin absorption in humans and the degree to which pH influences transfer of anthocyanins from the GI tract to the bloodstream.  An understanding of these factors will lead to strategies for enhancing efficiency of absorption of anthocyanins.


Garlic 2010

Main Study Question

 

Does ingestion of garlic result in gene expression changes consistent with decreased risk of cancer?

 

Motivation for Research

 

There is a significant body of epidemiological evidence linking intake of certain vegetables with decreased risk of several cancers. Consumption of garlic (Allium sativum L.) has been associated with prevention of breast, colorectal, lung, liver, and stomach cancers. The epidemiological evidence for the cancer preventive properties of garlic has been supported by cell and animal studies, but there is a significant need to conduct human studies that investigate the efficacy of garlic for cancer prevention. In particular, we propose to investigate whether garlic consumption causes gene expression changes that reflect protection against DNA damage, oxidative stress, or inflammation, all of which are associated with cancer risk.

 

 

 

This study ran from the end of July till the end of August 2010.

 

 

 


Almond

 

 

Main Study Questions

 

The objective of this study is to measure the energy value of almonds in the human diet and study molecular mechanisms that may help explain the beneficial health effects of almonds.

 

Motivation for Research

 

The aim of this study is to determine the energy value of almonds in the human diet and to probe mechanisms by which almonds impart health benefits. The metabolizable energy value of the almonds will be calculated based on the chemical composition and energy content of the consumed diet and excreta. In addition to determining the energy value of almonds, we will evaluate the effects of almond-rich diets on plasma phytonutrient levels and on gene expression changes to determine what protective mechanisms are activated by almond consumption.

 

  

The study ran from mid-March 2010 till the end of May 2010. 


Pistachio
 

 

 

Main Study Questions

 

The objective of this study is to measure the energy value of pistachios in the human diet and study molecular mechanisms that may help explain the beneficial health effects of pistachios.

 

Motivation for Research

 

The aim of this study is to determine the energy value of pistachios in the human diet and to probe mechanisms by which pistachios impart health benefits. The metabolizable energy value of pistachio nuts will be calculated based on the chemical composition and energy content of the consumed diet and excreta. In addition to determining the energy value of pistachios, we will evaluate the effects of pistachio-rich diets on plasma phytonutrient levels and on gene expression changes to determine what protective mechanisms are activated by pistachio consumption.

 

 

 

The study ran from the beginning of October 2009 through December 2009. The data analysis phase is currently being completed.

 

 

 

 

 

 

 

 

 


Lipid

 

 

Main Study Questions

 

1. Do naturally occurring trans fatty acids raise LDL cholesterol in when compared to trans fatty acids from partially hydrogenated vegetable oils?

 

2.  Do naturally occurring trans fatty acids raise LDL cholesterol compared to a control diet?

 

3.  Do trans fatty acids from partially hydrogenated vegetable oil raise LDL cholesterol compared to a low trans fatty acid diet?

  

Motivation for Research

 

There are two primary sources of dietary trans fatty acids in the food supply: 1) those from partially hydrogenated vegetable oils and 2) those found naturally in ruminant products (e.g., dairy, beef, lamb).

 

Since dietary trans fatty acids have been linked to cardiovascular disease, recent food labeling regulations have required that the trans fatty acid content of certain foods be listed on the Nutrition Facts panel.  

 

It is unclear if all isomers of trans fatty acids have the same effect on risk factors for cardiovascular disease.  Results from animal studies suggest that some naturally occurring trans fatty acids may actually lower cholesterol and decrease plaque buildup in arteries.  

 

The aim of this study is to determine if the different trans fatty acid isomers have different effects on markers for heart disease. The U.S. Department of Agriculture (USDA) wants to learn about how different types of fat in your diet can change your cholesterol level.

 

You may be eligible if:

 

Your BMI is between 20 and 38 kg/m2 (Click here to find your BMI)

You are between 25 and 65 years of age during the intervention

Your fasting glucose (blood sugar) is less than 126 mg/dl

Your blood pressure is less than 160/100 mm Hg (may be controlled with certain medications)

Your total plasma cholesterol is less than 280 mg/dl

Your fasting triglycerides are less than 300 mg/dl

    
You will not be eligible if:     

 

You use prescription or over-the-counter medications or supplements that alter lipid metabolism.

You have type 2 diabetes requiring the use of oral antidiabetic agents or insulin.

You have active cardiovascular disease (such as heart attack or procedure within the past three months or participation in a cardiac rehabilitation program within last three months, stroke or history/treatment for transient ischemic attacks in the past three months, or documented history of pulmonary embolus in past six months).

You smoke or use tobacco during the 6 months prior to the start of the study.

 

 

The Lipid Study has been complete since September 2009 and the data analysis phase has begun.  

 

 

 

 

 

 

 

Principal Investigator:

David Baer 301-504-8719 (david.baer@ars.usda.gov)

 


Whey Protein and Blood Pressure

 

 

Main Study Questions

 

Does the consumption of whey protein, in overweight and obese adult humans fed at weight maintenance, result in reduced systolic and diastolic blood pressure?

 

Motivation for Research

 

Several lines of evidence suggest that consumption of dairy foods, and specifically whey protein, may reduce blood pressure.  This proposed study is designed investigate the effect of whey protein compared to another protein source.

 

Since blood pressure is a recognized risk factor for cardiovascular disease, if there is clear evidence that whey protein reduces blood pressure, dietary recommendations may be made regarding whey protein intake.  However, dietary recommendations to consume whey protein as a means to improve health status must be science-based.  Results from this study will provide a scientific basis for dietary recommendations regarding whey protein intake.

 

 

 

 

 

 

 

 

 

 

 

 


Last Modified: 11/8/2013