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Trial Outcomes & Findings for The Dietary Guidelines 3 Diets Study (NCT NCT04981847)

NCT ID: NCT04981847

Last Updated: 2026-06-15

Results Overview

Change in Healthy Eating Index (HEI) total score was calculated as 3-month follow-up score minus baseline score. HEI total scores range from 0 to 100, with higher scores indicating better diet quality and greater adherence to dietary guidelines. The change score could potentially range from -100 to +100. Positive change scores indicate improvement in diet quality, whereas negative change scores indicate worsening diet quality. HEI total scores were calculated from three averaged 24-hour dietary recalls collected at each time point using the National Cancer Institute's Automated Self-Administered 24-hour Dietary Recall (ASA24).

Recruitment status

COMPLETED

Study phase

NA

Target enrollment

63 participants

Primary outcome timeframe

From baseline to the end of the intervention at 3 months

Results posted on

2026-06-15

Participant Flow

The DG3D Aim 1 study was a 12-week, 3-arm randomized dietary intervention. Recruitment was implemented through news, media, and online/social media advertisements, electronic mailing lists, community outreach events, and flyers. Recruitment occurred from July - September 2021.

Eligible and interested participants were offered a choice of orientation session times. During the session, the study coordinator provided a comprehensive overview of the study, addressed participant questions, and obtained informed consent. Those who successfully completed baseline procedures were subsequently randomized.

Participant milestones

Participant milestones
Measure
Healthy U.S.-Style Eating Pattern
Participants in this group will be assigned to follow the Healthy US dietary pattern as presented by the US Dietary Guidelines. This eating pattern is based on the types and amounts of foods Americans typically consume. The main types of food in this eating pattern include a variety of vegetables; fruits; whole grains; fat-free or low-fat dairy; seafood, poultry, meat, and eggs; and nuts, seeds, and soy products.
Healthy Mediterranean-Style Eating Pattern
Participants in this group will be assigned to follow the Mediterranean dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains more fruits and seafood and less dairy than the Healthy U.S.-Style Eating Pattern. There is also less calcium and vitamin D because it includes fewer dairy foods.
Healthy Vegetarian Eating Pattern
Participants in this group will be assigned to follow the Vegetarian dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains no meat, poultry, or seafood. Compared with the Healthy U.S.-Style Eating Pattern, it contains more soy products, eggs, beans and peas, nuts and seeds, and whole grains.
Overall Study
STARTED
21
22
20
Overall Study
COMPLETED
17
19
14
Overall Study
NOT COMPLETED
4
3
6

Reasons for withdrawal

Reasons for withdrawal
Measure
Healthy U.S.-Style Eating Pattern
Participants in this group will be assigned to follow the Healthy US dietary pattern as presented by the US Dietary Guidelines. This eating pattern is based on the types and amounts of foods Americans typically consume. The main types of food in this eating pattern include a variety of vegetables; fruits; whole grains; fat-free or low-fat dairy; seafood, poultry, meat, and eggs; and nuts, seeds, and soy products.
Healthy Mediterranean-Style Eating Pattern
Participants in this group will be assigned to follow the Mediterranean dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains more fruits and seafood and less dairy than the Healthy U.S.-Style Eating Pattern. There is also less calcium and vitamin D because it includes fewer dairy foods.
Healthy Vegetarian Eating Pattern
Participants in this group will be assigned to follow the Vegetarian dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains no meat, poultry, or seafood. Compared with the Healthy U.S.-Style Eating Pattern, it contains more soy products, eggs, beans and peas, nuts and seeds, and whole grains.
Overall Study
Lost to Follow-up
4
3
6

Baseline Characteristics

The Dietary Guidelines 3 Diets Study

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure
Healthy U.S.-Style Eating Pattern
n=21 Participants
Participants in this group will be assigned to follow the Healthy US dietary pattern as presented by the US Dietary Guidelines. This eating pattern is based on the types and amounts of foods Americans typically consume. The main types of food in this eating pattern include a variety of vegetables; fruits; whole grains; fat-free or low-fat dairy; seafood, poultry, meat, and eggs; and nuts, seeds, and soy products.
Healthy Mediterranean-Style Eating Pattern
n=22 Participants
Participants in this group will be assigned to follow the Mediterranean dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains more fruits and seafood and less dairy than the Healthy U.S.-Style Eating Pattern. There is also less calcium and vitamin D because it includes fewer dairy foods.
Healthy Vegetarian Eating Pattern
n=20 Participants
Participants in this group will be assigned to follow the Vegetarian dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains no meat, poultry, or seafood. Compared with the Healthy U.S.-Style Eating Pattern, it contains more soy products, eggs, beans and peas, nuts and seeds, and whole grains.
Total
n=63 Participants
Total of all reporting groups
Age, Continuous
46.8 y
STANDARD_DEVIATION 11.2 • n=20 Participants
49.4 y
STANDARD_DEVIATION 11.3 • n=20 Participants
47.8 y
STANDARD_DEVIATION 9.3 • n=40 Participants
48.0 y
STANDARD_DEVIATION 10.6 • n=5 Participants
Sex: Female, Male
Female
18 Participants
n=20 Participants
18 Participants
n=20 Participants
16 Participants
n=40 Participants
52 Participants
n=5 Participants
Sex: Female, Male
Male
3 Participants
n=20 Participants
4 Participants
n=20 Participants
4 Participants
n=40 Participants
11 Participants
n=5 Participants
Race/Ethnicity, Customized
Race · Black
21 Participants
n=20 Participants
22 Participants
n=20 Participants
20 Participants
n=40 Participants
63 Participants
n=5 Participants
Race/Ethnicity, Customized
Race · Black and other race
0 Participants
n=20 Participants
0 Participants
n=20 Participants
0 Participants
n=40 Participants
0 Participants
n=5 Participants
Education
Some college
3 Participants
n=20 Participants
4 Participants
n=20 Participants
4 Participants
n=40 Participants
11 Participants
n=5 Participants
Education
College graduate
10 Participants
n=20 Participants
7 Participants
n=20 Participants
9 Participants
n=40 Participants
26 Participants
n=5 Participants
Education
Advanced degree
8 Participants
n=20 Participants
11 Participants
n=20 Participants
7 Participants
n=40 Participants
26 Participants
n=5 Participants
Occupation
Employed for wages
14 Participants
n=20 Participants
14 Participants
n=20 Participants
9 Participants
n=40 Participants
37 Participants
n=5 Participants
Occupation
No current employment
0 Participants
n=20 Participants
0 Participants
n=20 Participants
2 Participants
n=40 Participants
2 Participants
n=5 Participants
Occupation
Retired
6 Participants
n=20 Participants
4 Participants
n=20 Participants
2 Participants
n=40 Participants
12 Participants
n=5 Participants
Occupation
Other
1 Participants
n=20 Participants
4 Participants
n=20 Participants
7 Participants
n=40 Participants
12 Participants
n=5 Participants
Marital Status
Single
7 Participants
n=20 Participants
4 Participants
n=20 Participants
6 Participants
n=40 Participants
17 Participants
n=5 Participants
Marital Status
Married
8 Participants
n=20 Participants
12 Participants
n=20 Participants
11 Participants
n=40 Participants
31 Participants
n=5 Participants
Marital Status
Partnered/living with someone
0 Participants
n=20 Participants
0 Participants
n=20 Participants
1 Participants
n=40 Participants
1 Participants
n=5 Participants
Marital Status
Divorced or separated
6 Participants
n=20 Participants
6 Participants
n=20 Participants
2 Participants
n=40 Participants
14 Participants
n=5 Participants
Body Mass Index (BMI)
35.7 kg/m2
STANDARD_DEVIATION 4.9 • n=20 Participants
36.5 kg/m2
STANDARD_DEVIATION 8.1 • n=20 Participants
35.9 kg/m2
STANDARD_DEVIATION 6.1 • n=40 Participants
35.9 kg/m2
STANDARD_DEVIATION 0.8 • n=5 Participants
Body weight
98.2 kg
STANDARD_DEVIATION 17.3 • n=20 Participants
101.6 kg
STANDARD_DEVIATION 24.1 • n=20 Participants
101.4 kg
STANDARD_DEVIATION 16.9 • n=40 Participants
100.4 kg
STANDARD_DEVIATION 19.4 • n=5 Participants
HbA1c
5.9 %
STANDARD_DEVIATION 0.3 • n=20 Participants
5.8 %
STANDARD_DEVIATION 0.4 • n=20 Participants
5.5 %
STANDARD_DEVIATION 0.4 • n=40 Participants
5.6 %
STANDARD_DEVIATION 0.3 • n=5 Participants
Systolic Blood Pressure
124.1 mmHg
STANDARD_DEVIATION 11.4 • n=20 Participants
130.9 mmHg
STANDARD_DEVIATION 16.7 • n=20 Participants
128.9 mmHg
STANDARD_DEVIATION 12.2 • n=40 Participants
128.0 mmHg
STANDARD_DEVIATION 13.6 • n=5 Participants
Diastolic Blood Pressure
81.6 mmHg
STANDARD_DEVIATION 8.7 • n=20 Participants
80.9 mmHg
STANDARD_DEVIATION 6.1 • n=20 Participants
80.4 mmHg
STANDARD_DEVIATION 9.0 • n=40 Participants
81.0 mmHg
STANDARD_DEVIATION 7.8 • n=5 Participants
Healthy Eating Index (HEI) Score
55.0 Scores on a scale
STANDARD_DEVIATION 13.0 • n=20 Participants
54.6 Scores on a scale
STANDARD_DEVIATION 12.0 • n=20 Participants
57.8 Scores on a scale
STANDARD_DEVIATION 12.7 • n=40 Participants
55.8 Scores on a scale
STANDARD_DEVIATION 12.6 • n=5 Participants

PRIMARY outcome

Timeframe: From baseline to the end of the intervention at 3 months

Change in Healthy Eating Index (HEI) total score was calculated as 3-month follow-up score minus baseline score. HEI total scores range from 0 to 100, with higher scores indicating better diet quality and greater adherence to dietary guidelines. The change score could potentially range from -100 to +100. Positive change scores indicate improvement in diet quality, whereas negative change scores indicate worsening diet quality. HEI total scores were calculated from three averaged 24-hour dietary recalls collected at each time point using the National Cancer Institute's Automated Self-Administered 24-hour Dietary Recall (ASA24).

Outcome measures

Outcome measures
Measure
Healthy U.S.-Style Eating Pattern
n=21 Participants
Participants in this group will be assigned to follow the Healthy US dietary pattern as presented by the US Dietary Guidelines. This eating pattern is based on the types and amounts of foods Americans typically consume. The main types of food in this eating pattern include a variety of vegetables; fruits; whole grains; fat-free or low-fat dairy; seafood, poultry, meat, and eggs; and nuts, seeds, and soy products.
Healthy Mediterranean-Style Eating Pattern
n=22 Participants
Participants in this group will be assigned to follow the Mediterranean dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains more fruits and seafood and less dairy than the Healthy U.S.-Style Eating Pattern. There is also less calcium and vitamin D because it includes fewer dairy foods.
Healthy Vegetarian Eating Pattern
n=20 Participants
Participants in this group will be assigned to follow the Vegetarian dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains no meat, poultry, or seafood. Compared with the Healthy U.S.-Style Eating Pattern, it contains more soy products, eggs, beans and peas, nuts and seeds, and whole grains.
Delta Dietary Quality
7.1 Scores on a scale
Standard Error 3.2 • Interval 0.7 to 13.5
15.2 Scores on a scale
Standard Error 3.1 • Interval 9.0 to 21.4
4.6 Scores on a scale
Standard Error 3.4 • Interval -2.1 to 11.4

PRIMARY outcome

Timeframe: From baseline to the end of the intervention at 3 months

Change in body weight from baseline to the end of the intervention at 3 months

Outcome measures

Outcome measures
Measure
Healthy U.S.-Style Eating Pattern
n=21 Participants
Participants in this group will be assigned to follow the Healthy US dietary pattern as presented by the US Dietary Guidelines. This eating pattern is based on the types and amounts of foods Americans typically consume. The main types of food in this eating pattern include a variety of vegetables; fruits; whole grains; fat-free or low-fat dairy; seafood, poultry, meat, and eggs; and nuts, seeds, and soy products.
Healthy Mediterranean-Style Eating Pattern
n=22 Participants
Participants in this group will be assigned to follow the Mediterranean dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains more fruits and seafood and less dairy than the Healthy U.S.-Style Eating Pattern. There is also less calcium and vitamin D because it includes fewer dairy foods.
Healthy Vegetarian Eating Pattern
n=20 Participants
Participants in this group will be assigned to follow the Vegetarian dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains no meat, poultry, or seafood. Compared with the Healthy U.S.-Style Eating Pattern, it contains more soy products, eggs, beans and peas, nuts and seeds, and whole grains.
Delta Body Weight
-2.4 kg
Standard Error 0.7
-2.6 kg
Standard Error 0.7
-2.4 kg
Standard Error 0.8

PRIMARY outcome

Timeframe: From baseline to the end of the intervention at 3 months

Change in HgbA1c from baseline to the end of the intervention at 3 months

Outcome measures

Outcome measures
Measure
Healthy U.S.-Style Eating Pattern
n=21 Participants
Participants in this group will be assigned to follow the Healthy US dietary pattern as presented by the US Dietary Guidelines. This eating pattern is based on the types and amounts of foods Americans typically consume. The main types of food in this eating pattern include a variety of vegetables; fruits; whole grains; fat-free or low-fat dairy; seafood, poultry, meat, and eggs; and nuts, seeds, and soy products.
Healthy Mediterranean-Style Eating Pattern
n=22 Participants
Participants in this group will be assigned to follow the Mediterranean dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains more fruits and seafood and less dairy than the Healthy U.S.-Style Eating Pattern. There is also less calcium and vitamin D because it includes fewer dairy foods.
Healthy Vegetarian Eating Pattern
n=20 Participants
Participants in this group will be assigned to follow the Vegetarian dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains no meat, poultry, or seafood. Compared with the Healthy U.S.-Style Eating Pattern, it contains more soy products, eggs, beans and peas, nuts and seeds, and whole grains.
Delta Hemoglobin A1c
0.03 HbA1c %
Standard Error 0.05
-0.10 HbA1c %
Standard Error 0.05
0.07 HbA1c %
Standard Error 0.06

SECONDARY outcome

Timeframe: From baseline to the end of the intervention at 3 months

Change in systolic blood pressure from baseline to the end of the intervention at 3 months

Outcome measures

Outcome measures
Measure
Healthy U.S.-Style Eating Pattern
n=21 Participants
Participants in this group will be assigned to follow the Healthy US dietary pattern as presented by the US Dietary Guidelines. This eating pattern is based on the types and amounts of foods Americans typically consume. The main types of food in this eating pattern include a variety of vegetables; fruits; whole grains; fat-free or low-fat dairy; seafood, poultry, meat, and eggs; and nuts, seeds, and soy products.
Healthy Mediterranean-Style Eating Pattern
n=22 Participants
Participants in this group will be assigned to follow the Mediterranean dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains more fruits and seafood and less dairy than the Healthy U.S.-Style Eating Pattern. There is also less calcium and vitamin D because it includes fewer dairy foods.
Healthy Vegetarian Eating Pattern
n=20 Participants
Participants in this group will be assigned to follow the Vegetarian dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains no meat, poultry, or seafood. Compared with the Healthy U.S.-Style Eating Pattern, it contains more soy products, eggs, beans and peas, nuts and seeds, and whole grains.
Delta Systolic Blood Pressure
-5.5 mm Hg
Standard Error 2.7
-3.2 mm Hg
Standard Error 2.5
-2.4 mm Hg
Standard Error 2.9

SECONDARY outcome

Timeframe: From baseline to the end of the intervention at 3 months

Change in diastolic blood pressure from baseline to the end of the intervention at 3 months

Outcome measures

Outcome measures
Measure
Healthy U.S.-Style Eating Pattern
n=21 Participants
Participants in this group will be assigned to follow the Healthy US dietary pattern as presented by the US Dietary Guidelines. This eating pattern is based on the types and amounts of foods Americans typically consume. The main types of food in this eating pattern include a variety of vegetables; fruits; whole grains; fat-free or low-fat dairy; seafood, poultry, meat, and eggs; and nuts, seeds, and soy products.
Healthy Mediterranean-Style Eating Pattern
n=22 Participants
Participants in this group will be assigned to follow the Mediterranean dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains more fruits and seafood and less dairy than the Healthy U.S.-Style Eating Pattern. There is also less calcium and vitamin D because it includes fewer dairy foods.
Healthy Vegetarian Eating Pattern
n=20 Participants
Participants in this group will be assigned to follow the Vegetarian dietary pattern as presented by the US Dietary Guidelines. This eating pattern contains no meat, poultry, or seafood. Compared with the Healthy U.S.-Style Eating Pattern, it contains more soy products, eggs, beans and peas, nuts and seeds, and whole grains.
Delta Diastolic Blood Pressure
-5.2 mm Hg
Standard Error 1.8
-2.0 mm Hg
Standard Error 1.7
-3.5 mm Hg
Standard Error 1.9

Adverse Events

US Healthy Diet

Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths

Mediterranean Diet

Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths

Vegetarian Diet

Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Brie Turner-McGrievy

University of South Carolina

Phone: 803-777-3932

Results disclosure agreements

  • Principal investigator is a sponsor employee
  • Publication restrictions are in place