The Adventist Health Study-2 (AHS-2)

The Study

Adventist Health Study-2 (AHS-2) is a large prospective cohort study of Seventh-day Adventists in the United States and Canada. Enrollment began in 2002, and 96,469 participants joined the original cohort.

Links to This Study

• Official Adventist Health Study website
  The official study website from Loma Linda University provides information about the study, participants, findings, publications, and continuing research.
• PubMed record — AHS-2 cohort profile
  The U.S. National Library of Medicine’s record for the paper describing the Adventist Health Study-2 cohort and its research design.
• DOI — permanent identifier for the cohort paper
  The DOI is the paper’s permanent digital identifier and should continue to direct readers to the official publisher page even if the journal’s web address changes.

Why Study Seventh-day Adventists?

Seventh-day Adventists are particularly interesting to nutrition researchers because many follow health-conscious lifestyles, while their dietary patterns vary considerably.

Some participants eat vegan diets, others eat vegetarian diets that include dairy products or eggs, some eat fish but little or no other meat, and others regularly eat meat.

Why Is That Useful Scientifically?

Smoking and heavy alcohol use can make nutrition research difficult because they are powerful confounding factors. These behaviors are relatively uncommon among Seventh-day Adventists.

At the same time, the population contains substantial differences in diet. This combination gives researchers an unusual opportunity to examine associations between different dietary patterns and long-term health.

Who Participated?

AHS-2 enrolled 96,469 Seventh-day Adventist men and women from throughout the United States and Canada.

The cohort also includes a substantial number of Black participants, allowing researchers to examine some diet-health relationships in a more diverse population than many earlier nutrition cohorts.

What Dietary Patterns Have Researchers Compared?

AHS-2 researchers have commonly classified participants into dietary patterns including vegan, lacto-ovo vegetarian, pesco-vegetarian, semi-vegetarian, and nonvegetarian.

These categories allow researchers to examine whether long-term health outcomes differ across a spectrum of animal-food consumption rather than simply comparing all vegetarians with all nonvegetarians.

What Health Outcomes Have Researchers Studied?

Researchers have examined body weight, obesity, type 2 diabetes, cardiovascular disease, cancer, mortality, and many other health outcomes.

The cohort has generated a large number of scientific publications rather than one single Adventist Health Study-2 paper.

One Landmark Dietary-Pattern Paper

A widely cited 2013 analysis examined vegetarian dietary patterns and mortality among more than 73,000 AHS-2 participants.

• Free full text — PubMed Central (PMC)
  The complete study can be read free on PubMed Central, an archive of the U.S. National Library of Medicine.
• PubMed record
  The U.S. National Library of Medicine’s record for the study Vegetarian Dietary Patterns and Mortality in Adventist Health Study 2.
• DOI — permanent study identifier
  The DOI provides a permanent route to the official journal record for the paper.

What About Body Weight and Diabetes?

AHS-2 research has found substantial differences in average body mass index across dietary groups, with lower average BMI among participants following vegetarian and particularly vegan dietary patterns.

Other analyses have examined whether these dietary patterns are associated with the prevalence or incidence of type 2 diabetes.

An Important Limitation

AHS-2 is observational. Researchers do not randomly assign participants to eat vegan, vegetarian, pescatarian, or meat-containing diets for decades.

People who choose different dietary patterns may also differ in physical activity, education, body weight, socioeconomic factors, and other characteristics. Researchers adjust statistically for many of these differences, but observational studies cannot eliminate every possible confounding factor.

Can AHS-2 Prove That a Vegan or Vegetarian Diet Is Healthier?

No single observational cohort can prove that a particular dietary pattern causes better health.

AHS-2 is valuable because it provides one important line of evidence that can be considered alongside randomized trials, other prospective cohorts, mechanistic research, and the larger body of nutrition evidence.

The Earlier Adventist Health Study

AHS-2 was preceded by earlier research involving Seventh-day Adventists, including Adventist Health Study-1. These earlier studies helped establish the Adventist population as an important resource for investigating relationships among diet, lifestyle, and chronic disease.

AHS-2 greatly expanded the size, dietary information, diversity, and research possibilities of the Adventist cohort.

Why Is This Included Under “What Happens Over a Lifetime?”

AHS-2 follows a very large population over many years while comparing people who habitually eat substantially different diets.

That long-term perspective allows researchers to investigate whether dietary patterns maintained over years are associated with differences in chronic disease and longevity later in life.