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Disease Rates of Vegetarians and Vegans

Below is a summary of the research done on mortality and disease rates of vegetarians. It does not include cancer rates which can be found on the Cancer, Vegetarianism, and Diet page.

In the tables, statistically significant findings are in red type. In order for the rate to be statistically significant, the confidence interval (the numbers in the parentheses) must be either less than or greater than 1.00. If you are not familiar with statistics, click here for a quick explanation of disease rate statistics.

Contents

• Studies
• Death Rates (Standardized Mortality Ratios)
• 1999 Meta-Analysis
• 2012 Meta-Analysis
• EPIC-Oxford
• EPIC-Oxford: Heart Disease (2013)
• EPIC-Oxford: Heart Disease (2009)
• EPIC-Oxford: Cataracts (2011)
• EPIC-Oxford: Diverticular Disease (2011)
• EPIC-Oxford: Bone Fractures (2007)
• EPIC-Oxford: Preliminary Results (2003)
• Adventist Health Study
• Heidelberg Study (German Vegetarians)
• Conclusion
• Additional Reading
• References

Studies

For an explanation of the different types of studies and their pros and cons, please see the article Basics of Nutrition Research.

The following studies have compared disease rates between people with different diets but similar lifestyles:

Population Studies with Large Numbers of Vegetarians
Study	Country	Years	Number of Vegans
Adventist Mortality	USA	1960-65
Adventist Health	USA	1974-97
Health Food Shoppers	UK	1976-88
Oxford Vegetarian	UK	1981-2000
Heidelberg	Germany	1978-99
Meta Analysis - of the above studies		1999
EPIC-Oxford	UK	1993 -	2,600
Adventist Health Study-2	USA	2002 -	4,000

Death Rates (Standardized Mortality Ratios)

The following studies compared the death rates (deaths per 100,000 people per year, under age 90) of their entire study population to the greater population in that region, known as a Standardized mortality ratios (SMRs). The SMRs were:

• EPIC-Oxford - 52% (8)
• Adventist Mortality Study - 49% (3)
• Health Food Shoppers - 56% (3)
• Oxford Vegetarian Study - 46% (3)
• Heidelberg Study - 48% (3)

This means that people in these studies died at about half the rates of the overall populations in their region. The researchers considered most of this difference to be due to lower smoking rates in the study groups (3), and the healthy volunteer effect (3) (healthy people are more likely to volunteer for studies than unhealthy people) but some difference may have been due to a generally healthier diet overall than in the population at large (3, 8).

1999 Meta-Analysis Results

The 1999 Meta-Analysis (3) compared vegetarian death rates to non-vegetarians (click here for cancer rates). Although there have been more recent studies on vegetarian mortality rates, the 1999 Meta-Analysis remains the one study that included vegetarians from both North America and Europe and still probably deserves the most weight of anything that has been released to date.

Table 1. Vegetarian vs. Non-vegetarian Death Rates.
Disease	Rates and Confidence Interval
Ischemic heart disease	Non-Veg 1.00 Vegetarians   .76 (.62, .94)
Cerebrovascular disease	Non-Veg 1.00 Vegetarians   .93 (.74, 1.17)
All causes	Non-Veg 1.00 Vegetarians   .95 (.82, 1.11)

Table 1 shows that vegetarians had a 24% lower risk of ischemic heart disease, but there was no difference for stroke or all causes.

There was also a sub-section that separated the vegetarian group into lacto-ovo vegetarians and vegans. The Health Food Shoppers Study was left out of this portion of the analysis because it did not distinguish between lacto-ovo vegetarians and vegans (6). Compared to 31,766 people who ate meat at least once per week:

• Occasional meat eaters (8,135 people who ate meat less than once per week) had a 20% reduced rate of dying of heart disease and a 10% reduced rate of overall mortality.

• Those who ate no meat other than fish (2,375 people) had a 34% reduced rate of dying from heart disease and an 18% reduced rate of overall mortality.

• Lacto-ovo vegetarians (23,265 people) had a 38% reduced rate of dying from lung cancer, a 34% reduced rate of dying from heart disease, and a 15% reduced rate of mortality.

• Vegans (753 people) had a heart disease rate of .74 (.46, 1.21) and a mortality rate of 1.00 (.70, 1.44). There were no statistically significant differences between the vegans and the regular meat-eaters for any causes of death.

Table 2. Causes of 68 Vegan Deaths
Disease	Number
Heart disease	17
Stroke	4
Lung cancer	2
Stomach cancer	2
Colorectal cancer	1
Breast cancer	0
Prostate cancer	0
Other causes	42
Total	68

There were only 68 vegan deaths in this population over the course of the studies, as distinct from 3,017 for regular meat-eaters. The breakdown of vegan deaths is shown in Table 2.

In personal communication, an author of the study said the "Other causes" category of death did not appear to be diet-related and so was not subdivided into smaller categories (4).

Could Vegans Have Fared Better?

It should be noted that when these studies began, the full importance of vegans' getting a reliable supply of vitamin B12 was not known.

2012 Meta-Analysis

Although the 2012 meta-analysis by Huang et al. (11) is more recent, it may not be as reliable as the 1999 meta-analysis because it includes a 1984 study on Zen priests (12) who were mostly semi-vegetarian and which used a standardized mortality ratio (comparing all the Zen priests to the greater population rather than comparing the "vegetarians" to non-vegetarians within the same group). The Heidelberg Study results were also included and its control group was semi-vegetarians, which means there were semi-vegetarians in both the "vegetarian" and "non-vegetarian" group in the 2012 meta-analysis; while this is not ideal, it should have biased the results against finding a beneficial effect of a vegetarian diet. In its favor, the 2012 meta-analysis includes data from EPIC-Oxford that was not available for the 1999 meta-analysis. The table shows the results.

2012 Meta-Analysis
	Mortality Rate of Vegetarians
All-cause mortality	0.91 (0.66, 1.16)
Ischemic heart disease mortality	0.71 (0.56, 0.87)
Cerebrovascular disease mortality	0.88 (0.70, 1.06)
Combined ischemic heart and circulatory disease mortality	0.84 (0.54, 1.14)
Cancer incidence	0.82 (0.67, 0.97)

EPIC-Oxford: Heart Disease (2013)

Heart disease rates of all vegetarians compared to all non-vegetarians were calculated for EPIC-Oxford from 1993 until 2009 (13). These participants were all thought to be free of heart disease at the beginning of the study. The results showed that vegetarians had a statistically significant, ~30% reduced risk of heart disease. This finding held even after adjusting for body mass index (BMI) and removing the first two years of follow-up.

The researchers believed the difference in heart disease rates to be due mainly to the lower non-HDL cholesterol levels and systolic blood pressure rates of the vegetarians.

Risk of Heart Disease in Vegetarians Compared to Non-vegetarians in EPIC-Oxford
Adjustments	Rate
Model 1: age, smoking, alcohol, physical activity, education, socioeconomic status, oral contraceptives, hormone replacement therapy	0.68 (0.58, 0.81)
Model 1 plus Body Mass Index	0.72 (0.61, 0.85)
Model 1 excluding first 2 years of follow-up	0.69 (0.58, 0.82)

EPIC-Oxford: Heart Disease (2009)

Results of death from heart disease, stroke, and all causes through June 2007 were released from EPIC-Oxford in 2009 (8). There were no statistically significant differences between vegetarians and meat-eaters for deaths from any of these diseases. However, this was likely due to the relatively few deaths from heart disease overall, not allowing for statistical power.

There was also no difference between regular meat-eaters, fish-only meat eaters, and vegetarians. Vegans were not separated from the vegetarian group.

The authors stated:

Average meat intake among the meat eaters was only moderate, at 79 g/d in men and 67 g/d in women; these intakes are much lower than those reported in the National Diet and Nutrition Survey for the United Kingdom. Consumption of vegetables and fruit was higher among vegetarians than among nonvegetarians, but the differences were not large (< 20%). Thus, if high intakes of meat had an adverse effect and high intakes of fruit and vegetables had a beneficial effect, the relatively low meat intake and high fruit and vegetable intake of the nonvegetarians in this cohort could reduce the chance of observing lower mortality rates in the vegetarians than in the nonvegetarians.

EPIC-Oxford: Diverticular Disease (2011)

After a mean follow-up time of 11.6 years, EPIC Oxford found that vegetarians had a 31% lower risk (0.69, 0.55-0.86) of diverticular disease compared with meat eaters (14).

EPIC-Oxford: Cataracts (2011)

In an analysis of EPIC-Oxford participants ≥ 40 years old, a statistically significant, lower risk of cataracts was found in vegetarians than meat-eaters (9). Vegans had a 40% lower risk of cataracts than those eating more than 100 g/day of meat. More detailed results are in the table below. The results mainly applied to those aged ≥ 65 years at recruitment.

Risk of Cataracts in EPIC-Oxford9
Group	Number	Risk
High meat eaters, ≥ 100 g/day	329	1.00
Moderate meat eaters, 50 - 99 g/day	489	0.96, 0.84-1.11
Low meat eaters, < 50 g/day	301	0.85, 0.72-0.99
Fish eaters	148	0.79, 0.65-0.97
Lacto-ovo vegetarians	198	0.70, 0.58-0.84
Vegans	19	0.60, 0.38-0.96
Results adjusted for: age, smoking, ethnicity, prior high blood pressure, receipt of long-term medical treatment, hormone replacement therapy.

EPIC-Oxford: Bone Fractures (2007)

In a 2007 analysis of bone fractures from EPIC-Oxford, vegans had a 37% higher fracture rate than meat-eaters (10). When the results were adjusted for calcium intake, the vegans no longer had a higher fracture rate. And among the subjects who got 525 mg of calcium a day (only 55% of the vegans compared to about 95% of the other diet groups), vegans had the same fracture rates as the other diet groups.

More information can be found in the article Bones, Vitamin D, and Calcium.

Epic-Oxford: Preliminary Results (2003)

In 2003, preliminary results from EPIC-Oxford (Oxford component of the European Prospective Investigation into Cancer and Nutrition) comparing death rates of 46,562 subjects were reported (7). About 33% of the subjects were vegetarian (including many vegans). The results showed no statistically significant differences between the vegetarians and non-vegetarians in any of the mortality categories which included cancer, circulatory disease, ischemic heart disease, cerebrovascular disease (stroke), all other causes, and all causes combined.

Adventist Health Study

The Adventist Health Study (1) is the only major study on the general health and mortality of vegetarians in the USA. Table 4 shows the main results (except for cancer).

• Data collected from 1976-1988
• 34,192 participants, members of the Seventh-day Adventist church
• 29% were vegetarian; 7-10% of the vegetarians were vegan.

Table 4. Adventist Health Study Results
	Men		Women
	Vegetarians	Non-vegetarians	Vegetarians	Non-vegetarians
BMIa	24.3	26.2	23.7	25.9
Heart disease	38% Lower for Men		No Difference for Women
Overall mortality	Lived 3.21 more yrs		Lived 2.52 more yrs
aBMI - Body Mass Index. A measure of healthy body weight. Lower than 20 is underweight, while ≥ 25 is overweight.

Compared to the non-vegetarians, vegetarians had about:

• 1/2 the high blood pressure and diabetes
• 2/3 the rheumatoid arthritis

Life expectancies in the Adventist Health Study were published in 2001 (2). They showed that white, non-Hispanic Seventh-day Adventists live longer than other white Californians (7.28 more years for men, 4.42 more years for women). According to the researchers, this group of Seventh-day Adventists were the longest-lived, formally studied population in the world (with an average life span of 78.5 years for men, 82.3 for women).

The following variables were shown to increase life expectancy:

• vegetarian diet
• eating nuts regularly
• physical activity
• lower body weight
• no smoking

Heidelberg Study (German Vegetarians)

In 2005, results from 21 years of follow-up of the Heidelberg Study were published (5). The 1999 Meta-Analysis included only 11 years of follow-up from this population.

There were only 60 vegans in the Heidelberg Study, which was 3% of the study group. The authors state, "Being a vegan was associated with a higher mortality risk (1.59; 95% CI (confidence interval), 0.98-2.59) than being a lacto-ovo vegetarian (1.08; 95% CI, 0.86-1.34), when compared with nonvegetarians with moderate meat/ fish consumption, accounting for all other variables (data not shown)."

Table 5. Heidelberg Study Results
Activity	Rates and Confidence Interval	Notes
Smoking	Non-smoker 1.00 Smoker 2.00 (1.40, 3.00)	Mortality
Physical Activity	Low 1.00 Moderate   .62 ( .43, .89) High   .64 ( .44, .93)	Mortality
Meat Intake	Never 1.00 >3x per week 4.80 (1.90, 12.00)	Ischemic heart disease
Fish Intake	Never 1.00 >1x per month 2.10 (1.10,  4.00)	Ischemic heart disease

As you can see, these findings were not statistically significant, but they were close for the vegans. Also note that these "nonvegetarians" were semi-vegetarians, eating very little meat. It wouldn't surprise me to find out these vegans did not do much to supplement their diet with vitamin B12.

Other results of interest are shown in Table 5.

The authors had the following to say about physical activity:

Our findings corroborate epidemiologic evidence indicating that regular and vigorous physical activity is an effective means of preventing circulatory diseases and cancers at different sites.

Conclusion

In summary, not enough is yet known about vegan mortality to draw any conclusions other than that vegans do not have unusually high rates of mortality and they probably do better than the average person due either to diet or a healthier lifestyle.

Additional Reading

Do Vegetarians Live Longer? by Paul Appleby of EPIC.

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References