Vegetarians and vegans have lower mortality rates than the general population according to several prospective cohort studies from 1960-2014. A 1999 meta-analysis found vegetarians had a 24% lower risk of heart disease but no difference for other causes of death. A 2012 meta-analysis found lower cancer incidence and heart disease mortality for vegetarians, but no difference for other outcomes. More recent studies find vegetarian diets associated with lower risks of various diseases and all-cause mortality, with some evidence that pescatarian diets may have the lowest risks.

1. DEATH AND DISEASE
RATES OF VEGETARIANS
AND VEGANS
Summary of Prospective Cohort Studies, 1960–2014
1Notes by Jussi Riekki

2. Death Rates (Standardized
Mortality Ratios, SMRs)
Vegetarians and vegans die
at about half the rates of the
overall populations in their
region—reasons for this
may include lower smoking
rates, healthier diet and
lifestyle in general, healthy
volunteer effect (i.e. healthy
people are more likely to
volunteer for studies than
unhealthy people).
• EPIC-Oxford – 52%
• Adventist Mortality Study – 49%
• Health Food Shoppers –56%
• Oxford Vegetarian Study – 46%
• Heidelberg Study – 48%
2

3. Why Vegetarians Might
Live Longer?
Lets take a look at the research done on mortality and
disease rates of vegetarians. But first...
3

4. Hierarchy of Evidence
(Micha & Mozaffarian, 2010)
Randomized Trials of Risk Factors!
!
!
Retrospective Case-Control Studies of Disease Outcomes!
!
!
Animal Studies, Ecologic Studies, Prevalence Reports!
!
!
Case series / reports
Randomized Trials!
and Prospective Cohorts!
of Disease Outcomes
Our Focus is on!
Prospective Cohorts of!
Disease Outcomes
4

5. Different Diets, Similar Lifestyles.
Prospective Cohort Studies, 1960–2014
Study Country Years Key et al. 1999 Huang et al. 2012
Adventist Mortality USA 1960–65 Included Included
Adventist Health USA 1974–97 Included Included
Health Food
Shoppers
UK 1976–88 Included Included
Oxford Vegetarian UK 1981–2000 Included Included
Heidelberg Germany 1978–99 Included Included
EPIC-Oxford UK 1993– Not included Included
Adventist Health
Study 2
USA 2002– Not included Not included
Meta-Analyses
5

6. Keep in Mind: Most of the Cohorts
had Low Mortality Rates Overall
”Note that for the comparison of the mortality between vegetarians
and non vegetarians reported here, standardized mortality ratios
(SMRs) for all causes of death were considerably <100% in the 4
studies that reported SMRs [i.e. Adventist Mortality Study, Health
Food Shoppers, Heidelberg Study, Oxford Vegetarian Study]. …
Therefore, certain lifestyle aspects shared by the vegetarians and
non vegetarians in these studies appear to confer a substantially
lower mortality rate than national rates. This lower mortality was
due largely to the relatively low prevalence of smoking in these
cohorts, but some of it may have been due to differences in diet
between the subjects and the general population in each
country.”
(Key et al. 1999)
6

7. Key et al. 1999
Mortality in vegetarians and nonvegetarians: detailed findings from a
collaborative analysis of 5 prospective studies. American Journal of Clinical
Nutrition. 1999 Sep;70(3 Suppl):516S-524S.
7

8. 1999 Meta-Analysis
Highlights
Vegetarians had a 24% lower risk of ischemic heart disease,
but there was no difference for stroke, cancer or all causes.
Cancer
Stomach Colorectal Lung Breast Prostate IHD Stroke
Other
causes
All causes
Vege-
tarians
1.02 (0.64,
1.62)
0.99 (0.77,
1.27)
0.84 (0.59,
1.18)
0.95 (0.55,
1.63)
0.91 (0.60,
1.39)
0.76 (0.62,
0.94)
0.93 (0.74,
1.17)
1.06 (0.90,
1.24)
0.95 (0.82,
1.11)
Statistically significant findings are in red.
8
(Key et al. 1999)

9. Additional Findings,
Key et al. 1999
• Occasional meat eaters (meat less than once per wk)
had a 20% reduced rate of dying of IHD and a 16%
reduced rate of overall mortality.
• Those who ate no meat other than fish had a 34%
reduced rate of dying from IHD and an 18% reduced
rate of overall mortality.
• Lacto-ovo vegetarians had a 38% (0.62 [0.38, 1.00])
reduced rate of dying from lung cancer, a 34% reduced
rate of dying from heart disease, and a 15% reduced
rate of mortality—see next slide for details.
9
(Key et al. 1999)

10. Death Rates by Diet, Key et al. 1999
”…exclusion of data from the Health Food Shoppers Study in this analysis
tended to lower the death rate ratio in the vegetarian groups compared with
the nonvegetarian groups.” (Key et al. 1999)
10
Cancer
Stomach Colorectal Lung Breast Prostate IHD Stroke All-Causes
Occasional
meat eaters
0.36 (0.11,
1.18)
1.14 (0.72,
1.82)
0.69 (0.39,
1.22)
0.97 (0.56,
1.71)
1.06 (0.60,
1.89)
0.80 (0.69,
0.93)
0.97 (0.75,
1.25)
0.84 (0.77,
0.90)
Pesco
0.86 (0.20,
3.74)
1.00 (0.42,
2.38)
1.04 (0.41,
2.64)
1.50 (0.74,
3.04)
1.25 (0.30,
5.22)
0.66 (0.48,
0.90)
1.04 (0.65,
1.64)
0.82 (0.77,
0.96)
Lacto-ovo
0.71 (0.42,
1.21)
1.10 (0.79,
1.54)
0.62 (0.38,
1.00)
0.75 (0.49,
1.14)
0.75 (0.47,
1.21)
0.66 (0.52,
0.83)
0.87 (0.66,
1.13)
0.84 (0.74,
0.96)
Vegan
2.18 (0.43,
11.2)
0.83 (0.11,
6.17)
2.79 (0.39,
20.0)
– –
0.74 (0.46,
1.21)
0.70 (0.25,
1.98)
1.00 (0.70,
1.44)

11. Disease Rates
of Vegans,
Key et al. 1999
subanalysis
No statistically significant
difference were found
between vegans and regular
meat-eaters for any causes of
death. Vegans (n=753) had a
heart disease rate of 0.74
(0.46, 1.21) and a mortality
rate of 1.00 (0.70, 1.44).
Disease Number of deaths
IHD 17
Stroke 4
Lung cancer 2
Colorectal cancer 1
Breast cancer 0
Prostate cancer 0
Other causes 42
Total 68
11

12. Huang et al. 2012
Cardiovascular disease mortality and cancer incidence in vegetarians: a meta-
analysis and systematic review. Annals of Nutrition and Metabolism. 2012;60(4):
233-40.
12

13. 2012 Meta-Analysis
Highlights
The overall cancer
incidence and mortality
from IHD were
significantly lower, but
there were no
associations of a
vegetarian diet with all-
cause mortality and
mortality from circulatory
and cerebrovascular
diseases.
Disease Hazard Ratio
All-cause mortality 0.91 (0.66, 1.16)
Ischemic heart disease 0.71 (0.56, 0.87)
Cerebrovascular disease 0.88 (0.70, 1.06)
Circulatory diseases 0.84 (0.54, 1.14)
Cancer incidence 0.82 (0.67, 0.97)
13(Huang et al. 2012)

14. All-Cause Mortality and IHD, Huang et al.
2012
14(Huang et al. 2012)

15. Cerebrovascular Disease and Circulatory
Diseases, Huang et al. 2012
15(Huang et al. 2012)

16. Cancer Incidence, Huang et al. 2012
16(Huang et al. 2012)

17. Something to Consider…
Comment by Jack Norris, RD: ”Although the 2012 meta-
analysis by Huang et al. is more recent, it may not be as reliable
as the 1999 meta-analysis because it includes a 1984 study on
Zen priests 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.”
17

18. A Closer Look on EPIC-
Oxford and Adventist
Health Study 2
Ischemic Heart Disease, Diverticular Disease, Cataracts,
Bone Fractures, Hypothyroidism and Diabetes Incidence.
18

19. EPIC-Oxford: IHD, Diverticular
Disease, Cataracts, Bone Fractures
Consuming a vegetarian diet was associated with a 32% lower
IHD risk—”a finding that is probably mediated by differences
in non-HDL cholesterol, and systolic blood pressure”.!
Authors comment: ”Compared with nonvegetarians, vegetarians
had a lower mean BMI [in kg/m(2); -1.2 (95% CI: -1.3, -1.1)], non-
HDL-cholesterol concentration [-0.45 (95% CI: -0.60, -0.30) mmol/
L], and systolic blood pressure [-3.3 (95% CI: -5.9, -0.7) mm Hg].
Vegetarians had a 32% lower risk (HR: 0.68; 95% CI: 0.58, 0.81) of
IHD than did nonvegetarians, which was only slightly attenuated
after adjustment for BMI and did not differ materially by sex, age,
BMI, smoking, or the presence of IHD risk factors.”
(Crowe et al. 2013) 19

20. EPIC-Oxford: IHD, Diverticular
Disease, Cataracts, Bone Fractures
Both a vegetarian diet and a higher intake of fibre were
significantly associated with a lower risk of diverticular disease.!
Authors comment: ”After adjustment for confounding variables,
vegetarians had a 31% lower risk (relative risk 0.69, 95% confidence
interval 0.55 to 0.86) of diverticular disease compared with meat
eaters. The cumulative probability of admission to hospital or death
from diverticular disease between the ages of 50 and 70 for meat
eaters was 4.4% compared with 3.0% for vegetarians. There was
also an inverse association with dietary fibre intake; participants in
the highest fifth (≥25.5 g/day for women and ≥26.1 g/day for men)
had a 41% lower risk (0.59, 0.46 to 0.78; P<0.001 trend) compared
with those in the lowest fifth (<14 g/day for both women and men).”
(Crowe et al. 2011) 20

21. EPIC-Oxford: IHD, Diverticular
Disease, Cataracts, Bone Fractures
Among participants ≥ 40 y old, a statistically significant, lower
risk of cataracts was found in vegetarians than meat-eaters.
Vegans had a 40% lower risk of cataracts than those eating more
than 100 g/day of meat.
(Appleby et al. 2011)
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)
21

22. EPIC-Oxford: IHD, Diverticular
Disease, Cataracts, Bone Fractures
Vegans had a 30% increased risk of bone fractures. Compared
with meat eaters, fracture incidence rate ratios in men and
women combined were 1.01 (0.88–1.17) for fish eaters, 1.00
(0.89–1.13) for vegetarians and 1.30 (1.02–1.66) for vegans.!
Authors comment: ”The higher fracture risk in the vegans appeared
to be a consequence of their considerably lower mean calcium
intake. An adequate calcium intake is essential for bone health,
irrespective of dietary preferences.” … ”After further adjustment for
dietary energy and calcium intake the incidence rate ratio among
vegans compared with meat eaters was 1.15 (0.89-1.49). Among
subjects consuming at least 525 mg/day calcium the corresponding
incidence rate ratios were 1.05 (0.90-1.21) for fish eaters, 1.02
(0.90-1.15) for vegetarians and 1.00 (0.69-1.44) for vegans.”
(Appleby et al. 2007) 22

23. Adventist Health Study 2
(AHS-2) Highlights
Vegans, lacto-ovo-vegetarians, pesco-vegetarians, and semi-
vegetarians combined in one group had a 12% lower risk of
mortality. After adjusting for BMI, the finding dropped to 10%.!
Authors conclude: ”In conclusion, in a large American cohort, we
found that vegetarian dietary patterns were associated with lower
mortality. The evidence that vegetarian diets, or similar diets with
reduced meat consumption, may be associated with a lower risk
of death should be considered carefully by individuals as they
make dietary choices and by those offering dietary guidance.”
(Orlich et al. 2013) 23

24. Death Rates of Vegetarian Men and
Women, AHS-2
Associations in men were larger and more often
significant than were those in women (Orlich et al. 2013).
All-Cause IHD CVD Cancer Other
Vegetarian
0.88 (0.80–
0.97)
0.81 (0.64–
1.02)
0.87 (0.75–
1.01)
0.92 (0.78–
1.08)
0.85 (0.73–
0.99)
Vegetarian
Men
0.82 (0.72–
0.94)
0.71 (0.51–
1.00)
0.71 (0.57–
0.90)
1.02 (0.78–
1.32)
0.83 (0.66–
1.04)
Vegetarian
Women
0.93 (0.82–
1.05)
0.88 (0.65–
1.20)
0.99 (0.83–
1.18)
0.87 (0.71–
1.07)
0.88 (0.72–
1.08)
24

25. Death Rates by Dietary Pattern, AHS-2
Pesco-vegetarians had a lowest risk of all-cause mortality, ischemic
heart disease and other causes of death (Orlich et al. 2013).
All-Cause IHD CVD Cancer Other
Vegan
0.85 (0.73–
1.01)
0.90 (0.60–
1.33)
0.91 (0.71–
1.16)
0.92 (0.68–
1.24)
0.74 (0.56–
0.99)
Lacto-ovo
0.91 (0.82–
1.00)
0.82 (0.62–
1.06)
0.90 (0.76–
1.06)
0.90 (0.75–
1.09)
0.91 (0.77–
1.07)
Pesco
0.81 (0.69–
0.94)
0.65 (0.43–
0.97)
0.80 (0.62–
1.03)
0.94 (0.72–
1.22)
0.71 (0.54–
0.94)
Semi
0.92 (0.75–
1.13)
0.92 (0.57–
1.51)
0.85 (0.63–
1.16)
0.94 (0.66–
1.35)
0.99 (0.72–
1.36)
25

26. Vegan Diets and Hypothyroidism,
AHS-2 analysis
Following a vegan diet tended to be associated with
protection against hypothyroidism, though statistical
significance was not attained (see table in the next
slide).!
Authors conclude: ”With the exception of the lacto-ovo
vegetarian diet findings in the prevalence study,
vegetarian diets were not associated with increased risk of
hypothyroidism. Vegan diets which may be expected to
lack iodine due to complete exclusion of animal products
tended to be protective.”
(Tonstad et al. 2013) 26

27. Hypothyroidism Rates by Dietary Pattern,
AHS-2
Hypothyroidism rates were reported both cross-sectionally at baseline
and prospectively after about 4–6 years of follow-up (Tonstad et al. 2013).
Diet Cross-Sectional Prospective
Regular meat-eaters 1.00 1.00
Semi-vegetarian 1.04 (0.91–1.19) 0.87 (0.65–1.17)
Pesco-vegetarian 1.02 (0.90–1.15) 0.87 (0.65–1.17)
Lacto-ovo vegetarian 1.09 (1.01–1.18) 1.07 (0.91–1.24)
Vegan 0.89 (0.78–1.01) 0.78 (0.59–1.03)
27

28. Incidence of Diabetes in
AHS-2
Vegetarian diets (vegan,
lacto ovo, semi-) were
associated with a
substantial and
independent reduction in
diabetes incidence.
Vegan diet was
associated with a ~60%
lower diabetes
incidence.
28
Diet Diabetes
Vegan 0.38 (0.24–0.61)
Lacto-ovo 0.62 (0.50–0.76)
Pesco 0.79 (0.58–1.09)
Semi 0.49 (0.31–0.76)
(Tonstad et al. 2013)

29. Noncancer, Noncardiovascular (”Other”)
Mortality, AHS-2
The most common causes of death: septicemia (infectious); Alzheimer and Parkinson
disease (neurologic); influenza and pneumonia, emphysema and COPD, interstitial lung
disease (respiratory); renal failure (renal); diabetes mellitus (endocrine) (Orlich et al. 2013).
29
Infectious Neurologic Respiratory Renal Endocrine
Vegetarian
0.93 (0.53–
1.62)
0.93 (0.67–
1.29)
0.95 (0.68–
1.32)
0.48 (0.28–
0.82)
0.61 (0.40–
0.92)
Vegetarian
Men
0.85 (0.39–
1.86)
0.86 (0.53–
1.40)
1.13 (0.67–
1.92)
0.42 (0.19–
0.91)
0.48 (0.25–
0.92)
Vegetarian
Women
0.97 (0.44–
2.11)
0.97 (0.63–
1.49)
0.88 (0.57–
1.36)
0.57 (0.28–
1.19)
0.76 (0.44–
1.30)

30. My Conclusions
✓ Vegetarians die at about half the rates of the
overall populations.!
✓ Vegetarian dietary pattern is associated with a
lower rate of ischemic heart disease, but no
associations with other major causes of death
have been found.!
✓ Vegans do not have unusually high rates of
mortality or disease, except for the slightly
higher fracture risk (low calcium intake).
30