DEATH AND DISEASE RATES OF VEGETARIANS

AND VEGANSSummary of Prospective Cohort Studies, 1960–2014

1Notes by Jussi Riekki

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%

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Why Vegetarians Might Live Longer?

Lets take a look at the research done on mortality and disease rates of vegetarians. But first...

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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

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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

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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

Key et al. 1999Mortality 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.

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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)

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)

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)

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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)

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

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

233-40.

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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)

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

14(Huang et al. 2012)

Cerebrovascular Disease and Circulatory Diseases, Huang et al. 2012

15(Huang et al. 2012)

Cancer Incidence, Huang et al. 2012

16(Huang et al. 2012)

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.”

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A Closer Look on EPIC-Oxford and Adventist

Health Study 2Ischemic Heart Disease, Diverticular Disease, Cataracts, Bone Fractures, Hypothyroidism and Diabetes Incidence.

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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

EPIC-Oxford: IHD, Diverticular Disease, Cataracts, Bone FracturesBoth 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

EPIC-Oxford: IHD, Diverticular Disease, Cataracts, Bone FracturesAmong 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)

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EPIC-Oxford: IHD, Diverticular Disease, Cataracts, Bone FracturesVegans 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

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

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)

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Death Rates by Dietary Pattern, AHS-2Pesco-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)

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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

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)

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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.

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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)

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)

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).

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