Updated 18 July 2023
Summary of all summaries: At the moment we don't know much about the life expectancy of vegans. Vegan diets can be healthy or unhealthy, and diet is only one lifestyle factor, ... and genetics are also an important factor that influences our health. Vitamin B12 deficiency could lead to a lower life expectancy. A healthy vegan diet (or another type of healthy plant-based diet) can likely lead to a longer life expectancy, better health, and better quality of life - compared to the not so very healthy diets of typical meat eaters. Note that it does not make much sense to compare yourself (a single individual) to another single individual - even if that individual is your grandmother. You both have different genetics, a different history of life events, and likely, but not only, different lifestyle factors.
If you are a vegan or a near-vegan plant-based diet "eater" it is useful to know some basic things about several nutrients - especially vitamin B12. You can see my recommendations here.
If you are a vegan or a near-vegan plant-based diet "eater" it is useful to know some basic things about several nutrients - especially vitamin B12. You can see my recommendations here.
At the moment, there are two studies which include large numbers of vegans: the EPIC-Oxford study and the Adventist Health Study 2 (AHS-2) - see below.
--- For people not used to these kind of risk ratios: How do you read these numbers? For example, 0.73 means (1.00 minus 0.73 = 0.27 = 27%) a 27% lower risk; 1.00 would mean no difference (1.00 is the same as 1.00) in risk; 1.35 means a 35% higher risk. However, only if the confidence interval is either completely below or completely above 1.00 (not including the 1.00) the result is considered statistically significant. ---
Meta-analysis by Dybvik et al. 2023
[This meta-analysis doesn't add anything new regarding vegans. You can skip down to Dinu et al. (2017).]
Studies included: Adventist Mortality Study (USA), Oxford Vegetarian Study (UK), Heidelberg Study (Germany), Adventist Health Study 1 (USA), Adventist Health Study 2 (USA), EPIC-Oxford (UK)
A meta-analysis by Dybvik et al. (2023), from Dagfin Aune’s working group (Norway), looked at health effects, including mortality, of vegetarian, including vegan, diets.
In the table below you can see the results regarding vegans. None of the results were statistically significant.
In the table below you can see the results regarding vegans. None of the results were statistically significant.
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Table: characteristics of the included cohort publications (men and women combined) |
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| Reference, country | Study name | Study period, follow-up | Number of participants, age, number of cases / deaths |
|
Outcome |
|
Statistical adjustment |
| Key et al. (1999), USA, Germany, UK (pooled analysis) | AMS (USA) + AHS-1 (USA) + HBS (Germany) + OVS (UK) | 11.7 years of follow-up | n = 76172 Age: 16–89 years 3173 CVD deaths; 2264 IHD deaths; 909 CBVD deaths; 43048 (with detailed info regarding confounders available): 1047 IHD deaths |
Vegans vs. regular meat-eaters | CVD mortality §, ^ |
0.73 (0.47–1.14) §, ^ |
see below |
|
Vegans vs. regular meat-eaters |
IHD mortality ^ | 0.74 (0.46–1.21) ^ | |||||
|
Vegans vs. regular meat-eaters |
CBVD mortality ^ | 0.70 (0.25–1.98) ^ | |||||
| Orlich et al. (2013), USA | AHS-2 (USA) | 2002–2007 – 2009, 5.79 years of follow-up | n = 73308 Age: ≥25 years: 987 CVD deaths; 372 IHD deaths |
Vegans vs. nonvegetarians | CVD mortality |
0.91 (0.71– 1.16) |
see below |
|
Vegans vs. nonvegetarians |
IHD mortality | 0.90 (0.60–1.33) | |||||
| Tong et al. (2019), UK | EPIC-Oxford (UK) | 1993–2001 – 2016, 18.1 years of follow-up | n = 48188 Age: 20–90 years 3892 CVD cases; 2820 IHD cases; 1072 stroke cases; 519 ischemic stroke cases; 300 hemorrhagic stroke cases |
Vegans vs. meat-eaters |
CVD incidence § |
0.94 (0.75–1.17) § | see below |
| Vegans vs. meat-eaters | IHD incidence |
0.82 (0.64–1.05) | |||||
|
Vegans vs. meat-eaters |
Total stroke incidence |
1.35 (0.95–1.92) |
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| "Total" | All six studies above | see above | n = 197 668 5456 IHD cases |
Vegans vs. nonvegetarians | IHD incidence | 0.82 (95% CI: 0.68–1.00 |
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| n = 197 668 8052 CVD cases |
Vegans vs. nonvegetarians | CVD incidence | 0.92 (0.79–1.06 |
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| Note that the fourth column lists the number of all participants in that study, including omnivores, pescetarians, lacto-ovo-vegetarians, and vegans. "The relative risk estimates (RRs) compare […] vegans to nonvegetarians and the main analysis uses incidence and mortality data on both sexes combined, but only incidence data if studies reported both." I think, this is why this meta-analysis does not include the more recent mortality data regarding vegans from EPIC-Oxford (Appleby et al. 2016). Statistical adjustment: Key et al. (1999): Age, sex, and smoking Orlich et a. (2013): Age, sex (all), race, smoking, exercise, income, education, marital status, alcohol, region, sleep, and for women: menopause and hormone therapy Tong et al. (2019): Age, sex (all), method of recruitment, region, year of recruitment, education, Townsend deprivation index, smoking, alcohol, physical activity, dietary supplements, plus oral contraceptive, and hormone replacement therapy use in women § Data on IHD and total stroke were pooled into RRs for CVD for these publications: Key 1999 (AMS, AHS-1) and Tong 2019 (EPIC-Oxford) ^ The risk estimate is a pooled RR and was only used in the analysis on vegan diets and the risk of CVD, IHD and total stroke Abbreviatons: AHS-1: Adventist Health Study 1, AHS-2: Adventist Health Study 2, AMS: Adventist Mortality Study, CBVD: cerebrovascular disease, CI: confidence interval, CVD: cardiovascular disease, EPIC-Oxford: European Prospective Investigation into Cancer and Nutrition - Oxford (EPIC-Oxford is the Oxford cohort of the multicentre-, international EPIC study), HBS: Heidelberg Study, |
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In terms of healthy vs. not very healthy plant-based dietary choices, Dybvik et al. write:
"[…] The current analysis was not able to assess the association between quality of vegetarian (or vegan) diets and CVD, IHD or stroke risk, as there were no studies that have investigated this directly to date. Other studies that have assessed the association between plant-based dietary indices and CVD risk have reported inverse associations between plant-based dietary indices overall as well as for healthy plant-based dietary indices (characterized by high intake of whole plant foods) and CVD risk, while unhealthy plant-based dietary indices (characterized by high intake of sugar-sweetened beverages, French fries, chips, cookies, and other fast foods) have been associated with increased CVD risk [Quek et al. 2021], suggesting the importance of emphasizing whole plant foods.
[…] Further studies from other geographic regions are also needed. Detailed and repeated dietary assessments may be important to take into account dietary changes during follow-up. Future studies should focus on recruiting more vegans as there were few studies with sufficient numbers to detect a clear association among the vegans. [...]"
Meta-analysis by Jafari et al. (2020)
[This meta-analysis doesn't add anything new regarding vegans. You can skip down to Dinu et al. (2017).]
Number of vegans in this analysis: 5548Studies included: Adventist Health Study 2
Comparison between Jafari et al. 2020 and Orlich et al. 2013 | ||||||||
Table: Associations of Dietary Patterns With All-Cause and Cause-Specific Mortality From a Cox Proportional Hazards Regression Model Among Participants in the Adventist Health Study 2, 2002–2009 [Orlich et al. 2023] | ||||||||
Mortality risk vegans vs. nonvegetarians; deaths, Hazard Ratio (95% CI) | ||||||||
| Number of vegans | Number of vegans deaths | All-Cause | Coronary heart disease mortality | Ischemic Heart Disease | Cardiovascular Disease | Cancer | Other |
Orlich et al. 2013 | 5548 | 197 | 0.85 (0.73–1.01) Adjusted for body mass index: 0.84 (0.72–1.00) | Same as à | 0.90 (0.60–1.33) | 0.91 (0.71–1.16) | 0.92 (0.68–1.24) | 0.74 (0.56–0.99) |
Jafari et al. 2020 | Not reported | Not reported | Reported in Table 2: 0.85 (0.72–1.00) [Maybe this is a mistake.] Reported in Table 1: 0.85 (0.73–1.01)
| Reported in Table 2: 0.90 (0.60–1.34) [Orlich et al. 2023 do not report the value 1.34 as part of a hazard ratio for vegans. Maybe this is a mistake.] Reported in Table 1: 0.90 (0.60–1.33) | ß same as | Reported in Tables 1 and 2: 0.91 (0.71–1.16) | Reported in Tables 1 and 3: 0.92 (0.68–1.24) | Not reported |
In their Table 4 (where you can find the data above), Orlich et al. include the letters „a, b“, which means that the results by Orlich et al. are adjusted for the factors listed below: a Adjusted by age (ie, attained age as time variable), race (black, nonblack), smoking (current smoker, quit <1 year, quit 1–4 years, quit 5–9 years, quit 10–19 years, quit 20–29 years, quit ≥30 years, and never smoked), exercise (none, ≤20 min/week, 21–60 min/week, 61–150 min/week, and ≥151 min/week), personal income (≤$20 000/y, >$20 000–$50 000/y, >$50 000–$100 000/y, and >$100 000/y), educational level (up to high school graduate, trade school/some college/associate degree, bachelor degree, and graduate degree), marital status (married/common-law and single/widowed/divorced/separated), alcohol (nondrinker, rare drinker [<1.5 servings/mo], monthly drinker [1.5 to <4 servings/mo], weekly drinker [4 to <28 servings/mo], and daily drinker [≥28 servings/mo]), region (West, Northwest, Mountain, Midwest, East, and South), and sleep (≤4 h/night, 5–8 h/night, and ≥9 h/night). b Also adjusted by sex (male and female), menopause (in women) (premenopausal [including perimenopausal], postmenopausal), and hormone therapy (in postmenopausal women) (not taking hormone therapy, taking hormone therapy) | ||||||||
I also do not see a good reason why the EPIC-Oxford results were excluded. Jafari et al. write: "We included prospective cohort studies that 1) were conducted in the general adult population (≥18 years); 2) considered different types of plant-based eating style including PDI, and vegetarian, vegan, semi-, lacto-, lacto-ovo-, and pesco-veteran diets as exposure of interest; 3) reported all-cause, CVD, site-specific and total cancer mortalities as well as other causes of death; and 4) reported adjusted estimates including relative risk (RR), risk ratio, or hazard ratio (HR) and 95% confidence interval (CI) as the effect size […]." All of these prerequisites seem to be fulfilled by EPIC-Oxford.
Full text article: see here: Jafari et al. 2020 (not open access)
Meta-analysis by Dinu et al. (2017)
Number of vegans in this analysis: 6301Studies included: EPIC-Oxford and Adventist Health Study 2
Results: The vegans in this analyis had a 12% lower risk of early death (risk ratio: 0.88 [0.75-1.02]) - but this result was not quite statistically significant, possibly because the number of vegans is still too low for such an analysis.
Statistical gibberish:
Figure 2. Forest plot summary of all-cause mortality, incidence and mortality from cardio-cerebrovascular diseases, total cancer, and specific type of cancer. P value is for Z test of no overall association between exposure and outcome; P het is for test of no differences in association measure among studies; I 2 estimates from heterogeneity rather than sampling error.
Full text article: see here: Dinu et al. 2017
EPIC-Oxford (2016)
Number of vegans in this study: 2228Summary EPIC-Oxford 2016 (United Kingdom):
Vegans who did not change their diet during the study period on average had the same risk of death before age 90 (all causes of death combined), compared to the (relatively health-conscious) non-vegetarians in this study (0% difference in risk).
The vegans in this study on average showed a higher risk (50% higher) of death from stroke - but this result was not statistically significant. What this means is that from these data we cannot know whether vegans' real risk of death from stroke is higher, or actually lower, compared to non-vegetarians.
Note: Many of the vegans in the EPIC-Oxford study consumed too little vitamin B12 (see here).
Speculation: Vitamin B12 deficiency could raise the risk of stroke (and therefore the risk of death from stroke). Vitamin B12-deficient vegan diets could raise the risk of stroke. Well-planned vegan diets could possibly lower the risk of stroke.
Statistical gibberish:
"For 6 major causes of death (including all causes combined), vegetarians and vegans were separated and HRs compared with regular meat eaters were calculated for each of low meat eaters, fish eaters, vegetarians, and vegans (Table 4). For all causes of death, there was no significant difference in risk between diet groups as follows: low meat eaters, HR: 0.93 (95% CI: 0.86, 1.00); fish eaters, HR: 0.96 (95% CI: 0.87, 1.06); vegetarians, HR: 1.00 (95% CI: 0.93, 1.08); and vegans, HR: 1.14 (95% CI: 0.97, 1.35) compared with regular meat eaters; P-heterogeneity = 0.056. There was significant heterogeneity of risk between diet groups for cerebrovascular disease and respiratory disease mortality (P-heterogeneity = 0.023 and 0.015, respectively), with vegans having the highest mortality for both of these causes of death [BUT NOT STATISTICALLY SIGNIFICANT; compared with regular meat eaters, HR: 1.63 (95% CI: 0.98, 2.69) and HR: 1.57 (95% CI: 0.92, 2.67), respectively], but the CIs for the HRs in vegans were wide, precluding any clear conclusions. Further adjustment for BMI made little difference to the results. When we repeated this analysis after excluding data for participants known to have changed diet group at least once during follow-up, there was significant heterogeneity of risks between diet groups for malignant cancer mortality alone (P-heterogeneity = 0.015; results not shown). HRs for vegans compared with regular meat eaters for deaths from malignant cancer, circulatory disease, IHD, cerebrovascular disease, diseases of the respiratory system, and all causes combined were HR: 0.97 (95% CI: 0.72, 1.29); HR: 1.09 (95% CI: 0.76, 1.56); HR: 0.79 (95% CI: 0.44, 1.43); HR: 1.50 (95% CI: 0.84, 2.68); HR: 1.00 (95% CI: 0.50, 2.01); and HR: 1.00 (95% CI: 0.83, 1.20), respectively. Again, further adjustment for BMI made little difference to the results."
"TABLE 4
Number of deaths before age 90 y and HRs (95% CIs) by diet group for common causes of death, showing separate results for vegetarians and vegans [1]
[1] Estimated by Cox proportional hazards regression with age as the underlying time variable. Basic model adjusted for smoking (never smoker; former smoker; current smoker of 1–9, 10–19, or ≥20 cigarettes per day; other current smoker; unknown); alcohol consumption (<1, 1–7, 8–15, or ≥16 g ethanol/d or unknown); physical activity (low, high, or unknown); whether married or cohabiting (yes, no, or unknown); and regular use of nutritional supplements (no, yes, or unknown), and stratified by study/method of recruitment (Oxford Vegetarian Study, EPIC-Oxford postal, or EPIC-Oxford general practice); all possible combinations of sex, parity (nulliparous, parous, or unknown), oral contraceptive use, and hormone therapy use (both ever, never, or unknown); prior diabetes; prior high blood pressure; and receipt of long-term medical treatment (each no, yes, or unknown), with the use of separate models for each endpoint. Model +BMI is further adjusted for BMI (in kg/m2; <18, 18.0–19.9, 20.0–21.9, 22.0–23.9, 24.0–25.9, 26.0–27.9, 28.0–29.9, 30.0–32.4, or ≥32.5, or unknown). EPIC-Oxford, European Prospective Investigation into Cancer and Nutrition–Oxford; het, heterogeneity; ICD, International Classification of Diseases.
[2]Chi-square test of heterogeneity of risk between the 5 diet groups."
Full text article: see here: Appleby et al. 2016
"Mean reported duration of adherence to current dietary pattern [...] was 21 years for vegans."
Summary of AHS-2 2013 (United States and Canada):
Full text article: see here: Appleby et al. 2016
AHS-2 (Adventist Health Study 2) (2013)
Number of vegans in this study: 5548"Mean reported duration of adherence to current dietary pattern [...] was 21 years for vegans."
Summary of AHS-2 2013 (United States and Canada):
When risk of early death was expressed as "hazard ratio for all-cause mortality", the AHS-2 study found that vegans had a lower risk of early death (15% lower; compared to the (relatively health-conscious) meat eaters who ate meat, including fish) - but this result was not quite statistically significant. Vegan men however (i.e. when all women were excluded from the analysis), had a lower risk of early death from all causes combined, and a lower risk of death from heart attack, and of cardiovascular disease in general (heart attack and stroke combined).
When risk of early death was expressed as "mortality rate" (= what percentage of vegans died within the study period), the vegans, ovo-lacto-vegetarians, and pescatarians each had a lower risk compared to the (relatively health-conscious) meat eaters (who ate meat, including fish). The differences in risk between vegans, ovo-lactos, and pescatarians was quite possibly due to chance (significance not given).
Note: The vegans in the AHS-2 study (USA & Canada) consume more vitamin B12 and on average have a good vitamin B12 status (see here). They also consume more fibre and vitamin C, compared to the vegans in the EPIC-Oxford study. This indicates that firstly, they use more vitamin B12 supplements and/or fortified foods, and secondly, they eat more fruits and vegetables, and healthy "whole" foods in general (such as whole grains, legumes, and nuts).
Speculation: The reason for the better life expectancy of vegans in this study was quite possibly that they consumed enough vitamin B12 and had a healthier diet in general (more fruits, vegetables, nuts, legumes, and/or whole grains).
Statistical gibberish: "The adjusted HR for all-cause mortality in vegans was 0.85 (95% CI, 0.73–1.01) [not statistically significant]; in lacto-ovo–vegetarians, 0.91 (95% CI, 0.82–1.00); in pesco-vegetarians, 0.81 (95% CI, 0.69–0.94); and in semi-vegetarians, 0.92 (95% CI, 0.75–1.13) compared with nonvegetarians."
"Vegans, lacto-ovo–vegetarians, and pesco-vegetarians had significantly lower mortality rates compared with nonvegetarians."
"Vegans had significantly reduced risk in both sexes combined for other mortality (HR, 0.74; 95% CI, 0.56–0.99) ["OTHER MORTALITY" MEANS NOT HEART ATTACK, NOT STROKE, NOT CANCER] and in men for all-cause mortality (0.72; 0.56–0.92), IHD mortality (0.45; 0.21–0.94), and CVD mortality (0.58;0.38–0.89)."
"Table 4
Associations of Dietary Patterns With All-Cause and Cause-Specific Mortality From a Cox Proportional Hazards Regression Model Among Participants in the Adventist Health Study 2, 2002–2009
aAdjusted by age (ie, attained age as time variable), race (black, nonblack), smoking (current smoker, quit <1 year, quit 1–4 years, quit 5–9 years, quit 10–19 years, quit 20–29 years, quit ≥30 years, and never smoked), exercise (none, ≤20 min/week, 21–60 min/week, 61–150 min/week, and ≥151 min/week), personal income (≤$20 000/y, >$20 000–$50 000/y, >$50 000–$100 000/y, and >$100 000/y), educational level (up to high school graduate, trade school/some college/associate degree, bachelor degree, and graduate degree), marital status (married/common-law and single/widowed/divorced/separated), alcohol (nondrinker, rare drinker [<1.5 servings/mo], monthly drinker [1.5 to <4 servings/mo], weekly drinker [4 to <28 servings/mo], and daily drinker [≥28 servings/mo]), region (West, Northwest, Mountain, Midwest, East, and South), and sleep (≤4 h/night, 5–8 h/night, and ≥9 h/night).
bAlso adjusted by sex (male and female), menopause (in women) (premenopausal [including perimenopausal], postmenopausal), and hormone therapy (in postmenopausal women) (not taking hormone therapy, taking hormone therapy);
cAlso adjusted by menopause (premenopausal [including perimenopausal], postmenopausal) and hormone therapy (postmenopausal women) (not taking hormone therapy, taking hormone therapy)."
"A sensitivity analysis in which body mass index was added to the model generally had only a modest effect on the results. Overall HRs for vegetarians were then 0.90 (95% CI, 0.82–0.98) for both sexes combined, 0.83 (0.72–0.96) for men, and 0.95 (0.84–1.06) for women. The adjustment for body mass index did not consistently move results toward the null. Mortality results adjusted for body mass index affected statistical significance in the following instances. For all vegetarians combined compared with nonvegetarians: IHD mortality in men (HR, 0.77; 95% CI, 0.54–1.10), endocrine mortality in both sexes combined (HR, 0.71; 95% CI, 0.46–1.09), and diabetes mortality in both sexes combined (HR, 0.65; 95% CI, 0.38–1.11). For specific vegetarian dietary patterns compared with nonvegetarians: vegans, all-cause mortality in both sexes combined (HR, 0.84; 95% CI, 0.72–1.00) and IHD mortality in men (0.50; 0.24–1.06); lacto-ovo–vegetarians, all-cause mortality in both sexes combined (0.92; 0.84–1.02) and CVD mortality in men (0.81; 0.63–1.05); pesco-vegetarians, IHD mortality in both sexes combined (0.69; 0.45–1.05), other mortality in both sexes combined (0.77; 0.60–1.00), CVD mortality in men (0.68; 0.45–1.04), and other mortality in men (0.65; 0.43–1.00). Additional adjustment by dietary energy intake resulted in negligible changes. Formal tests for interaction of the diet variable (vegetarian vs nonvegetarian) with sex revealed significant interaction for CVD mortality (P = .01), but no significant interaction for all-cause mortality or other categories of mortality."
"The lack of similar findings in British vegetarians28 [and vegans; EPIC-Oxford] remains interesting, and this difference deserves careful study. In both cohorts, the nonvegetarians are a relatively healthy reference group. In both studies, the nutrient profiles of vegetarians differ in important ways from those of non-vegetarians, with vegetarians (especially vegans) consuming less saturated fat and more fiber.38,43 It appears that British vegetarians [EPIC-Oxford] and US Adventist vegetarians [& Canadian; AHS-2] eat somewhat differently.44 For instance, the vegetarians in our study consume more fiber and vitamin C than those of the EPIC-Oxford cohort: mean dietary fiber in EPIC-Oxford vegans was 27.7 g/d in men and 26.4 g/d in women compared with 45.6 g/d in men and 47.3 g/d in women in AHS-2 vegans; mean vitamin C in EPIC-Oxford vegans was 125 mg/d in men and 143 mg/d in women compared with 224 mg/d in men and 250 mg/d in women in AHS-2 vegans.38,43"
Full text article: see here: Orlich et al. 2013
Another smaller study, with much fewer vegans, has looked at vegans' life expectancy.
Summary of the Heidelberg Vegetarian Study (Germany):
aAdjusted by age (ie, attained age as time variable), race (black, nonblack), smoking (current smoker, quit <1 year, quit 1–4 years, quit 5–9 years, quit 10–19 years, quit 20–29 years, quit ≥30 years, and never smoked), exercise (none, ≤20 min/week, 21–60 min/week, 61–150 min/week, and ≥151 min/week), personal income (≤$20 000/y, >$20 000–$50 000/y, >$50 000–$100 000/y, and >$100 000/y), educational level (up to high school graduate, trade school/some college/associate degree, bachelor degree, and graduate degree), marital status (married/common-law and single/widowed/divorced/separated), alcohol (nondrinker, rare drinker [<1.5 servings/mo], monthly drinker [1.5 to <4 servings/mo], weekly drinker [4 to <28 servings/mo], and daily drinker [≥28 servings/mo]), region (West, Northwest, Mountain, Midwest, East, and South), and sleep (≤4 h/night, 5–8 h/night, and ≥9 h/night).
bAlso adjusted by sex (male and female), menopause (in women) (premenopausal [including perimenopausal], postmenopausal), and hormone therapy (in postmenopausal women) (not taking hormone therapy, taking hormone therapy);
cAlso adjusted by menopause (premenopausal [including perimenopausal], postmenopausal) and hormone therapy (postmenopausal women) (not taking hormone therapy, taking hormone therapy)."
"A sensitivity analysis in which body mass index was added to the model generally had only a modest effect on the results. Overall HRs for vegetarians were then 0.90 (95% CI, 0.82–0.98) for both sexes combined, 0.83 (0.72–0.96) for men, and 0.95 (0.84–1.06) for women. The adjustment for body mass index did not consistently move results toward the null. Mortality results adjusted for body mass index affected statistical significance in the following instances. For all vegetarians combined compared with nonvegetarians: IHD mortality in men (HR, 0.77; 95% CI, 0.54–1.10), endocrine mortality in both sexes combined (HR, 0.71; 95% CI, 0.46–1.09), and diabetes mortality in both sexes combined (HR, 0.65; 95% CI, 0.38–1.11). For specific vegetarian dietary patterns compared with nonvegetarians: vegans, all-cause mortality in both sexes combined (HR, 0.84; 95% CI, 0.72–1.00) and IHD mortality in men (0.50; 0.24–1.06); lacto-ovo–vegetarians, all-cause mortality in both sexes combined (0.92; 0.84–1.02) and CVD mortality in men (0.81; 0.63–1.05); pesco-vegetarians, IHD mortality in both sexes combined (0.69; 0.45–1.05), other mortality in both sexes combined (0.77; 0.60–1.00), CVD mortality in men (0.68; 0.45–1.04), and other mortality in men (0.65; 0.43–1.00). Additional adjustment by dietary energy intake resulted in negligible changes. Formal tests for interaction of the diet variable (vegetarian vs nonvegetarian) with sex revealed significant interaction for CVD mortality (P = .01), but no significant interaction for all-cause mortality or other categories of mortality."
"The lack of similar findings in British vegetarians28 [and vegans; EPIC-Oxford] remains interesting, and this difference deserves careful study. In both cohorts, the nonvegetarians are a relatively healthy reference group. In both studies, the nutrient profiles of vegetarians differ in important ways from those of non-vegetarians, with vegetarians (especially vegans) consuming less saturated fat and more fiber.38,43 It appears that British vegetarians [EPIC-Oxford] and US Adventist vegetarians [& Canadian; AHS-2] eat somewhat differently.44 For instance, the vegetarians in our study consume more fiber and vitamin C than those of the EPIC-Oxford cohort: mean dietary fiber in EPIC-Oxford vegans was 27.7 g/d in men and 26.4 g/d in women compared with 45.6 g/d in men and 47.3 g/d in women in AHS-2 vegans; mean vitamin C in EPIC-Oxford vegans was 125 mg/d in men and 143 mg/d in women compared with 224 mg/d in men and 250 mg/d in women in AHS-2 vegans.38,43"
Full text article: see here: Orlich et al. 2013
Another smaller study, with much fewer vegans, has looked at vegans' life expectancy.
Heidelberg Vegetarian Study (published 2005)
Number of vegans in this study: 60Summary of the Heidelberg Vegetarian Study (Germany):
The vegans in this study had a 59% higher risk of early death compared to the non-vegetarians (who were semi-vegetarians; very low meat consumption) - but this result was not statistically significant.
Note: These vegans were recruited in 1978, and only then were they asked about their diet. So, the "vegans" were "people who were vegan in 1978". The study went from 1978 to 1999. So, it includes all the deaths that occurred in this time period.
There is no info on vitamin B12 intake in these vegans. But it is very likely that many of these vegans (or all) were deficient in vitamin B12. Speaking from personal experience as a German vegan who became vegan in 1997, there was insufficient information available in Germany regarding vitamin B12 for vegans until well into the 2000s.
(Nerd info: See my German translation of Stephen Walsh's "What every vegan should know about vitamin B12" here; I had already tried to circulate this translation on vegan internet forums from around 2006/2007, and back then this type of information was rare/possibly otherwise non-existent. Stephen Walsh's text was the basis of current B12 recommendations for vegans - which have pretty much stayed the same since. To the best of my knowledge there were no precise vitamin B12 recommendations for vegans of this kind available in German before this translation of Stephen Walsh's "What every vegan should know ...". In 2008 the Vegan Society (UK) also produced printed booklets and PDFs of translations in several languages of their "Plant Based Nutrition" booklet which was a summary of Stephen Walsh's book "Plant Based Nutrition". The German version of the "Plant Based Nutrition" booklet/brochure - which you can see here - was a slightly eccentric mix of my translation and another German's translation (whom I don't know). This German booklet was distributed, personally by Stephen Walsh and Vanessa Clarke, at the IVU congress in Dresden in 2008.)
(Nerd info: See my German translation of Stephen Walsh's "What every vegan should know about vitamin B12" here; I had already tried to circulate this translation on vegan internet forums from around 2006/2007, and back then this type of information was rare/possibly otherwise non-existent. Stephen Walsh's text was the basis of current B12 recommendations for vegans - which have pretty much stayed the same since. To the best of my knowledge there were no precise vitamin B12 recommendations for vegans of this kind available in German before this translation of Stephen Walsh's "What every vegan should know ...". In 2008 the Vegan Society (UK) also produced printed booklets and PDFs of translations in several languages of their "Plant Based Nutrition" booklet which was a summary of Stephen Walsh's book "Plant Based Nutrition". The German version of the "Plant Based Nutrition" booklet/brochure - which you can see here - was a slightly eccentric mix of my translation and another German's translation (whom I don't know). This German booklet was distributed, personally by Stephen Walsh and Vanessa Clarke, at the IVU congress in Dresden in 2008.)
Another interesting finding in the Heidelberg Vegetarian Study was that eating fish more than once a month (!) increased (!) the risk of heart disease (see the table 4 "Meat and fish consumption ..." from this study below).
Speculation: The likely deficiency in vitamin B12 was possibly one important factor in the lower (though not statistically significant) life expectancy in the vegans/"vegans" in this study. It could also be that some of these vegans were people who, for example, became fruitarians later on, or went back to eating meat, or who were not feeling healthy in 1978 and ended up trying out different diets and remedies in this time period.
Background & statistical gibberish: "In 1978, a detailed study questionnaire was mailed out to those willing to participate as well as to their close family members ages ≥10 years. Data collected included information on sociodemographic characteristics, dietary habits, smoking and drinking habits, physical activity, and previous medical history. Dietary information was collected using semiquantitative questions on usual frequency of consumption (in five categories) of vegetables overall as well as specific vegetables, fruits, nuts, cereal, different milk products, eggs, fish, meat, and processed meat."
"Participants were categorized according to their response regarding dietary habits at the time point of enrollment. The study participants were classified into vegan (those who avoid meat, fish, eggs, and dairy products), lacto-ovo vegetarian (those who avoid meat and fish but eat eggs and/or dairy products), and nonvegetarian (those who occasionally or regularly eat meat and/or fish). In previous reports, we used the term ‘‘moderate vegetarians’’ instead of nonvegetarians but included also those who did not strictly avoid but seldom ate meat or fish. Self-reported height and weight were used to calculate body mass index (BMI, kg/m2). Physical activity was analyzed using the self-evaluation of the participants on a three-level scale. The vital status of the study participants by December 31, 1999 was requested from the Registrar’s Office at the last documented place of residence. Copies of the death certificates were obtained from the public health office in charge. The underlying cause of death was coded by a trained nosologist according to the ninth revision of the International Classification of Diseases and Causes of Death. The mortality analysis included all deaths occurring in the cohort until December 31, 1999."
"We also tested for possible differences between a vegan and a lactoovo vegetarian diet, although there were only 60 vegans and 23 deaths in this group. Being a vegan was associated with a higher mortality risk (1.59; 95% CI, 0.98-2.59) [NOT STATISTICALLY SIGNIFICANT] 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)."
"[...] even among the nonvegetarians in our study, there were only 0.4% (1.6%) who reported consuming meat (meat products) daily, 6.5% (4.9%) frequently (≥3 times/ wk but not daily), and 28.1% (18.7%) occasionally (more than once a month but <3 times/wk). Therefore, the meat consumption was quite moderate [IN THE NONVEGETARIANS IN THIS STUDY] compared with the general population".
Full text article: see here: Chang-Claude et al. 2005
An older meta-analysis (1999) of 5 studies, including the Heidelberg Vegetarian Study, also looked at vegans' life expectancy.
Meta-analysis by Key et al. (1999)
Number of vegans in this study: 753
Summary of the 1999 Meta-analysis by Key et al. (USA, UK, Germany):
Number of vegetarians who did not consume dairy (including the 753 vegans): 1146
Summary of the 1999 Meta-analysis by Key et al. (USA, UK, Germany):
The vegans in this analysis had a 26% lower risk of death from heart attack compared to (the relatively health-conscious) non-vegetarians. Vegans' risk of death from all causes combined was no different from non-vegetarians (0% difference.) Vegans in this analysis had a higher risk of death from stomach cancer and lung cancer - but this was not statistically significant and was based on only two deaths each from stomach and lung cancer. So, this could have quite possibly been due to chance - and it is impossible to draw conclusions from this result.
The "vegetarians who did not consume dairy" in this analysis had an 11% lower risk of death from heart attack (not statistically significant), a 49% lower risk of death from stroke (almost but not quite statistically significant), a 39% higher risk of death from "other causes" (statistically significant). The risk of early death from all causes combined was not statistically significant (6% higher risk).
Note: Drinking large amounts of alcohol, eating large amounts of salt-preserved foods, and being overweight or obese seems to increase the risk of stomach cancer. Consuming no grilled/barbecued meat or fish, and no processed meat, and consuming a lot of fruit (maybe especially citrus fruit) might lower the risk of stomach cancer (see here). If you experience regular stomach pain you should see a doctor and get tested for Helicobacter pylori infection in the stomach (this runs in families, and increases stomach cancer risk, but it can easily be treated).
Not smoking and avoiding air pollution (see here), but rather exercising a lot (physical activity), and eating large amounts of fruit, vegetables, and maybe soya can lower the risk of lung cancer (see here).
Speculation: The results were probably influenced by many vegans in these older studies being vitamin B12 deficient.
Statistical gibberish:
"Further categorization of diets showed that, in comparison with regular meat eaters, mortality from ischemic heart disease was 20% lower in occasional meat eaters, 34% lower in people who ate fish but not meat, 34% lower in lactoovovegetarians, and 26% lower in vegans. There were no significant differences between vegetarians and nonvegetarians in mortality from cerebrovascular disease, stomach cancer, colorectal cancer, lung cancer, breast cancer, prostate cancer, or all other causes combined."
"The number of vegans was small (n = 753 subjects, 68 deaths), so the analyses in Table 7 were repeated with the inclusion of data from the Health Food Shoppers Study, making the assumptions that all nonvegetarians were regular meat eaters and that vegetarians who reported that they did not consume dairy products were vegans. This increased the number of vegans to 1146, of whom 165 died before age 90 y. However, the numbers of deaths from individual cancers among vegans remained small (range: 3–8). The death rate ratios for the vegans [IN THIS CASE: VEGETARIANS WHO DID NOT CONSUME DAIRY] compared with the regular meat eaters from the other causes of death were: for ischemic heart disease, 0.89 (95% CI: 0.65, 1.24; NS); for cerebrovascular disease, 0.51 (95% CI: 0.26, 1.00; NS); for other causes, 1.39 (95% CI: 1.12, 1.72; P < 0.01); and for all causes, 1.06 (95% CI: 0.81, 1.38). However, these death rate ratios should be interpreted with caution because of the uncertainty of the dietary classification of subjects in the Health Food Shoppers Study"
"TABLE 7
All-studies death rate ratios and 95% CIs and the number of deaths by diet category 1
1 Adjusted for age, sex, smoking status, and study using a random-effects model. Data from the Health Food Shoppers study (2) were excluded because information on fish, egg, and frequency of meat consumption was not collected.
2 Reference group (ate meat ≥1 time/wk).
3 Ate meat occasionally but < 1 time/wk.
4 Never ate meat but did eat fish.
5 Ate dairy products, eggs, or both.
For more info on vegan mortality see veganhealth.org.