- Click here for explanation of classification scheme.

The purpose of this research was to examine associations among diet, distance run and coronary artery disease risk factors in vegetarian and omnivorous runners.

• No previous history of heart disease or cancer
• No medications that might affect lipoprotein concentrations.

• Previous history of heart disease or cancer
• Medications that might affect lipoprotein concentrations.

• Recruitment: Participants were recruited at national running races and through advertisements in Runner's World magazine.
• Design: Cross-sectional study.
• Statistical analysis: Multiple-regression analyses were used to test for linear relations between distance run and risk factor status. Logistic regression was used to examine trends for nominal data.

Timing of Measurements

Runners completed a two-page self-admininstered questionnaire. The questionnaire included a request to obtain the runner's height, weight, blood lipid profile, blood pressure and resting heart rate from their physicians.

Variables

• Assessed using a two-page self-administered questionnaire:
  • Demographics
  • Running history
  • Weight history
  • Diet (self-identified vegetarianism and current weekly intakes of alcohol, red meat, fish and fruit)
  • Cigarette use
  • Medical and medication history
  • Anthropometrics (height, weight, waist circumference, hip circumference, chest circumference).
• Assessed via physician-supplied information:
  • Height
  • Weight
  • Blood lipid profile
  • Blood pressure
  • Resting heart rate.

Initial N

It was estimated that 15% to 19% of potential participants who recieved the questionnaire responded. Of those who responded, physician-obtained HDL-cholesterol was obtained from 26% of the respondents, including:

• 820 male and 357 female vegetarian runners
• 7,054 male and 1,837 female omnivorous runners.

Final N

After excluding self-proclaimed vegetarians who reported occasional weekly red meat or occasional fish intake, the sample in these analyses included:

• 199 male and 152 female vegetarian runners
• 7,054 male and 1,837 female omnivorous runners.

Age

• Male vegetarians (45.18±9.36)
• Male onmivores (38.05±9.64)
• Female vegtarians (38.83±9.13)
• Female onmivores (40.42±9.53).

Ethnicity

All white.

Characteristics

• Among all runners, no significant differences between vegetarians and omnivores in the number of years run, resting pulse rate, blood pressure or ratio of total cholesterol to HDL-cholesterol
• When compared to omnivorous runners, male and female vegetarians ran significantly further, consumed less alcohol, consumed more fruit, had lower BMIs and had smaller hips
• When compared to omnivorous runners, male vegetarians had smaller waists and chests; lower total cholesterol, HDL-cholesterol and LDL-cholesterol; higher triacylglyerol concentration.

Comparisons Between Vegetarians and Omnivores

• Male vegetarians were significantly lower on all blood lipid measures, except triglyceride levels (in which case, mean omnivore levels were lower). In contrast, there were no significant differences between female vegetarians and omnivores.
• There was no significant difference in blood pressure measures for either male or female vegetarians and omnivores
• For males, all measures of body composition were significantly lower in vegetarians than omnivores. For females, only BMI and hip circumference were significantly lower in vegetarians than omniovres.

Male Runners

Variables		Male Vegetarians (N=199) Mean±SD	Male Omnivores (N=7,054) Mean±SD	Significance of Difference
Blood Lipids	Total Cholesterol (mmol/L)	4.91±1.0	5.08±0.89	P<0.01
	HDL (mmol/L)	1.26±0.32	1.34±0.35	P<0.01
	LDL (mmol/L)	3.08±0.91	3.22±0.81	P<0.05
	Total:HDL (mmol/L)	4.13±1.32	4.03±1.23	NS
	Triacylglcerol (mmol/L)	1.26±0.71	1.16±0.72	P<0.05
Blood Pressure	Systolic BP (mmHg)	122.09±15.04	121.66±13.37	NS
	Diastolic BP (mmHg)	76.58±10.54	77.06±8.74	NS
Weight	Body Mass Index	22.91±2.43	23.78±2.47	P<0.0001
	Waist (cm)	83.22±6.41	84.95±6.03	P<0.0001
	Hip (cm)	92.85±6.53	95.23±7.09	P<0.001
	Chest (cm)	100.37±7.24	101.58±6.95	P<0.05

Female Runners

• Blood lipids: No significant difference on any blood lipids
• Blood pressure: No significant difference in systolic or diastolic.

Variables		Female Vegetarians (N=152) Mean±SD	Female Omnivores (N=1,837) Mean±SD	Significance of Difference
Weight Measures	Body Mass Index	20.8±2.03	21.28±2.46	P<0.05
	Waist (cm)	67.89±6.05	68.56±6.97	NS
	Hip (cm)	90.72±5.83	91.82±6.5	P<0.05
	Chest (cm)	87.98±4.48	87.95±5.38	NS

Associations with the Reported Distance Run Per Week

Among both male and female vegetarians, greater distance run was associated with greater concentrations of HDL-cholesterol and lower waist, hip and chest circumferences. Greater distance run was also associated with lower ratios of total-to-HDL-cholesterol in male vegetarians and lower BMI in female vegetarians.

When comparing vegetarians to omnivorous runners, the regression slopes reveal:

• No significant difference relating weekly distance run to HDL-cholesterol, LDL-cholesterol, total cholesterol-to-HDL-cholesterol, triacylglycerols, systolic blood pressure and circumferences of the waist, hip and chest 
• Per kilometer run per week, the associated reduction in BMI was 0.021±0.007 smaller in male vegetarians, compared to male omnivores (P=0.002; no difference in females)
• Per kilometer run per week, the associated reduction in diastolic blood pressure was 0.08±0.04 greater in female vegetarians, compared to female omnivores (P=0.05; no difference in males).

Vegans (32 Males and 30 Females)

In a sub-analysis of vegans, greater weekly running distance was associated with the following (reported as slope±SE):

• Greater HDL-cholesterol concentrations [by 0.006±0.002 (mmol per L) per km; P=0.002]
• Lower systolic blood pressure [by 0.18±0.08 (mmol per L) per km; P=0.02]
• Lower waist circumference (by 0.11±0.083cm per km; P=0.001)
• The regression slopes for the remaining variables were not significant.

Alcohol

In the following multiple-regression analyses, omnivores and vegetarians were combined because results were nearly identical when analyzed separately. These analyses include a stratification of runners into five categories of alcohol intake (ml per week: Zero, one to 59, 60 to 118, 119 to 177 and more than 178) and four categories of running distance (km per week: Zero to 24, 24 to 48, 48 to 72 and more than 72).

For Men and Women

• For nearly every level of alcohol intake, each 24-km increment in weekly running distance was associated with significantly higher HDL concentrations
• Regression slopes between running distance and HDL-cholesterol were strongly significant regardless of alcohol consumption
• Alcohol intake was associated with higher HDL-cholesterol regardless of running level.

For All Men

• HDL-cholesterol increased (slope±SE) 0.0008±0.0001mmol per L per ml of alcohol consumed per week
• HDL-cholesterol increased 0.0034±0.0002mmol per L per km run
• There was no interaction between the effects of alcohol and weekly running distance on HDL (P=0.43 for interaction).

For All Women

• HDL-cholesterol increased (slope±SE) 0.0009±0.0001mmol per L per ml of alcohol consumed per week
• HDL-cholesterol increased 0.0034±0.0005mmol per L per km run
• There was no interaction between the effects of alcohol and weekly running distance on HDL (P=0.68 for interaction).

Additional Alcohol Analyses Reveal

• The percentage of men with high HDL was significantly greater with greater alcohol intake within all running distance strata (P<0.001) and significantly greater with greater running distance within all alcohol strata (P<0.001)
• The percentage of women runners with high HDL-cholesterol increased linearly with increases in alcohol intake regardless of running distance and increased linearly with weekly running distance in three of the four alcohol-consumption groups (significance level not reported) 
• In men, systolic and diastolic blood pressures were significantly greater with alcohol intake in all categories of running distance
• In women, blood pressures were only weakly associated with alcohol intake.

Red Meat and Fruit Consumption

• For men and women, diets containing high amounts of red meat were associated with higher BMIs and broader waistlines, generally significant within all running categories
• For men (but not in women), diets containing higher amounts of fruit were associated with lower BMIs and slimmer waistlines
• In men, the associations of BMI with fruit and meat diminishes with greater weekly running.

• Vigorous exercise provides important health benefits beyond those obtained by eating a vegetarian diet or consuming moderate amounts of alcohol alone
• When compared to male omnivores, male vegetarian runners had lower BMIs; narrower waists, hips and chests; lower plasma concentrations of total-, HDL- and LDL-cholesterol; higher triacylglycerol concentrations
• When compared to female omnivores, female vegetarians were leaner
• Vegetarians and vegans who ran the farthest had higher HDL and lower waist circumferences
• Running distance and alcohol intake contribute independently and additively to the production of high HDLs in runners
• Runners who reported high intakes of red meat and low intakes of fruit tended to have a higher BMI
• Limitations include:
  • Potential response bias
  • The use of conventional clinical measurements may be less precise than measurements made under usual research conditions
  • The assessment of diet was limited by only examining weekly intakes of red meat, fish and fruit.

Government:

NHLBI

• The representativeness of the sample is a concern: HDL-cholesterol was only obtained from 26% of respondents and the entire sample was white. Furthermore, it is of interest to note that 621 of 820 (75%) self-proclaimed male vegetarians and 205 of 357 (42%) of self-proclaimed female vegetarians were completely excluded in the analyses because they subsequently reported occasional weekly red meat or occasional fish intake. It is unclear if the complete exclusion of these survey responders (i.e., as opposed to including then in the omnivores group) introduces bias. Furthermore, the validity of the fish consumption question is problematic: It was weakly correlated (R=0.19) to a four-day food record, presumably related to the infrequent intake of fish. Nevertheless, this question was used to exlude self-proclaimed vegetarians.
• Due to the high misclassification of self-reported vegetarianism, the sub-analysis performed on vegans is concerning. There were no questions to confirm vegans (no dietary questions on dairy and eggs). 
• It is unclear if the height and weight values used in the analyses were self-reported or provided by the physicians. It is assumed they are self-reported.