VN: Nutrition Status Outcomes (2023)

Intervention
In presumably healthy adults in the general population, what is the relationship between vegetarian diets and BMI?
- Conclusion
  In recent systematic reviews of observational studies with presumably healthy adults in the general population, following a vegan diet may be associated with a lower BMI compared to a non-vegetarian diet, but evidence is uncertain (Very Low certainty). Evidence was not available to evaluate the impact of vegetarian diets that were not vegan .
- Grade: Very Low (D)
  - Grade I means there is Good/Strong evidence supporting the statement;
  - Grade II is Fair;
  - Grade III is Limited/Weak;
  - Grade IV is Expert Opinion Only;
  - Grade V is Not Assignable.
  - High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
  - Moderate (B) means we are moderately confident in the effect estimate;
  - Low (C) means our confidence in the effect estimate is limited;
  - Very Low (D) means we have very little confidence in the effect estimate.
  - Ungraded means a grade is not assignable.
- Evidence Summary: In presumably healthy adults in the general population, what is the relationship between vegetarian diets and BMI?
- Search Plan and Results: VN: Vegetarian Nutrition and Disease Prevention (2023)
In presumably healthy adults in the general population, what is the relationship between vegetarian diets and fat/fat-free mass?
- Conclusion
  There were no systematic reviews examining the relationships between vegetarian diets and fat free mass and fat mass that targeted presumably healthy adults in the general population.
- Grade: Ungraded
  - Grade I means there is Good/Strong evidence supporting the statement;
  - Grade II is Fair;
  - Grade III is Limited/Weak;
  - Grade IV is Expert Opinion Only;
  - Grade V is Not Assignable.
  - High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
  - Moderate (B) means we are moderately confident in the effect estimate;
  - Low (C) means our confidence in the effect estimate is limited;
  - Very Low (D) means we have very little confidence in the effect estimate.
  - Ungraded means a grade is not assignable.
- Evidence Summary: In presumably healthy adults in the general population, what is the relationship between vegetarian diets and fat/fat-free mass?
  - Detail
  - Quality Rating Summary
    For a summary of the Quality Rating results, click here.
  - Worksheets
    
    Remde A, DeTurk S, Almardini A, Steiner L, Wojda T. Plant-Predominant Eating Patterns - How Effective are they for Treating Obesity and Related Cardiometabolic Health Outcomes? - a Systematic Review. Nutrition reviews 2022; 80:1094-1104
- Search Plan and Results: VN: Vegetarian Nutrition and Disease Prevention (2023)
In presumably healthy adults in the general population, what is the relationship between vegetarian diets and bone mineral density?
- Conclusion
  In recent systematic reviews of observational studies with presumably healthy adults in the general population, following vegetarian or vegan diets may be associated with lower lumbar spine, femoral neck, and whole-body bone mineral density compared to non-vegetarian diets, but evidence is uncertain.
- Grade: Very Low (D)
  - Grade I means there is Good/Strong evidence supporting the statement;
  - Grade II is Fair;
  - Grade III is Limited/Weak;
  - Grade IV is Expert Opinion Only;
  - Grade V is Not Assignable.
  - High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
  - Moderate (B) means we are moderately confident in the effect estimate;
  - Low (C) means our confidence in the effect estimate is limited;
  - Very Low (D) means we have very little confidence in the effect estimate.
  - Ungraded means a grade is not assignable.
- Evidence Summary: In presumably healthy adults in the general population, what is the relationship between vegetarian diets and bone mineral density?
- Search Plan and Results: VN: Vegetarian Nutrition and Disease Prevention (2023)
In presumably healthy adults in the general population, what is the relationship between vegetarian diets and vitamin B12 concentrations?
- Conclusion
  In available systematic reviews of observational studies with presumably healthy adults in the general population, evidence suggests following vegan or vegetarian diets is associated with lower serum vitamin B12 concentrations compared to non-vegetarian diets, and concentrations were lowest for vegan diets. In addition, evidence suggests following vegan or vegetarian diets is associated with higher serum homocysteine concentrations compared to non-vegetarian diets, and concentrations were highest for vegan diets.
- Grade: Very Low (D)
  - Grade I means there is Good/Strong evidence supporting the statement;
  - Grade II is Fair;
  - Grade III is Limited/Weak;
  - Grade IV is Expert Opinion Only;
  - Grade V is Not Assignable.
  - High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
  - Moderate (B) means we are moderately confident in the effect estimate;
  - Low (C) means our confidence in the effect estimate is limited;
  - Very Low (D) means we have very little confidence in the effect estimate.
  - Ungraded means a grade is not assignable.
- Evidence Summary: In presumably healthy adults in the general population, what is the relationship between vegetarian diets and vitamin B12 concentrations?
- Search Plan and Results: VN: Vegetarian Diet and Disease Prevention: Vitamin B12 (2023)
In presumably healthy adults in the general population, what is the relationship between vegetarian diets and vitamin D concentrations?
- Conclusion
  In recent systematic reviews of observational studies with presumably healthy adults in the general population, following a vegan diet may be associated with lower blood total vitamin D and 25(OH)D concentrations compared to non-vegetarian diets, particularly in the winter, but evidence is uncertain. Evidence was not available to evaluate the impact of vegetarian diets that were not vegan.
- Grade: Very Low (D)
  - Grade I means there is Good/Strong evidence supporting the statement;
  - Grade II is Fair;
  - Grade III is Limited/Weak;
  - Grade IV is Expert Opinion Only;
  - Grade V is Not Assignable.
  - High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
  - Moderate (B) means we are moderately confident in the effect estimate;
  - Low (C) means our confidence in the effect estimate is limited;
  - Very Low (D) means we have very little confidence in the effect estimate.
  - Ungraded means a grade is not assignable.
- Evidence Summary: In presumably healthy adults in the general population, what is the relationship between vegetarian diets and vitamin D concentrations?
- Search Plan and Results: VN: Vegetarian Nutrition and Disease Prevention (2023)
In presumably healthy adults in the general population, what is the relationship between vegetarian diets and iodine concentrations?
- Conclusion
  In recent systematic reviews of observational studies with presumably healthy adults in the general population, evidence suggests vegetarian diets including vegan diets are associated with lower urinary iodine excretion compared to non-vegetarian diets, and concentrations may be lower in vegans than in lacto-ovo vegetarians.
- Grade: Low (C)
  - Grade I means there is Good/Strong evidence supporting the statement;
  - Grade II is Fair;
  - Grade III is Limited/Weak;
  - Grade IV is Expert Opinion Only;
  - Grade V is Not Assignable.
  - High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
  - Moderate (B) means we are moderately confident in the effect estimate;
  - Low (C) means our confidence in the effect estimate is limited;
  - Very Low (D) means we have very little confidence in the effect estimate.
  - Ungraded means a grade is not assignable.
- Evidence Summary: In presumably healthy adults in the general population, what is the relationship between vegetarian diets and iodine concentrations?
- Search Plan and Results: VN: Vegetarian Nutrition and Disease Prevention (2023)
In presumably healthy adults in the general population, what is the relationship between vegetarian diets and ferritin concentrations?
- Conclusion
  In a recent systematic review with presumably healthy adults in the general population, vegetarian diets, including vegan diets, may be associated with lower circulating ferritin concentrations compared to non-vegetarian diets, but results were mixed and evidence is uncertain.
- Grade: Very Low (D)
  - Grade I means there is Good/Strong evidence supporting the statement;
  - Grade II is Fair;
  - Grade III is Limited/Weak;
  - Grade IV is Expert Opinion Only;
  - Grade V is Not Assignable.
  - High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
  - Moderate (B) means we are moderately confident in the effect estimate;
  - Low (C) means our confidence in the effect estimate is limited;
  - Very Low (D) means we have very little confidence in the effect estimate.
  - Ungraded means a grade is not assignable.
- Evidence Summary: In presumably healthy adults in the general population, what is the relationship between vegetarian diets and ferritin concentrations?
  - Detail
  - Quality Rating Summary
    For a summary of the Quality Rating results, click here.
  - Worksheets
    
    Haider L, Schwingshackl L, Hoffmann G, Ekmekcioglu C. The Effect of Vegetarian Diets on Iron Status in Adults: A Systematic Review and Meta-Analysis. Critical reviews in food science and nutrition 2018; 58:1359-1374
- Search Plan and Results: VN: Vegetarian Nutrition and Disease Prevention (2023)
In presumably healthy adults in the general population, what is the relationship between vegetarian diets and calcium, hemoglobin or omega 3 marker concentrations?
- Conclusion
  There were no current systematic reviews available that examined the relationship between vegetarian diets and calcium, hemoglobin or omega 3 marker concentrations.
- Grade: Ungraded
  - Grade I means there is Good/Strong evidence supporting the statement;
  - Grade II is Fair;
  - Grade III is Limited/Weak;
  - Grade IV is Expert Opinion Only;
  - Grade V is Not Assignable.
  - High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
  - Moderate (B) means we are moderately confident in the effect estimate;
  - Low (C) means our confidence in the effect estimate is limited;
  - Very Low (D) means we have very little confidence in the effect estimate.
  - Ungraded means a grade is not assignable.
- Search Plan and Results: VN: Vegetarian Nutrition and Disease Prevention (2023)