Nutritional advice

Vegetarianism

Scientific studies (review articles) on the relationship between diet/nutrients and vegetarianism:
One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of randomized, placebo-controlled double blind clinical trials (RCTs) will answer the following question:
"Do taking dietary supplements make sense?" Yes for a positive conclusion and no for a negative conclusion.

One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of (prospective) cohort studies or case-control studies will answer the following question:
"Should I change my diet?".

2021:

  1. Vegetarians and vegans have a lower bone mineral density than omnivores

2019:

  1. Vegetable-based diet reduces osteoporosis in postmenopausal women

2018:

  1. Asian vegetarian mothers have an increased risk to deliver babies with low birth weight

2017:

  1. Plant-based dietary patterns decrease cancer risk
  2. Vegetarian diet has a protective effect against diabetes risk

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Vegetarianism is the dietary pattern with no meat, fish, shellfish and poultry but with vegetables, fruits, grains and legumes.

Vegetarianism is derived from the Latin word "vegetus", meaning "lively, cheerful and powerful".

Vegetarianism can be adopted for different reasons. Most vegetarians do not want to eat meat out of respect for all living beings who can feel and experience pain. Other reasons are health reasons, environmental concerns and different religious and cultural reasons.

Vegetarianism has several variants. It ranges from eating certain animal products, such as meat or milk to avoid all animal products.

In general, vegetarians have often a pale skin. Pale skin is the result of a low status of vitamin B12 and iron.

Most common nutrient deficiencies among vegetarians are a deficiency of vitamin B12, iron and calcium. Animal products are in fact rich in vitamin B12, iron and calcium.

Vegetarians generally get more phytates, fiber and less cholesterol and saturated fat than non-vegetarians. Phytates can adversely influence the absorption of iron and zinc.

The RDA of zinc of vegetarians should be 1.5 times higher than that of non-vegetarians because they ingested more phytates through diet.

The RDA of iron of vegetarians should be 1.8 times higher than that of non-vegetarians because only 10% of iron is absorbed from a vegetarian diet, compared with 18% from a mixed diet that includes meat.

Unlike animal products, no plant products contain all the essential amino acids and therefore vegetarians should combine vegetables with cereals to obtain all essential amino acids. The human body needs essential amino acids to be able to synthesize body proteins.

Vegetarians generally have a lower body mass index (BMI) than non-vegetarians.

Dietary guidelines for vegetarianism:

  • A vegetarian diet (=all meals/products that you eat on a daily basis) should on average contain maximum 35 En% fat, of which maximum 10 En% saturated fat, maximum 0.3 gram salt per 100 kcal, minimum 1.3 grams of fiber per 100 kcal and fish supplying 250-500 mg of EPA and DHA per day.
  • Take a multivitamin supplement to prevent nutrient deficiencies.
  • Combine vegetable protein with cereal protein to obtain all essential amino acids.

 

Vegetarians and vegans have a lower bone mineral density than omnivores

Objectives:
Do vegetarians and vegans have a lower bone mineral density than omnivores?

Study design:
This review article included 17 cross-sectional studies with a total of 13,888 patients.

Results and conclusions:
The investigators found the pooled results indicated, those on plant-based diets exhibited a lower bone mineral density at the lumbar spine [MD = -0.04, 95% CI = -0.06 to -0.02, p < 0.0001] and femoral neck [MD = -0.04, 95% CI = -0.05 to -0.02, p < 0.00001] and a reduced whole-body bone mineral density [MD = -0.03, 95% CI = -0.06 to -0.01, p = 0.0009], compared to omnivores.

The investigators found both vegetarians and vegans exhibited lower lumbar spine, femoral neck and whole-body bone mineral density than omnivores.

The investigators concluded both vegetarians and vegans have a lower lumbar spine, femoral neck and whole-body bone mineral density than omnivores.

Original title:
Comparison of human bone mineral densities in subjects on plant-based and omnivorous diets: a systematic review and meta-analysis by Li  T, Li  Y and Wu S.

Link:
https://pubmed.ncbi.nlm.nih.gov/34145511/

Additional information of El Mondo:
Find more information/studies on plant-based diet right here.

Vegetarian diet has a protective effect against diabetes risk

Afbeelding

Objectives:
Does a vegetarian diet reduce diabetes risk?

Study design:
This review article included 2 cohort studies and 12 cross-sectional studies.

Although the funnel plot showed a slight asymmetry, publication bias was not detected based on statistical tests such as the Egger’s [p = 0.465] and Begg’s tests [p = 0.584].

Results and conclusions:
The investigators found vegetarians had a 27.4% lower risk of having diabetes than omnivores [OR = 0.726, 95% CI = 0.608-0.867].

The investigators found in the subgroup analyses by sex, study design, region of study and vegetarian type, the pooled OR of all subtotal estimates suggested that vegetarians had a lower prevalence or incidence of diabetes than omnivores. Vegetarian men were less likely to have diabetes than their omnivorous counterparts; in contrast, no such significant association was found in women.

The investigators found in the subgroup analysis, the inverse association between a vegetarian diet and diabetes incidence/prevalence tended to be stronger for the 3 studies conducted in the Western Pacific region [OR = 0.514, 95% CI = 0.304-0.871] and the 7 studies performed in Europe & North America [OR = 0.756, 95% CI = 0.589-0.971] than for the 4 studies conducted in Southeast Asia [OR = 0.888, 95% CI = 0.718-1.099].

The investigators found in the subgroup analysis by types of vegetarianism, most types (vegan, lacto- and lacto-ovo-vegetarians) were significantly associated with a lower prevalence or incidence of diabetes than omnivorous participants, except for pesco-vegetarians.

The investigators found the influence analysis showed that the pooled OR was not dramatically changed when it was recalculated after dropping one study at a time. In other words, no one study had a substantial impact on the pooled effect size; this is indicative of a statistically robust result.

The investigators concluded that a vegetarian diet has a protective effect against diabetes risk. However, well-designed prospective cohort studies from various countries that obtain information on the participants’ motivations for vegetarianism, the duration of adherence to a vegetarian diet and verification of a vegetarian diet are needed to strengthen these findings.

Original title:
Adherence to a Vegetarian Diet and Diabetes Risk: A Systematic Review and Meta-Analysis of Observational Studies by Lee Y and Park K.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5490582/

Additional information of El Mondo:
Find more information/studies on vegetarianism and diabetes right here.