Nutrition and Diet Tips

Calcium

It is recognized that vegetarians may have a higher overall intake of calcium, but the percentage of the total consumed absorbed is estimated below. This mineral is important for health, education, growth and maintenance of bones. Several studies have found a direct association between dietary calcium intake, bone density and fracture risk reduction. However, the largest meta-analysis of 33 studies on the subject, shows that the contribution of dietary calcium on bone density is modest.

The authors suggest that differences in the intake of this mineral or animal consumption sources (milk and dairy products, sardines) or plant (nuts, seeds, legumes) have no significant effect on the observed variation in bone density. If we look at these data, it is unlikely that the reduced strength of vegetarians in this analysis due to differences in dietary calcium intake.

Proteins

The relationship between protein intake and bone health has been much discussed. The strongest hypothesis argues that a diet high in animal protein has a negative effect on bone health because it generates an acid load that requires resorption of bone calcium to balance homeostasis. This mineral loss is associated with an increased risk of fragility and fracture. In vegetarian diets, due to reduced consumption of animal protein, they did not contemplate a negative nutrient.

Some authors suggest that protein and calcium act synergistically on bone function if both elements are ingested in sufficient quantities in the diet. However, proteins can have negative effects on bone density when calcium intake is low.

Vegetarian diets, especially vegan, are associated with lower bone mineral density, but not at a level that translates into a clinical concern. The density of bone is a complex physiological phenomenon influenced by multiple genetic and environmental factors. This explains that any change exclusive diet is not sufficient to improve bone health.

Isoflavones and Bone

A differential characteristic of vegetarian diets on the West is that the former contain more phytoestrogens. The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) of the United Kingdom estimated the average intake of isoflavones in vegans at 75 milligrams a day. This figure far exceeds the 12 milligrams a day of strict non-vegetarians, and even more the average Western consumers (2 mg/day).

It has been suggested that isoflavones may help prevent bone loss after menopause, although the association is unclear. The Department of Medical Statistics and Epidemiology, School of Public Health, University of Sun Yat-sen in Guangzhou (China), conducted a meta-analysis of randomized controlled trials on long-term use of supplements of soy isoflavones in bone density among women after menopause.

He reviewed ten studies conducted between 1990 and 2008, with a total sample of 896 women taking the supplement with an average dose of 87 mg of soy isoflavones for at least a year. The conclusion was clear: it is unlikely that consumption of these supplements have a significant positive effect on mineral density of lumbar spine and hip in women.