This feeding is associated with lower bone mineral density, but no cause for clinical concern.

The association between vegetarian diets and bone mineral density is controversial. The debate centers on the possibility that this type of food results in a lower bone mass, as some studies, compared to other investigations that have found no statistical significance in this relationship. The issue concerned because BMD is the strongest and most consistent predictor of fractures associated with osteoporosis.

In Western countries, a considerable proportion of the population has adopted a vegetarian diet that includes foods not found in traditional diets as the best for the formation and growth of bones.

The quality and quantity of ingested nutrients (calcium, phosphorus, magnesium, vitamin D, A, K) and the consumption of other dietary elements that promote or hinder the absorption of minerals that nourish the bone, have a significant imprint on health marrow. These factors add up to each individual’s genetic predisposition to develop bone disorders.

The latest review on the possible association between diet and bone mineral density, a controversial issue, is a meta-analysis conducted by the Bone and Mineral Research Program Garvan Institute of Medical Research, picked up this October in the American Journal of Clinical Nutrition.

Vegetarian DietDifferences between vegetarian diets

The density of bone is a complex physiological phenomenon that is influenced by multiple genetic and environmental factors.

One of the criteria of this review was to clarify the different concepts of vegetarian diet, since he could have some interesting differences between the consumption of nutrients that serve the bone depending on the type of food.

A range of studies analyzed bone density from four types of vegetarian diets: semivegetarian, which excludes only the consumption of meat as animal feed, lacto-ovo-vegetarian, which also rules out fish, but includes milk and eggs; lacto-vegetarian, which allows only milk and dairy products such as animal protein source, and the vegan diet, which dispenses with all foods of animal origin.

The analysis took into account nine studies, with a total sample of 869 women and 1880 men. The most relevant results revealed that vegetarians had 4% lower bone mineral density (femoral neck and lumbar spine) than omnivores. This parameter was lower in vegan, with 6% less bone thickness.

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.