October 2017: Gut health Bone health

Fermented milk products are linked with strong healthy bones

fermented-milk-bone-health

Consuming fermented milk products such as yogurt is linked with healthy growth of bones when we’re young, reduced bone loss when we’re older, and a lower risk of broken bones in our old age.

These benefits seen at all stages of life are achieved through several mechanisms, say the authors of this review article. Not only do yogurts deliver nutrients vital for strong healthy bones, but they also contain prebiotics and probiotics, which may benefit the bones by modifying the microbiota that inhabit our gut.

A rich source of nutrients

Fermented milk products in the form of yogurts or soft cheese have long been used to preserve milk. They are rich in calcium, phosphorus and protein, all key nutrients for promoting bone growth and maintaining healthy bones.

Yogurt and soft cheeses may be richer in these nutrients than plain milk because of milk powder that is added to yogurt to make it thicker.

Healthy growth for children and teenagers

Intervention trials have shown that giving fermented dairy products to children and adolescents has a positive influence on their bone health especially their bone mineral density.

Protection against age-related bone loss

In adults, fermented dairy product consumption protects against bone loss and maintains bone strength as we get older.

Among the studies reviewed was an Irish study of over 4000 people aged over 60 years. A higher yogurt intake was associated with a lower risk of osteoporosis – a greater effect than that seen with milk intake. In another study of 65-year-old women, bone loss was reduced in those who consumed fermented dairy products and not in those who drank milk or ate cheese.

Dairy products and fractures

Data on the link between dairy product and risk of broken bones are limited but the Framingham Offspring study showed a weak protective trend against hip fracture seen with yogurt consumption but not with other dairy products. In a long-term Swedish study, women who had a high intake of cheese or fermented milk products were less likely to die or to suffer a hip fracture during the follow-up than those who had a low intake.

Prebiotics and probiotics

Additional benefits to our bones may come from prebiotics and probiotics that fermented dairy products may contain.

Prebiotics such as inulin – derived from chicory roots – may be added to yogurt to make it thicker. They are fibre compounds that stimulate the growth and/or activity of the bacteria living in the large bowel. Furthermore, prebiotics may be converted in the large intestine through a process of fermentation to short chain fatty acids. These have several beneficial effects in the bowel including increasing calcium bioavailability and absorption through a reduction in bowel content pH and enhancing intestinal barrier functions.

Probiotics are live micro-organisms which, when administered in adequate amounts, confer health benefits on the host. Probiotics provide a way to deliver beneficial bacteria directly to the gut.

Prebiotics and probiotics in fermented milk products may exert specific effects not seen with other types of dairy foods by modifying the composition and metabolism of the gut microbiota. The gut microbiota has several possible beneficial influences:

·      It affects intestinal wall permeability – the gut microbiota is involved in the digestion of dietary nutrients, and can increase calcium absorption.

·      It is thought to affect endocrine pathways – the increased calcium absorption may lead to a reduction in parathyroid hormone production which in turn can lead to a reduced bone resorption. The secretion of serotonin may also be modulated thereby increasing bone formation.

·      It plays an important role in modulating the immune system – this is significant because inflammation is linked with bone loss.

Eating more yogurt could save money

The authors of this review suggest increasing dairy consumption could lead to cost savings because of its protective effect on our bones. Hence eating one yogurt every day is cost effective in reducing the risk of bone fracture in people aged over 70 years, while eating two yogurts daily is cost effective for reducing fracture risk in those aged over 80 years.

As yogurts tend to be flavoured and sweetened, they may be useful in achieving a higher consumption of milk products, say the authors.

They conclude that further research is needed to clarify whether consuming fermented milk products may be a causal factor or whether it is simply a marker of a healthy lifestyle that promotes healthy bones.

Find out more: read the original article.

Source: Rizzoli R, Biver E. Effects of fermented milk products on bone. Calcif Tissue Int. 2017 Aug 19.