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Nutrients that keep your bones healthy: Part II

Rohini Diniz


Phosphorus is a mineral that makes up 1 per cent of a person’s total body weight. Next to calcium, it is the second most abundant mineral in the body and is required by every cell for normal functioning. Approximately 85 per cent of the body’s phosphorus is found in the bones and teeth along with calcium in the form of hydroxyapatite that gives bones strength and rigidity.

Apart from its role in maintaining bone health, phosphorus is part of the phospholipids that form the major structural components of cell membranes; it plays a very important role in the process of energy production as energy production and storage is dependent on phosphorylated compounds – adenosine triphosphate (ATP) and creatine phoisphate. Phosphorus is an essential component of the nucleic acids (DNA and RNA), that are responsible for storage and transmission of genetic information, and is also needed for the activation of a number of enzymes, hormones and cell signalling molecules. It also helps maintain normal acid-base balance of the body and as a part of 2.3 diphosphoglycerate, it has a role to play in the regulation of oxygen delivery to the tissues.

Phosphorus is found in most foods like dairy products, cereals, meat and fish. It is also a component of many food additives that are used in food processing particularly phosphoric acid in cola soft drinks.

Vitamin D is a critical nutrient for bone health and isn’t just a vitamin that we eat, but also a hormone that our bodies produces. Adequate vitamin D nutrition is crucial at every stage of our lives, from childhood to old age.

Vitamin D is needed for the absorption of calcium and phosphorus and aids in the process of bone mineralisation. Evidence from newer research studies have shown that, vitamin D has a far wider role to play, not only in musculoskeletal health, but also for in preventing chronic diseases. Although more research is needed to determine the beneficial effects of vitamin D in these areas, studies have shown that vitamin D helps reduce the risk of developing diabetes, cardiovascular disease, certain types of cancers, depression, autoimmune disorders, allergy, infectious diseases such as tuberculosis, asthma and even frailty.

Vitamin D is a metabolically inactive compound that requires to be transformed into several active metabolites in the liver and kidney. The skin contains 7-dehydrocholesterol, a cholesterol derivative, which in the presence of sunlight gets converted into Vitamin D-3 or cholecalciferol. Cholecalciferol obtained from food and from the conversion of 7-dehydrocholesterol is then converted into 25 hydroxy Vitamin D-3 in the liver. This 25 hydroxy vitamin D-3 is then converted in the kidney into the metabolically active form 1, 25 dihydroxy vitamin D-3 or calcitriol. Calcitriol functions as a hormone and increases the intestinal and renal absorption of calcium and phosphorus; promotes the deposition of calcium and phosphorus in the bones.

For most individuals, vitamin D requirements are primarily met from the synthesis of vitamin D in the skin in the presence of sunlight. Very few foods naturally contain vitamin D. Milk and milk products, egg yolk, fatty fish and fish liver oils and vitamin D fortified foods are good dietary sources.

Magnesium is another mineral that contributes to the strength and firmness of bones and teeth. Calcium and magnesium function together, so deficiency of one markedly affects the metabolism of the other. Magnesium plays a major role in bone cell function, hydroxyapatite crystallization and growth. It is necessary for the conversion of vitamin D into its active form and for the activation of alkaline phosphatise – the enzyme required for the formation of new calcium crystals. If magnesium levels are low, it can result in abnormal bone crystal formation.

As with calcium, about half of the body’s magnesium is found in the bones and serves as a storage reservoir transferring magnesium into the blood stream in times of need. Magnesium is an essential cofactor in 80 per cent of all cellular enzymes and is needed for more than 300 biochemical reactions in the body. It also helps maintain normal nerve and muscle function, supports a healthy immune system, keeps the heart beat steady and helps regulate blood glucose levels and aids the production of energy and protein.

Magnesium is present in a wide variety of foods. Dietary sources rich in magnesium include dark green, leafy vegetables, nuts, seeds, pulses, legumes, soy, whole grain cereals, millets and fish.

To be continued. . .

The writer is a Consultant Nutritionist with 17 years of experience, practising at Panaji and Margao)

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