01 December 2021 |

Vitamin D and calcium: differences and benefits for bone health

vitamina d e calcio per le ossa - immagine grafica di un medico davanti alla proiezione della colonna vertebrale e del bacino

The role of Vitamin D and calcium in maintaining bone health has been well known for a long time in medicine, but the difference between the two is not always clear, warranting the question whether it is useful to take supplements for both or if it is simply sufficient to follow a calcium-rich diet to prevent the risk of problems such as osteoporosis.

Indeed, bone health is an issue that concerns most of the population, in particular for women, who are more subject to the risk of osteoporosis during menopause, but also at other times of life. Children and young people in the growing phase also need to be considered, to understand which nutrients are useful to build strong bones and teeth. Among all vitamins, the most important for bones are vitamin D and vitamin K, while the minerals that act directly on the bone metabolism are calcium and magnesium.

Let’s see how these four elements are related and how they act to maintain good bone health.

This article looks at:

  1. Vitamin D and calcium supplements: why both are important
  2. The role of vitamin K in the bone metabolism
  3. How does magnesium deficiency affect the health of bones and teeth?
  4. Preventing disorders caused by deficiency of Vitamin D and calcium

Vitamin D and calcium supplements: for bone and teeth health: why are these two elements so closely connected? How do they act biochemically?

In our body, Vitamin D plays a number of roles (in fact is it considered to all effects more a hormone than a vitamin), but undoubtedly the first to be discovered and the one we know well is its key role in the regulation of bone health.

Dating back to 1919, it was observed that children suffering from rickets tended to heal if exposed to sunlight or if treated with cod liver oil: from that moment on, after in-depth studies in this area, the medical field identified Vitamin D as the factor responsible for stimulating bone growth.

On the other hand, calcium is the most abundant mineral present in our body, where it performs a number of functions, ranging from muscle contraction to the transmission of nerve pulses (read more in this article on the roles of minerals). Nearly all (around 99%) of the calcium however is found mineralised in the bones and teeth: in fact bones, contrary to what we may believe, are not static structures, but are highly dynamic and subject to a continuous process of remodelling, which involves simultaneous processes of reabsorbing and depositing calcium.

In view of the above, it is therefore evident that vitamin D and calcium are closely tied and cooperate to maintain healthy bones and teeth. More specifically, vitamin D acts to maintain the balance of calcium in the bones, aiding intestinal absorption, the process of bone reabsorption and regulating PTH, the hormone produced by the parathyroid glands, which in turn regulates the serum levels of calcium.

Not only Vitamin D and calcium: the role of vitamin K in the bone metabolism

The term Vitamin K is a general term covering various isoforms, in particular Vitamin K1 and Vitamin K2, similar in chemical structure, but with different roles in our body.

In this case, it is mainly Vitamin K2 that is involved in bone health: in fact it acts in synergy with vitamin D to maintain the right levels of calcium in our bones, and published studies confirm that a deficiency of this vitamin is associated with an increase in the risk of bone fractures. It is no coincidence that in Japan, the cases of osteoporosis are very low: in fact the Japanese consume high quantities of Natto, made from fermented soy beans, known as a source very rich in vitamin K2.

In particular, vitamin K2 in our body acts as a co-enzyme, in other words it facilitates the action of a specific enzyme responsible for activating osteocalcin, a protein that embeds calcium in the bone. It is thus clear how a deficiency of vitamin K2 can endanger the normal process of depositing calcium in the bones, leading to progressive weakening of the bone structure.

Unfortunately, deficiency of vitamin K2 is not rare and, as the body is unable to produce sufficient quantities, it is necessary to support intake with a suitable supplement.

But magnesium is also involved, and how?

How does magnesium deficiency affect the health of bones and teeth?

Unlike calcium, whose role in bone metabolism is well known to many, perhaps not all know that magnesium is directly involved in the health of bones and teeth. There is even a claim approved by the EFSA (European Food Safety Authority) that states that “magnesium contributes to the maintenance of normal bones and teeth”.

In fact the bone represents the main organ for deposits of magnesium in our body: it’s enough to consider that 60% of the magnesium in our body is stored inside the bone matrix. In conditions of hypomagnesemia, i.e. the reduction in levels of circulating magnesium, the bone is therefore the first area that our body resorts to to re-establish the serum concentration of magnesium, and this leads to a progressive weakening of the skeleton.

It is therefore fundamental to avoid magnesium deficiency, following a healthy diet, and when this is not enough, by the intake of specific supplements, above all in the elderly who are most at risk of osteoporosis.

If you’d like to know more about magnesium and its functions, read more in Ultramag.it.

Disorders caused by deficiency of Vitamin D and calcium: can we avoid this with the correct diet and supplements?

Although scientific data state that in Italy, Vitamin D deficiency is widespread – around 80% of the Italian population suffers from a deficiency of Vitamin D -, a lack of this vital nutrient should be avoided whenever possible as it has a negative impact on the process of bone calcification. This can lead to the development of disorders and illnesses such as rickets in children, osteoporosis (a reduction in bone density), often the cause of fractures, above all among the elderly, or even various types of bone deformation. Vitamin D deficiency also weakens the teeth, making them more subject to cavities.

Meanwhile, a deficiency of calcium may be asymptomatic in the initial stages, but if not dealt with early on, can lead to symptoms such as tingling or numbness of the fingers, muscle cramps, convulsions, sleepiness, lack of appetite and irregular heartbeat.

It is therefore extremely important to ensure, through a healthy and balanced diet, the correct intake of both these nutrients, in order to guarantee sufficient quantities so that they work together for a healthy bone structure.

The following is a table of the top calcium-rich foods (note these are not all dairy products!):

Dairy products Milk, yoghurt and cheese
Fish Oily fish, octopus, squid and prawns
Green vegetables Rocket, kale, turnip greens, broccoli, artichokes, chard
Nuts Almonds, peanuts, pistachio, walnuts, hazelnuts
Legumes Chickpeas, lentils, cannellini beans, borlotti beans, black eye beans
Citrus fruits Oranges (also containing vitamin C, potassium and beta carotene)

Table 1: list of food rich in calcium. Source: Italian Ministry of Health.

And when diet is not enough, or when we need an extra intake of calcium, for example in the cases of women in the menopause or the elderly, intake can be integrated with  calcium-based supplements, vitamin D and vitamin K2, such as Bonecal.