The present dietary supplement market offers multiple possibilities of completing everyday menu with various, sometimes unnecessary, substances. Apart from many useless products, there are also very useful for routine supplementation ones. There is a group of products, which often contain scarce components of our diet, such as long-chained fatty acids from the omega-3 group and vitamin D.
The supplement pressure
Highly-processed food available in shops nowadays is not very rich in components crucial for our health. Instead of that it is rich in refined carbohydrates and fats, which are only energetic material. As a result, when basing on such type of food, it's very easy to lead to a situation when there is excessive amount of energy in diet and we are exposed to the insufficiency of nutrients. This fact is often used by the producers of dietary supplements who encourage us to buy products supplying “crucial components”, which “nourish our bodies from inside”.
We are often invited to buy products, which contain vitamins, minerals, particular fatty acids or fibre, as well as various plant extracts, antioxidants, sterols, phospholipids, amino acids and many others. In practice, majority of those substances doesn't need to be supplemented, but there are also components, in case of which additional supply may be justified for significant part of our population. I mean, most of all, such components as:
Fatty acids omega 3 – basic information
Alpha-linolenic acid (ALA) belongs to the group of fatty acids, just like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). All of the mentioned lipids belong to the group of polyunsaturated acids (polyene acids), in case of which the last double bound in the carbon chain is by the last but two carbon atom (therefore, the name “omega 3). As long as the ALA acid is not so hard to find in diet – because it is present in linseed, walnuts and some kinds of oil, providing proper supply of EPA and DHA acids is sometimes difficult. Their only sensible source is fatty fish and some seaweed.
Various sides of omega 3
Despite the fact that only ALA acid is considered to be indispensable, and the EPA and DHA acids may be created out of it in the processes of desaturation and elongation, in practice that conversion is not so efficient. It means that even with relatively high intake of alpha-linolenic acid, we can be exposed to low availability of its long-chained derivatives. Whereas, out of the EPA and DHA acids eicosanoids with antiinflammatory and antiplatelet properties, are formed.
The influence of omega 3 acid on the body
Properly high intake of omega 3 acid is important in order to sustain good condition of cardiovascular system. Scientific data point that providing optimal supply of EPA and DHA in diet may decrease the risk of developing ischaemic heart disease and high blood pressure. It is also suggested in present literature, that omega 3 acid decreases the risk of developing neurodegenerative disiseas, cancer and probably also autoimmune diseases. These lipids may probably be able to lower indirectly the risk of developing overweight, although, more advanced studies are required in this matter.
Recommended intake of omega 3 acid
If it comes to the recommended intake of omega 3 acid, the nutrition norms are following:
the consumption of alpha-linolenic acid should equal at least 0.5% of the daily energy supply from food,
the consumption of EPA and DHA acid should range between 250 – 500mg.
Such institutions as Heart Foundation recommend the daily total dose of EPA and DHA on the level of 500mg or 3500mg per week. In case of present health anomalies, such as hypercholesterolaemia or hypertension, it is advised to supply the doses of EPA and DHA on the level of 1 – 3g per day, or even higher. On the other hand, it's good to know that excessive amount of those lipids in diet is also inadvisable.
Too much of omega 3
The consequence of too high supply of this fatty acid is the increase of the level of low-density lipoproteins (LDL – the “bad cholesterol”) on the one hand, and on the other – bigger proneness to their oxidation. As far as the increase of the level of LDL does not have to be a problem (because this phenomenon is usually accompanied with advantageous change of the size of lipoprotein particles), but the oxidated fractions of LDL are extremely dangerous for the condition of the vascular endothelium and may increase the risk of developing atherosclerosis. In one of the scientific experiments it was observed that the intake of 4g of highly concentrated fish oil causes increased oxidation of LDL by 25%!
Vitamin D – key information
There has been a lot of information on vitamin D recently. This fact should not be surprising, because in the past few years there have been many studies pointing that the insufficiency of vitamin D is very common, and its influence on the body is more extended than it was thought. In fact, when describing vitamin D, I should write about a group of vitamins and their derivatives. From the nutrition physiology point of view, the following forms matter:
ergocalciferol, called vitamin D2, which occurs naturally in plant tissues,
cholecalciferol, called vitamin D3, present in animal bodies.
The biological role of vitamin D
Vitamin D, most of all, regulates the homeostasis of calcium and phosphorus in the body. However, in practice, the influence of that compound on the body could be considered on various levels, whether it impacts particular systems, organs or tissues. Nowadays we know that it influences the following parts of the body:
skeletal system – vitamin D influences the process of bone mineralisation, its insufficiency in children causes rachitis, and in adults it causes bone ache, osteomalacia and osteoporosis,
nervous system – vitamin D influences the process of nervous cells recovery, and its insufficiency may contribute to depression and sleep disorder,
cardiovascular system – vitamin D influences the renin-angiotensin-aldosterone system, and its insufficiency may increase the risk of developing hypertension,
immune system – the influence of vitamin D on the immune system is quite complicated and concerns both, larger ability of coping with virus and bacterial infections, and lower risk of developing autoimmune diseases. There are also reasons to believe that vitamin D insufficiency increases the risk of developing some kinds of cancer,
reproductive system – vitamin D insufficiency has negative impact on the production of sex hormones and decreases fertility,
skeletal muscles – the influence of vitamin D on muscles, including their growth, has been studied intensively. There are reasons to believe that properly high status of this vitamin is advanageous from the sports form point of view.
The problem of alleviating the body's needs
Vitamin D, just like other vitamins, is indispensable for proper functioning of human body. Unfortunately, it does not occur that much in foodstuffs we eat, and its sensible source is basically only fatty fish. What's interesting, its insufficiency is very frequent in our population, despite the fact that it may be synthetised in human body within skin under the influence of the ultraviolet radiation! Unfortunately, in our latitude, the angle of sunlight from September to April is too small to enable proper production of cholecalciferol in the skin. In that time the supplementation of this vitamin should be common. In summer – taking products with vitamin D is not necessary, provided that you sunbathe regularly.
The demand for vitamin D
The demand for vitamin D for majority of healthy people without any insufficiency ranges between 800 – 1000 IU per day. In some cases it is advised to use higher dose of 2000 to 4000 IU. There's no doubt that supplying such high dose only with conventional food is extremely hard. If you want to provide about 1000 IU of vitamin D, you have to eat: 200 – 250g of salmon or 3 – 4kg of pork neck, or 25 – 30 eggs... That's why the supplementation is a good choice, but it does not replace totally the natural source of the mentioned substance.
Too much of vitamin D
It's good to mention that, although overdosing vitamin D is not that easy, excessive zeal in supplementation and using very high doses may be harmful. It's good to know that in our society significant group of people copes with tertiary hyperparathyroidism, which may be caused by long-lasting vitamin D insufficiency. That ailment develops when the intake of calcium from digestive tract is very low comparing to the demand, which mobilises parathyroid to excrete more parathormone. When the supply of vitamin D increases extremely in that condition, there may be an increase of the concentration of calcium in blood serum to the level that will cause significant increase of risk of developing nephrolithiasis, cholelithiasis and pancreas diseases. Therefore, before taking large dose of vitamin D, you should check the level of its metabolites in the body and the level of calcium, phosphorus and parathormone.
Among many dietary supplements present on the market there are also those, which provide very precious for the body nutrients that are often insufficient. Consuming such supplements, therefore, is very important in malnutrition prophylaxis, which lead to health disorders. The example of such supplements are the products containing vitamin D and long-chained fatty acids from the omega 3 group.