Vitamin and Mineral Supplements - An Overview
Discussion of Vitamin and Mineral Supplements
Vitamins and some minerals are essential to health for all living organisms, although most plants and almost all bacteria are capable of producing their own vitamins internally. It’s also true that some compounds are vitamins for some animals and not for others. Two examples are the little-known taurine, which has to be in a cat’s diet but not in human diets, and the much better known vitamin C - which for the majority of animals is not a vitamin at all in the sense of the animal needing an external supply, because vitamin C is made internally in most animals. Vitamin C is needed by humans, anthropoid apes, fruit bats, guinea pigs and some obscure birds - but your pet dog, for example, doesn’t need it.
However, since most people consider supplements for themselves and possibly for other humans, I’ll concentrate on that from now on.
Vitamin and mineral requirements vary greatly from nutrient to nutrient. Examples are vitamin B12 which is needed in quantities of 5 micrograms or so per day (0.000005 grams) all the way to calcium, which for some people is needed in quantities of 1500 grams or so per day. This is a factor of a billion different in requirements. Despite that, the invisibly small amount of vitamin B12 is just as important as the 1500 grams of calcium.
Vitamin and mineral requirements also vary greatly from person to person; young teenagers, for example, need perhaps double the amount of zinc that someone of 60 needs. This is regarding the amount actually absorbed, of which more later. People with malabsorption problems may well need very large amounts of the relevant nutrients.
And finally, vitamin and mineral requirements vary from time to time, over a relatively short period, for an individual. This is probably the most controversial aspect of such variation. For example, someone who has lost a lot of blood requires a great deal more iron; more controversially, it is extremely probable that someone who has just undergone major trauma and/or surgery requires greatly increased amounts of vitamin C.
Vitamin and Mineral Requirements
There are many terms and acronyms for the daily requirements of vitamins and minerals. The most commonly used term is RDA (Recommended Dietary Allowance) but there are other terms used. The various measures of requirements vary between applications and also between countries; this matters because food and supplement labelling may well be using a different measure of requirement from the one used by nutritionists. This may well mean that a supplement that is advertised as having the “full RDA” of a particular nutrient may well not have enough for the body. In addition, RDAs only exist for some of the nutrients known to be essential; for example, boron (which is now known to be essential) does not have an official RDA, at least in the UK.
Also, RDA levels are more-or-less defined as levels that will prevent overt deficiency symptoms; for example the RDA of vitamin C will stop you getting scurvy. For these reasons, it is my opinion and that of most clinical nutritionists that the RDA should be regarded as definitely being a minimum requirement, with the actual need for optimum health usually being considerably greater. This is particularly true in the case of vitamin C, whose official EU RDA is 80mg; many nutritionists would recommend at least 1000mg of vitamin C, and more in some circumstances (such as viral infection or after injury).
Vitamin and Mineral Toxicity
Consumption of vitamins and minerals in amounts greater than required can lead to toxicity. This applies to all nutrients, although in practice toxic levels of some nutrients are very difficult to reach. An extreme example is vitamin B12; the requirement is somewhere between 2 and 5 micrograms but taking 5000 micrograms per day usually doesn’t cause any problems.
Overdosing of some nutrients, however, is fairly easy - which is why one has to be careful. Selenium is probably the most extreme example here; nutritionists would say that most people need 200 micrograms per day, with long-term consumption of 500 micrograms potentially causing problems.
High doses of some nutrients can cause drastic, possibly worrying but essentially harmless side effects. A good example is vitamin B2 (riboflavin) which in large doses causes the urine to be bright yellow for the simple reason that riboflavin itself is that colour and is also water-soluble. So much so, in fact, that riboflavin is sometimes used as a food colouring.
Taking a reputable supplement in the recommended amount is unlikely to cause toxicity problems. A possible route, however, to such problems is to take multiple supplements with an ingredient in common.
This is possibly the most important consideration when thinking about nutritional supplements. Minerals in their free (elemental) form are completely useless to the human body and some would be dangerous. For example, potassium is an essential mineral; but pure potassium is a soft, silvery metal which reacts with water so violently that it sometimes explodes - and the human body is about 70% water. Therefore, all minerals have to be combined with something to make them soluble in water and useful to the body; such compounds are what go into supplements.
However, not all forms of a particular mineral will be equally useful. The sole possible exception to this is potassium, which is just about equally useful in all its possible forms. (The same applies to sodium, but sodium is rarely put into supplements because deficiency is very uncommon.) For most minerals, there are three general classes of supplement.
The first form is inorganic salts. The most common salt used varies from mineral to mineral but examples might be ferrous sulphate (which provides iron) and calcium carbonate. The second form is organic acid salts such as ferrous gluconate. The third form is chelated; the actual method of chelation best used varies from mineral to mineral.
The word “chelation” comes from the Greek word meaning “claw”. This describes the molecular situation quite well; a chelated supplement is one in which the mineral ion is surrounded by some organic compound or other, in a way rather like the way minerals are found in animal tissue. If a mineral supplement is described as chelated, it is usually combined with various amino acids; but other forms can be regarded as chelated from a nutritional point of view - a good example of this is chromium picolinate.
From the point of view of usefulness in supplements, the distinction between these forms is absorbability. As a rule of thumb, inorganic supplements such as ferrous sulphate are roughly 5% absorbed. The organic acid-combined forms such as gluconates are roughly 20% absorbed, and chelates average out at about 80%. Efficiency of absorption varies with age, general health (people in poor health, particularly digestive, don’t absorb nutrients well) and also how deficient the person is. But in the case of minerals, the best forms are absorbed possibly 15 times as well as the worst.
Poorly-absorbed minerals also often cause digestive upset and can reach toxic levels more readily, so for these among other reasons the inorganic forms of minerals are worth avoiding. The reasons why the poorer forms are used at all are that the inefficient forms usually contain a greater proportion of the actual mineral and lead to smaller pills, and also cost; ferrous sulphate is much cheaper than chelated iron. Companies with more devotion to profit than to quality might well take the decision to use the inefficient forms, for that reason.
These are useful but not essential compounds, often found in foods, which make vitamins and minerals more effective and/or have useful effects of their own. Two examples are citrus bioflavonoids and carotenoids. Neither class of compounds are either pure substances or essential; but citrus bioflavonoids are powerfully antioxidant and also make vitamin C more effective, and carotenoids have powerful antioxidant effects. Many of the higher-end vitamin/mineral supplements would contain one or both of these.
From the above, it follows that a good general supplement is one that contains vitamins and minerals in optimum amounts, which are higher than RDA; that contain all the known essential nutrients, not just those with an official RDA; that present the minerals in well-absorbed forms; and, ideally, contain some of the useful non-essential compounds such as bioflavonoids and carotenoids. Such supplements are often found in specialist retailers; they are very seldom found in supermarkets and convenience stores, and not often found in pharmacies.
This discussion has been about supplements for preventative use by people who are already in fairly good health. Specific vitamin and mineral supplements can also be used for therapeutic purposes in various types of ill-health, but this is a Hub not a book so I’ll stop there - except to say that some of them are covered in my other Hubs.