Greg from Canada is about to commence a course of nutritional supplements. He has asked about how much to take of various vitamins and minerals. Should he go by the recommended doses on the labels? Should he take more or less?
Here is my response:
The recommended daily allowances (RDA) for nutrients, as set down by the World Health Organisation are levels of nutrients deemed by health researchers to be necessary to maintain life. The levels necessary for a given nutrient to maintain optimum function may be several times that of its RDA.
So, the vitamin C dose of 500mg per day, as may be advised on the label of the bottle you have is the minimum and the optimum for you may in fact be 2,000mg per day and much higher during times of stress and infection (Refer here for an expert opinion about vitamin C).
The doses of natural vitamin E as recommended of 500iu per day is fine; but there is research that shows a daily supplementary intake of about 1,000iu is beneficial for improving the flexibility of arterial walls which is an important consideration if you have raised blood pressure.
Most vitamin D supplements supply about 500iu per day at the most; whereas some experts say that we can safely take up to 10,000iu per day. During winter, I recommend taking about 1-2,000iu per day unless advised otherwise as the result of a blood test of your vitamin D levels.
Magnesium is another example where up to 800mg can be safely consumed per day which is several times more than what is usually recommended on the label.
The point about all of this is that, if you have built up a deficiency in any nutrients over the years, then taking just the RDA will only halt or slow further loss. RDA doses are most unlikely to have any appreciable effect on restoring body levels of a depleted nutrient anywhere back to optimum levels. If you have a nutritional deficiency and health is at an ebb then it is necessary to take greater than the RDA for three or more months in order to restore healthy levels and to see an appreciable improvement in health and vitality.
While I am presenting the case for taking more than the RDA to counter a deficiency, this is making the assumption that there is a deficiency in the first place. I am not all that keen on making broad generalised recommendations about supplementation. However; we can make a number of educated assumptions about nutritional deficiency based on a person’s health history, and how they look and feel and what the research tells us about certain populations.
For example; we can pretty much assume that a vegetarian female who is feeling lethargic and prone to infection, is probably deficient in iron and some of the B vitamins. These assumptions should be confirmed by blood tests and a hair tissue mineral analysis (HTMA).
The HTMA is the most valuable test for determining what nutrients to take more or less of because it gives a history of internal cell nutrition which a blood test can not provide. It eliminates the educated guesswork and replaces it with hard science. When these tests are repeated, the effectiveness of any interventions can be accurately measured. So, please place the blood tests and HTMA at the top of the list when it comes to deciding about how much to take.