It was about 250 years ago that the link between diet and disease was firmly established. The need to consume a sufficient quantity of fresh fruit to prevent scurvy was recognised in the 18th century, first of all by various seafarers.
The word "limeys" was applied to British sailors following tradition of providing them with a regular ration of limes.
Of course it was many years later that vitamin C (ascorbic acid) was shown to be the active ingredient responsible for saving the lives of so many seamen.
Since then many other vitamins have been isolated and synthesised – the term "vitamin" meaning a substance essential for life. Essential they may be, however, clinical trials in recent years indicate that these so-called micronutrients may not give the same benefit when taken as supplements as when the same nutrients are provided by the diet.
Dr Rosemary Stanton, writing this month in the medical journal Australian Doctor states that for many people, taking a supplement makes them feel they are taking positive action. Nutritional supplements are often seen as "natural cures". But, whilst supplements can sometimes be beneficial, they may also provide a false sense of security and reduce the chances of a person giving up junk food.
No supplement, says Dr Stanton, can undo the damage of saturated and trans fats, and the high levels of salt, sugar and refined starches that accompany poor food choices.
Meanwhile the National Health and Medical Research Council (NHRMC) has published new dietary guidelines and recommended daily intakes (RDIs) for nutrients considered necessary to keep us healthy.
In many cases the new recommendations are for a greater intake of vitamins and other micronutrients compared with the original recommendations some 50 years ago, but in the case of salt the suggested dietary target (SDT) is now just 1.6 grams daily – down from 2.3 grams.
Reducing our intake of salt to this level will be quite a challenge if our diet consists mainly of processed foods.
Calcium, iron and iodine are not classified as vitamins but these elements are also essential in small doses for our health and well-being; and many Australians, especially women, are deficient in these nutrients.
To meet the new and increased recommendation of 1300mg of calcium each day, particularly important for teenagers, women after menopause and men over 70, it may be necessary to consume dairy products fortified with extra calcium or calcium supplements.
Pregnant and breastfeeding women may need extra iodine. Natural sources are seafood and milk, and the food authorities are considering the need to fortify foods such as bread.
Fish (especially oily fish) is also a good source of the omega-3 fatty acids. There's evidence that these substances have a protective effect against heart disease and stroke with possible benefit against depression, dementia and rheumatoid arthritis.
The production of vitamin D is stimulated by sunlight; and for most of us in Australia we get enough sun to meet our vitamin D requirements. However, certain groups of people – those who are confined indoors or stay covered up perhaps for cultural reasons, are at risk of deficiency and consequently brittle bones. In this case a supplement will be needed.
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