Diet and nutrition play an important role in many of the diseases that are major causes of death, illness and disability in Australia, including coronary heart disease, stroke, hypertension, atherosclerosis, some forms of cancer, type 2 diabetes, osteoporosis, dental caries, gall bladder disease, and nutritional anaemias.1
In contrast to most other Western countries, there is no continuous nutritional surveillance in Australia and current information about food and nutrient consumption is not available. Three national nutrition surveys have been conducted in Australia, a survey of adults in 1983, children in 1985, and adults and children in 1995.2 The data that is available shows that Australian diets are lacking in key food groups that are important for healthy nutritional status. According to the 1995 survey, 2 in 3 Australians were not consuming the National Health and Medical Research Council's recommended level of vegetables, 4 in 5 were not consuming enough fruit, and 1 in 2 men and 1 in 3 women were not eating recommended levels of cereal foods.3
A population’s nutritional adequacy can be assessed by the percentage of people whose diet provides less than 70% of the Recommended Dietary Intake (RDI) of nutrients. Using this method of assessment, in 1988 15% of women aged 18–59 years had low iron intakes; 13% of men over 40 years and women over 18 years had low calcium intakes; 10% of men aged over 40 years had low magnesium intakes; and 20% of older people had low intakes of vitamin E.4 Since the last nutrition survey was carried out, RDI values have been updated and changed to Nutrient Reference Values (NRV), available at www.nrv.gov.au.
Those vulnerable to nutritional inadequacies are women of reproductive age, men and women born in Asia or southern Europe, women with no secondary education, men and women who are obese, women who are pregnant or lactating, elderly people, indigenous Australians, children who do not eat breakfast, children of non-English-speaking background and children from single-parent homes.4 Elderly people are particularly at risk of malnutrition.5
The lack of current data makes it difficult to be certain of the extent of micronutrient malnutrition in the Australian population. Across all surveys, calcium and iron have been shown to be consistently low in Australian diets. A study of young Australian women found that iron deficiency was present in 7.2% and iron deficiency anaemia in 4.5%.6 Those at greatest risk of iron deficiency in Australia are adolescent girls, pregnant women, female blood donors, and vegetarians, with prevalence estimates of 9-10% in these groups.6
Iodine is low in soils in parts of Australia and is therefore lacking in food grown on these soils. Surveys of schoolchildren, healthy adult volunteers, pregnant women, and patients with diabetes in the Sydney metropolitan area have shown that iodine deficiency is re-emerging in Australia.7 A national study of schoolchildren found mild iodine deficiency in New South Wales and Victoria, borderline levels in South Australia and adequate intake in Queensland and Western Australia.8 The 22nd Australian Total Diet Study 2008 investigated intake of selected trace elements and found that iodine intakes of most of the adults surveyed were lower than Estimated Average Requirements (EAR).9
Vitamin D deficiency is becoming an issue in Australia, with 80% of dark-skinned, veiled, pregnant women and mothers of infants treated for rickets having a deficiency.10 Marginal deficiencies have been found in 76% of nursing home residents, 53% of elderly hostel residents, and 23% and 43% of younger Australian adults.10 Vitamin D deficiency has been found in 8% of young Victorian women at the end of winter.10
A wide-ranging review of the use of vitamins for health disorders concluded that suboptimal intake of some vitamins is common in the general population, especially the elderly, and, as most diets do not provide an optimal amount of all the vitamins, it appears prudent for all adults to take vitamin supplements.11 A survey of healthy people found that multivitamin users had a 2% better nutritional intake from their diet than non-users but an 8% better nutritional intake when their intake from multivitamins was taken into account.12 The study concluded that multivitamins can contribute substantially to total nutrient intakes.
Several studies have found that multivitamins can have positive effects on physiology and risk factors for chronic disease. Healthy older people already consuming a diet fortified with folic acid took a multivitamin formulated at about 100% Daily Value (U.S.) for 56 days.13 Mean homocysteine levels reduced by 9.6%, plasma folate increased by 41.6%, pyridoxal phosphate increased by 36.5% and vitamin B12 increased by 13.8%, with no changes in the placebo group. The multivitamin users’ micronutrient levels increased to levels associated with reduced risk of several chronic diseases.
A study of aged care residents in Victoria found that multivitamin supplementation raised serum vitamin B12 and folate levels and increased serum vitamin D, with a positive effect on bone density and a trend towards a reduction in falls.14 The cross-sectional Blue Mountains Eye Study in New South Wales found that use of multivitamin supplements was associated with a 40% reduced prevalence of nuclear cataract and longer duration of multivitamin use was associated with reduced nuclear and cortical cataract.15 Vitamin B1 supplements were found to be protective against nuclear and cortical cataract and both vitamin B2 and vitamin B3 supplements were protective against cortical cataract. Vitamin A supplements protected against nuclear cataract, as did folate supplements, and folate and vitamin B12 supplements were each strongly protective against cortical cataract.
Cardiovascular risk factors can be modulated by multivitamin use. An open-label pilot investigation into the effects of a 24-ingredient multivitamin formula found that levels of vitamin B6, vitamin B12, folic acid, vitamin C, vitamin E, and beta-carotene were significantly elevated at weeks 12 and 24 and homocysteine concentration decreased.16 LDL oxidation lag time increased and oxidation rate reduced. A cross-sectional study from Germany found that a multivitamin containing vitamin E, in combination with vitamin C, vitamin B1, B2, B3, B5, B6, B12, folic acid, and selenium, reduced levels of C-reactive protein, a key promoter of inflammation, and had the potential to influence the inflammatory process contributing to atherosclerosis.17 In the Stockholm Heart Epidemiology Program, men who were regular multivitamin supplement users were found to have a 21% lower risk of MI and women users had a 34% lower risk, after adjustment for major cardiovascular risk factors.18