This article provides a comprehensive review of the change in vitamin A status and the extent of vitamin A deficiency among different population groups in Bangladesh up to the present time. The result of experience with different strategies and interventions designed to improve vitamin A status are then reviewed, leading to a discussion of key options for action, as well as important areas for research and evaluation.

All the available data have been examined in detail, including data from nationally representative samples and nationwide surveys, as well as small studies in different population groups. Reports on the effectiveness of different intervention programmes have been used.

Over the past three decades a number of studies, which include national nutrition surveys, have been carried out to investigate the prevalence of vitamin A deficiency among different population groups in Bangladesh, and they have demonstrated a significant public health problem. Studies have shown that the prevalence of severe deficiency, based on the prevalence of night blindness in preschool children, decreased from 3.6% in 1982–83 to 1.78% in 1989 and 0.6% in 1996. However, there is still a high prevalence of subclinical vitamin A deficiency, based on the biochemical assessment of serum retinol levels in preschool children, estimated mainly from hospital-based groups. Night blindness and Bitot's spot are also found to exist among school-age children and adolescents. Recent reports indicate that night blindness among rural mothers is as high as 1.4%. Only a limited number of studies, with small sample sizes, are available where serum retinol has been reported for school-age children, adolescents and pregnant women. Nevertheless, these studies confirm the presence of low levels of serum retinol and hence, the existence of subclinical vitamin A deficiency. Furthermore, the dietary intake of vitamin A in each population group has been found to be less than the Recommended Daily Allowance (RDA), indicating a significant risk of deficient intakes of vitamin A.

To address the problem of vitamin A deficiency, the government of Bangladesh started the Nutritional Blindness Programme in 1973. The main activities of the programme include vitamin A capsule (VAC) supplementation to children of 6 months to 6 years old, nutrition education to increase the production and consumption of vitamin A rich foods, and training of primary health-care workers on the clinical diagnosis and treatment of vitamin A deficiency, VAC distribution and nutrition education. Since 1988, as a long-term strategy, Helen Keller International has been implementing community home gardening promotion projects. To date, the possibility that foods may be fortified with vitamin A, has not been explored as a possible approach in Bangladesh.

Although short- to long-term prevention and control programmes are to some extent in place, to improve the situation of vitamin A deficiency, Bangladesh needs a more appropriate mix of interventions for the entire population. More operational research and evaluation are needed if a fully effective programme to alleviate the problem of vitamin A deficiency is to be developed. Finally, to achieve the goal of virtual elimination of vitamin A deficiency will require an integrated approach which brings together appropriate actions at every level, within and across the many sectors of society.

To describe the extent of use of medicines by older people living in Britain, and to explore relationships with vitamin status indices.

The National Diet and Nutrition Survey of people aged 65 years and over collected data from a British sample during 1994–95. The present study has made novel use of it, to relate medicine use with biochemical indices of vitamin status.

Eighty postcode areas, selected randomly from mainland Britain.

1506 people, 65 years and over gave information about use of medication, and a 4-day weighed food record. Three-quarters gave blood for status indices.

78% of those living in the community and 93% of those in institutions were using medication. Certain vitamin status indices: plasma retinol, erythrocyte folate and riboflavin, paradoxically suggested better status in users than in non-users of antihypertensive, gastrointestinal, central nervous system, corticosteroid or diabetic drugs. There was evidence of a link with renal insufficiency, especially for plasma retinol, but neither this nor increased nutrient intake, acute phase effects or haemoconcentration could explain the paradoxical associations.

Caution is needed in interpreting certain vitamin status indices, especially in older people who are extensively using medicines. New vitamin indices are needed, to avoid confounding interferences.

To describe an approach for assessing the prevalence of nutrient inadequacy in a group, using daily intake data and the new Estimated Average Requirement (EAR).

Observing the proportion of individuals in a group whose usual intake of a nutrient is below their requirement for the nutrient is not possible in general. We argue that this proportion can be well approximated in many cases by counting, instead, the number of individuals in the group whose intakes are below the EAR for the nutrient.

This is a methodological paper, and thus emphasis is not on analysing specific data sets. For illustration of one of the statistical methods presented herein, we have used the 1989–91 Continuing Survey on Food Intakes by Individuals.

We show that the EAR and a reliable estimate of the usual intake distribution in the group of interest can be used to assess the proportion of individuals in the group whose usual intakes are not meeting their requirements. This approach, while simple, does not perform well in every case. For example, it cannot be used on energy, since intakes and requirements for energy are highly correlated. Similarly, iron in menstruating women presents some difficulties, due to the fact that the distribution of iron requirements in this group is known to be skewed.

The apparently intractable problem of assessing the proportion of individuals in a group whose usual intakes of a nutrient are not meeting their requirements can be solved by comparing usual intakes to the EAR for the nutrient, as long as some conditions are met. These are: (1) intakes and requirements for the nutrient must be independent, (2) the distribution of requirements must be approximately symmetric around its mean, the EAR, and (3) the variance of the distribution of requirements should be smaller than the variance of the usual intake distribution.

To develop and test a quantitative, interviewer-administered food frequency questionnaire (FFQ) to ascertain nutrient intakes of individuals in northern India.

A 92-item FFQ was developed based on food use and market surveys of the study area. A validation study was conducted consisting of 24-h diet recalls (24HR) administered on 6 randomly selected days over 1 year. Two FFQs were administered, one each at the beginning and end of the 1-year period. FFQ and 24HR-derived nutrient scores were compared using correlation and regression analyses and by computing differences between nutrient intakes estimated by the two methods.

Rural villages in Bhavnagar District, Gujarat, North India.

60 individuals who agreed to provide all necessary data.

Pearson (parametric) correlation coefficients averaged 0.69 in comparing nutrient scores derived from the 24HR with those from the first FFQ and 0.72 in comparing the second FFQ (P < 0.0001). Spearman correlation coefficients were virtually identical to the Pearson correlations, averaging 0.68 and 0.72, respectively. In regression analyses, most coefficients were close to 1.0 (perfect linear association). Nutrient scores were significantly and consistently higher on both FFQs relative to the 24HR.

This FFQ produces results broadly comparable, and superior in some respects, to those commonly used in the West. Higher than average measures of association indicate its suitability for comparing exposures within this study population in reference to health-related endpoints.

To examine the association between self-reported consumption of foods and plasma vitamin C levels.

A cross-sectional analysis of dietary data and plasma vitamin C levels. Subjects placed the following foods into frequency categories: fresh fruit, leafy greens, other vegetables, fatty fish, other fish, chicken, meat, meat products, eggs, cheese and brown bread. The six frequency categories ranged from ‘never’ to ‘at least daily’. Plasma vitamin C was measured by fluorometric assay.

A population-based cohort study in Norfolk, UK.

598 men and 566 women aged 45–74 years not taking vitamin supplements.

Plasma vitamin C was positively correlated with intake of fresh fruit (r = 0.29 in men and r = 0.25 in women, P < 0.001), leafy greens (r = 0.20 in men P < 0.001, r = 0.13 in women P < 0.01), other vegetables (r = 0.20 in men P < 0.001, r = 0.14 in women P < 0.01) and brown bread (r = 0.28 in men, r = 0.17 in women, P < 0.001) and negatively associated with intake of meat products (r = −0.13 in men P = 0.02, r = −0.10 in women P < 0.01). The difference in plasma vitamin C between never and daily eaters of brown bread was 13.6 μmol l−1 in men and 9.9 μmol l−1 in women, P < 0.001

These data suggest that plasma vitamin C is not only a marker of foods rich in vitamin C but of certain patterns of food consumption. Such patterns are likely to be population specific and might explain inconsistencies in biomarker–disease associations.

To report on energy and nutrient intakes, as a risk factor for coronary heart disease in Indian South Africans.

Cross-sectional dietary study as part of a coronary heart disease survey.

Metropolitan area of Durban, South Africa.

Free-living Indian men (n = 406) and women (n = 370) 15–69 years of age.

Dietary data were collected by three interviewers using a 24-h dietary recall and expressed as median intakes of macronutrients.

Results reported a low energy intake and the percentage of energy derived from total fat varied between 32.3 and 34.9% in men and between 33.1 and 36.1% in women. The energy intake to basal metabolic rate (EI: BMR) ratios were low for all age groups suggesting potential under-reporting. Intake of polyunsaturated fatty acids was high, more than 10% of energy, with a median polyunsaturated to saturated fatty acid ratio (P: S ratio) that varied between 1.38 and 1.96 for the various age and sex groups. Dietary cholesterol varied between 66 and 117 mg per 4.2 MJ in men and between 76 and 109 mg per 4.2 MJ in women. Dietary fibre intakes were low and varied between 8.0 and 11.0 g per 4.2 MJ in men and between 7.6 and 9.6 g per 4.2 MJ in women.

The dietary P:S ratios were high and the effect of such a high P:S ratio on the oxidation of low density lipoprotein in this population, with a high prevalence of coronary heart disease (CHD), should be investigated as a possible risk factor for CHD.

To assess the quality of a narrative form diet history (DH).

Reproducibility assessed with data obtained at 6-week intervals. Criterion validity assessed using energy intake to estimated energy expenditure (EI: BMR) cut-off limits. Relative validity assessed by comparing results for energy and macronutrients at baseline and month 2 of an intervention trial with those obtained from 3-day food records (FR).

Community-based dietary intervention trials for the study of metabolic syndrome in the Illawarra region of New South Wales, Australia.

Reproducibility: 43 healthy female volunteers. Mean age 58.72 years (range 50–67), mean body mass index (BMI) 25.79 (range 21–36). Validity: 45 healthy volunteers—18 males (mean age 46.9 years, mean BMI 27.8), and 27 females (mean age 45.7 years, mean BMI 26.2), attending a study on the effect of diet on metabolic variables.

Reproducibility: wide SD values indicated a high degree of intraindividual variation, but correlation coefficients were comparable to those of similar studies. Validity: underreporting was inconsistent with individuals, but was greater with the DH than the FR at each stage of the dietary trial (significant at month 1, P > 0.01). Underreporters indicated higher intakes of protein during the trial (P > 0.05). Weaker associations were found between the DH and FR data for energy values, but there was strong agreement for per cent fat consumed as saturated and monounsaturated fat at each stage of the trial.

The narrative form DH performs as well as standardized interviews, but more work needs to be done at the micro level, focusing on aspects which deal with foods likely to be underreported in the particular study context. This can be achieved through continued research using combined methodologies.

To describe the characteristics of dietary supplement users in a large cohort of women and test the hypothesis that supplement users would be more likely to have a healthier lifestyle than non-users.

Comparison of nutrient intakes from food frequency questionnaire (FFQ) data for 8409 supplement users and 5413 non-users. Use of logistic regression modelling to determine predictors of supplement use in this cohort.

13,822 subjects from the UK Women's Cohort Study (UKWCS) for whom data on supplement use was available.

Significant differences in nutrient intakes from FFQ were seen between the two groups, with supplement users having higher intakes of all nutrients, except for fat and vitamin B12. Use of dietary supplements was associated with being vegetarian, vegan or fish-eating, consuming more fruit and vegetables, being more physically active and having a lower alcohol intake. Supplement use was less likely in those with a body mass index above 25 and those who reported smoking regularly.

The findings are consistent with the hypothesis that supplement use is associated with a healthier lifestyle profile and an adequate nutritional intake, suggesting that supplement users do not need to take supplements to meet a nutrient deficiency.