Micronutrient deficiencies and anaemia associated with body mass index in Australian adults: a cross-sectional study

Aim To estimate the prevalence of micronutrient
deficiencies and anaemia, and their association with body
mass index (BMI) categories among Australian adults.
Method We analysed data from the 2011–2013
Australian Health Survey from 3539 participants aged
18 years and over (without known pregnancy) with
measured weight and height, and nutrient biomarkers.
To address complex sampling, survey weights were
used when estimating the prevalence of micronutrient
deficiencies (vitamin B12 deficiency; serum vitamin
B12<145 pmol/L; iron deficiency; ferritin<30 µg/L and
vitamin D deficiency; 25-hydroxyvitamin D<50 nmol/L)
and anaemia (haemoglobin <120 g/L for females and
<130 g/L for males) and when assessing associations with
logistic regression models with adjusted ORs (AORs) for
BMI categories: healthy weight (BMI 18.5 to <25.0 kg/m2
reference; overweight (BMI 25.0 to <30.0 kg/m2
), obesity
class I (BMI 30.0 to <35.0 kg/m2
), obesity class II/III (BMI
35.0 kg/m2
or more).
Result The prevalence of vitamin B12 deficiency (range
0.9%─2.8%) and anaemia (range 3.9%─6.7%) were
variable across BMI groups. The prevalence of iron
deficiency in the obesity class I group was 12.0 percentage
points lower than healthy weight group with an AOR
of 0.50 (95% CI 0.30 to 0.83). The prevalence of
vitamin D deficiency in the obesity class II/III group was
7.9 percentage points higher than the healthy weight group
with an AOR of 1.62 (95% CI 1.01 to 2.60). Vitamin B12
deficiency and anaemia were not consistently associated
with BMI groups.

Conclusion We found a consistent association between
severe obesity and vitamin D deficiency in Australian
adults. We also found obesity class I was negatively
associated with iron deficiency, whereas there was no
consistent association between BMI groups and vitamin
B12 deficiency and anaemia. Public health strategies are
needed to prevent vitamin D deficiency in this high-risk