VOLUME 9 NUMBER 3 • SEPTEMBER 2012
121
SA JOURNAL OF DIABETES & VASCULAR DISEASE
EDUCATOR’S FOCUS
Taking a basic multivitamin that provides nutrients approximating
recommended intakes should pose no safety risks to healthy people.
However, individuals who take multivitamins and other supplements
and eat a healthy and/or fortified diet might consume some nutrients in
excess, increasing the possibility of adverse affects.
When choosing multivitamin preparations, find one that is tailored
to age, gender and other situations (e.g. pregnancy). Multivitamins for
men usually contain no iron, for example, whereas those for seniors
contain more calcium, vitamin D and vitamin B
12
.
Patients and clinicians should ensure that all vitamins are present in
dosages meeting 100% of the RDA. Patients who need supplementa-
tion of calcium or magnesium might need to take these supplements
separately from their multivitamins, as the required dosage is relatively
large.
Vitamin D
Vitamin D is a fat-soluble vitamin that is naturally present in very few
foods, added to others, and is available as a dietary supplement. It is pro-
duced endogenously when ultraviolet rays from sunlight strike the skin
and trigger vitamin D synthesis.
Vitamin D obtained from sun exposure, food and supplements is bio-
logically inert and must undergo two hydroxylations in the body for activa-
tion. High rates of vitamin D insufficiency have been reported in obese
individuals and in diabetics.
The following are risk factors for vitamin D deficiency:
high skin pigmentation: 50-fold reduction
•
elderly, institutionalised or housebound people
•
lack of exposure to sunlight
•
–
geographic location: research indicates a worldwide vitamin D
deficiency
–
time of day and calendar season
present 10:00 to 15:00, blocked by ozone
•
sunscreen use, protective clothing
•
–
SPF 8 = 97.5%
–
SPF > 15 = 99%
obesity
•
renal and liver disease
•
multiple or short-interval pregnancies
•
medications: anticonvulsants, rifampicin, cholestyramine, anti-retro-
•
viral usage.
The prevalence of vitamin D insufficiency (defined as < 30 mg/dl) in
type 2 diabetes individuals ranges from 80 to 90%.
Several studies are providing evidence that the protective effect of
vitamin D on the heart could be via the renin–angiotensin hormone sys-
tem, through the suppression of inflammation, or directly on the cells
of the heart and blood vessel walls. In the Framingham Heart study,
patients with low vitamin D concentrations (< 15 ng/ml) had a 60%
higher risk of heart disease than those with higher concentrations.
The Framingham study found that subjects with low vitamin D con-
centrations (< 15 ng/ml) were twice as likely to have a heart attack
than those with high concentrations (> 30 ng/ml). In another study,
which followed men and women for four years, patients with low vita-
min D concentrations (< 15 ng/ml) were three times more likely to be
diagnosed with hypertension than those with high concentrations (>
30
ng/ml).
Research indicates that replenishing vitamin D in patients with type
2
diabetes was found to improve insulin secretion, peripheral insulin
sensitivity and glycosylated haemoglobin levels
Supplementation guidelines for vitamin D
Vitamin D supplementation is the most practical means of address-
ing vitamin D insufficiency. I would recommend that any type 2 diabetes
patient considering supplementation of vitamin D to have his/her blood
level of vitamin D checked first. The dosage of vitamin D supplementation
depends on the blood level; 1 000 IU calciferol a day raises serum 25(OH)
D by 20 ng/ml (25 nmol/l), and is given for six weeks.
Vitamin D analogues: 1-calcidol or Calcitriol are ineffective to correct
vitamin D deficiency. For deficiency < 20 ng/ml (< 25 nmol/l):
•
Calciferol 10 000 IU daily or 60 000 IU weekly for eight to 12
weeks
OR
•
Calciferol 300 000 IU monthly for three months (intramuscular
injection), followed by the same dose once or twice a year (severe
malabsorption).
For insufficiency, 20–29 ng/ml (25–50 nmol/l) or maintenance therapy
following deficiency:
•
Calciferol 1 000–2 000 IU daily or 10 000 IU weekly
•
Vitamin D3 supplementation of at least 800–1 000 IU/day ap-
pears to be appropriate year-round for all women
•
Best taken in conjunction with a dietary fat source, i.e. avocado.
Chromium
Chromium has long been of interest for its possible connection to vari-
ous health conditions. Among the most active areas of chromium re-
search are its use in supplement form to treat diabetes, lower choles-
terol levels, promote weight loss, and improve body composition.
Chromium is an essential micronutrient and also a toxic metal. Chro-
mium is essential for the proper metabolism of carbohydrates, fat and
protein in the body. Chromium improves insulin sensitivity by means
of increasing insulin binding to cells, increasing insulin receptor
numbers, and activation of insulin receptor kinase, leading to increased
insulin sensitivity.
