NO - Besoin d'assistance

Observational epidemiological surveys (WG 3) page 70
_________________________________________________________________________________________
4.4 Vitamin C
4.4 1 Cataract (Table 40)
Among the eight studies published between 1989 and 1996, three studies based on the plasma
vitamin C level found no effect or a non significant effect on nuclear or cortical and early
cataract. Taking into account vitamin C intake, three studies showed a significant lower risk
in persons consuming more than 290 mg/day. Three other studies found no changes even if in
one of these studies, adjustment on women taking vitamin C for more than 10 years showed a
low relative risk (OR: 0.27 CI 0.11-0.67). Vitamin C is normally present at relatively high
concentration in the lens and the aqueous humor of diurnal mammals including humans
(about 1 mmol/l and 1.2 mmol/kg wet weight in humor and lens of humans respectively
(Varma, 1991). It has been noticed that aqueous humor vitamin C in patients with cortical
cataract was fifty percent lower than those with nuclear cataract (Varma, 1991). In an
investigation comparing the self reported consumption of vitamin supplements by 175
patients and a same number of matched controls, it was reported that individuals from the
control group took significantly more vitamin C (p = 0.01) and vitamin E supplements (p =
0.004). In the follow-up of the Beaver Dam Eye Study (Lyle et al., 1999) smokers and
subjects with hypertension showed a reduced risk of nuclear cataract (Table 39).
4.4.2 AMD (Table 41)
Two studies indicated that a blood vitamin C concentration of 80 µmol/L led to a protective
effect against AMD (OR = 0.55 CI 0.3-1.1 and 0.60 CI 0.4-0.9). One of these studies also
indicated that for the highest values there was no better protection and perhaps even less
protection.