Low plasma vitamin C in Alzheimer patients despite an adequate diet.

OBJECTIVE

To compare the vitamin C and E plasma levels in patients with Alzheimer's disease (AD) and to assess the vitamin C intake and nutritional status.

DESIGN

Case-control study. Four groups of sex- and age-matched subjects were compared: severe AD and moderate AD, in patients with moderate AD and controls.

SETTING

Community and hospitalized patients in the region of Toulouse, France.

PARTICIPANTS

Patients with dementia who fulfilled criteria for Alzheimer's disease: severe Alzheimer group (N = 20), Mini-Mental State Examination (MMSE) score range 0-9; moderate Alzheimer group (N = 24), MMSE 10-23; hospitalized Alzheimer group (N = 9), MMSE 10-23. Control group (N = 19), MMSE 24-30.

MEASURES

Plasma vitamin E and C were quantified by HPLC-fluorescence. Consumption of raw and cooked fruit and vegetables was evaluated in order to determine the mean vitamin C intakes. Mini Nutritional Assessment (MNA) and plasma albumin were used to measure nutritional status.

RESULTS

Institutionalized and community subjects were analysed separately. MNA scores were normal in home-living Alzheimer subjects with moderate dementia and significantly lower in those with severe disease, despite normal plasma albumin levels. In the home-living Alzheimer subjects, vitamin C plasma levels decreased in proportion to the severity of the cognitive impairment despite similar vitamin C intakes, whereas vitamin E remained stable. The hospitalized Alzheimer subjects had lower MNA scores and albumin levels but normal vitamin C intakes, but their plasma vitamin C was lower than that of community-living subjects. Institutionalized Alzheimer subjects had significantly lower MNA scores but normal vitamin C and albumin levels and vitamin C intakes compared with community-dwelling subjects of similar degree of cognitive impairment.

CONCLUSION

Plasma vitamin C is lower in AD in proportion to the degree of cognitive impairment and is not explained by lower vitamin C intake. These results support the hypothesis that oxygen-free radicals may cause damage.