VITAMIN D
and cholesterol
The importance of the sun
DR DAVID GRIMES
Vitamin D and Cholesterol:
The importance of the sun
Vitamin D and cognitive decline
Llewellyn DJ et alArch Int Med 2010; 170:1135-1141
One of the concerns about getter older is the development of dementia, or more commonly cognitive decline. It has been observed that low blood levels of vitamin D are associated with reduced life expectancy, and vitamin D appears to be protective against neurological illness. The relationship between vitamin D and cognitive decline in the elderly has therefore been investigated by an observational study.
The study was in Italy, of 858 adults aged 65 years or older. They were followed up for 7 years and during this time measurements of cognitive function were made using standards methods the Mini-Mental State Examination (MMSE).
Blood vitamin D levels were assessed at the time of recruitment of the subjects. They were grouped into quartiles according to the vitamin D levels, as shown below. Those with the highest levels of vitamin D were given a standardised score of 1 and the other groups were scored relative to this.
It was felt that vitamin D would be influenced by various social factors including age, sex, education, baseline cognitive score, season of testing, alcohol consumption, smoking status, depressive symptoms, body mass index, total energy intake, and impaired mobility. The scores were therefore adjusted to take these factors into consideration.
The adjusted and unadjusted results are displayed. It is clear that in both cognitive decline is more rapid in those with the lowest levels of vitamin D compared to those with higher levels.
The rate of cognitive decline is only marginally increased when the blood level of vitamin D is in the range 10-20ng/mL (25-50nmol/L). It is much increased when the blood level is below 10ng/mL (25nmol/L), and this appears to be a major threshold level.
It is now appreciated that a blood level of vitamin D greater than 40ng/mL (100nmol/L) is ideal, but this was not assessed in this study.
This study provides another demonstration of the advantage of a high level of vitamin D in the blood.
| Vit D 25(OH)Dnmol/L | >75 | 50-75 | 25-50 | <25 |
| Vit D 25(OH)Dng/mL | >30 | 20-30 | 10-20 | <10 |
| Cognitive declineunadjusted | 1 | 1.27 | 1.26 | 1.78 |
| Cognitive declineadjusted | 1 | 1.19 | 1.09 | 1.6 |
