Editing Human nutrition (section)

==== Elderly Nutrition: Vitamin-B Complex ====
The [[Vitamin b complex|Vitamin-B complex]], which includes eight water-soluble vitamins, plays a crucial role in maintaining cellular function and preventing brain atrophy. Among the elderly, deficiencies in vitamins [[Vitamin B12|B12]], [[Vitamin B6|B6]], and [[folate]] are linked to cognitive decline and depressive symptoms.<ref name=":4">{{Cite journal | last1=Ali | first1=Mennatallah A. | last2=Hafez | first2=Hala A. | last3=Kamel | first3=Maher A. | last4=Ghamry | first4=Heba I. | last5=Shukry | first5=Mustafa | last6=Farag | first6=Mohamed A. | date=2022-09-22 | title=Dietary Vitamin B Complex: Orchestration in Human Nutrition throughout Life with Sex Differences | journal=Nutrients | language=en | volume=14 | issue=19 | pages=3940 | doi=10.3390/nu14193940 | doi-access=free | issn=2072-6643 | pmc=9573099 | pmid=36235591}}</ref>

The Recommended Dietary Allowance (RDA) for vitamin B12 is 0.9-2.4 μg/day, while the estimated average requirement in the U.S. and Canada is 0.7-2 μg/day. Elderly individuals with plasma vitamin B12 levels below 148 pmol/L are considered severely deficient, and those with levels between 148 and 221 pmol/L are marginally deficient. A deficiency in these B-vitamins, particularly B6, B12, and folate, is associated with elevated [[homocysteine]] levels, which increase the risk of [[alzheimer's disease]] and [[dementia]]. Increased intake of these vitamins can lower homocysteine levels and reduce the risk of these conditions.<ref name=":4" /> According to the [[National Health and Nutrition Examination Survey]], about 6% of elderly Americans over 70 are severely deficient in vitamin B12, and more than 20% of those over 60 are mildly deficient. This deficiency is often due to insufficient food intake and [[malabsorption]] caused by degenerative digestive conditions, as indicated by elevated plasma [[gastrin]] levels in older adults. The deficiency of vitamin B6 among institutionalized elderly in Europe ranges from below 1% to 75%. B-vitamins are primarily found in animal-based foods, making deficiencies more common among those with limited animal food intake due to cultural, religious, or economic reasons. For vegetarians, fortified foods can be a viable alternative to ensure adequate vitamin B12 levels, especially when reducing laxative use to improve absorption.<ref name=":0" />