very interesting topic indeed...i personally feel there must be an impact of spirituality on psychological and physiological health and in turn on nutritional status...i will try to search for the related articles.

best of luck

Relationships of Religion and Spirituality to Glycemic Control in Black Women With Type 2 Diabetes

Newlin, Kelley; Melkus, Gail D.; Tappen, Ruth; Chyun, Deborah; Koenig, Harold G.

Generally, faith or belief in some deity has been strongly associated with general well-being and good general health. This has been attributed to the strict observance of many ethical standards most people of faith abide by. The hope created by the faith in God's word helps many people to withstand and comfortably overcome adversities in life which helps them to reduce the incidence of depression. Most of these findings have been documented and can be obtain from the internet. 

In terms of nutrition and nutritional status, it can be both positive and negative. In cultures where good nutritious food may be prohibited to mothers and children this can negatively affect their nutritional status. When the best source of a particular nutrient in the culture or community is proscribed by the religion this can pose serious nutritional challenge to the mothers and children.

Where the belief encourages healthy eating, living and choices of nutritious foods then this can improve nutritional status. Advocacy for good nutritional practices often has great impact on behavior changes especially in people of faith if it can be demonstrated that it accords with their faith. 

Most people of faith also embark on fasting. This helps to reduce excessive accumulation especially of fat in the body when done regularly and well monitored to avoid excessive hunger.

http://www.ruhanisatsangusa.org/pdf/VegetarianDiet-2013.pdf is by Sant Kirpal Singh and his Master Hazur Baba Sawan Singh

The Compasssionate Diet is by a disciple of Kirpal Singh (the founder of the Nature's Path company), Arran Stephens: http://www.arranstephens.com/books/the-compassionate-diet/

http://spritualview.blogspot.com.br/2011/06/vegetarian-way-of-life-by-sant-darshan.html is by the current living master Rajinder Singh. 

Hello Geoffrey,

I cannot give you references but what food one consumes, is said to have a relationship to the state of one´s mind or surface consciousness.  In India they talk of food that is sattvic, ragastic and tamasic.  Sattvic food is said to produce more clarity of mind whereas non vegetarian food is generally considered tamarsic - it produces dullness and is heavy.  Rajastic is more energetic  and can cause imbalances. These days there is an additional problem with food as much of our diet may  be  full of toxins such as pesticides etc if it is not grown organically. Hence people on the spiritual path need to also be aware of this. It would be interesting finding out more about these differences with regards to food intake in elderly people  so I wish you every success in your research. 

Warm regards Tina