Title: Safety of low-carbohydrate diets
Author(s): Crowe TC
Source: OBESITY REVIEWS Volume: 6 Issue: 3 Pages: 235-245 Published: AUG 2005
Title: Low-carbohydrate diets: what are the potential short- and long-term health implications?
Author(s): Bilsborough SA, Crowe TC
Source: ASIA PACIFIC JOURNAL OF CLINICAL NUTRITION Volume: 12 Issue: 4 Pages: 396-404 Published: 2003
Title: Ketogenic diets for weight loss: A review of their principles, safety and efficacy
Author(s): Sumithran P, Proietto J
Source: OBESITY RESEARCH & CLINICAL PRACTICE Volume: 2 Issue: 1 Pages: 1-13 Published: MAR 2008
I could certainly keep going. All warn of serious side effects -- not just vitamin deficiencies -- with Atkin's-type diets followed long term in the manner in which average people -- especially left to their own devices rather than guided by a health professional -- tend to follow them.
Cause, you know, three people who don't know each other all developing a vit. C deficiency which was directly linked by doctors to their dietary choices isn't enough to ring alarm bells.
Your parents, with their medical background, I am sure are doing it in a perfectly safe way, as would most people who are doing the diet in consultation with a doctor. A hell of a lot of people don't: they buy a book and leap straight in. That book is often produced with limited or no input from any health professional, and there are no regulations on what warnings, etc, must be published. I've laughed over vegan rawfood diet books that actively rubbish the mainstream medical opinion, and insist that vitamin B12 is not a neccessary nutrient for the body, and that it's all anti-vegan suppresive lies. Hmmmm....