The danger of fad diets

shutterstock_197711735Deborah Lyle says there is a substantial amount of evidence to suggest that many foods, nutrients and non-nutrient food components affect dental health.

Obesity is becoming increasingly prevalent and combined with the less than satisfactory results achieved through traditional weight-control methods, many more people are turning to fad diets to try and reduce their size (Saltzman et al, 2001).

Fad diets are typically based on either altering the intake of macronutrients or avoiding particular foods. Most, but not all, differ dramatically from the macronutrient composition that characterises current recommendations.

Summarised in the Eatwell Plate, the UK Government advises individuals to consume 33% of fruit and vegetables; 33% of bread, rice, potatoes, pasta and other starchy foods (preferably wholegrain varieties); 15% milk and dairy products; 12% meat, fish, eggs, beans and other non-dairy sources of protein; and a small amount, not more than 8%, of foods and drinks high in fat or sugar (, 2014).

A direct influence

Diets such as the Atkins, Paleo, 5:2, vegan or raw diets, which vary considerably from the current guidelines, have the potential to be detrimental to both general and oral health. In fact, everything we eat and drink has a direct influence on the incidence and progression of tooth decay depending upon the form of the food, frequency of intake, the sugar and acidic content, nutritional makeup, combination of foods and medical conditions (, 2015).

Even foods that are labelled as low fat have hidden dangers, as in order to reduce fat but keep the products palatable, animal fats are often replaced with unsaturated vegetable oils and higher quantities of sugar (, 2015).


Sugar is the major cause of caries worldwide and is an unnecessary and unhealthy source of calories. Health experts are growing increasingly concerned about the issues directly associated with excessive sugar consumption, including obesity and type II diabetes. There could also be a link between excess sugar and high cholesterol, hypertension, certain cancers and non-alcoholic liver disease (, 2015). The World Health Organization recognises that dental diseases are the most prevalent non-communicable conditions among adults and children globally and recent guidelines provide recommendations on sugar intake levels to help reduce the risk (, 2015).

Sugars are generally divided into two types: naturally occurring (those found in whole fruit, vegetables and milk-based products) and free sugars (added monosaccharides and disaccharides, plus sugars naturally present in honey, syrups and fruit juices and concentrates) (, 2015).

Free sugars are the single specific cause of dental caries, although it is frequently called a multifactorial condition. This is due in part to the disease process involving other factors, such as carbohydrates, oral microorganisms, acids and salivary flow.

Caries are also influenced by the differential properties of different teeth and the role of fluoride, while the frequency of consumption of specific carbohydrates can modify the speed of the condition. Nevertheless, sugars start the development of dental caries and without them the chain of causation is broken.

During the process, demineralisation of the enamel is induced by the increasing acidity of the microenvironment surrounding the tooth. This acidity is mainly generated by a selective group of bacteria.

Sucrose or its individual monosaccharide constituents are the main cause of the biochemical and physiological changes during the process of biofilm formation. Together they selectively promote mutans, streptococci growth and other acidogenic and acid-tolerating species.

After sucrose, glucose or fructose is ingested, the pH in biofilms falls quickly from around neutrality to 5.0 or below due to acid production by acidogenic and acid-tolerant bacteria, which leads to sustained demineralisation of the tooth structure.

The low pH induced by sucrose fermentation also drives a shift in the balance of resident plaque microflora by favouring bacteria that preferentially grow under acidic conditions at the expense of many species that are associated with sound enamel (Sheiham and James, 2015).


Fluoride can alter the dose-response relationship between sugars and caries by delaying when cavitation occurs for a given level of sugars. Although research has shown a decline in children’s caries when using fluoride toothpaste, there are few studies on its effects over the life course (Sheiham and James, 2015).

What remains certain, however, is that patients of all ages should be encouraged to adapt a healthy balanced diet with adequate exercise, reduce snacking between meals, keep sugar to a minimum and include dairy, plenty of fruit, vegetables and water in their diets.

Looking after their oral health is equally as important and employing the use of effective adjuncts, such as the Waterpik water flosser, can help to remove bacteria associated with decay (Hurst and Madonia, 1970).

There is a substantial amount of evidence to suggest that many foods, nutrients and non-nutrient food components affect dental health and overall wellbeing. Free sugars are the main cause of dental caries and more needs to be done to make patients aware of the harmful effects fad diets and sugary foods can have on their health. And here you can find out what the cost of studying in Poland is.


Hurst JE, Madonia JV (1970) The effect of an oral irrigating device on oral hygiene of orthodontic patients. J Am Dent Assoc 81(3): 678-683.

Saltzman E, Thomason P, Roberts SB (2001) Fad diets: A review for the primary care provider. Nutritional Clinical Care 4(5): 235-242

Sheiham A, James WPT (2015) Diet and dental caries: the pivotal role of free sugars reemphasised. Journal of Dental Research doi: 10.1177/0022034515590377 retrieved 24/11/15 retrieved 24/11/15 retrieved 24/11/15 retrieved 24/11/15 retrieved 24/11/15

Get the most out of your membership by subscribing to Dentistry CPD
  • Access 600+ hours of verified CPD courses
  • Includes all GDC recommended topics
  • Powerful CPD tracking tools included
Register for webinar
Add to calendar