Raisins do not cause hike in dental plaque acidity, study

By Jane Byrne

- Last updated on GMT

Related tags Sugar Carbohydrate

Bran cereal with unsweetened raisins does not increase the levels of acid in dental plaque than bran flakes alone, which may put paid to the commonly held perception that raisins are acidogenic, claims a new US study.

However, eating commercially marketed raisin bran led to significantly more acid in the plaque, according to the findings of research published in the journal Pediatric Dentistry.

The research, led by Christine Wu, professor and director of cariology research at the University of Illinois at Chicago (UIC), was supported by the California Raisin Marketing Board.

Achint Utreja, a research scientist and dentist formerly on the research team, said the study showed that consumption of raisins or bran flakes with unsweetened raisins did not reduce plaque below pH 6, with pH 5.5 being a well-documented ‘danger zone’ of dental plaque acidity.

However, he noted that eating commercially marketed raisin bran led to significantly more acid in the plaque, straying towards the ‘danger zone’ marker, in comparison to the other test foods.

Lead investigator Wu claims that though some dentists believe sweet, sticky foods such as raisins cause cavities because they are difficult to clear off the tooth surfaces, previous studies have indicated that raisins are, in fact, rapidly cleared from the surface of the teeth just like apples, bananas and chocolate.

Study details

In order to investigate the effect of raisins and raisin-containing cereals on dental plaque pH in young children, 20 children aged between 7 and 11 years participated in a randomized controlled study, said the team.

The researchers said that the four test food groups were raisins, bran flakes, commercial raisin bran cereal (cRB) and mix of bran flakes with raisins lacking any added sugar, while sucrose, or table sugar, and sorbitol, a sugar substitute often used in diet foods, were also tested as controls.

Subjects refrained from oral hygiene for 24 hours prior to each test, they added.

Children chewed and swallowed the test foods within two minutes. The acid produced by the plaque bacteria on the surface of their teeth was measured at intervals, continued the researchers.


The research team reported that all test foods, except the sorbitol solution, promoted acid production in dental plaque over 30 minutes, with the largest reduction noted between the first 10 to 15 minutes. Moreover, they found that ingesting cRB produced the highest plaque pH drop after 10 minutes.

But the authors said that the addition of raisins to bran flakes (eRB) promoted a less pronounced pH drop beyond 10 minutes when compared to bran flakes alone, and thus they concluded that the consumption of raisins or adding raisins to bran flakes (eRB) did not reduce plaque pH.

Sugary cereals

Earlier this month, General Mills said that it intends to reduce sugar in cereals advertised to children to single-digit grams per serving but it did not commit to a timeline for the reduction.

The company came under fire recently when its Cocoa Puffs cereal – among sugary cereals made by other companies – was included in the Smart Choices food labelling program, despite containing 33 per cent sugar, or 11 grams per serving.

Widespread criticism of its inclusion led the US Food and Drug Administration (FDA) to announce it would carry out an investigation of the scheme, and the program was dropped in October.

In November, researchers at Yale’s Rudd Center for Food Policy and Obesity found that cereals marketed directly to children have 85 per cent more sugar, 65 per cent less fiber, and 60 per cent more sodium than cereals marketed for adult consumption

Source: Pediatric Dentistry
Title: Raisins and Cereals Containing Raisins on Plaque Acidogenicity in Children
Authors: A. Utreja, P. Lingstrom, L. Salzman, C. Evans, C. D. Wu

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