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Scientific Opinion on the substantiation of health claims related to wheat bran fibre and increase in faecal bulk (ID 3066), reduction in intestinal transit time (ID 828, 839, 3067, 4699) and contribution to the maintenance or achievement of a normal body weight (ID 829) pursuant to Article 13(1) of Regulation (EC) No 1924/2006[sup]1[/sup] EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)2, 3 European Food Safety Authority (EFSA), Parma, Italy
Słowa kluczowe: Wheat bran fibre   faecal bulk   health claims   intestinal transit time   weight management  
ID:    3066      3067      839      4699      828      829  
Produkty: Błonnik z otrębów pszennych  

1. Charakterystyka żywności / składnika

The food constituent that is the subject of the health claims is “wheat grain fibre”, “wheat bran and wheat bran products”, and “Triticum aestivum – wheat bran”. The Panel assumes that the active food constituent is wheat bran fibre.
Wheat bran fibre is a component of wheat bran, which consists of the outer coat (pericarp, testa and aleuron layer) of the wheat grain (Triticum aestivum L). Wheat bran is separated from the other parts of the wheat kernel by milling and the chemical composition of wheat bran varies with the extraction rate. Wheat bran is predominantly composed of non-starch polysaccharides (∼38 %), starch (∼19 %), protein (∼18 %) and lignin (∼6 %), with the non-starch polysaccharides being primarily ∼70 % arabinoxylans, ∼19 % cellulose and ∼6 % β-(1,3)/β-(1,4)-glucan. Wheat bran typically contains approximately 45 % of dietary fibre, of which about 95 % is non-soluble fibre (Cornell and Hoveling, 1998; Pomeranz, 1988). Wheat bran products may differ with regard to chemical composition and particle size depending on the milling process.
The Panel considers that the food constituent, wheat bran fibre, which is the subject of the health claims, is sufficiently characterised.

2. Znaczenie oświadczenia dla zdrowia człowieka


2.1. Zwiększenie masy stolca (ID 3066)

The claimed effect is “intestinal health: faecal bulking”. The Panel assumes that the target population is the general population.
The Panel considers that an increase in faecal bulk might be a beneficial physiological effect.

2.2. Skrócenie czasu pasażu jelitowego (ID 828, 839, 3067, 4699)

The claimed effects are “gut health” and “intestinal transit time, intestinal health”. The Panel assumes that the target population is the general population.
In the context of the clarifications provided by Member States, the Panel assumes that the claimed effect refers to a reduction in intestinal transit time.
The Panel considers that a reduction in intestinal transit time within the normal range might be a beneficial physiological effect.

2.3. Udział w utrzymaniu lub osiągnięciu prawidłowej masy ciała (ID 829)

The claimed effect is “weight control”. The Panel assumes that the target population is the general population.
Weight management can be interpreted as the contribution to the maintenance of a normal body weight. In this context even a moderate weight loss in overweight subjects without achieving a normal body weight is considered to be a beneficial physiological effect.
The Panel considers that contribution to the maintenance or achievement of a normal body weight is a beneficial physiological effect.

3. Naukowe uzasadnienia wpływu na zdrowie człowieka - 

Forty seven studies were cited for the scientific substantiation of two claimed effects: “increase in faecal bulk” and “reduction in intestinal transit time”.
Several studies were considered as not being pertinent for the scientific substantiation of the claimed effects evaluated in sections 3.1 and 3.2: a study with patients with severe constipation following spinal cord injury (Cameron et al., 1996), a study measuring the effect of wheat bran on faecal bile acid concentration (Alberts et al., 1996) and publications targeted for the general public (Medical News Today; Mindell, 1994). The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claimed effects. The data from two references were identical (Fuchs et al., 1976; Floch and Fuchs, 1978) and were treated as one study. The text of the unpublished study was not available to the Panel (Dodi, unpublished).

3.1. Zwiększenie masy stolca (ID 3066)

The effect of wheat bran fibre on stool bulk was evaluated in 32 human intervention studies.
In 29 out of 32 studies, a statistically significant increase of wet and/or dry stool weight was found. In the remaining three studies statistically significant differences were also demonstrated but were limited to the higher doses of wheat bran fibre (Spiller et al., 1986) or coarse wheat bran (Smith et al., 1981; Wyman et al., 1976).
In several studies a dose dependent effect of wheat bran on faecal bulk was demonstrated. Jenkins et al. (1987) estimated that 1 g of wheat bran produced a mean increase of 2.7 g in faecal weight and Cummings calculated that 1 g of dietary fibre from wheat bran increased stool weight by about 5.3 g (SEM±0.7g) (Cummings, 1976). Chen et al. (1998) found an increase in mean wet stool weight of 4.5 g for each additional gram of wheat fibre consumed, while Stephen et al. (1986) calculated that 1 g of non-starch polysaccharides (the main component of dietary fibre) from wheat bran increased stool weight by 5 g/day. The effect is independent of the initial daily faecal weight.
The results of a meta-analysis of 20 studies also showed that wheat bran fibre increased stool weight (Muller-Lissner, 1988), and this effect is also supported by an animal study (Kahlon et al., 2001).
The insoluble components of fibre are minimally degraded by colonic bacteria, and thus remain to trap water, thereby increasing faecal bulk (Graham et al., 1982).
In weighing the evidence, the Panel considered that the majority of the human intervention studies showed a consistent effect of wheat bran fibre on faecal bulk, and that no threshold dose for the effect can be established. A linear dose dependent relationship was demonstrated in several studies.
The Panel concludes that a cause and effect relationship has been established between the consumption of wheat bran fibre and an increase in faecal bulk.

3.2. Skrócenie czasu pasażu jelitowego (ID 828, 839, 3067, 4699)

In 23 human intervention studies the effect of wheat bran fibre on intestinal transit time was evaluated.
The studies differed by design (randomised controlled trials, single or double-blind, cross-over design, non-randomised). Different doses of wheat bran fibre were used and the dose used was expressed in different ways (e.g. dose of wheat bran, dose of fibre given or administered, portion of food enriched by wheat bran); different methods were used to assess transit time (several radio-opaque markers and scintigraphic methods) and different methods were applied to calculate the results (e.g. mean transit time, time needed to pass 50 %, 75 % or 80 % of pellets, number of pellets in first two stools passed at least 24 h after ingestion of the marker, percent of pellets in faeces within three days after marker intake). Taking into account the different designs of the studies presented, it is not possible to compare all of these results directly.
From the 23 studies provided, the results of 14 studies (with the dose of wheat bran fibre from 4 to 27 g daily) demonstrated a statistically significant decrease of intestinal transit time (Arffmann et al.,1985; Badiali et al., 1995; Cummings et al.,1976; Graham et al., 1982; Lampe et al., 1993; Lewis and Heaton, 1997; Melcher et al., 1991; Mortensen et al., 1987; Muir et al., 2004; Rees et al., 2005; Spiller et al., 1986; Stephen et al., 1986; Stevens et al., 1988; Tomlin and Read, 1988). In three studies, administration of wheat bran (with the dose of fibre from 6 to 8 g daily) did not significantly affect transit time (Eastwood et al., 1973, 1983; Vincent et al., 1995). The remaining six studies measured multiple endpoints and their results were not consistent (Ziegenhagen et al.; 1991; Balasubramanian et al., 1987; Hebden et al., 2002; Wrick et al., 1983; Wyman et al., 1976; Smith et al., 1981).
A meta-analysis of 20 cross-over studies (with wheat bran fibre 5–18 g/day) demonstrated an effect of wheat bran fibre on decreasing intestinal transit time but the dose effect was not assessed (Muller- Lissner, 1988).
The amount of at least 10 g/day of wheat bran fibre was connected with a statistically significant decrease in intestinal transit time in 14 out of 16 studies submitted. In another two studies, only some of the methods used for assessing intestinal transit time showed an effect (Wrick et al. 1983; Ziegenhagen et al., 1991).
The results of nine studies in which wheat bran fibre was used at the daily dose of 4-9.9 g revealed inconsistent results. In four studies a decrease in intestinal transit time was found (Spiller et al., 1986; Muir et al., 2004; Rees et al., 2005; Graham et al. 1982) while in another three studies, no effect on transit time could be demonstrated (Eastwood et al., 1973, 1983; Vincent et al., 1995). In the remaining two studies, intestinal transit time was measured by several methods and only the results of part of the measurements showed a statistically significant effect (Wyman et al., 1976; Smith et al., 1981).
The Panel notes the dose-dependency of the results and that trials with daily doses of wheat bran fibre below 10 g resulted in inconsistent outcomes.
Wheat bran fibre increases water holding capacity of the content of the intestine, increases intestinal and pancreatic fluid secretion and thus increases the velocity of chyme displacement through the intestine (Jenkins et al., 1987).
In weighing the evidence, the Panel took into account that the studies provided consistently indicated that wheat bran fibre consumed at an amount of at least 10 g/day decreased intestinal transit time.
The Panel concludes that a cause and effect relationship has been established between the consumption of wheat bran fibre and a reduction in intestinal transit time.

3.3. Udział w utrzymaniu lub osiągnięciu prawidłowej masy ciała (ID 829)

None of the references provided for the scientific substantiation of the claimed effect addressed the effect of consumption of wheat bran fibre on maintenance or achievement of a normal body weight.
One human study submitted for the scientific substantiation of another claim evaluated in this opinion (ID 828) dealt with the effect of a formula diet providing 692 kcal per day, consisting of 50.7 g of protein, 13.6 g of fat and 91.3 g of carbohydrates, and containing 14.3 g of wheat bran and 3 g of apple pectin, on the reduction of body weight in eight obese subjects (Matzkies et al., 1982). The Panel considers that no conclusions can be drawn from this study for the scientific substantiation of the claimed effect.
The Panel concludes that a cause and effect relationship has not been established between the consumption of wheat bran fibre and contribution to the maintenance or achievement of a normal body weight.

4. Uwagi do zaproponowanego brzmienia oświadczenia


4.1. Zwiększenie masy stolca (ID 3066)

The Panel considers that the following wording reflects the scientific evidence: “Wheat bran fibre contributes to an increase in faecal bulk”.

4.2. Skrócenie czasu pasażu jelitowego (ID 828, 839, 3067, 4699)

The Panel considers that the following wording reflects the scientific evidence: “Wheat bran fibre contributes to a reduction in intestinal transit time”.

5. Warunki i możliwe ograniczenia stosowania oświadczenia


5.1. Zwiększenie masy stolca (ID 3066

The Panel considers that in order to bear the claim a food should be at least “high in fibre” as per Annex to Regulation (EC) No 1924/2006. The target population is the general population.

5.2. Skrócenie czasu pasażu jelitowego (ID 828, 839, 3067, 4699)

The Panel considers that in order to obtain the claimed effect at least 10 g per day of wheat bran fibre should be consumed in one or more servings. The target population is the general population.

Wnioski

On the basis of the data presented, the Panel concludes that:
The food constituent, wheat bran fibre, which is the subject of the health claims, is sufficiently characterised.
Increase in faecal bulk (ID 3066)
The claimed effect is “intestinal health: faecal bulking”. The target population is assumed to be the general population. An increase in faecal bulk might be a beneficial physiological effect.
A cause and effect relationship has been established between the consumption of wheat bran fibre and an increase in faecal bulk.
The following wording reflects the scientific evidence: “Wheat bran fibre contributes to an increase in faecal bulk”.
In order to bear the claim a food should be at least “high in fibre” as per Annex to Regulation (EC) No 1924/2006. The target population is the general population.
Reduction in intestinal transit time (ID 828, 839, 3067, 4699)
The claimed effects are “gut health” and “intestinal transit time, intestinal health”. The target population is assumed to be the general population. A reduction in intestinal transit time within the normal range might be a beneficial physiological effect.
A cause and effect relationship has been established between the consumption of wheat bran fibre and a reduction in intestinal transit time.
The following wording reflects the scientific evidence: “Wheat bran fibre contributes to a reduction in intestinal transit time”.
In order to obtain the claimed effect at least 10 g per day of wheat bran fibre should be consumed in one or more servings. The target population is the general population.
Contribution to the maintenance or achievement of a normal body weight (ID 829)
The claimed effect is “weight control”. The target population is assumed to be the general population. Contribution to the maintenance or achievement of a normal body weight is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of wheat bran fibre and contribution to the maintenance or achievement of a normal body weight.