ID 716 - Kwas stearynowy

PL: Kwas stearynowy
EN: Stearic acid
Pdf: stearic acid

Oświadczenie (2)

1. Charakterystyka żywności / składnika

The food constituent that is the subject of the health claim is stearic acid.
Stearic acid (octadecanoic acid) is a saturated fatty acid (SFA) with 18 carbon atoms. Stearic acid is found at varying amounts in all dietary fats. In most vegetable fats it comprises 1-5% of fatty acids, but in certain fats (cocoa butter, shea butter, sal fat, illipe butter, mango kernel oil) much higher proportions (36-45%) are found. Milk and meat fats contain 10-20% stearic acid. Stearic acid can be measured in foods by established methods.
The Panel considers that the food constituent, stearic acid, which is the subject of the health claim is sufficiently characterised.

2. Znaczenie oświadczenia dla zdrowia człowieka

The claimed effect is “lipid metabolism”. The Panel assumes that the target population is the general population.
In the context of the proposed wording, the Panel assumes that the claimed effect refers to maintenance of normal blood cholesterol concentrations.
Low-density lipoproteins (LDL) carry cholesterol from the liver to peripheral tissues, including the arteries. Elevated LDL-cholesterol, by convention >160 mg/dL, may compromise the normal structure and function of the arteries.
The Panel considers that maintenance normal blood cholesterol concentrations is a beneficial physiological effect.

3. Naukowe uzasadnienia wpływu na zdrowie człowieka - Utrzymanie prawidłowego stężenia cholesterolu we krwi

Two meta-analyses of intervention studies in humans addressing the effects of stearic acid on blood lipids where presented in relation to this claim (Mensink et al., 2003; Yu et al., 1995).
In a meta-analysis including 35 studies reporting the effects of individual saturated fatty acids on blood cholesterol concentrations, Mensink et al. (2003) concluded that stearic acid does not increase blood LDL-cholesterol concentrations like saturated fatty acids (SFA) with 12 to 16 carbon atoms (lauric, myristic and palmitic acids) when 1% of dietary energy as carbohydrates are replaced isoenergetically by these fatty acids, but it also increased HDL-cholesterol concentrations less than other SFA.
Using a different approach, Yu et al. (1995) compiled the results from 18 intervention studies in healthy and mostly normocholesterolaemic adults to derive prediction equations on the effects of replacing 1% energy of the diet (diets with 30-40% of energy from fat) by particular fatty acids (SFA (12-16C), stearic acid, MUFA and PUFA) on total, LDL-, and HDL-cholesterol concentrations. The coefficients of these prediction equations for stearic acid were -0.0008 for total cholesterol, +0.0018 for LDL-cholesterol and -0.0016 for HDL-cholesterol concentrations, whereas for MUFA, the corresponding coefficients were -0.0214 for total cholesterol; -0.0178 for LDL-cholesterol and +0.01 for HDL-cholesterol. From these equations, replacing 1% of energy in a typical American diet by stearic acid would induce an increase in LDL- and a decrease in HDL-cholesterol concentrations.
A number of individual intervention studies in humans have also been cited in the list in relation to this claim.
Grande et al. (1970) compared the effects of four diets, one rich in palmitic acid and three rich in stearic acid (30-38% of fatty acids) during periods of 18 days in 30 men following a randomised cross-over design. Total blood cholesterol concentrations were highest on the palmitic acid diet compared to the three stearic acid diets. Bonanome and Grundy (1988) compared three liquid formula diets during 18 weeks in 11 subjects. As compared with a diet rich in palmitic acid, diets rich in stearic acid or oleic acid induced a decrease of 14% and 10% in total blood cholesterol concentrations and of 21% and 15% in LDL-cholesterol concentrations, respectively. In a study by Denke and Grundy (1991) four liquid formula diets with 40% of energy from fat were compared in 10 men. One diet was based on butter (4% of total fatty acids as stearic acid), one on beef tallow (7.6% of total fatty acids as stearic acid), one on cocoa butter (13.7% of total fatty acids as stearic acid) and one on olive oil (1.2% of total fatty acids as stearic acid). LDL-cholesterol concentrations were highest (4.23 mmol/L) after the butter diet, slightly lower (4.03 mmol/L) after the beef tallow diet, still lower (3.82 mmol/L) after the cocoa butter diet, and lowest (3.62 mmol/L) after the olive oil diet. Tholstrup et al. (1994) compared a diet with 43% stearic acid from shea butter (S) with a 42% palmitic acid (P) diet and a 30% lauric acid + 10% myristic acid (LM) diet. Diet S showed a reduction of 22% in total cholesterol, of 26% in LDL-cholesterol and of 13% in HDL-cholesterol concentrations compared with diet P, and a reduction of 28% in total cholesterol, of 29% in LDL-cholesterol and of 28% in HDL- cholesterol concentrations compared with diet LM. The LDL/HDL cholesterol ratio was lower on diet S compared with diet P but was unchanged in the S diet compared to the LM diet. Thijssen and Mensink (2005) compared three diets with 7% energy from either stearic acid, oleic acid or linoleic acid in 45 subjects over 5 weeks and did not find statistically significant differences in blood lipid concentrations between diets.
The clinical trials show that stearic acid does not increase total and LDL-cholesterol concentrations as much as SFA with 12-16 carbon atoms. When replacing carbohydrates by stearic acid, its effects on blood lipids seem to be rather similar to those of the monounsaturated fatty acid oleic acid, in part because stearic acid can be partially desaturated to oleic acid in the human organism (9-14 %, Emken, 1994; Rhee et al., 1997).
Dietary fats rich in stearic acid also contain considerable amounts of other SFA, particularly palmitic acid. This explains why higher LDL-cholesterol concentrations are found after feeding cocoa butter (about 36% stearic acid, 26% palmitic acid, 34% oleic acid) as compared with olive oil, which is rich in oleic acid but includes smaller amounts of palmitic acid than cocoa butter. Mensink et al (2003) estimated, based on the fatty acid composition of chocolate fat, that intake of the stearic acid-rich cocoa butter would increase the total/HDL cholesterol ratio as compared with the fatty acid composition of the average US diet.
In weighing the evidence, the Panel took into account that stearic acid differs from other long-chain saturated fatty acids in its effects on blood cholesterol but the scientific evidence does not demonstrate that intake of stearic acid would decrease total and/or LDL-cholesterol with respect to monounsaturated fatty acids or carbohydrates, which are considered neutral compared to their effects on LDL-cholesterol concentrations (Yu et al., 1995; Mensink et al., 2003), or that the addition of stearic acid per se to the diet would decrease LDL-cholesterol concentrations in humans. The Panel also notes that stearic acid is not consumed alone, and that foods rich in stearic acid do also contain considerable amounts of palmitic and other SFA with 12 to 16 atom carbons, which are known to increase LDL-cholesterol concentrations.
The Panel considers that a cause and effect relationship has not been established between the consumption of stearic acid and maintenance of normal blood cholesterol concentrations.

Warunki i możliwe ograniczenia stosowania oświadczenia

Up to 5% daily energy intake as stearic acid