Veröffentlichungen • Zinc status in pregnancy assessed by hair analysis - nutritional influences
U. Heins, C. Koebnick, C. Leitzmann
Poster for the 10th International Symposium on Trace Elements in Man and Animal, Evian, France 1999
A reduction of meat consumption is recommended internationally to prevent nutrition-related diseases (1,2). However, meat is an important nutritional source of zinc in western diets. In western countries serious zinc malnutrition is found rarely but marginal lack of zinc seems to be more spread than assumed up to now. An adequate supply with zinc in pregnancy is necessary for fetal growth and development (3).
To investigate the zinc status of pregnant women following recommendations for an overall healthy diet, Wholesome Nutrition (WN), in comparison to an average mixed diet.
Pregnant women adhering
to WN for about 2 years (preference of foods of plant
origin, ovo-lacto-vegetarian diet or low-meat diet
- up to two portions of meat per week; little processing
of food e.g. whole grain products) (n=56) were compared
to women practising an average western diet (control
group, CG, n=32). Data were collected in each trimester
(9th to 12th, 20th to 22th and 36th to 38th week of
pregnancy). The nutritional zinc intake was assessed
by an estimated dietary food record (3 x 4 d, Sunday
to Wednesday) and calculated with the German Food
Code and Nutrition Data Base (Bundeslebensmittelschlüssel
The nutrient density of zinc is higher in the WN group [1,5 mg/MJ (1.3/1.6)] than in the control group [1,3 mg/MJ (1.2/1.5)] (p=0.001). The absolute intake of zinc (~12.4 mg/d) show no difference between WN and CG. WN get less zinc from meat, fish and eggs (p<0.0001) but more from whole grain products (p<0.0001) than CG. About 30 % of the zinc intake by WN derives from whole grain products, only 7 % from products from refined flour and 5 % from meat, fish and eggs. Only 10 % of the zinc eaten by CG comes from whole grain products, 19 % from refined flour products and 27 % from meat, fish and eggs (figure 2).
The concentration of zinc in serum declines during pregnancy mainly caused by plasma dilution. The activity of the alkaline phosphatase increases due to placental alkaline phosphatase, which is measurable in the mothers blood from the 16th week of pregnancy (5). Therefore both parameters are limited in their evidence. Hair zinc concentration is not influenced by plasma dilution or placental enzymes, it represents a useful additional analytical material for zinc (6). The supply with zinc for both groups is adequate during pregnancy, while zinc content in hair is higher in WN group than in the CG. This indicates that zinc from WN is better biavailable than zinc from an average western diet. Because of the more favourable zinc status of those consuming more whole grain products (WN) the current discussion of the lower zinc bioavailiability due to phytate cannot be supported (7). More studies are necessary to determine the bioavailiability of whole diets instead of single nutritional factors.
This study shows that a well balanced low-meat or ovo-lacto vegetarian diet during pregnancy may lead to a better supply with zinc.
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