Витаминно-минеральные комплексы во время беременности

[Oleg Garin]

Уважаемые коллеги,

Очень бы хотелось узнать ваше мнение о целесообразности применения витаминно-минеральных комплексов типа "[Ссылки доступны только зарегистрированным пользователям ]" во время беременности.
Если целесообразность присутствует - можете ли вы прокомментировать столь существенную разницу между препаратами разных производителей, как например между "[Ссылки доступны только зарегистрированным пользователям ]" и вот этим: [Ссылки доступны только зарегистрированным пользователям ]

Большое спасибо.

[yananshs]

[Ссылки доступны только зарегистрированным пользователям ]
VITAMINS IN PREGNANCY

Vitamin A

Vitamin A, a fat-soluble vitamin, is important for maintenance of visual function. Its main influence is on the retina, but it also aids glycoprotein synthesis and promotes cellular growth and differentiation in other tissues. Vitamin A is found in green leafy vegetables and yellow-orange vegetables. The nonpregnancy RDA is 800 mcg, and this remains the same in pregnancy. The lactation RDA is 1300 mcg. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended. Doses exceeding 15,000 IU/d, often used to treat acne, are associated with an increased risk of birth defects and should not be used in pregnancy; however, alpha-carotene, a vitamin A precursor, is not teratogenic.

Vitamin B-1

Vitamin B-1, also known as thiamine, is a water-soluble B-complex vitamin. It is involved in the release of energy from cells. Its food sources include milk and raw grains. The RDA is 1.1 mg. In both pregnancy and lactation, the RDA increases to 1.5 mg. Well-balanced diets provide the pregnant and lactating RDA; therefore, routine supplementation is not recommended.

Vitamin B-2

Vitamin B-2, also known as riboflavin, is a water-soluble B-complex vitamin. It is also involved in the release of energy from cells. Vitamin B-2 is found in green vegetables, milk, eggs, cheese, and fish. The RDA is 1.3 mg. In pregnancy, the RDA increases to 1.6 mg; in lactation, it increases to 1.8 mg. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended.

Vitamin B-6

Vitamin B-6, also known as pyridoxine, is a water-soluble B-complex vitamin. It is important in protein, carbohydrate, and lipid metabolism. It is also involved in the synthesis of heme compounds. Vitamin B-6 is found mostly in vegetables. The RDA is 1.5 mg. In both pregnancy and lactation, the RDA increases to 2.2 mg. Well-balanced diets provide the pregnant and lactating RDA; therefore, routine supplementation is not recommended.

Vitamin B-12

Vitamin B-12, a water-soluble B-complex vitamin, is essential for DNA synthesis and cell division. It is found in animal proteins. Deficiency is usually secondary to compromised intestinal function. Dietary deficiency is rare, but it is occasionally encountered in persons who follow strict vegan diets. The RDA is 2 mcg. The pregnancy RDA is 2.2 mcg. The RDA increases to 2.6 mcg with lactation. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended.

Vitamin C

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin with numerous functions. These include reducing free radicals and assisting in procollagen formation. Vitamin C is found in fruits and vegetables. Chronic deficiency impairs collagen synthesis and leads to scurvy. The RDA is 60 mg. The pregnancy RDA is 70 mg. The RDA increases to 95 mg with lactation. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended.

Vitamin D

Vitamin D, a fat-soluble vitamin, is found in fortified milk. Exposure to ultraviolet light is necessary for vitamin conversion. Deficiency of vitamin D is associated with tooth enamel hypoplasia. The RDA is 200-400 IU. The RDA in both pregnancy and lactation is 400 IU. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended.

Vitamin E

Vitamin E, a fat-soluble vitamin, is an important antioxidant. It is found in animal protein and fats. Deficiency is not a major issue in obstetrics but has been implicated in newborn hemolytic anemia. The RDA is 8 mg. The pregnancy RDA is 10 mg; the lactation RDA is 12 mg. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended.

Vitamin K

Vitamin K, a fat-soluble vitamin, is required for synthesis of clotting factors VII, IX, and X. It is found in green leafy vegetables, tomatoes, dairy products, and eggs. Transportation of vitamin K from mother to fetus is limited; nevertheless, significant bleeding problems in the fetus are rare. However, newborn infants are often functionally deficient in vitamin K and receive parenteral supplementation at birth. The RDA is 60 mg. In pregnancy and lactation, the RDA increases modestly to 65 mg. Well-balanced diets provide the RDA for women who are pregnant or lactating RDA; therefore, routine supplementation is not recommended.

Folic Acid

Folic acid, a water-soluble B-complex vitamin, is important for DNA synthesis and cell replication. It is found in fortified grains, dried beans, and leafy greens (American College of Obstetricians and Gynecologists, 1996). Much has been written about folic acid and pregnancy. Deficiency in pregnancy has been linked with maternal megaloblastic anemia and fetal neural tube defects. The RDA is 0.2 mg. The pregnancy RDA is 0.4 mg; the RDA decreases to 0.2 mg in lactation.

In 1998, the US Food and Drug Administration mandated fortification of grains with folate. The degree of fortification was calculated to provide only 0.1 mg/d of dietary folate. This was enacted to avoid having supplemental folate mask evidence of vitamin B-12 deficiency in susceptible populations, especially elderly persons. Cereal fortification has resulted in a 32% decrease in the prevalence of elevated maternal serum alpha-fetoprotein values (Evans, 2004) and a 25% decline in the prevalence of open neural tube defects (Centers for Disease Control and Prevention, 2004).

Despite fortification, sufficient folic acid is not provided by the average American diet and routine supplementation of 0.4 mg/d is recommended for healthy women. Folate supplements should be administered 3 months prior to conception and throughout the first trimester. If the mother has a prior child affected by a neural tube defect, supplementation in the subsequent pregnancy should be increased to 4 mg/d.

Niacin

Niacin is a water-soluble vitamin involved in the release of energy from cells. It is found in poultry, fish, and nuts. Deficiency results in pellagra. The RDA is 15 mcg. In pregnancy, the RDA increases to 17 mcg, and to 20 mcg in lactation. Well-balanced diets provide the RDA for women who are pregnant and lactating; therefore, routine supplementation is not recommended.

[yananshs]

MINERALS AND TRACE ELEMENTS IN PREGNANCY

Iron

Iron is essential to the production of hemoglobin. Its dietary sources include animal protein, dried beans, fortified grains, and any food cooked in cast iron cookware. Despite its numerous sources, women have difficulty maintaining iron balance using only a healthy diet. A well-balanced diet with 10,460 kJ/d (2500 kcal) contains approximately 15 mg of elemental iron; however, the absorption of iron is very inefficient and only approximately 10% of this is absorbed. With each normal menses, 12-15 mg of elemental iron is lost. Estimates indicate that a woman's diet must include 1.5-2 mg/d of elemental iron to compensate for menstrual losses alone. In pregnancy, 500 mg of additional iron is needed to expand maternal red cell mass. Another 500 mg is needed to supply fetal and placental tissues. On average, an additional 3 mg/d of elemental iron must be absorbed from dietary sources.

The RDA for elemental iron reflects these increased requirements. The RDA for women who are not pregnant is 15 mg, 1.5 mg of which is absorbed. In pregnancy, the RDA is 30 mg, 3 mg of which is absorbed. During lactation, the RDA returns to 15 mg. Well-balanced diets do not provide the pregnancy RDA for elemental iron; therefore, iron supplementation is recommended in normal pregnancy.

Various iron preparations are commercially available, and each delivers a slightly different amount of elemental iron. These preparations include ferrous sulfate, ferrous fumarate, ferrous gluconate, and polysaccharide iron complex. Pure elemental iron is available in 50-mg caplets of carbonyl iron. Providers should be aware of the elemental iron contained in any one specific preparation, and they should understand that only 10% of this is absorbed from the maternal gut. Absorption is enhanced by concurrent ingestion of foods containing vitamin C. Usually, one dose of any preparation containing at least 30 mg of elemental iron meets the RDA. Larger doses are required only to treat maternal iron deficiency anemia and only serve to constipate patients without anemia. Physicians should remember that iron competes with zinc at absorption sites. The clinical implications of this are discussed in the Zinc section.

Iron deficiency anemia is one of the most common pregnancy complications. Screening for iron deficiency anemia is recommended at the first prenatal visit and, thereafter, as indicated. Iron deficiency anemia is suggested if the complete blood cell count suggests a microcytic, hypochromic anemia. Confirmatory test results include a reduced serum iron level, increased total iron-binding capacity, decreased transferrin saturation, and reduced serum ferritin levels. If a provider is unable to perform the complete battery of confirmatory tests, the serum iron and ferritin levels usually suggest the correct diagnosis. Treatment is increased oral iron supplementation.

Many studies have shown that high hemoglobin values are associated with adverse pregnancy outcomes; however, iron supplementation cannot, in itself, raise hemoglobin to these levels (Yip, 2000). Any adverse outcomes are more likely secondary to underlying conditions responsible for high hemoglobin values.

Calcium

Calcium is a major component of bone; therefore, large quantities of calcium are required in pregnancy for construction of fetal tissues, especially in the third trimester. Pregnant women younger than 25 years also still require calcium for maternal bone mass. Hormonal adaptations and increased intestinal absorption protect maternal bone while meeting fetal calcium requirements. A well-balanced diet provides adequate calcium to meet all of these needs, and supplementation is not recommended. The RDA for nonpregnant, pregnant, and lactating women is 1000 mg (Allen, 1998).

Calcium is found in dairy products and leafy green vegetables such as collard, kale, turnip, and mustard greens. Vitamin D is required for calcium absorption.

Phosphorus

Along with calcium, phosphorus is required for bone formation. Maternal serum inorganic phosphorus levels remain constant during pregnancy because of maternal adaptations. The RDA for nonpregnant, pregnant, and lactating women is 1000 mg. Well-balanced diets easily provide the RDA for nonpregnant, pregnant, and lactating women; supplementation is not recommended. In fact, phosphorus is not usually in vitamin supplements.

Zinc

Zinc is involved in nucleic acid and protein metabolism; therefore, zinc is important in early gestation. The RDA is 12 mg. The RDA for pregnant women is 15 mg, which increases to 19 mg during lactation. Well-balanced diets provide the RDA for women who are pregnant and lactating, and supplementation is not recommended. Both iron and copper compete with zinc at absorption sites; therefore, zinc supplementation is recommended when elemental iron supplementation exceeds 60 mg/d. Likewise, whenever zinc supplements are used, copper should also be supplemented. Different prenatal vitamin formulations contain different amounts of copper and zinc. Usually, copper or zinc supplementation can be accomplished by careful selection of a prenatal vitamin formulation.

Sodium

Sodium is present in large quantities in the average American diet. It has received much attention. In pregnancy, sodium should neither be restricted nor used excessively. Well-balanced diets “salted to taste” satisfy sodium requirements and obviate any need for supplementation. Pregnant women should remember that most processed and pre-prepared foods are high in sodium.

[yananshs]

PRENATAL VITAMIN SUPPLEMENTS

A standard prenatal vitamin formulation contains the following supplements:

* Iron - 30 mg

* Zinc - 15 mg

* Calcium - 250 mg

* Vitamin B-6 - 2 mg

* Folate - 0.3 mg

* Vitamin C - 50 mg

* Vitamin D - 5 mcg

Of course, contents vary by individual formulation, and nutrient supplementation should be chosen with attention to individual patient needs. A normal pregnancy and a well-balanced diet generally provide the RDA of all nutrients except elemental iron and folate, both of which must be supplemented. Prenatal vitamins are not otherwise necessary for every patient; however, these supplements are routinely prescribed to most patients for various important reasons. A major reason is that a nutritionally compromised pregnancy can be difficult to identify, and the potential benefits of routine supplementation overshadow any risk that can be attributed. Also, the psychological impact of supplementation cannot be overlooked. Many patients are uncomfortable with the idea of foregoing prenatal vitamins and are reassured by their prescription.

[yananshs]

Для России нужно добавить иодиды. В Kанаде иододефицита, кажется, нет.

[Oleg Garin]

Яна, большое спасибо.

[DrSusha]

megley! Реклама своих сайтов не участникам группы ВРАЧИ запрещена. Хотите поделиться, копируйте сюда текст.