Role of Vitamin A (Retinol) During Pregnancy Could Be Extended to Human Kidney Development
Your health care provider will most likely prescribe a prenatal vitamin and mineral supplement. This will help make sure you get the vitamins and minerals you need, such as calcium, iron, and folic acid. Scientists know that your diet can affect your baby's health — even before you become pregnant. For example, recent research shows that folic acid helps prevent neural tube defects (including spina bifida) from occurring during the earliest stages of fetal development — so it's important for you to consume plenty of it before you become pregnant and during the early weeks of your pregnancy.
Even though lots of foods, particularly breakfast cereals, are fortified with folic acid, doctors now encourage women to take folic acid supplements before and throughout pregnancy (especially for the first 28 days). Be sure to ask your doctor about folic acid if you're considering becoming pregnant.
Calcium is another important nutrient for pregnant women. Because your growing baby's calcium demands are high, you should increase your calcium consumption to prevent a loss of calcium from your own bones. Your doctor will also likely prescribe prenatal vitamins for you, which contain some extra calcium.
Retinol, the animal form of vitamin A, is a yellow fat-soluble, antioxidant vitamin important in vision and bone growth. It belongs to the family of chemical compounds known as retinoids. Retinol is ingested in a precursor form; animal sources (milk and eggs) contain retinyl esters, whereas plants (carrots, spinach) contain pro-vitamin A carotenoids.
But during pregnancy do not take additional vitamins and minerals unless your health care provider says that you should. Large amounts of vitamins and minerals, especially vitamin A, can be harmful.
According to the government, you need to get about 770 micrograms RAE of vitamin A each day during pregnancy. (This is approximately equal to 2,565 IU.) While you're nursing, your needs increase to 1,300 mcg RAE (4,330 IU) per day.
Mothers will low levels of vitamin A during pregnancy have an increased chance of giving birth to an infant with small kidneys, new research suggests.
The results of animal studies suggest a role for vitamin A, also known as "retinol," in the development of kidney structures called nephrons. Recent reports have also linked kidney size at birth with high blood pressure in later life. This prompted Dr. Paul Goodyer from the McGill University Health Centre in Montreal, and colleagues to compare the vitamin A status of pregnant women with the kidney size of their offspring at birth.
As reported in the journal Pediatric Nephrology, 48 women from Montreal and 46 from Bangalore, India with uncomplicated pregnancies were enrolled in the study. Nutritional status and blood retinol levels were assessed between 10 and14 weeks, 20 and 28 weeks, and 32 and 36 weeks. Kidney size in the newborns was determined within 2 days of birth using ultrasound.
The researchers found that retinol levels were lower in the Bangalore group compared with the Montreal group. At the same time, they found that the infants in Bangalore had smaller kidneys than their counterparts in Montreal.
Animal studies have shown that fetal kidney development depends on a chemical derived from vitamin A passed from the mother to the fetus, co-author Dr. Kishore Phadke, from St. John's Academy of Health Sciences, Bangalore, told Reuters Health.
"This concept could be extended to human kidney development," he said, "wherein maternal vitamin A levels will be crucial to determine the nephron number, size and function of kidneys in the developing fetus."
If the link between maternal vitamin A and fetal kidney size is confirmed by larger studies, "there may be important public health implications for regions of the world where maternal vitamin A deficiency is prevalent," the researchers conclude.
However, Phadke noted that vitamin A supplements are not routinely recommended for pregnant women in India, because of the narrow therapeutic dose range. "Excess vitamin A supplementation can cause (harmful effects) in the growing fetus and this makes universal supplementation of vitamin A difficult in pregnant women."Do not take more thatn 5,000 IU (international units) of vitamin A a day.
Choose a diet that includes a variety of healthy, nutritious foods. What are some good choices? Fruits, vegetables, whole-grain breads and pastas, milk products, and low-fat protein sources such as lean red meat, beans, tofu, poultry and some fish.Actually, it's easy to get plenty of vitamin A from the average American diet, since it's widely available in meat, dairy, fish, eggs, and fortified cereals in the form of "preformed vitamin A" as well as in most fruits and vegetables in the form of beta-carotene (a nutrient that gets converted to vitamin A by your body as needed).
The risk of birth defects from getting too much vitamin A is also the reason that pregnant women and those trying to conceive should stay away from the prescription acne drug isotretinoin (also known by the brand name Accutane, among others) and other drugs related to retinol (a compound of vitamin A), including topical tretinoin (Retin-A), a cream that's used for skin conditions.