Pregnant moms have been told for years to take extra calcium to protect their bones. Now, research is showing that it’s also important to get enough fat-soluble vitamins like vitamin D and vitamin K, not only for their effect on calcium metabolism but also for their ability to protect your growing baby.
Pregnancy is hard on a woman’s bones, where about 99 percent of a woman’s calcium is normally stored. Throughout pregnancy, calcium is transferred from the mother to the baby, ensuring the developing baby has enough calcium to grow strong bones and develop properly.
However, at the same time calcium is being drawn out from your bones, your body is making adjustments to protect your calcium supply and hopefully prevent bone disorders later in life. These adjustments include changes to your hormone levels, your ability to absorb calcium from foods, and how quickly calcium turns over in bones.
Still, studies have shown that calcium levels typically decline throughout pregnancy, leading doctors to recommend that pregnant women take steps to protect their calcium supply. Pregnant women are advised to get at least 1,300 mg of calcium daily.
Vitamin D and Pregnancy
Vitamin D is a critical factor in transporting calcium to the developing baby, where it is used to help build healthy bones and teeth, skin, and develop eyesight. The primary source of vitamin D comes from the sun. Vitamin D is synthesized in the skin in response to exposure to the sun’s ultraviolet rays.
Because exposure to sun varies by region, many experts recommend that pregnant women take vitamin D supplements to ensure they are receiving enough. A number of studies have shown that vitamin D supplements may contribute to higher birth-weight babies and reduce the rate of some complications in newborns, including calcium deficiency.
Vitamin D also has other benefits. Newer research has shown that levels of vitamin D “skyrocket” in early pregnancy, reaching levels that would be toxic in a non-pregnant person. Researchers believe this is because vitamin D plays an important role in regulating the immune systems of both the mother and her developing baby.
Pregnant and breastfeeding women should get a total of 600 IU of vitamin D every day. A typical daily prenatal vitamin offers about 400 IU. Good food sources of vitamin D include fortified milk, fatty fish like salmon, and egg yolks.
Vitamin K and Pregnancy
Although not as well known as vitamin D, research also shows that vitamin K is important during pregnancy to help maintain healthy calcium levels. Vitamin K works closely with vitamin D to help transfer calcium into the bones. It also increases the activity of a protein called osteocalcin, which makes it possible for the bones to absorb calcium.
Deficiencies in vitamin K have been linked to osteoporosis and “hardening” of the arteries, or arterial calcification. Other studies have suggested that daily intake of 800 IU of vitamin D combined with 45 mcg of vitamin K and 1,300 mg of calcium can reduce the lifetime risk of bone fracture by as much as 25 percent.
The daily recommended intake of vitamin K is 90 mcg a day for women. Good sources of vitamin K include leafy greens like spinach, as well as broccoli, kidney beans, and other food sources.
Before beginning any dietary supplementation program, it’s always a good idea to check with your healthcare provider.
Reviewed by Jennifer Lincoln, March 2020
- Pregnancy is challenging for bone health, because of increased calcium needs.
- Vitamin D and vitamin K are both related to calcium levels and bone health.
- Pregnant women should ensure an adequate supply of both.
- Most prenatal vitamins offer vitamin D and vitamin K.