A pregnant woman shops for oranges at a grocery store.

Researchers set out to see if women who smoked during pregnancy could benefit from vitamin C supplementation and what effect it might have on the respiratory health of their babies.

Two studies conducted years apart have shown both the short- and long-term benefits of vitamin C on the children of women who smoked during their pregnancies. The first study, published in 2017, randomized pregnant women for vitamin C or a placebo, then tested their babies at three and 12 months to evaluate their lung function.

The researchers state that 12 percent of American women cannot quit smoking while pregnant, resulting in more than 450,000 infants born yearly who are exposed to smoke. They continue, saying that smoking during pregnancy is the largest preventable cause of respiratory illnesses in children, which include wheezing and asthma, and that recent studies have shown that vitamin C has a protective effect on the lung function of offspring exposed to in-utero smoke in both a nonhuman primate and initial human trial.

This study was a randomized, double-blind, placebo-controlled trial that took place between 2012–2016. The women were randomized to receive 500 mg a day of vitamin C versus a placebo during pregnancy. Once the babies were born, their lung function was evaluated at three months, and lung function and the incidence of wheezing were evaluated at 12 months. The results showed significant improvements in lung function and a significant decrease in wheezing in the babies whose mothers had taken vitamin C.

The follow-up study looked at those same babies—now 5 years old—and tested them to see if the benefits of the vitamin C were still apparent.

This study, published in November 2022 in the Journal of the American Medical Association, revisited the 213 children of smokers in the original study at 5 years of age to evaluate if the effects of the vitamin C their mothers took while pregnant were still benefiting their lung function. The follow-up study took place between 2018 to 2021.

Results showed that the children of pregnant smokers who took vitamin C during pregnancy had significantly increased airway function at 5 years of age and significantly decreased instances of wheezing. The findings suggest that vitamin C supplementation for pregnant smokers may reduce the effects of smoking in pregnancy on childhood lung function and respiratory health.

The Importance of Vitamin C

According to the U.S. National Institutes of Health, vitamin C, or ascorbic acid, is a water-soluble nutrient and powerful antioxidant our bodies need to perform a number of vital functions. Vitamin C helps fight infections and is one of the best vitamins to boost the immune system and fight foreign invaders. An article published in the journal Nutrients states that vitamin C exerts many beneficial effects on the innate and adaptive immune systems and appears able to prevent and treat respiratory as well as systemic infections.

Vitamin C benefits the body in multiple ways. It promotes healthy skin and collagen production, improves wound healing, enhances iron absorption, boosts the immune system, fights free radical damage, supports heart health, protects the brain in neurodegenerative disorders, and helps to fight cancer.

Vitamin C is also a potent antioxidant—which helps defend against free radicals that, in excess, can damage our cells, adversely alter our DNA, and accelerate aging. Inside the body, free radicals are a natural byproduct of converting food into energy; however, they can also form from external sources like exposure to cigarette smoke, X-rays, air pollution, toxic chemicals, and ultraviolet light from the sun.

There is tremendous interest in the clinical uses of vitamin C because it benefits oxidative damage—a crucial factor in the development of many diseases. Studies show that individuals with high intakes of vitamin C have a lower risk of many chronic diseases, including heart disease, cancer, eye diseases, and neurodegenerative conditions.

Vitamin C is an essential nutrient, meaning we cannot produce it, and our bodies do not store it, making it vital that we get enough from the foods we eat or from supplements. The best way to get vitamin C is from the foods we eat, as they are forms our bodies recognize, so eating vitamin-rich foods will help you reap the most benefits. In fact, a study published in the Annals of Internal Medicine showed that eating your veggies is a better way to get your vitamins than taking supplements. Below are some of the best food sources of vitamin C:

• rose hips
• black currants
• bell peppers
• strawberries
• chili pepper
• guava
• cantaloupe
• oranges
• grapefruits
• kiwis
• papaya
• tangerines
• spinach
• snow peas
• kale
• tomatoes
• parsley
• pineapple
• mango
• lemon
• honeydew
• Camu camu
• acerola cherry
• Chinese red dates
• cruciferous vegetables (broccoli, Brussels sprouts, cabbage, cauliflower)

Recommended Daily Intake

The recommended dietary allowance (RDA) for adults older than 19 years of age is 90 milligrams (mg) for men and 75 mg for women. Pregnant women need 85 mg, and for lactating women, the RDA is 120 mg daily. Smoking depletes vitamin C levels in the body, and smoke increases the amount of vitamin C the body needs to repair the damage caused by free radicals (from cigarette smoke). Smokers need 35 mg more per day than nonsmokers.

Not Enough Vitamin C

Getting less than 10 mg daily of vitamin C is considered a deficiency and can cause scurvy. Scurvy was made famous by pirates and British sailors in the 18th century because they spent months or years at sea without access to fresh produce—and back then, the disease killed more sailors than storms and shipwrecks combined. Today, scurvy is less of a concern, and most people in the developed world can easily get the recommended daily amount with access to fresh fruits and vegetables and by eating a varied diet. Symptoms of scurvy include depression, fatigue, swollen and bleeding gums, loose teeth, bruising, poor wound healing, rashes, joint pain, small red or purple spots on the skin, and corkscrew hairs.

More Vitamin C

On the other end of the spectrum, some recommend taking considerably more than the RDA—up to 1,000 mg (1 gram) of vitamin C daily. Because it’s a water-soluble vitamin, it isn’t stored in the body, and any extra the body can’t use is passed through the urine. If you want to take these larger amounts of vitamin C that exceed RDA guidelines, increase gradually and track your tolerance. If you experience digestive discomfort and diarrhea, you are likely taking too much.

Final Thoughts

Vitamin C is a powerful antioxidant that serves multiple essential functions, boosts the immune system, and protects us against numerous diseases. Many of us consider taking supplements or adding specific foods to our diet to improve our health, but the tangible benefits can be difficult to measure. The study mentioned early in this article offers a concrete example that vitamin C supplementation had very real benefits to the children of the mothers who took it, in both the short and the long term (until at least 5 years of age). So adding bell peppers to a salad, grabbing a citrus fruit on the go, and incorporating a handful of kale into the occasional smoothie can help add some vitamin C to your diet so you, too, can begin reaping the health benefits of this crucial vitamin.