The ketogenic diet (KD), characterized by high fat, moderate protein, and very low carbohydrate intake, has gained popularity for weight loss and other health reasons. However, its suitability during pregnancy is a complex issue that requires careful consideration. This article aims to provide an informative and structured overview of the potential risks and benefits of following a keto diet during pregnancy, drawing on available research and expert opinions.
Introduction
Pregnancy is a critical period marked by increased nutritional demands to support both maternal health and fetal development. Dietary nutrition plays a crucial role in determining pregnancy outcomes, with poor diet being a major contributor to pregnancy metabolic syndrome and metabolic disorders in offspring. While carbohydrates are essential for fetal development, the excessive consumption of low-quality carbohydrates can increase the risk of pregnancy complications and have lasting negative effects on offspring development. The increasing use of the ketogenic diet (KD), particularly by women of child-bearing age, raises a question about its suitability during gestation. The central question is whether restricting carbohydrate intake and inducing ketosis poses any risks to the developing fetus.
Understanding the Ketogenic Diet
The term “ketogenic diet” generally refers to a diet that is very low in carbohydrate, modest in protein, and high in fat. On the keto diet, you’re typically allowed lots of meat and fat, but less than 50 grams (g) of carbs a day - that’s about one all-seasonings bagel or two bananas in 24 hours! The diet also has an unusually high fat requirement. This means that in a 2,000 calorie-a-day keto diet, each meal might have:165 g fat, 40 g carbohydrates and 75 g protein.
The idea behind the keto diet is that getting most of your calories from fat jumpstarts your body’s natural fat-burning. (Carbohydrates are easier for the body to use as fuel. When you eat plenty of carbs, they’re used for energy first.) A keto diet is supposed to help shift your body from burning carbs to burning fat for energy. This state is called ketosis. Burning more fats for energy may help you lose weight - at least in the short term. Simple, right?
When carbohydrate intake is severely restricted, the body enters a metabolic state called ketosis. Instead of using glucose, its usual fuel, the body uses ketone bodies, which are produced by the breakdown of fat. While some people go on keto diets for medical reasons, others follow low carb/high-fat diets as a way to lose weight. The word "ketogenic" comes from the break down products of fats. When fat is broken down in the body, it makes chemicals called ketones. While glucose is important for the successful development of an early pregnancy, too much sugar can cause large spikes in blood sugar and have health consequences.
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Potential Risks of Keto Diet During Pregnancy
Neural Tube Defects
One of the primary concerns associated with low-carbohydrate diets during pregnancy is the increased risk of neural tube defects (NTDs). A study by researchers at the University of North Carolina at Chapel Hill suggests that following a low-carbohydrate diet during pregnancy may increase a woman’s risk of having a baby with serious birth defects. Compared with pregnant women who didn’t restrict their carbohydrate intake, those on a diet that reduced or eliminated carbs were 30 percent more likely to have babies with neural tube defects. Those include spina bifida (spine and spinal cord malformations) and anencephaly (missing parts of the brain and skull).
These birth defects can cause death or lifelong disability, the study authors said.
Because folate deficiency in pregnant women has been associated with an increased risk of neural tube defects, including anencephaly and spina bifida, it is recommended that all women take folic acid supplements during pregnancy. In addition, the Food and Drug Administration (FDA) has required (since 1998) the addition of folic acid to many enriched breads and cereals in order to increase the amount of folic acid in our diets. The concern here is that women who adhere to low carbohydrate diets would not benefit from the folate added to grain products, such as wheat flour, rice, and pasta. And for women who have celiac disease or gluten sensitivity, a recent study found that gluten-free breads, cereals, and pasta are typically not fortified with folic acid.
In order to answer this question, researchers examined the association between carbohydrate intake and neural tube defects, analyzing data from the National Birth Defects Prevention Study which included 1,740 mothers of infants, stillbirths, or terminations with anencephaly or spina bifida (cases), and 9,545 mothers of live born infants without a birth defect (controls). Using a food frequency questionnaire, women provided information regarding carbohydrate and folic acid intake before conception. Restricted carbohydrate intake was defined as ? 5th percentile. The researchers found that women with restricted carbohydrate intake were slightly more likely to have an infant with a neural tube defect after accounting for potential variables, including use of prenatal vitamins (AOR?=?1.41, 95% CI: 1.11, 1.79).
Based on these findings, the authors recommend that women who are pregnant or planning to become pregnant may want to avoid diets that reduce or eliminate carbohydrates, as they could increase the risk of having a child with a neural tube defect.
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Nutrient Deficiencies
During pregnancy you need even higher doses of these nutrients as you and your baby grow rapidly. Not getting enough of some vitamins and minerals can lead to problems in your baby’s growth and development. Vital nutrients for your baby include: vitamin D for healthy bones and teeth, vitamin E for healthy muscles and blood, vitamin B-12 for healthy spinal cord and nerves, and folic acid for a healthy spinal cord (and also to prevent a neural tube condition in babies called spina bifida).
If not done carefully, keto diets can be seriously deficient in some nutrients, especially folate, a B vitamin critical in early pregnancy to help prevent neural tube defects, serious abnormalities of the brain and spinal cord. Some people who follow the keto diet also have low levels of key vitamins such as vitamin A, C, K, all of which are important for Mom and baby. If you’re eating a keto diet you might have low levels of: magnesium, B vitamins vitamin A, vitamin C vitamin D, and vitamin E.
A prenatal vitamin - a necessity during pregnancy - does provide extra nutrients. But it’s best to get these vitamins and minerals in foods, too.
Fiber Deficiency and Constipation
Some keto diets can be low in fiber because they don't include many fruits. This can cause constipation - a common concern already among pregnant women - and has also been linked to other health conditions during pregnancy like prediabetes and diabetes, preeclampsia, and excessive weight gain. Long term, a diet deficient in fiber is a risk factor for many cancers, such as breast and colorectal cancer.
Potential Impact on Fetal Organ Development
Animal studies have raised concerns about the potential impact of maternal keto diets on fetal organ development. One such 2013 study showed that pregnant mice that were fed a keto diet gave birth to baby mice that had a larger heart and smaller brain than typical. A 2015 study found that pregnant mice on a keto diet had babies that had a higher risk of anxiety and depression when they became adult mice.
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A ketogenic diet during gestation results in alterations in embryonic organ growth. To fill this knowledge gap we imaged CD-1 mouse embryos whose mothers were fed either a Standard Diet (SD) or a KD 30 days prior to, as well as during gestation. An anatomical comparison of the SD and KD embryos revealed that at E13.5 the average KD embryo was volumetrically larger, possessed a relatively larger heart but smaller brain, and had a smaller pharynx, cervical spinal cord, hypothalamus, midbrain, and pons, compared with the average SD embryo.
The "Keto Flu" and Pregnancy Symptoms
For some people, the keto diet causes so many side effects that they even have a name for it. The “keto flu” includes side effects like: fatigue, dizziness, nausea, vomiting, dehydration bloating, stomach pain, gassiness, constipation, diarrhea, high cholesterol, headaches and bad breath.
Pregnancy comes with its own (very normal) side effects, which can include nausea, vomiting, tiredness, stuffy nose, and aches. You definitely don’t need to add the keto flu or uncomfortable stomach symptoms to this!
Concerns about Saturated Fat Intake
Protein is part of the keto diet, but most keto diets don’t differentiate between healthy, lean protein and the kinds with lots of saturated fats like beef and pork. In fact, since fat is so encouraged, the diet can actually lead people to eat more unhealthy meat - as well as oils, butter, and lard.
Make no mistake: Healthy fats are essential for your growing baby. But too much saturated fat can cause health problems like higher cholesterol for you, which puts a strain on your heart and therefore your pregnancy.
The keto diet also doesn’t stop you from eating processed sandwich meats like hot dogs, bacon, sausages, and salami. These meats have added chemicals and colors that may not be healthy for your tiny, growing baby - or for your body.
Potential Benefits and Considerations
Epilepsy Management
The keto diet may be one way to help treat people with epilepsy. This brain condition causes people to sometimes have seizures. And a 2017 case study found that the keto diet might help control symptoms in pregnant women with epilepsy. Case studies are often tiny - with just one or two participants. In this case, the researchers followed two pregnant women with epilepsy. The keto diet helped to treat their condition. Both women had normal, healthy pregnancies and delivered healthy babies. The women’s only side effects were slightly low vitamin levels and raised cholesterol levels.
Gestational Diabetes Management
Some case studies show that a keto diet can help manage or prevent some kinds of diabetes. However, you don’t have to go full keto to lower your risk of gestational diabetes. Eating a low carb diet that has plenty of healthy fat, protein, fiber, fresh fruit, and vegetables is a safer bet while you’re pregnant. It’s also vital to get moving - 20 minutes of exercise after each meal can also help you balance your blood sugar levels during and after pregnancy.
Potential Role in Improving Fertility
Some articles and blogs claim that the keto diet can help you get pregnant. This is thought to be because going keto can help some people balance their weight. If you’ve been told by your doctor that you need to lose weight, doing so may help improve your chances of getting pregnant. However, there’s not yet medical evidence that shows that the keto diet can boost fertility. And if you’re trying to get pregnant, the keto diet might actually slow things down. Several vitamins and minerals can help make men and women more fertile. Being on a keto diet might lower the levels of nutrients that are important for fertility.
Importance of Carbohydrate Quality
Recent studies not only highlighted the link between carbohydrate intake during pregnancy, maternal health, and offspring well-being, but also suggested that the quality of carbohydrate foods consumed is more critical.
Maternal glucose response is influenced not only by the total amount of carbohydrate, but also by the type of carbohydrate consumed. Slow-digesting, absorbing, and metabolizing carbohydrates are typically high in dietary fiber and rich in phytochemicals. Complex carbohydrates are either oligosaccharides containing up to 10 monosaccharide units, or polysaccharides containing very long monosaccharide chains. The starch contained in noodles, bread, etc., is a polysaccharide, which is digested and decomposed into glucose by amylase after intake, and then slowly enters the blood without causing a sharp rise in blood sugar.
Expert Recommendations and Guidelines
Given the limited research, expecting moms should avoid strict keto diets unless their doctor specifically recommends it to treat a medical condition. For ethical reasons, there's been very little research on keto diets during pregnancy, but in general, significantly restrictive diets can be dangerous during pregnancy and are usually not recommended. It’s not usually considered ethical to use pregnant women as subjects in clinical studies because of the risks. So medical research on the keto diet during pregnancy has mostly been done on animals like mice.
A balanced, healthful diet is always recommended for the health of both you and your baby. It's not safe to diet to lose weight during pregnancy. With the exception of the first trimester, when some women lose weight or don't gain due to morning sickness or food aversions, in the second and third trimesters it's important to gain weight for a healthy pregnancy and baby.Rather than focusing on trying keto, providers often recommend focusing on cutting back on unhealthy foods and paying attention to how you feel. They may also be able to refer you to a nutritionist who can ensure your goals and nutritional needs are being met.