Dietary preferences

No matter what your dietary preferences, vegan, vegetarian, paleo, pegan, etc., your body's requirement for vitamins and minerals during pregnancy are the same. And whichever diet you choose, you can become deficient in nutrients if you aren’t careful to eat a quality diet. One of the keys to obtaining all the nutrients our bodies need to thrive each day, is to eat a wide variety of whole foods.
We don’t want to get all nutritionism on you and break everything down to its nutritional components, we really just want you to enjoy eating whole foods. However, because some diets have nutrients that can be more difficult to obtain than others, and given the importance of complete nutrition for your health, and your baby’s development during pregnancy, we will break a few nutrients down, provide the Australian and New Zealand Recommended Dietary Intake (RDI) and suggest foods that contain these nutrients. 

Vitamin B12 (RDI pregnancy - 2.6mcg/day; RDI lactation - 2.8mcg/day)

Vitamin B12 is essential for the health of nerves, the formation of red blood cells and DNA synthesis for you and your baby. We don’t need a lot of vitamin B12, but a deficiency can lead to serious health consequences, including megaloblastic anemia - where red blood cells grow, but because DNA synthesis is impaired, the cells don’t divide, resulting in large red blood cells that are dysfunctional. Symptoms such as fatigue, weakness, constipation, loss of appetite and weight loss can follow. If left undetected vitamin B12 deficiency can lead to neurological changes such as numbness and tingling in the hands and feet. Other symptoms include depression, confusion, dementia, poor memory and soreness of the mouth and tongue. If you experience these symptoms we encourage you to discuss these with your healthcare provider.
Vitamin B12 is only found naturally in animal products (fish, poultry, meat, eggs and dairy). Vegetarians who eat eggs and dairy can derive adequate vitamin B12 from these foods. Vegans will need to supplement their diets with vitamin B12 supplements, or choose foods that are fortified or enriched with vitamin B12. There are some soy milks that are enriched with vitamin B12, as well as some vegan burgers / sausages. It is important to check the label to confirm fortification / enrichment with vitamin B12 if you are relying on these foods for your vitamin B12 requirements.

Calcium (RDI pregnancy and lactation - 1000mg/day RDI)

Calcium is necessary for the normal development and maintenance of the skeleton and proper functioning of our nerves and muscles including our heart. Calcium is stored in our teeth and bones. Insufficient calcium intake is associated with low bone density which can lead to osteoporosis. During pregnancy, our growing baby relies on our calcium to meet its needs. If our intake is insufficient, calcium stored within our bones / teeth will be taken to meet our babies needs. There is however no need for additional dietary intake of calcium (above normal requirements) in pregnancy, as maternal adaptations to pregnancy, include increased efficiency of calcium absorption in the gut.
Many consider dairy as the primary source of calcium. Other excellent sources of calcium include fish where you eat the bones, such as sardines. Almonds, green leafy vegetables such as cabbage, kale, chinese broccoli and bok choy, hard tofu and unhulled tahini (sesame seed paste) are other good sources of calcium.
Calcium requires vitamin D to effectively maintain our, and baby’s, bone health.

 Vitamin D (RDI pregnancy and lactation - 5.0mcg/day)

Vitamin D is essential for maintaining bone health by enhancing the small intestinal absorption of calcium from the diet to regulate blood calcium concentrations. Vitamin D also enhances the absorption of phosphorus from the diet and its optimal concentrations are essential for your baby’s bone development. There is no need for dietary intake of vitamin D if you get adequate sun exposure. In Australia, we require as little as 10 minutes per day of sun exposure during summer and 2-3 hours per week during winter. We do however need to include fat in our diet to assist with the conversion of sunlight into vitamin D that our cells can use. Synthesis of vitamin D in our skin takes place over several days and requires 7-Dehydrocholesterol (an intermediary on the cholesterol synthesis pathway) to convert UVB light from the sun into vitamin D3.
Despite relatively low targets for sun exposure, 1 in 4 Australians are vitamin D deficient. Elderly women, dark-skinned people, people from areas with a thick layer of ozone, women using sunscreen lotions, seasonal variation in sun exposure and veiled women are at highest risk for vitamin D deficiency. There is emerging evidence for vitamin D’s role in our immune system, and associations between vitamin D levels and a range of diseases including osteoporosis, rheumatoid arthritis, multiple sclerosis, hypertension, cardiovascular disease, obesity, psoriasis, and psychiatric diseases, including seasonal affective disorder.
Where you can’t obtain adequate vitamin D from sun exposure, you can get vitamin D from a range of foods including oily fish (salmon, mackerel and herring), egg, mushrooms and some fortified products. Mushrooms have been challenged as a source of vitamin D, because direct from the dark forest floor, their vitamin D levels are relatively low. But when placed in the sunshine, mushrooms can produce and store vitamin D. We like to think of mushrooms as a little ray of sunshine to brighten our day during the colder, darker months.

Iron (RDI pregnancy - 27mg/day; RDI lactation - 9mg/day)

Iron, a component of hemoglobin and myoglobin, is essential for moving oxygen from our lungs to the tissues and muscles of our body. Iron is necessary for growth, development and cell function. Iron deficiency is common, affecting ~1 in 3 women of reproductive age.
One of the issues with iron, is its absorption via the gut. Iron in food comes in two forms - haem iron, and non-haem iron. The gut is more effective at absorbing haem iron, than non-haem iron (i.e., haem iron is more bioavailable). Our capacity to absorb iron depends on our individual iron status (if we have more iron stored we will absorb less iron and vice versa), the iron content of the meal and the composition of the meal such as the presence of nutrients that can influence the absorption of iron. In pregnancy, maternal adaptations to pregnancy include increased efficiency of iron absorption (increasing from ~7% at 12 weeks to ~36% at 24 weeks and ~59% at 36 weeks).
The richest sources of iron are red meat, fish and chicken which contain haem and non-haem iron. Non-animal sources of iron include legumes, tofu, nuts and seeds, wholegrains, dried fruits and dark green leafy vegetables which contain only non-haem iron. Including vitamin C-rich foods with meals, such as citrus fruits, berries, tomatoes, broccoli, capsicum can boost the absorption of non-haem iron. Other organic acids, citric, malic and lactic acid, as well as vitamin A and beta-carotene can increase non-haem iron absorption.
Phytates (found in legumes, rice and other grains) can decrease the absorption of haem and non-haem iron by binding to the iron. To overcome this, soak or sprout legumes, rice and grains before eating to reduce phytate levels. Polyphenols (such as those found in tea) can decrease the absorption of non-haem iron, so don’t drink a cup of tea during an iron rich meal. Meat enhances non-haem iron absorption, but animal proteins (milk protein, egg proteins and albumin) can reduce iron absorption. Evidence suggests that these enhancers and inhibitors of iron absorption have a minimal effect on iron status over the long term. They are only relevant during any one meal, there is no carry over, so simply separating meals that are high in iron rich foods from those that may inhibit iron absorption, will maximise iron uptake. Our body stores iron, releasing it from our stores only when our cells require it.

Omega fatty acids (RDI Pregnancy - ALA 1.0mg/day, DHA+EPA+DPA 115mg/day; RDI lactation - ALA 1.2mg/day, DHA+EPA+DPA 145mg/day)

Fats provide the most concentrated form of energy for the body and are necessary for the absorption of fat-soluble vitamins, A, D, E and K. Most of the fats in food are triglycerides, made up a unit of glycerol combined with 3 (tri-) fatty acids. Omega fatty acids are one type of fatty acids. Omega fatty acids must be obtained via our diet because we have no capacity to make them ourselves. A deficiency of omega fatty acids is characterised by rough, scaly skin, dermatitis, increased transepidermal water loss and reduced growth.
There are 4 key omega fatty acids, alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA). ALAs are found in legumes, linseed oil, chia seeds, walnuts, leafy green vegetables and canola oil.  ALA is the ‘parent’ omega fatty acid. EPA, DHA and DPA are found predominantly in oily fish such as mackerel, herrings, sardines, salmon, tuna and other seafood. EPA, DHA and DPA can be made from ALA but the conversion is slow. DHA is an important structural membrane lipid, particularly for nerves and the retina in the eye. It is important that the intake of DHA is met during pregnancy to ensure the optimal development of babies nerves and eyes. There are vegan omega fatty acid supplements available - talk to your care provider about which of these might be most suitable for you if required.

General Comments

  • During the planning phase for a pregnancy, have blood work done to measure your levels of nutrients, if you aren’t deficient then there is no need to supplement. 
  • If you've been on the oral contraceptive pill, you may have a number of micronutrient deficiencies. These can be corrected with a nutrient dense diet. Discuss this with your care provider.
  • Remember that during pregnancy, our bodies undergo remarkable adaptations that include changes in our gut structure that increase the capacity for absorption of nutrients from our food. In other words, during pregnancy we become more efficient at extracting nutrients from our food. 
  • Many of the recommended dietary intakes for nutrients during pregnancy are estimates based on evidence in non-pregnant adults. The specific nutrient requirements during pregnancy have rarely been studied. So observe and listen to your body - how do you feel? How do you look? We want to feel good, energised, clear headed, we want clear, hydrated skin and clear eyes. These are the signs of health and wellbeing.
  • To meet your nutritional needs, means really knowing yourself and taking responsibility for what goes in. Simply ask yourself the question: “is this a whole, real, nutritious food and will it serve me well to eat it?” You’ll always know the answer.
  • Always discuss your dietary preferences with your pregnancy care provider.

 References

https://www.nrv.gov.au/nutrients for RDI of nutrients during pregnancy

Saunders AV, Craig WJ, Baines SK, Posen JS (2013) Iron and vegetarian diets, Med J Aust 199(4):S11-S16 


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