Protein is a crucial macronutrient, further divided in to 20 amino acids (AAs) that the body needs during pregnancy. Proteins are necessary and are deposited in newly forming tissue during pregnancy in both the mother and baby. Protein deposition can be used towards the uterus, breast tissue, extracellular fluid, increased blood volume, and adipose tissue. Approximately 40% of the protein consumed during pregnancy goes towards the placenta, amniotic fluid, and the fetus. When the diet is deficient in protein intake, it can increase the risk for negative outcomes.
How much Protein do you need during Pregnancy?
In the first trimester, the protein requirement does not change, and remains at an average of 46 grams of protein per day (based on a requirement of 0.80 grams/Kg of body weight per day; assuming a weight of 57.5 kg). Interestingly, studies have shown that certain amino acids are rapidly used in early pregnancy and demand may increase. The bioavailability of amino acids, such as tryptophan, increases to facilitate this requirement.
By the second trimester (and onwards), the protein requirement per day is approximately 71 grams of protein (or 1.1 grams of protein/Kg of body weight per day; assuming a body weight of 64.5 kg in the 2nd trimester).
Should you take protein supplements during pregnancy?
Available research does not support the use of protein supplements during pregnancy. For vegetarian and vegan patients, the consumption of plant-based proteins can help to achieve the recommended amounts of protein in the perinatal period.
An issue with some protein supplements is that they focus on certain amino acids and may be deficient in other important amino acids. To prevent this imbalance of amino acids in the diet, it is recommended to increase dietary sources of protein first. It is also important to evaluate if you are consuming sufficient amounts of essential amino acids. In a diet that is deficient in protein, the body can create many of the amino acids within the body (these are called non-essential amino acids), while there are certain amino acids the body cannot produce (essential amino acids).
What are the essential amino acids?
Phenylalanine: a precursor for various neurotransmitters, such as, norepinephrine, epinephrine, tyrosine and dopamine
Valine: used in muscle growth and energy production [RDA is 31 mg/kg per day]
Threonine: necessary for immune function, used in collagen and connective tissues [RDA is 26 mg/kg per day]
Tryptophan: necessary for the production of Serotonin, an important neurotransmitter necessary for mood, sleep, and appetite [RDA is 7 mg/kg per day]
Methionine: used to support absorption of certain minerals and has an important role in detoxification
Leucine: necessary for muscle growth and repair, wound healing, regulates blood sugar levels and can affect sugar metabolism [RDA is 56 mg/kg per day]
Isoleucine: is also needed for muscle growth and repair, supports hemoglobin production and immune function [RDA is 25 mg/kg per day]
Lysine: important for hormone production and immune function [RDA is 51 mg/kg per day]
Histidine: needed for production of histamine, affects immune response, sexual function, and for neurological health (helps to maintain myelin sheath) [RDA is 18 mg/kg per day]
*RDA is recommended daily allowance (amount needed to meet minimum daily requirement for 97-98% of people in a specific age group and gender)
If your diet is deficient in protein and you are using a protein supplement, check to make sure your protein includes the essential amino acids in suitable amounts as your body cannot produce these important amino acids. Many protein supplements are heavy on the non-essential aminos, so if you are relying on your protein powder for your daily protein intake, chances are you are missing a lot of the essential amino acids from your diet. This is why dietary sources of protein should be the first choice.
Is too much protein harmful?
While we have discussed the benefits of protein intake above, it should be noted that when your total protein intake accounts for > 25% of your daily caloric intake, it has been associated in some studies with intrauterine growth restriction. So while your protein intake should increase by the 2nd trimester, so should your total caloric intake from other macronutrients, such as fats and carbohydrates. The total amount of protein one should be consuming daily is highly debated, with some research showing 100 grams of protein a day by the 2nd trimester was associated with improved outcomes during pregnancy compared to those with lower protein intake.
Supplements for Individual Amino Acids
The lack of concrete research should discourage supplementing with single amino acids if not necessary as they can impact the balance of amino acids (as some will compete for absorption with other amino acids). This should be discussed with your healthcare provider before taking any supplements. Dietary sources should be the best source of meeting your daily requirement for protein intake.
Elango, R., & Ball, R. O. (2016). Protein and amino acid requirements during pregnancy. Advances in Nutrition: An International Review Journal, 7(4).
Canada, H. (2006, June 29). Government of Canada. Retrieved March 08, 2021, from https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/dietary-reference-intakes/tables/reference-values-macronutrients-dietary-reference-intakes-tables-2005.html