Let’s look at the exciting world of protein supplementation in pregnancy!
Someone thought to look at whether your protein intake during pregnancy would affect postpartum weight. They calculated ‘normal’ postpartum weight loss at approximately 0.5kg per month, and found that by ensuring ‘adequate’ protein intake (≥1.2g protein per kg body weight), a woman would lose an additional 0.1kg per month post-delivery.
In simple terms:
- If your dietary protein is ‘inadequate’: you can lose 0.5kg per month post-delivery.
- If your dietary protein is ‘adequate’: you can lose 0.6kg per month post-delivery.
An extra 0.1kg (or 100g) weight loss per month – woo hoo!
(I know, until I’ve been there I shouldn’t knock it…)
It’s also been found that an increase in protein intake of 10g per day during pregnancy resulted in slightly less ‘obese’ (but not low birth weight) babies. Another study found that an increase in 1g per day of maternal protein intake during preconception and throughout pregnancy resulted in an increase of birth weight of 7-14g. The significance of that weight increase would depend on how heavy your newborn is (ie. it may be significant for a very prem baby, but not for a ‘regular’ full-term baby).
With the above two studies, it should be noted that the protein intake levels discussed can be can be considered ‘normal’ (and not too excessive).
So that is the ‘good’ news about protein in pregnancy… now on to the bad news…
One study done in Mexico found that sheep given protein supplementation had lower fertility rates and decreased embryo numbers compared with sheep on a ‘normal’ diet. This resulted in early pregnancy losses and embryo growth retardation, with resultant low birth weights.
A Cochrane review (the mother of all reviews) found that high-protein or protein supplementation is not beneficial and may be harmful to the infant. They looked at several trials and overall found that protein supplementation is associated with increased maternal weight, decreased birth weight, increased risk of small-for-gestational-age birth, and increased risk of neonatal death.
Just as an aside, a brief mention on the effects of inadequate protein intake during pregnancy: it can result in underweight babies, and reduced docosahexaenoic acid (DHA) accumulation in the foetal brain. DHA is essential for growth and functional development of the brain in infants, improves learning ability, and is said to enhance newborn visual acuity.
In summary, it seems my mother was right when she said (repeatedly) “all things in moderation”:
- The Australia & New Zealand RDI (Recommended Dietary Intake) for protein in pregnancy (and lactation) ranges from 58-67g per day (roughly 1.0-1.1g/kg body weight). You will note that this differs from some of the studies mentioned above, which are carried out in different countries, with different RDIs.
- No upper level has been set as there is insufficient data; however an upper level of intake of 25% protein as energy is recommended (ie. make sure protein forms <25% of your total energy intake - eg. calories ingested). This is due to the relationship between excessive protein intake and risk of cancer, renal disease, obesity, coronary artery disease and osteoporosis. Please note however that the source of protein is important as well - eg. vegetable-based is not as harmful as animal-based protein.
- Natural sources include: duck, chicken, fish, turkey, lamb, beef, soybeans, ricotta and cottage cheese, and pork.
- From the literature reviewed above, it is not recommended to intake more than your RDI of protein, as it can have negative effects on the developing baby.
- If protein is lacking in your diet however, it is unlikely to be harmful to supplement extra protein to ensure you are meeting (but not exceeding) your RDI.
IMPORTANT: if you do use protein powder, please ensure it is just that… protein powder… and that it doesn’t have any other fancy additives/ stimulants/ carcinogens etc. If in doubt, check with your healthcare provider or skip it altogether.
Next post we’ll have a look at other workout supplements (e.g. Protein Promo discounted sports and nutrition supplements).
- Castro MB, Kac G, Sichieri R. Assessment of protein intake during pregnancy using a food frequency questionnaire and the effect on postpartum body weight variation. Cad Saude Publica. 2010 Nov;26(11):2112-20.
- Meza-Herrera CA, Ross TT, Hallford DM, Hawkins DE, Gonzalez-Bulnes A. High periconceptional protein intake modifies uterine and embryonic relationships increasing early pregnancy losses and embryo growth retardation in sheep. Reprod Domest Anim. 2010 Aug;45(4):723-8. doi: 10.1111/j.1439-0531.2009.01341.x. Epub 2009 Feb 10.
- Andreasyan K, Ponsonby AL, Dwyer T, Morley R, Riley M, Dear K, Cochrane J. Higher maternal dietary protein intake in late pregnancy is associated with a lower infant ponderal index at birth. Eur J Clin Nutr. 2007 Apr;61(4):498-508. Epub 2006 Nov 29.
- Cucó G, Arija V, Iranzo R, Vilà J, Prieto MT, Fernández-Ballart J. Association of maternal protein intake before conception and throughout pregnancy with birth weight. Acta Obstet Gynecol Scand. 2006;85(4):413-21.
- Kramer MS, Kakuma R.Cochrane Database Syst Rev. Energy and protein intake in pregnancy. 2003;(4):CD000032.
- Burdge GC, Delange E, Dubois L, Dunn RL, Hanson MA, Jackson AA, Calder PC. Effect of reduced maternal protein intake in pregnancy in the rat on the fatty acid composition of brain, liver, plasma, heart and lung phospholipids of the offspring after weaning. Br J Nutr. 2003 Aug;90(2):345-52.
- Horrocks LA, Yeo YK. Health benefits of docosahexaenoic acid (DHA). Pharmacol Res. 1999 Sep;40(3):211-25.
- Nutrient Reference Values for Australia & New Zealand (http://www.nrv.gov.au).