Friday 17th November was World Prematurity Day. According to the charity Bliss (1), whose strapline is ‘for babies born premature or sick’, World Prematurity Day is ‘a global movement to raise awareness of premature birth and the devastating effect it can have on families’.
Last year my local special care baby unit raised awareness by the provision of cupcakes.
This year I spent World Prematurity Day travelling for seven hours from Liverpool to London in order to set up the U-Turn Health stall at VegFest at London Olympia, which doesn’t immediately strike one as an obvious way to raise awareness about premature birth.
On my first day back at work this week I was part of the team caring for a baby born three months early because her mother had an eclamptic fit. Since I started working as a paediatrician back in 2002, I have cared for hundreds of babies born too soon.
So now I want to tell you why prematurity, which can have devastating lifelong effects for both the child and the family, is (often, at least) a diet-related chronic disease.
Premature birth can happen for a lot of different reasons, so I am certainly not here to make sweeping generalisations about causation, or to say that in all cases it could have been prevented. Equally, we must be careful not to lay the blame at the feet of individuals: what is happening in our society today in relation to diet is happening to all of us, and it is not the fault of the individuals who suffer because of it.
Today I am just going to tell you about one piece of the scientific jigsaw. Please note that the rest of this article discusses an experiment carried out in rats. I do not condone animal experiments, but these results are freely available on the internet, and they are arguably informative.
Eclampsia is a word used to describe the onset of seizures in a woman who is pregnant or who has recently delivered a baby. Eclamptic seizures, or fits, occur against a background of ‘pre-eclampsia’. Pre-eclampsia is a condition characterised by high blood pressure, kidney damage resulting in protein in the urine, and a kind of swelling known as ‘oedema’. Oedema happens when the levels of protein in the blood fall because of loss of protein via the kidneys. The kidneys also play an important role in the regulation of blood pressure. Therefore, the main problem in eclampsia and pre-eclampsia is with the kidneys.
The NHS website (2) tells us that ‘the exact cause of pre-eclampsia is not known, it’s thought to occur when there’s a problem with the placenta’. Amongst other things, you are more likely to develop pre-eclampsia if you are obese or if you have pre-existing diabetes or high blood pressure: all things that are already well-recognised as being generally dietary in origin.
In June 2021, Science Daily (3) reported on two studies (4, 5) by researchers in the US on colonies of rats that had been bred specifically to develop high blood pressure and kidney problems in response to a high salt diet. These rats were normally fed a milk-based diet containing the milk protein casein, but researchers noticed that when a group of rats were moved to a different laboratory where they were fed a grain-based diet containing the wheat protein gluten instead, they did not develop the same level of high blood pressure or protein in the urine in response to the high salt-diet.
The researchers wondered whether the protection against high-blood pressure and kidney disease that they had noted might be mediated by a change in the gut microflora: the bacteria that live in the intestine and contribute to the digestion of food. To test this, they put some poo from the milk-fed rats into the grain-fed rats, and lo and behold the grain-fed rats developed higher blood pressure, more protein in their urine, and higher levels of inflammation in the kidneys.
The researchers also did some DNA sequencing of the gut bacteria and demonstrated distinctly different profiles between the two groups, which correlated with disease severity.
The researchers also noticed that the grain-fed rats appeared to be protected from what they called ‘maternal syndrome’: the combination of high blood pressure and protein in the urine that we call pre-eclampsia. They noted that in comparison, around half of the milk-fed rats developed this complication of pregnancy. They also noted that in humans, pre-eclampsia is ‘the leading cause of maternal and fetal morbidity and mortality’ (4).
The authors hypothesised that ‘dietary protein source could have beneficial effects’ (4) in pre-eclampsia.
It would be a rather enormous leap purely from these observations in genetically modified rats to any firm conclusions about the potential of plant-based diets in general for the prevention of premature birth. However, Perry, Stephanou and Rayman (6) provided a narrative review of the literature with 169 references: interest in the role of diet in pre-eclampsia is certainly not new. A full discussion of this paper is beyond the scope of this blog post, but suffice it to say that maintaining a normal weight and eating a diet high in fruits and vegetables and low in fat, sugar and salt are key for pregnant women or women contemplating pregnancy, and especially for those with a family history or previous history of pre-eclampsia (who, like the rats, have a genetic predisposition), as this quote from the abstract highlights:
Body mass index is proportionally correlated with pre-eclampsia risk, therefore women should aim for a healthy pre-pregnancy body weight and avoid excessive gestational and interpregnancy weight gain. The association between the risk and progression of the pathophysiology of pre-eclampsia may explain the apparent benefit of dietary modifications resulting from increased consumption of fruits and vegetables (≥400 g/day), plant-based foods and vegetable oils and a limited intake of foods high in fat, sugar and salt. Consuming a high-fibre diet (25–30 g/day) may attenuate dyslipidaemia and reduce blood pressure and inflammation.
There is a slight sense of heroism around the act of resuscitating a premature baby. These babies would certainly die if we did not do what we do at the moment of their births, but the reality is that many of them go on to have sometimes mild and sometimes severe levels of disability, that they must live with for the rest of their lives. Spending seven hours travelling to London to stand on a cold stall for two days hoping someone will come and talk to you (if you did… thank you… you are amazing!), in an effort to raise awareness about the health benefits of a low fat, high raw, plant-based diet, is arguably less glamorous, but resuscitation is a ‘downstream’ activity (pulling people out of the water) that shouldn’t be happening at all. It is much better to stop them from falling into the river in the first place.
Perry, Stephanou and Rayman (6) report that pre-eclampsia complicates 3-5% of all pregnancies, and is estimated to cause 42,000 maternal deaths annually (citing Chappell, Cluver and Kingdom, 2021). We may not know absolutely all of the answers yet, but it is definitely time to top telling women that we don’t know why pre-eclampsia happens, or how to stop it.
References:
1. BLISS, n.d.. World Prematurity Day [online]. Available from: https://www.bliss.org.uk/support-bliss/world-prematurity-day [Accessed 25 November 2023].
2. NHS, n.d.. Pre-eclampsia [online]. Available from: https://www.nhs.uk/conditions/pre-eclampsia/ [Accessed 25 November 2023].
3. SCIENCE DAILY, 2021. Plant-based diet protects from hypertension, preeclampsia [online]. Available from: https://www.sciencedaily.com/releases/2021/06/210614110811.htm [Accessed 25 November 2023].
4. DASINGER, J. H., ABAIS-BATTAD, J. M., BUKOWY, J. D., LUND, H., ALSHEIKH, A. J., FEHRENBACH, D. J., ZEMAJ, J., and MATTSON, D. L., 2021. Dietary protein source contributes to the risk of developing maternal syndrome in the Dahl salt-sensitive rat. Pregnancy and Hypertension. 24, pp. 126-134.
5. ABAIS-BATTAD, J. M., SARAVIA, F. L., LUND, H., DASINGER, A. J., FEHRENBACH J. H., ALSHEIKH, A. J., ZEMAJ, J., KIRBY, J. R., and MATTSON, D. L., 2021. Dietary influences on the Dahl SS rat gut microbiota and its effects on salt-sensitive hypertension and renal damage. Acta Physiologica (Oxford). 232 (4).
6. PERRY, A., STEPHANOU, A., and PERRY, M. P., 2022. Dietary factors that affect the risk of pre-eclampsia. BMJ Nutrition, Prevention and Health. 0:e000399. doi:10.1136/ bmjnph-2021-000399
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