The internet has quite a lot to say about how eating pineapple cores may help fertility by improving the chances of implantation. We all want to feel that there is something special we can do to help us at crucial times, and rituals bring comfort. But does this one work? The theories and arguments include… that pineapple enables a shift in the immune system, that it increases blood flow to the uterus, and that it has long been used in traditional Chinese medicine to help fertility…
The immune theory – Th1 and Th2 helper cells and implantation – and what we now know about Treg cells
The theory is that pineapple core contains bromelain which is known to have an anti-inflammatory effect, and that an anti-inflammatory immune response may assist implantation. The immune system includes helper cells and 2 types of these are Th1 and Th2 cells. They each produce different proteins known as cytokines…
The shift from Th1 to Th2 dominance during implantation
Th1 cells produce more defensive and pro-inflammatory cytokines – this is thought to be beneficial before and after ovulation
Th2 cells produce more tolerant and anti-inflammatory cytokines – this is thought to help implantation and pregnancy
There is a natural shift from Th1 to Th2 dominance in the second part of the menstrual cycle – progesterone levels and sexual activity both help this shift
High Th1 levels have been linked to implantation failure and miscarriage (though this is unsurprising as it suggests there may be underlying inflammation in the uterus which needs treating)
So does Bromelain help with Th2 dominance? Perhaps not… 12 men taking high dose Bromelain of 3,000units showed increases in both Th1 and Th2 activity. The increases were only seen at high doses and a pineapple slice will contain considerably less than this.
Treg cells are now known to be important for implantation
The Th1 Th2 theory has been questioned in recent years and is now thought to be an oversimplification. Implantation is now known to be helped by immune regulatory cells known as Treg cells which depend on progesterone and oestrogen levels and are supported by the right levels of Vitamin D, fatty acids and probiotics The bromelain in pineapple is known to have an immune modulating effect but no studies have focused on its effect on Treg cells yet.
The increased blood flow theory - Bromelain may help blood flow to the uterus – but reduced blood flow is needed during implantation
The theory is that by acting as a blood thinner the bromelain in the pineapple core ‘drives’ blood flow to the uterus
Blood flow to the uterus is important during the first part of the cycle while you are growing follicles and your uterine lining.
Blood flow is high at the time of ovulation BUT then reduces in preparation for implantation.
Some people do need help with blood flow
Bromelain is thought to have blood thinning properties similar effect to aspirin, and there is evidence that anticoagulants can improve blood flow to the uterus
Some people will benefit from taking blood thinners because they have clotting disorders, uterine artery impedance, antiphospholipid antibodies or an autoimmune condition like Lupus – they may need to take their anticoagulant while preparing to conceive or during their IVF cycle
Taking something to thin the blood only at the time of implantation is unlikely to be helpful
Pineapple isn’t one of the foods stated to help fertility in Traditional Chinese Medicine (TCM)
A number of sites suggest that pineapple has a long history of use in treating infertility in TCM. Foods are regarded as having energetic or medicinal properties in TCM and some foods are considered to assist fertility but pineapple hasn’t been one of them historically. It is used in TCM to calm stomach upsets and intestinal inflammation and Western research supports this showing that Bromelain calms intestinal inflammation and spasm. TCM nutritional prescriptions are tailored to each person just as herbal prescriptions are - so pineapple may suit some people but not everyone.
should you take the pineapple before or during implantation?
Websites vary in the advice they give about timing but the usual recommendation is to eat pineapple for 5 days starting the day after ovulation, the day of IUI or the day of embryo transfer. Implantation takes place from day 7 to day 10 after fertilisation, so this means that…
if you are trying to conceive naturally you would be taking the pineapple before implantation has started (day 1 to 5 after fertilisation)
most IVF cycles are transferred on day 5 so you would be taking the pineapple during implantation (day 5 to 10 after fertilisation)
Summary
there isn’t any research or traditional medicine history to support taking pineapple to assist implantation
pineapple has a known anti-inflammatory effect and so may be useful for women with endometriosis and auto-immune disorders
preparation is important - your pre-conception diet and supplements are more likely to influence the immune system favourably toward implantation than 5 days of pineapple
if you are already on aspirin or clexhane check with your doctor before taking pineapple as too many blood thinners at once may affect success
if you do decide to take it during an IVF cycle it may be more logical to start from the day after egg collection