We explore the research on the gender swaying diet and whether or not the boy diet and girl diet for sex selection actually works.
For years now people have taken huge interest in being able to select the sex of their baby. Whether it’s to create family balance, due to culturally imposed sex preferences, or in some cases, to apparently aim to prevent hereditary gender-specific diseases.
In the IVF world, I can tell you that choosing your future baby’s sex is actually quite common. While this is illegal in Canada, a lot of my fellow infertility warriors in the USA do it all the time. But while sperm sorting, albumin separation and IVF in general are medical methods for manipulating the sex of your future offspring, these techniques require medical assistance and can be pretty expensive. They’re also not without their risks. Not surprisingly, this has led many people to explore alternative, more “natural” methods to get their dream baby including the so called “gender swaying diet”. Now this may sound ridiculous, but as someone who spends a gross amount of time lurking in mom Facebook groups and forums, I can tell you that there are entire online communities who aim to talk about how food choices can impact whether you conceive a boy or a girl. But is there any merit to these sex selection suggestions or is it just a bunch of BS? I did some research to determine whether or not there is any validity to this gender swaying diet.
What’s Sex vs Gender?
Before we get too far into this, I have to deal with the first issue I have with this gender swaying diet theory- the name is totally F*cked. If this is ACTUALLY a thing we can manipulate, what we’re actually talking about is SEX, biological SEX. NOT gender. Gender is a social construction and we cannot manipulate it in any way. To find out if we can manipulate sex may be a whole other story. Okay, so let’s get into the science of that.
What Influences Sex?
Most of us rational people would assume that sex selection is comparable to rolling a dice as it’s about a 50/50 chance you’ll get a boy or a girl. According to the World Health Organization, the global sex ratio is around 105. Meaning that for every 100 females, there are 105 males. However, how many of us know a family who has 5 boys or 5 girls? Is this just probability or is there something going on that is resulting in these extremes? Well, some early research has shown that two factors have shown some potential promise in influencing sex. These factors include:
- The mineral content of maternal diet
- The timing of intercourse related to ovulation
Mineral Content of Maternal Diet
The idea that the mineral content of a maternal diet can sway gender is based off of studies conducted on animals dating back to 1935! One small experiment done on marine worms (Bonellia viridis) found that by altering the potassium levels in the water, the sex ratio (that is the number of female to male offspring) for this species could be strongly influenced with ratios ranging from 0.1 to 10. Other studies done on cattle, sows and rats concluded that higher Na+ and K+ concentrations and less Mg2+ and Ca2+ also had a significant influence on changing sex ratio within their respective species. All of these studies, however, were fairly small (we’re talking 72 rats) AND we cannot confidently extrapolate animal research to humans. Just an FYI.
Timing of Intercourse
Timing of intercourse is also believed to play a role in sex selection, with research suggesting that Y-bearing sperm (male chromosome bearing sperm) are slightly lighter and faster while at the same time more fragile and likely to have shorter life spans compared to X-bearing sperm (female chromosome bearing sperm). Based on this information, it’s believed that intercourse closer to ovulation could possibly favour having a boy. With this being said, intercourse closer to ovulation in general can increase chances of any pregnancy ( with research showing only a 5% chance of survival after 4.4 days.)
Sex Ratios in IVF
There is some talk that in-vitro fertilization is associated with a sex ratio imbalance that generally favours males. Some research suggests that this could be due to the fact that a small percentage of x-bearing sperm are the fastest to travel to the supernatant followed by the y-bearing sperm. The majority of x-bearing sperm remain in the pellet during this technique and this is what ends up being collected. This resilience is thought to result in male sperm being selected more often. One prospective study found that two medical centres reported more male births when using a modified swim up technique for insemination. The conventional swim-up technique involves the collection of the entire supernatant, while the modified technique discards the very top layer and only collects what is remaining. With that being said, many IVF centres are not presently implementing this modified method and research is still pretty limited so I wouldn’t read too much into this theory.
What Does The Gender Swaying Diet Involve?
Since I’m a dietitian and not a fertility endocrinologist, I’m going to focus on the diet aspect of this. Based on these theories and animal research, the gender swaying diet focuses on the concentration of minerals you get from the foods you eat. Calcium, magnesium, sodium and potassium are thought to influence gender selection so the foods you eat will vary depending on the gender you are trying to conceive.
The “Girl Diet”
To conceive a female, the gender swaying diet would suggest consuming foods high in calcium and low in sodium.
Some examples of calcium rich foods include dairy products like milk, cheese, and yogurt. Other sources include dark leafy greens (kale, collard, swiss chard, okra, broccoli), beans and lentils, soy and some fish (with bones) like sardines. Processed/packaged foods like chips, canned soups, frozen dinners and other fast foods are known to be high in sodium and would be some definite no-go’s under this girl diet.
The “Boy Diet”
In order to conceive a boy, the opposite is recommended. This diet suggests that having a dietary intake that is higher in sodium/potassium, and lower in calcium and magnesium. Some of the recommended food items for this diet include potatoes, peaches, apricots, cantaloupe, bananas, apples, cherries, rice and zucchini, and you could increase your intake of some of those higher salt foods, if you like.
Human Research for the Gender Swaying Diet- Does it Actually Work?
As previously discussed, many of the studies we have seen in this area have been completed in marine life and other mammals. The quality research on humans, in contrast, is very limited. One human study looked at the effects that adhering to a “gender swaying diet” with specific levels of calcium, magnesium, sodium, and potassium would have on sex selection. The study concluded that when couples adhered to specific mineral levels relative to the gender they desired to conceive, gender swaying worked in their favor 80% of the time. Although the results sound promising, only 281 couples were involved in this study, which is not a terrible, but not an amazing sample size.
Another study observed couples with three or more girls and no boys. This study found that levels of calcium and magnesium were dominant in the mother’s diet, while mothers of boys had an above average sodium level. However, this was also conducted on a small sample group and was retrospective in design, so again, it doesn’t provide significant merit to some of these gender swaying diet claims.
Another study looked at the blood mineral levels of 50 women going into labor and found that, for the most part, the levels were not different between women who conceived a boy vs girl. The only mineral that seemed to be different in moms of boys compared to moms of girls was zinc. Zinc levels appears to be higher in women with male babies. Again, this is a very small sample size, and because we’re looking at correlation, not causation, it’s very difficult to make conclusions about the effectiveness of the gender swaying diet.
Does The Gender Swaying Diet Pose Any Nutritional Risks?
It’s always important to have adequate dietary intake in order to maintain good health but this is especially true during pregnancy or when you’re trying to conceive. The foods you eat become the main source of nutrients for your baby, and your nutritional needs significantly increase. Inadequate levels of key nutrients can not only negatively impact maternal health, but can also compromise fetal development.
Is The “Boy Diet” Safe?
So lets talk about the “boy diet” first. This diet calls for higher levels of sodium and potassium and lower levels of magnesium and calcium. Switching to a low calcium diet is a bit concerning because of the bone building benefits provided from consuming adequate amounts. This is especially important during pregnancy for the mineralization of fetal bone. In fact, the Recommended Dietary Allowances suggest that calcium intake should be increased from 20 to 30 mmol (800 to 1200 mg) per day during pregnancy. The boy diet would suggest 250-400mg/day which is VERY low compared to the recommendation. In addition to this, some research suggests that there is an association between low calcium intake and the development of hypertension. Consuming higher levels of calcium may help regulate the renin-angiotensin system and therefore improve sodium-potassium balance. Magnesium is also thought to be associated with the regulation of blood pressure and bone building as it often works together with calcium. It also plays a role in muscle relaxation, and so research suggests that consuming adequate amounts can help inhibit spontaneous/premature contractions of the uterine muscle.
Another concern I have with these recommendations is the high intake of sodium. Excessive salt intake is a known risk factor for developing hypertension, cardiovascular disease and stroke. This is especially dangerous if you’re following this type of diet for the long term (i.e. you’ve been trying to conceive for a long period of time and/or dealing with infertility).
Likewise, too much potassium (hyperkalemia) can result in heart palpitations and life threatening rhythm abnormalities. Now if that isn’t enough to discourage you from following this ridiculous diet, I don’t know what is!
Is the “Girl Diet” Safe?
The girl diet recommends the complete opposite as it calls for higher levels of calcium and lower levels of sodium. We’ve already discussed the importance of calcium in your diet but can too much calcium also be harmful? The answer is yes. Tolerable Upper Intake Levels (UL) are set to highlight the highest daily intake of a nutrient, vitamin, or mineral that is likely to pose no adverse affects. If this level is exceeded, risk for adverse effects increases. The UL for calcium is set at 2500mg/day. However exceeding this through food alone is extremely difficult and is more associated with supplementation. Consuming more than the UL can cause constipation, increase risk for kidney stone formation and hypercalcemia. For gender swaying purposes, the diet suggests to stay within 1200-1800mg/day. This is well below the UL and if you are consuming 1200mg/day it actually aligns with the RDA of 800-1200mg/day for pregnant women.
As for sodium, the diet suggests that one consume between 700-1000mg/day while the current general recommended to consume less than 2300mg daily (aiming for the Adequate Intake of 1500mg/day). It’s true that some individuals can benefit from restricted sodium intake especially if advised from a doctor due to medical conditions like hypertension. However, sodium has many important functions in our body including maintaining water balance, acid-base balance, regulating muscle contractions and also the absorption and transport of some nutrients. Moreover, I would say that it would be really hard to stick to 700 mg of sodium unless you’re consuming everything from scratch and not adding sodium to your food.
So Should You Do the Gender Swaying Diet for Sex Selection and Family Planning?
Although there is some preliminary research favoring this diet in combination with the timing of intercourse, a lot of the studies lack the depth needed to make conclusive claims. In most cases, actual human evidence just isn’t there.
For starters, many of these studies are done on animals. While the experiments we’ve seen done on rats, marine life and sows may be promising, at the moment we don’t have really any solid evidence for humans.
The evidence that we do have for humans is often retrospective and based on very small sample sizes, so it’s difficult to make any conclusions based on that.
Personally, I am floored that there is money being put into research on sex selection, as I think this information could be dangerous in the wrong person’s hands. I’m not wanting to mom shame any parent for feeling like they desire a specific sex to complete their family, but eek, something about the process feels a bit like playing G-d, and I don’t know, I just feel nervous about that! Ha, I remember when I found out about this option in the states while doing IVF and my thought was “I think G-d would smite me if I chose a female or male egg to implant!”