urinary tract (bacterial adherence to cells is a necessary step in infections). While both of these hypotheses are biologically plausible and worthy of pursuit, multiple studies have looked at cranberry juice and found no benefit. In addition, juice has no nutritional value; it’s just nature’s soda. Cranberry juice, even unsweetened, has a lot of sugar, and some brands can have as much as soda.
Two small studies have linked a high dietary saturated-fat (animal fat, so meats and dairy) intake with bacterial vaginosis, but this is far from a certainty. A high-fat diet could also be a correlation, not a cause, meaning women with these diets are more likely to have other risk factors for bacterial vaginosis. How this connection might exist biologically is simply not known. There are other health reasons besides your vagina to try to avoid a diet that is very high in saturated fat.
Eating at least 25 g of fiber a day is the best preventative health advice I can offer vagina-wise, as fiber is a prebiotic, meaning it feeds good bacteria in the bowel. Fiber also draws water into the stool, softening it and helping it move along more quickly, thereby preventing constipation. Constipation can lead to straining, which can cause pelvic floor spasm (potentially causing pain with sex or pelvic pain) and hemorrhoids. The average American only eats 7–8 g of fiber a day, so I recommend a fiber count, meaning writing everything down that you eat for 1–2 days and then checking the fiber count so you know how much you are eating and can make changes if necessary. I’m a little lazy, so I just eat a cereal with 8–13 g of fiber a serving most days, so I know I’m one third to one half of the way there before I’ve even started my day.
Lots of people ask about fermented foods, such as yogurt, sauerkraut, or kombucha, to help cultivate good gut bacteria. Typically, these foods do not contain the right strains of lactobacilli for vaginal health, although they may have bacteria that is healthy for the gut. Some studies have linked fermented milk products like yogurt with a reduction in bladder cancer, heart disease, gum disease, and cardiovascular disease. Fermentation enhances the nutritional value of vegetables and may increase the iron that is available for absorption. Many women are iron deficient, so this obviously won’t hurt.
It is possible the bacteria in fermented dairy and vegetables could have a beneficial impact on normal gut bacteria after antibiotics, but we don’t have any research on the impact on vaginal health. Having fermented foods if you are on antibiotics is probably not a bad strategy to try to lessen the impact of antibiotics on your gut bacteria (this is a cause of antibiotic-related diarrhea). However, as there are no studies that prove this works, I wouldn’t sweat it if you don’t like fermented foods and that strategy doesn’t appeal to you. Personally, I despise sauerkraut and kombucha, and for me to give them a try there would need to be several very robust studies to show they definitively help protect gut bacteria after antibiotics.
BOTTOM LINE
• Food can’t change the vaginal scent.
• There is no anti-candida diet. If you don’t have diabetes, what you eat is not going to give you a yeast infection (and even if you do have diabetes, it is more about the urine and immune system).
• No evidence shows cranberry juice prevents bladder infections.
• Eating 25 g of fiber a day will help keep your gut healthy, and indirectly that will help your vagina.
• Fermented foods might (emphasis on might) be useful if you are taking antibiotics.
CHAPTER 8
The Bottom Line on Underwear
ALMOST EVERY WOMAN HAS BEEN TOLD at least once (and often more than once) to wear white cotton underwear as a medical recommendation to prevent yeast infections and other vaginal mayhem. This makes it sound as if vaginas and vulvas are accidents waiting to happen. The vulva can handle urine, feces, and blood, and vaginas can handle blood, ejaculate, and a baby, so this idea that a black lace thong is the harbinger of a vaginal or vulvar apocalypse is absurd.
I love pretty underwear. Perhaps it is from years of my mother buying the kind of underwear for me she thought “nice girls” (i.e., those who only have sex for procreation) should wear—hideously floral and large. It is also possible it’s from a lifetime of wearing surgical scrubs, where the only self-expression through clothing could be what was underneath. Regardless, if wearing lace or dyed fabric were bad for the vulva, I would know better than to expose myself to potential infection by wearing them.
Really, white cotton underwear doesn’t protect against yeast infections?
The white cotton underwear myth started before we knew about the vaginal ecosystem or the biology of yeast infections. How far it goes back I am not sure, but it wouldn’t surprise me if it dates back to the time when women were advised to douche with Lysol and “lace” meant “loose.”
There are low-quality studies that link polyester underwear and pantyhose with yeast infections. These studies interviewed women who did and didn’t have a history of yeast infections, and then asked them what kind of underwear they wore. The yeast infections were not proven by culture (the gold standard); rather self-diagnosis was used. This is problematic, for as many as 70 percent of women who self-diagnose with yeast infections are incorrect. When something bad happens, like vulvar or vaginal irritation, people are more likely to remember things they feel could be related than those who have not had the same bad experience. This is called recall bias. Finally, if you have a lot of itching and irritation and you have been told about wearing white cotton underwear, you may have switched and had a placebo effect. More recent studies of higher quality have shown no connection between underwear and yeast infections.
For underwear to cause an issue, it would have to change the ecosystem (perhaps by altering the pH of the skin), trap excess moisture, or cause friction. The combination of moisture and friction can cause microtrauma, which could allow the normal yeast on the skin to cause an infection.
Underwear can’t change vaginal pH; that is an inside job. There are a few studies looking at the effects of tight clothing on the vulvar skin, and there was no effect on bacterial colonization or pH. One study evaluated new underwear for athletics (performance underwear), which are not cotton but are designed to wick moisture away from the skin to improve comfort (wet underwear is unpleasant), and there were no health concerns. Thongs also appear to have no negative impact.
The only thing that can change the pH and microenvironment of the vulva is something occlusive—think waterproof, like plastic or latex. This can be an issue for women who have to wear waterproof incontinence underwear daily.
Underwear needs to fit correctly—if you are tugging at your groin or it is digging in or chafing, you could potentially develop skin irritation, but typically that kind of underwear is too uncomfortable to wear long enough to develop a health problem. It is probably also best to not wear underwear made of plastic or latex, as anything that causes you to sweat could be an issue.
What about a bathing suit?
The idea that women sit around in wet bathing suits all day intrigues me. I wonder if anyone promoting bathing suit panic has even seen a modern bathing garment? My suit tends to dry pretty quickly. That is sort of the point. Also, a little water against your skin is not going to damage anything. I mean honestly, if it does we have evolved rather unfortunately. Our vulvar skin gets wet a lot, and many humans spend a lot of time in the water. Dampness that dries relatively quickly is not going to cause an issue. If you sit in soaking wet clothes for several hours, you may develop skin irritation called maceration—a superficial skin injury from the combination of moisture and friction. This is why runners put petroleum jelly between their thighs before a long run, to prevent the maceration from friction and sweat. So if you throw on your clothes on top of a soaking wet bathing suit, you could potentially get some chafing, but the comfort factor of soaking shorts or pants is probably going to drive most women to change before they get a superficial skin injury.
Do I even need to wear underwear?
There is no medical reason to wear or not wear underwear. Many women tell me they don’t wear undergarments so their “vagina can breathe,” but the vulva and vagina don’t have lungs. The vagina doesn’t like