Dietary Intake of Selected Nutrients Affects Bacterial Vaginosis in Women
Yasmin H. Neggers Tonja R. Nansel William W. Andrews Jane R. Schwebke Kai-fun Yu Robert L. Goldenberg Mark A. Klebanoff
The Journal of Nutrition, Volume 137, Issue 9, September 2007, Pages 2128–2133
Bacterial vaginosis (BV), a condition of altered vaginal flora, is associated with various adverse reproductive health outcomes. We evaluated the association between diet and the presence of BV in a subset of 1521 women (86% African American) from a larger study of vaginal flora. Participants completed the Block Food Questionnaire and clinical assessments and self-report measures of sexual and hygiene behaviour. A total of 42% of the women were classified as having BV (Nugent score ≥7). Severe BV (Nugent score ≥9 and vaginal pH ≥5) was present in 14.9% of the women. BV was associated [adjusted OR (AOR)] with increased dietary fat (1.5, 1.1–2.4) after adjusting for other energy nutrients and behavioural and demographic covariates. Severe BV was associated with total fat (2.3, 1.3–4.3), saturated fat (2.1, 1.2–3.9), and monounsaturated fat (2.2, 1.2–4.1). Energy intake was only marginally associated (P = 0.05) with BV (1.4, 1.0–1.8). There were significant inverse associations between severe BV and intakes of folate (0.4, 0.2–0.8), vitamin E (0.4, 0.2–0.8), and calcium (0.4, 0.3–0.7). We conclude that increased dietary fat intake is associated with increased risk of BV and severe BV, whereas increased intake of folate, vitamin A, and calcium may decrease the risk of severe BV.1
This is a slightly older study (from 2007) that has been doing the rounds recently to support the idea that the ‘keto-crotch’ occurs in low-carb and keto diets. This keto-crotch refers to an increase in (unpleasant) smell from the vagina resulting either from increased bacterial vaginosis or from excretion of ketones.
Many people have suggested anecdotally that microbiome is negatively affected by a keto diet. But the research on this is equivocal at best (something I will be going into in a future research review).
Specific to bacterial vaginosis (an increase in unwanted bacteria [and fungus and yeasts] and distortion in the microbiome of the vagina) this study has been cited as a potential reason for keto-crotch in women and lays the blame at increased fat and saturated fat in the diet.
Did this study show that keto-diets cause bacterial vaginosis?
In short, no, it didn’t. The study looked at the association between many factors and vaginosis. Relatively strong associations were shown between fat (1.5, 1.1–2.4) and severe vaginosis with total fat (2.3, 1.3–4.3), saturated fat (2.1, 1.2–3.9), and monounsaturated fat (2.2, 1.2–4.1).
The diets themselves were not low-carb and there were many confounding influences on the results.
The diets were pretty shit overall
The mean energy intake of the women studied was ~2500 calories per day (or 500-700 calories over maintenance). So, they were in an overfed state and unsurprisingly, 42% of participants were overweight or obese. This suggests poor diet quality overall which is likely to have affected the outcomes significantly. We also know that there might be detrimental effects of increased fat and saturated fat consumption in a moderate to high carbohydrate, overfeeding diet.[REF] Interestingly, there was an association between greater intake of calories and increase in vaginosis and severe vaginosis.
Protein intakes of ~78 g per day were barely sufficient, while carbohydrate intakes averaged 308 g per day which is wildly excessive for a relatively sedentary group.
The poor quality of the diets consumed is indicated by the numbers of participants consuming less than 2/3 of the recommended daily intakes for vitamins and minerals including:
- Less than 2/3 recommended intake of Calcium: 41% of participants
- Potassium: 68%
- Zinc: 9%
- Iron: 38%
- Vitamin E: 53%
- Vitamin A: 14%
- Vitamin D: 13%
- Vitamin C: 8%
- Folate: 24%
ALL participants also failed to consume enough fibre. Given the importance of the gut microbiome to the vaginal microbiome, and protection against vaginosis, the poor quality of the diet, excessive carbohydrate intake, and lack of essential vitamins, minerals, and fibre that help to promote a healthy microbiome is incredibly informative.
Not surprisingly either, positive effects on vaginosis were associated with increased intakes of potassium and folate, which are both very good proxy measures for vegetable intake; and also associated with low intakes of vitamin E, iron, and calcium.
Associations were also shown between the frequency of douching, greater alcohol use, and income, all suggestive of the effect of the socio-economic and food environments of individuals, that are conducive to poorer health overall.
Weird ‘stuff’ happening with monounsaturated fats…
On reading this paper, it seemed strange that a relatively strong association was shown between monounsaturated fat and vaginosis…
This effect has not been reported in the mainstream citing of this study to support the idea that fat and saturated fat cause ‘keto-crotch’ but this was a stronger effect than saturated fat. Monounsaturated fats are typically given a ‘health halo’ and olive oil, high in the omega 9 monounsaturated fatty acid oleic acid, is almost universally recommended by higher- and lower-carb proponents alike.
While the actual food data is not available as a supplement to this paper, it would be interesting to see where these fats were coming from. I.e. were poorer people eating high oleic vegetable oils, or eating lots of peanut butter?
Then again, it’s most likely that irrespective of the type of fats consumed, the fats themselves were simply contributing to excessive energy intake in the context of a high-calorie, relatively high-fat, high-carb diet.
What does this all mean?
There could be some detrimental effects of total and saturated fat on some markers of health in the overfed state, especially in the context of a ‘metabolic shit-storm’ of high carbs + high fat + low-nutrient-density.
However, this study cannot be sued to support the idea that ‘keto-crotch’ results from a low-carb, higher-fat diet because of bacterial vaginosis, because the diets consumed were not low-carb and they certainly weren’t healthy.
Again, the take-home message is to eat a natural, unprocessed diet and then adjust your carb, protein, and fat intake based on your desired outcome, along with what you can tolerate well, and what you behaviourally can stick to.
1. Neggers YH, Nansel TR, Andrews WW, Schwebke JR, Yu K-f, Goldenberg RL, et al. Dietary Intake of Selected Nutrients Affects Bacterial Vaginosis in Women. The Journal of Nutrition. 2007;137(9):2128-33.