Ernährungsberatung Connie Jimbo

Women's Bodies As a Gap in Research


Recently, the unequal treatment of men and women has become more and more of a talking point. Anyone who doesn’t live in a hole in the
ground has certainly noticed this. I’m not talking about the gendered language here (I don’t know if this is a thing in English-speaking countries, but it is a relatively huge issue in Germany). In my opinion, equality does not primarily require new grammar. However, various things that are still commonplace for many women need to be discussed. Be it differences in salary, unequal treatment (as a blonde woman, I am sometimes perceived by men as incompetent for it and was even fired once for not obediently doing everything the male bosses said, but wanting to contribute my expertise and questioning certain procedures) – don’t even get me started on the #metoo movement that emerged in 2016 when it suddenly became clear that none of us are alone in our experiences of sexual harassment.

A glance at the world’s systems reveals a certain focus on masculinity: crash test dummies are based on male bodies, which means so are safety systems in cars. Training dummies for first aid courses are male torsos, smartphones are ideal for men’s hands, women’s hands often can’t reach the corners of the display. Women’s clothing is designed so that we have to buy handbags, as the clothing often has only relatively small pockets, or none whatsoever. Products aimed at women are often more expensive than those for men, like razors, for example. And so on and so forth. Men are the „standard“ and women are the „deviation“.

Where does science come into play here?

Even in clinical research, men are the standard and women are the deviation. My anatomy book, which was recommended to us by our professors at university back in 2011, only shows the male anatomy even if gender differences are to be expected, for example in the musculoskeletal or digestive system, unless a specifically female organ is addressed. Topics that only affect women and that are not cancer – to be fair, a lot of research is being done on ovarian and breast cancer, for example – and women as study subjects are generally underrepresented (1). Pubmed, one of the largest scientific databases in the world, provides six times as many results for erectile dysfunction as for premenstrual syndrome, two disorders with similar prevalence and severity. There is still a gender bias in clinical research, i.e. a bias towards male physiology as the standard (1,3). Failure to recognise the physiological differences between men and women in science and clinical trials could lead to economic as well as health damage and even death, particularly among women (2). This is a really big problem in which women lose out once again, but which the public hardly realises. The consequences are immense. Many drugs were developed at times when almost only men were the subjects of clinical trials. In the US, drugs have already been withdrawn from the market because they had such serious side effects in women that their use was no longer permitted (2).

...and where does nutritional science come in?

Now guess what I have problems finding scientific findings on? That’s right. On nutritional recommendations specifically for women. The fact that we are different from men seems to stop at acknowledging our different body fat content. Almost every woman has a menstrual cycle during a long part of her life, during which there are strong hormonal fluctuations, even a rise in body temperature in the second half of the cycle, which causes us to need 5-10% more energy – or correspondingly less before ovulation. I have found at least a little more, although not much, on nutrition during and after the menopause.

Excursus: the limits of the hypothesis

Of course, you could argue that the menstrual cycle is not a disease. Which is true, but here we also see how normal it is for clinical science to focus primarily on diseases and their specific prevention, and less on general health promotion. This is largely due to the approach of clinical research itself, which is rather set in stone. The so-called randomised controlled trial is regarded as the measure of all things in terms of clinical methodology, and the meta-analysis, a statistical summary of this type of study on a specific research question, as the pinnacle of clinical evidence. In other words, the result of the meta-analysis is the closest thing to something we could call „proof“. In fact, science never conclusively proves a result. Research must always be discussed and questioned. Please take every „research has shown that…“ you read in mass media with a grain of salt.

Randomised controlled trials are quite complex and extremely limited in the range of what can be tested per trial. Hypotheses are the two opposing answers to a research question to be analysed in one study. They are at the centre of that study and specify what is being tested, by means of data collection and statistical analysis. However, they only ever allow for a single very specific research object, otherwise it becomes statistically and logistically difficult.

·        Example for a research question: Does the regular consumption of ginger reduce the risk of breast cancer?

·        Zero hypothesis: Regular consumption of ginger has no influence on the risk of breast cancer.

·        Alternative hypothesis: Regular consumption of ginger reduces the risk of breast cancer.

The term „regular“ still needs to be precisely defined, as does the amount of ginger consumed per day or week, otherwise we are already presented with another research question: does the risk of breast cancer decrease the more ginger is consumed? This would be a completely different study with implications to how data is to be collected and which statistical analysis is to be applied. I hope this example makes it clear how thorough but limited a single clinical study is, how slow the closing of research gaps is, and how little room for innovation this leaves.

The eternal problem of translating science into everyday life

In this entry, I have only addressed the problem of „sex bias“ in science as far as bias in binary genders is concerned. This can even be applied to animal experiments, where often only male specimens are studied (3). In my experience, research on people of different ethnicities is also biased in a certain direction, which would deserve special attention and is a different discussion for another time. But researchers should also be aware of this: which target group should my study be applicable to? Does my sample fit this population? If I want to market a treatment or diet for everyone, does my sample cover the diversity of all people?

The problem of sampling and how (non-)representative it is, is one of the reasons why there are so many contradictory findings in science. For every study there seems to be another one with the opposite result, not only in nutritional science.

This brings us back to the topic of what should I actually eat to keep myself healthy? The nutritional recommendations issued in Germany by the German Nutrition Society (Deutsche Gesellschaft für Ernährung, DGE) aim at preventing deficiency symptoms. The recommendations as such are often based on average values that are calculated from typical body composition and existing research. As they are based on scientific findings, they are well-founded but may also contain these biases. In principle, dietary recommendations should therefore be seen as a direction, but not as a precise guide. Every body is individually different on top of everything.

Recommendations for staying healthy, including those issued by DGE, often come down to the same few basic rules. Lots of fruit and vegetables, plenty of fibre, enough water, little sugar and few processed foods.

Coming soon: what did I find out about women and nutrition then?

I started this entry by researching what kind of findings there are for a recommended diet along the menstrual cycle. For now, it was more important to me to share what I’ve found along my research and wanted to shed light on the limitations modern science is subject to. What I found out about nutrition along the menstrual cycle and afterwards deserves its own blog entry. That will come next. But it wasn’t much. Most of the current research initially relates to the how women actually eat along the cycle (exemplary, sources 4 and 5). This topic seems very new for research. The narrative review (5) is from this year. It’s as if menstruation is a modern phenomenon that has only emerged in recent years.

(1)    Yoon DY, Mansukhani NA, Stubbs VC, Helenowski IB, Woodruff TK, Kibbe MR. Sex bias exists in basic science and translational surgical research. Surgery. 2014 Sep;156(3):508-16. doi: 10.1016/j.surg.2014.07.001. PMID: 25175501.

(2)    Lee SK. Sex as an important biological variable in biomedical research. BMB Rep. 2018;51:167–173

(3)    Zucker I, Beery AK. Males still dominate animal studies. Nature. 2010 Jun 10;465(7299):690. doi: 10.1038/465690a. PMID: 20535186.

(4)    Gorczyca AM, Sjaarda LA, Mitchell EM, Perkins NJ, Schliep KC, Wactawski-Wende J, Mumford SL. Changes in macronutrient, micronutrient, and food group intakes throughout the menstrual cycle in healthy, premenopausal women. Eur J Nutr. 2016 Apr;55(3):1181-8. doi: 10.1007/s00394-015-0931-0. Epub 2015 Jun 5. PMID: 26043860; PMCID: PMC6257992.

(5)    Rogan MM, Black KE. Dietary energy intake across the menstrual cycle: a narrative review. Nutr Rev. 2023 Jun 9;81(7):869-886. doi: 10.1093/nutrit/nuac094. PMID: 36367830; PMCID: PMC10251302.

Hast du noch Fragen?

Sehr gerne beantworte ich deine Fragen im kostenlosen und unverbindlichen Infogespräch.

Chat öffnen
Wie kann ich Dir helfen?
Scan the code
Chat mit Connie Jimbo
hast Du eine Frage? Ich freue mich auf Deine Nachricht.