Does a plant-based diet really lead to more bone fractures?
26 November 2020
During the last week, there have been numerous headlines suggesting that a vegan diet is associated with a higher risk of bone fracture. ProVeg International looks beyond the headlines and provides recommendations for a healthy and balanced plant-based diet.
According to a new study, vegans face a 43% higher risk for bone fractures than meat eaters. Does this present bad news for plant-based-food lovers, or is it propaganda propagated by the meat and dairy industries? In fact, it is neither. Let’s take a closer look.
In November 2020, a team of scientists published a new analysis of the results of the EPIC-Oxford study, a long-term study of 65,000 men and women living in the UK, recruited between 1993 and 2001. Since then, numerous academic papers have been published on the results. Just as with previous analyses, the current paper provides important information about the long-term effects of diet and lifestyle factors on our health.1 It was a robustly designed study, with accurate analysis of the data.
This is why we should explore beyond the headlines which suggest that vegans and vegetarians may have a higher risk of bone fracture. First of all, we should not only look at percentages but also at the absolute numbers. The evaluation under discussion is based on a population of about 55,000 people, including about 2,000 vegans. With over 17 years of follow up, on average, participants reported a total of 3,941 fractures, with 147 fractures among vegans.2 Looking at the actual numbers may help to bring the facts into a clearer context. However the results are still significant, and, as such, we must also look at the factors which can lead to an increased risk of fracture.
The low BMI factor
Vegans and vegetarians tend to have a lower BMI (Body mass index) than meat eaters, which is a key factor when it comes to interpreting the data. The greater tissue padding of people with a higher BMI can have a protective effect against fall-related fractures. For example, results from the Million Women Study, which included about 1,155,000 postmenopausal participants, show that, compared with lean women, obese women had a 43% and 77% reduced risk of wrist and hip fractures, respectively.3
The authors of the current paper also point to the fact that their interpretation is limited by the small numbers of cases, “especially because of the strong correlation between diet group and BMI, which results in very few vegans in the higher BMI category, and vice versa comparatively small numbers of meat eaters with a low BMI”.4 It is important to note that this fact has not generally been acknowledged in the articles that have garnered so much attention in the last week.
Benefits of a plant-based diet
Although a high BMI can have a protective effect, minimising the risk of fractures, the benefits of a plant-based diet with a BMI in the normal range offers many more benefits compared to a diet centred on animal-based products. Type 2 diabetes, several types of cancer, and cardiovascular diseases can all be managed and even avoided by following a more plant-based diet that is less calorie dense and lower in saturated fats, salt, and refined sugars. Food from plants contains no dietary cholesterol and provides a plethora of vitamins, minerals, fibre, and secondary plant compounds, all of which play an important role in sustaining human health.
Pay attention to calcium and total calorie intake
However, vegans in the study did have a lower intake of calcium and protein than the other diet groups. This is often the result of insufficient total calorie intake, which leads not only to a low BMI, but also to poor bone mineral density. Although there is a risk of protein deficiency if too few calories are consumed on a vegan diet, protein requirements can easily be met with a plant-based diet. Pulses (including lentils, peas, and beans – and, above all, soya beans) and cereals (rice, oats, millet, wheat, spelt, rye) are of particular importance as protein sources for those on a plant-based diet. Soya products such as tofu and tempeh are also high in protein. The consumption of a wide range of plant foods and a sufficient intake of calories are key.
There are still a lot of prejudices about vegan and vegetarian lifestyles, including the idea that a plant-based diet does not provide sufficient protein.
Don’t forget calcium
Calcium is an important building block for bones and teeth, as well as other structures and tissues, and is prevalent in both animal- and plant-based foods.5 Calcium deficiency can lead to osteoporosis, and thus indeed to a higher risk of fractures. While dairy products and cow’s milk are often praised for their high calcium content, many plant foods contain adequate amounts of calcium. Chinese cabbage, kale, broccoli, collards, mustard greens, calcium-set tofu, navy beans, white beans, almonds, tahini, dried figs, and fortified products such as plant-based milk are all significant sources of calcium.
There is still a lot of misinformation about vegan diets, including the myth that people need to consume dairy products in order to get enough calcium.
Let the sun shine on you
Finally, vitamin D levels play a key role in calcium homeostasis and bone health. Sufficient levels of vitamin D can be achieved by sufficient bodily exposure to sunlight (this link was not examined in the current study). In the summer months, a supplementation of vitamin D should not be necessary, so long as one spends a minimum of 20 minutes a day outside, in the sun. However, in the colder months, especially for people living in the northern hemisphere, vitamin D supplementation may be essential. Specific populations (such as office workers, children, and the elderly) may need vitamin-D supplementation even in summer. Before taking any supplement, it is strongly advised to have appropriate blood tests and consult with a medical professional.
Fortified foods may be helpful
While the consumption of supplements should indeed be discussed with a medical professional, fortified foods also have a role to play. Although often shunned by vegans and non-vegans alike, fortified foods are not the same thing as dietary supplements, and it is important to make an informed choice when shifting to a plant-based lifestyle.
Approaches to fortification vary between countries. In some countries, food fortification is mandatory, while, in others, it is voluntary.6 The World Health Organisation promotes food fortification as a means of preventing malnutrition and, as such, provides governments with guidelines on appropriate measures.
In Europe, food fortification is generally voluntary. The responsibility to eat healthily and consume adequate amounts of nutrients lies in the hands of consumers themselves, regardless of the diet they follow. However, any diet can be nutrient deficient and thus lead to malnutrition. A mixed diet can be deficient in iodine, iron, fibre, folate, vitamin C, vitamin E, magnesium, vitamin B12 and vitamin D. In a plant-based diet specifically, the so-called critical nutrients are vitamin B12, calcium, zinc, iron, iodine, and omega-3 fatty acids.8
Overconsumption of nutrients through fortified foods is quite unlikely. Food fortification is strictly regulated in most countries: the amounts of added nutrients are based on safety recommendations, which is not always the case with dietary supplements. Usually, only a fraction of daily requirements is covered by fortified products, e.g. most calcium-fortified plant milks contain 15% of the recommended daily amount of calcium per 100 millilitres, which amounts to 120 milligrams of calcium. The tolerable upper limit for calcium intake (the safe amount of calcium which can be ingested) is 2,500 milligrams. One should also keep in mind that the biological availability of nutrients depends on many external and internal factors, including the cooking method used, the presence of other nutrients, and exposure to light and air, to name just a few.
Fortified soya milk should be considered part of the milk-and-dairy food group
As more and more people shift to a fully plant-based diet or become interested in doing so – which is to be welcomed in terms of sustainable nutrition – common dietary recommendations should provide the necessary support for doing so, while taking into account the habits of consumers. For example, in the US dietary guidelines, calcium-, vitamin A- and Vitamin-D-fortified soya milk is included in the ‘milk and dairy’ food group.9 The nutritional profile of fortified soya milk is similar to cow’s milk in terms of protein, calcium, and micronutrients. Fortified soya products are explicitly recommended for those on vegetarian or vegan diets.10
Whole foods are nutrient-dense, delicious, and should constitute the bulk of any human diet. However, covering all of the nutrient needs by eating whole foods alone can be difficult and even impossible for certain groups of people, whether because of one’s job, family situation, activity level, a specific health condition, or even location. Besides, nobody can keep up a so-called perfect diet 100% of the time. At the end of the day, food is not only about nutrition and calories, but also about enjoyment, culture, and community. Including fortified foods in one’s diet can prove useful in following a plant-based diet, while maintaining good health and taking a relaxed but informed approach to nutrition.
Particularly with regard to the newly published results of the EPIC study, the consumption of fortified foods should be encouraged in the plant-based community, not frowned upon. Fortified foods are an important tool for preventing deficiencies, while at the same time making it easier to follow a plant-based diet over the long-term.
A whole-food plant-based diet is a great way to prevent lifestyle disease and remain healthy.
- A plant-based diet can provide a sufficient supply of calcium if enough plant-based calcium sources are consumed.
- Valuable sources of calcium include cruciferous vegetables, leafy greens, beans, potatoes, almonds, sesame seeds and tahini, dried figs, algae, and mineral water, as well as fortified foods such as plant milks and tofu.
- Regular consumption of fortified foods, along with plant-based whole-foods, is recommended.
- Spend enough time in the sun and consider taking vitamin D supplements during periods when sunlight is scarce, in order to boost calcium absorption.
- A plant-based diet can provide a sufficient supply of protein if a broad selection of vegetable protein and a sufficient intake of calories is ensured.
- Pulses – especially soya products – are important sources of protein in a plant-based diet and should be eaten daily. In combination with protein from cereals,nuts, and seeds, they help to provide an optimal amino-acid profile. It is sufficient to eat different sources of protein throughout the day, rather than during a single meal.
- Exercise, especially resistance exercise and yoga, is very beneficial to bone and connective-tissue health.
- Having regular blood work and physical exams done should be a priority, regardless of dietary pattern or lifestyle.
These are general nutrition guidelines. If you have concerns about your diet, please talk to your doctor about seeing a dietitian. Discussing the use of supplements with a health professional will help to ensure that they are suitable for you. Never stop taking prescribed medications without first talking to your doctor.
|↑1||EPIC-Oxford (2020): The EPIC-Oxford Study. available at: http://www.epic-oxford.org/ [25.11.2020]|
|↑2||Tong, T. Y. N., P. N. Appleby, M. E. G. Armstrong, et al. (2020): Vegetarian and vegan diets and risks of total and site-specific fractures: results from the prospective EPIC-Oxford study. BMC Medicine 18(1), doi:10.1186/s12916-020-01815-3|
|↑3||Armstrong, M. E. G., B. J. Cairns, E. Banks, et al. (2012): Different effects of age, adiposity and physical activity on the risk of ankle, wrist and hip fractures in postmenopausal women. Bone 50(6), 1394–1400. doi:10.1016/j.bone.2012.03.014|
|↑4||Tong, T. Y. N., P. N. Appleby, M. E. G. Armstrong, et al. (2020): Vegetarian and vegan diets and risks of total and site-specific fractures: results from the prospective EPIC-Oxford study. BMC Medicine 18(1), doi:10.1186/s12916-020-01815-3|
|↑5||Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium (2011): Dietary Reference Intakes for Calcium and Vitamin D. National Academies Press (US) Verfügbar unter: http://www.ncbi.nlm.nih.gov/pubmed/21796828 [12.01.2019]|
|↑6||Global Fortification Data Exchange (2020). Available at: https://fortificationdata.org/interactive-map-fortification-legislation/ [26.11.2020]|
|↑8||Academy of Nutrition and Dietetics (2016): Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. Available at https://www.eatrightpro.org/-/media/eatrightpro-files/practice/position-and-practice-papers/position-papers/vegetarian-diet.pdf [26.11.2020]|
|↑9||U.S. Department of Health and Human Services and U.S. Department of Agriculture (2015): 2015–2020 Dietary Guidelines for Americans. 8th Edition. December 2015. Page 23. Available at http://health.gov/dietaryguidelines/2015/guidelines/|
|↑10||U.S. Department of Health and Human Services and U.S. Department of Agriculture (2015): 2015–2020 Dietary Guidelines for Americans. 8th Edition. December 2015. Page 86. Available at http://health.gov/dietaryguidelines/2015/guidelines/|