THE PLANT-BASED ATHLETE SERIES: MICRONUTRIENT CONSIDERATIONS
Updated: Feb 2
Annie Bothma, November 2022
Achieving micronutrient sufficiency is an important concern for all athletes. However, if you are following a vegan diet you need to pay extra attention to your vitamin B12, iron, zinc, calcium, iodine and vitamin D intake. Deficiency in these key micronutrients could have detrimental health and performance implications for plant-based athletes.
VITAMIN B12 (Cobalamin)
Due to an absence of animal and dairy products, vegans are at an increased risk of developing Vitamin B12 (cobalamin) deficiency. Cobalamin is synthesized from anaerobic microorganisms, in the rumen of cattle and sheep, and humans typically consume pre formed cobalamin from animal products, which are the main source of B12 in the diet. Plant-based sources of cobalamin are scares, unless the plant has been contaminated by manure or from animal waste. Cobalamin is essential for normal nervous system function,
homocysteine metabolism and DNA synthesis.
A cobalamin deficiency can lead to morphological changes to the blood cells and the development of hematological and neurological symptoms, such as megaloblastic anaemia and neuropathy. Long-term cobalamin deficiency can lead to irreversible neurological damage, and data indicates that veganism can lead to deficiency if cobalamin is not supplemented.
Data from the EPIC-Oxford cohort study in the UK indicated that ~50% of vegan participants were vitamin B12 deficient. (Rogerson, 2017)
An additional 21% of the vegans were also classified as having very low levels. Interestingly, despite 20% of participants consuming a B12 supplement, blood-vitamin levels between those that took the supplements vs. those that did not take any Vitamin B12 supplements were no different. This suggests that the supplementation practices of the cohort were inadequate to achieve B12 sufficiency.
Supplemental vitamin B12 products typically contain cyanocobalamin. However, the body appears to have a limited capacity to absorb vitamin B12 supplements orally, which is limited by the presence of intrinsic factor, a glycoprotein secreted by the stomach’s parietal cells that combines with B12 prior to absorption in the distal ileum via receptor-mediated endocytosis. For example for an ingested 500 μg oral supplement, only an approximated
10 μg might be absorbed due to the poor bioavailability. Sublingual drops, lozenges and transdermal products have been developed and marketed under the assumption that they offer better absorption, however research supporting these claims are not strong. Vegans are advised to consume fortified foods and/or take a daily supplement to ensure an adequate intake of vitamin B12.
Daily Recommended Intake:
The Dietary Reference Intake (DRI) for vitamin B12 is 2.4 μg/day for adults of both sexes and vegans are advised to consume up to 6 μg/day of supplemental B12.
Tips for boosting your Vitamin B12 intake on a plant-based diet:
Choose Vitamin B12-fortified foods like breakfast cereals, bars or non-dairy milk.
Sprinkle nutritional yeast over your pasta or use it to make a creamy "cheesy" sauce.
Include fermented soy products, such as tempeh, as part of your diet.
Mushrooms are good plant-based sources of vitamin B12. Try adding in dried shiitake mushrooms which contain the highest amount of vitamin B12 at 5.6 micrograms per 100 grams.
Consider taking a supplement to help you meet your needs.
The iron intake of vegetarians and vegans appears to be similar to omnivores athletes if they consume a diet rich in whole-grains and legumes. However, the problem arises with the bioavailability of plant-based iron may mean that vegans need to pay attention to avoid deficiency.
The main source of iron in the vegan diet is found in the non-heme form, which is less bioavailable than the heme iron found in animal products. Vegan diets also typically contain dietary inhibitors such as the polyphenols tannin (found in coffee, tea, and cocoa) and phytates (found in whole grains and legumes), which further reduce the amount of iron absorbed from the diet. Non-heme iron absorption can be enhanced by consuming non-heme iron-rich foods in conjunction with vitamin C.
Research indicates that the iron status of vegans has found that female vegans appear to have lower iron stores than omnivores, and are more prone to iron-deficiency anaemia. Interestingly, most male vegans appear to have a similar iron status as non-vegans and are less impacted by iron status. Thus, if you are a female vegan athlete or not consuming many foods rich in iron, you may need to consider supplementing this micronutrient.
Different types of iron deficiencies:
Iron-deficiency anaemia is caused by insufficient consumption of iron (or insufficient absorption of iron) and is decrease in red blood cells (RBCs) or hemoglobin, leading to symptoms such as tiredness and fatigue; weakness, shortness of breath and reduced exercise tolerance.
Iron deficiency without anaemia has also been shown to reduce endurance capacity, increase energy expenditure and impair adaptation to endurance exercise in females experiencing tissue depletion.
Recommended Daily Intake:
Due to reduced bioavailability the recommended intake for vegan and vegetarians is 80% higher.
Vegans and vegetarians need to aim for iron intakes of 14 mg/day for males and 33 mg/day for females (compared to 8 mg/day for males and 18 mg/ day for females on an omnivorous diet)
Tips for boosting your iron intake on a plant-based diet:
Choosing whole-food iron sources such as legumes, grains, nuts, seeds, fortified foods, green vegetables
Reducing your consumption of inhibitor-containing foodstuffs such as tea, coffee and cocoa (when eating iron-rich meals).
Consume vitamin C containing foods with iron-foods to enhance absorption.
Incorporate soaked, sprouted and/or fermented foods in your diets, if palatable.
If you are prone to iron deficiency, (for example females with large menstrual blood losses) monitor your iron status and consider taking a supplement if you are deficient.
Zinc is a constituent of enzymes involved in metabolic processes that relate to DNA stabilization and gene expression, and is important in cell growth, repair and protein metabolism. Similar to iron, zinc is widely available in plant-based foods but is also not readily absorbed.
The body appears to adapt to lower intakes of zinc by reducing losses and increasing absorption in order to maintain equilibrium. For this reason, it has been suggested that vegans and vegetarians do not need to pay special attention to consuming this mineral. However, due to the poor bioavailability it is recommended that vegans and vegetarians might need to consume up to 50% more zinc than non-vegetarians. Common vegan sources of zinc include beans, whole grains, nuts and seeds, but these foods also contain phytate, which may block zinc absorption. Processing your foods can help reduce phytate. For example, leavening bread activates phytase, breaking down phytic acid. By soaking, fermenting and sprouting nuts and grains can all reduce phytate levels and increase nutrient bioavailability.
Recommended Daily Intake:
It is recommended that male vegans consume up to 16.5 mg/day of zinc and females up to 12 mg/day (compared to 11 mg/day for males vs. 8 mg/day for females on an omnivorous diet).
Tips for boosting your zinc intake on a plant-based diet:
Zinc bioavailability appears to be enhanced by dietary protein.
Choose whole-food sources of folic acid, iron, calcium, copper and magnesium, since supplemental forms of these nutrients may inhibited zinc absorption.
Consume zinc-rich foods such as hemp and pumpkin seeds, and other grains, nuts and beans.
Adopt processing methods that improve mineral absorption, such as soaking and fermenting.
If you can't achieve the sufficient amount through your diet consider taking a supplement.
Do not take zinc supplements at the same time as other mineral supplements, such as iron or calcium.
Although, dairy products are not the only foods that are rich in calcium, data indicates that vegans consume less calcium than omnivores and other vegetarians. Green vegetables, such as spinach and arugula are rich in calcium, but they also contain oxalate, which impedes calcium absorption. Plant-based athletes on a vegetarian diet can meet their calcium requirements easier by consuming dairy-products and those that are following a Pesco-vegetarian diet can also include fish with bones, like salmon and sardines.
It is widely accepted that adequate calcium intake is necessary for blood clotting, nerve transmission, muscle stimulation, vitamin D metabolism and maintaining bone structure. (Rogerson, 2017)
Vegans have been shown to be at a higher risk of fractures due to lower calcium intakes. The importance of calcium for the vegan athlete is crucial in the maintenance of skeletal health during weight-bearing exercise, and increased calcium losses experienced during heavy perspiration. Low intakes of calcium are particularly problematic for children and teenagers, where higher calcium requirements are required for bone development.
Recommended Daily Intake:
The recommended intake for calcium is 1000 mg/daily. However, it has been suggested that the requirements of an athletic populations in most contexts may be higher than the general population.
Calcium requirements are also elevated during phases of calorie restriction, amenorrhea and if an athletes is suffering from RED-S (Relative Energy Deficiency in Sport).
Tips for boosting your calcium intake on a plant-based diet:
Consume plant-based sources of calcium such as beans, pulses and green vegetables in sufficient quantities to achieve the minimum requirement of 1000 mg of calcium per day.
Choose plant sources that contain low oxalate, like broccoli, bok choy and kale, which are particularly high in calcium when designing calcium-rich meals.
Buy calcium-fortified foods such as calcium-fortified soy, nut milks and fruit juices.
Vegans can also consume calcium-set tofu, which is also rich in protein, to help achieve their requirements.
If you can't achieve sufficient calcium levels through your diet consider taking a calcium supplement might also be required.
Make sure you have adequate Vitamin D levels, since it will improve the amount of calcium that is absorbed from the food you eat.
Iodine is an essential trace element needed for physical and mental growth and development, and plays an important role in thyroid function and metabolism.
Excessively high or low intakes of iodine can lead to thyroid dysfunction, and interestingly, vegans have been shown to consume both excessively high as well as very low intakes depending on their dietary choices. For example, seaweed is a concentrated form of iodine and for this reason excessively high iodine intakes have been reported in vegans who regularly consume seaweed. In some cases this may lead to elevated Thyroid Stimulating Hormone (TSH) levels. Elevated TSH might reflect iodine-induced hyperthyroidism or iodine-induced hypothyroidism. In contrast, in a study by Krajcovicova-Kudlackova and colleagues they found that 80% of Slovakian vegans were iodine deficient.
Common iodine sources include fish and dairy products, but the iodine content in foods vary greatly depending on the soil-iodine content (when growing produce), the farming methods used during production, the season it is grown in, and the species of fish (if non vegan). Goitrogens (a naturally occurring substances that can interfere with the function of the thyroid gland) found in cruciferous vegetables such as cabbage, cauliflower and rutabaga decrease iodine utilization and might affect adversely thyroid function if consumed in large amounts. However, cooking these foods helps to destroy many of the goitrogenic compounds present, making this effect very unlikely. However, raw-food vegans should try to limit the consumption of raw, goitrogenic foods if possible.
Recommended Daily Intake:
DRI for Iodine has been set at 150 μg per day for adults.
Tips for boosting your iodine intake on a plant-based diet:
Include a bit seaweed and sea vegetables in your diet, like vegan sushi or spring rolls.
Use Iodized table salt to help you achieve sufficient intakes.
If iodine sufficiency cannot be achieved through food alone, use a supplement that meets the 150 μg/day recommendation.
Vitamin D is a fat-soluble vitamin produced in the skin, is essential for calcium absorption and bone health, and plays an important role in many physiological processes. While humans synthesize vitamin D from exposure to sunlight, vitamin D can also be found in animal products and fortified foods.
Dietary intakes of vitamin D appear to be low in vegans who do not achieve sufficient sun exposure. (Rogerson, 2017)
Cholecalciferol (D3) is an animal-derived version of vitamin D that is now widely available as a supplement. For plant-based athletes, Ergocalciferol [D2] is a vegan-friendly version of vitamin D but appears to be less bioavailable compared to cholecalciferol. Recently, however, vegan-friendly versions of cholecalciferol derived from lichen, a composite fungal-algae organism, have become commercially available, offering vegans a more bioavailable
supplemental option. These supplements can be used as a like-for-like equivalent for animal-based counterparts with a recommended dosage of 200–1000 IU per day.
Research suggest that optimizing vitamin D status for athletes might improve athletic performance, if deficiency is present. Poor vitamin D status negatively affects muscle strength and oxygen consumption, and suggest that supplementation might protect against overuse injury via its role in calcium metabolism and skeletal muscle function. Thus, optimizing vitamin D status, should be an important consideration for all athletes, not just plant-based athletes.
Recommended Daily Intake:
Different countries have different recommendations for vitamin D, depending on the amount of sun-exposure the country gets. In the USA, the IOM recommend an RDA of 600 I.U/day for vitamin D.
While in the UK the Department of Health recommends individuals who do not achieve adequate sun exposure to supplement with 10 μg/day (400 I.U).
Data concerning performance-enhancing effects and toxicity at higher dosages of vitamin D have yet to be demonstrated, however, a tolerable upper intake of 4000 IU/day has been established by the Institute of Medicine (IOM).
In order to determine vitamin D status, plasma 25OHD levels can be sampled. Values <20 ng ∙ ml−1 are considered to be clinically deficient. The optimal range might fall between 40 and 70 ng ∙ ml−1.
Take note, vitamin D can be toxic if Blood 25OHD values >150 ng ∙ ml−1.
Tips for boosting your iodine intake on a plant-based diet:
Try get enough sun exposure.
Use a vitamin D Lichen-derived D3 supplement if you are deficient.
Each post in this series will include a recipe from Leozette Roode's new cook book: THE SOUTH AFRICAN VEGAN COOKBOOK to inspire you to bring more color into your plate.
FEATURED RECIPE: Vietnamese Rainbow Rolls with Marinated Tofu and Buttanutt Satay Dipping Sauce
By Leozette Roode
Cooking Time: 40-minutes
These beautiful, fresh rolls with its creamy and nutty satay sauce make for the perfect party pleaser! Serve it up as a starter, or better yet, get your guests to roll their own.
One block firm tofu
16 rice paper sheets
1 Red Pepper
1 Yellow Pepper
2 Carrots, peeled
¼ Purple Cabbage
½ Cup coriander/mint leaves
100gram vermicelli / rice / glass noodles
1 Tablespoon sesame oil
Edible flowers for garnish
For the tofu marinade sauce:
6 tablespoons soy sauce
1 tablespoon apple cider vinegar
1 garlic glove, minced
2 teaspoons ginger, grated
1 tablespoon Silan date syrup/maple syrup
¼ teaspoon siracha
Juice of ½ lemon (from lemon mentioned above - about 2 tablespoons)
2 teaspoons brown sugar (optional)
For the peanut satay sauce:
3-4 tablespoons ButtaNutt Almond Macadamia nut butter / unsweetened and unsalted peanut butter
5 tablespoons soy sauce
2 teaspoon apple cider vinegar
2 teaspoons maple syrup
1 fresh chilli, seeded and chopped
1 tablespoon coriander, chopped
2 teaspoons ginger, grated
8 tablespoons water
Juice from ¼ lemon (from lemon mentioned above - about 1 tablespoon)
Combine all the marinade ingredients in a mixing bowl and transfer to an elongated Tupperware (big enough for all the tofu to lie in flat).
Drain the water from the tofu and pat dry. Cut into 8 strips and lay flat on a paper towel. Place another paper towel on top of the tofu slices. Place a heavy object on top of the paper towel (for example, a book). I like using my cutting board and then I do the next few meal prep steps on top of the board as it applies pressure to the tofu. (Tip: I often replace the paper towels halfway through to drain more water).
On the cutting board, cut the carrot, red pepper, yellow pepper, cucumber and avocado into thin julienne strips and set aside.
Remove the paper towels from the tofu and cut each strip in half (so you are left with 16 strips). Place the tofu strips in the marinade - make sure every strip is covered in sauce. Set aside while you prep the noodles. Flip the tofu slices over halfway through.
Boil a kettle of water. Place rice noodles in a mixing bowl and top with boiling water. Stir through the noodles once they become loose. When the noodles are soft, drain the water and rinse the noodles with cold water to stop them from cooking. Add a tablespoon of sesame oil to the noodles to prevent them from sticking to each other. Set aside.
Make the dipping sauce by combining all the ingredients in a mixing bowl and whisking until smooth.
Assemble your rolls:
Fill a big bowl with very warm water (the bowl must be big enough for one round rice paper sheet to fit in comfortable.
Hold the top of the rice paper sheet and dip into the water, hold underwater for 15 seconds (or until the rice paper sheet is soft), lift out of the water and place in front of you.
Place your cucumber sticks one thumb away from the bottom of the sheet. Place a little bit of rice paper noodles on top (it’s okay if they fall off). Place carrot sticks behind the rice noodles. Place a strip of tofu on top of the rice noodles.
Fold the empty sheet part at the bottom over the filling and tuck in under the carrot stick. Place a few slices of avocado and red and yellow pepper against the roll. Hold it in place, while you place three coriander leaves, mint leaves or flowers one thumb away from the top of the sheet.
Fold the sides of the sheets in towards the middle (to make sure your second filling does not pop out on the sides) and finally roll the whole roll from the bottom all the way to the top. Seal the edges and place in a Tupperware container.
Repeat to create 16 rolls in total.
Cover the done rolls with a damp cloth to prevent them from drying out. If you want to cut the rolls in half before serving, place cling wrap around them first, then cut with a very sharp, non-serrated knife. Remove plastic and serve with your dipping sauce. You don’t have to use the veggies in the order mentioned above, have fun and play around with different varieties.
WHY I LIKE THIS RECIPE
These delicious rainbow rolls are packed with color and micronutrients. Adding to the nutritional value of this recipe, is the tofu, which is high in calcium and a good plant-based protein source. Plus, don't these rolls just look beautiful
KEY TAKE AWAYS:
Making sure you meet your micronutrient requirements on a plant-based diet requires a bit more planning and preparation, but it is definitely worth the extra time and effort to optimize your performance and stay healthy. As a plant-based athlete you need to pay extra attention to your intake of B12, iron, zinc, calcium, iodine and vitamin D. Below is a list of the common micronutrient deficiencies on a plant-based diet and which food sources can help you meet the daily recommended intake.
VEGAN-FRIENDLY FOOD SOURCES
Vitamin B12: Supplements, fortified foods, plant-milks, nutritional yeast (fortified), fermented soy, mushrooms
Iron: Legumes, grains, nuts, seeds, fortified foods, green vegetables
Zinc: Beans, nuts, seeds, oats, wheat germ, nutritional yeast
Calcium: Tofu (calcium set), fortified plant milks and juice, kale, broccoli, sprouts, cauliflower, bok choy.
Iodine: Seaweed, cranberries, potatoes, prunes, navy beans, iodized salt.
Vitamin D: Lichen-derived D3 supplements.
Adequate micronutrient intake is important for all athletes who wants to stay healthy and perform at their best, not just those on a plant-based diet. A diet with lots of variety and color will help, but even more importantly making sure you consume enough calories to support your physical activity level and health will allow you to meet your daily micronutrient requirements.
Vegan diets: practical advice for athletes and exercisers, (2017), By David Rogerson
Sport Nutrition, Third Edition. (2019) by Asker Jeukendrup, Micheal Gleeson