There is a global trend towards more people adopting a vegan diet, especially in developed countries. Although individual motivations may vary from animal welfare to religion, vegan diets are becoming more associated with environmental and health benefits. Quite often people will adopt a vegan diet to see if it helps with a chronic condition such as an Autoimmune disease.
A vegan diet is 'a plant-based diet avoiding all animal foods such as meat (including fish, shellfish and insects), dairy, eggs and honey' - the Vegan Society.
With more and more people eliminating animal-based food sources, there is a strong need for evidence-based guidance on the health effects, safety issues and clear guidelines around a well-balanced optimised vegan diet. Current research highlights the following benefits and drawbacks of vegan diets.
The Benefits
A vegan diet may be beneficial for body weight reduction and a lower body mass index (BMI).
Eating more plant foods encourages a higher intake of dietary fibre and associated phytochemicals. Studies have shown that dietary fiber can alter the composition of gut bacteria and increase bacterial diversity, hence improving the gut microbiome and leading to overall better health outcomes.
Plant-based diets may be associated with lower inflammation and reducing inflammatory markers. 19 out of 21 studies have shown that vegetarians have lower CRP levels than omnivores. The decrease in CRP correlated with duration and was prominent in people who had been on the plant-based diet for more than ten years.
A vegan diet ensures a lower intake of carcinogenic by-products of processed meats and meats cooked at high temperatures (e.g. aryl amines, nitrates).
A plant-based diet is characterised by a higher content of folic acid, vitamins C and E, potassium, magnesium, and unsaturated fats.
Plants are rich in antioxidants such as flavonoids, polyphenols and phytoestrogens found in fruits, vegetables, nuts, seeds, herbs and spices. Antioxidants reduce oxidative stress which is often underlying in chronic diseases.
Improvement of some cardiometabolic markers are seen with a vegan diet, such as: LDL-cholesterol, fasting glucose and blood pressure.
The Benefits in Autoimmunity
In the small number of clinical trials and studies to date on a vegan diet in autoimmune diseases such as rheumatoid arthritis, hashimoto's and lupus nephritis, small positive improvements were seen in symptoms such as joint pain, swelling and energy levels. Improvements were particularly seen in inflammatory markers, oxidative stress markers, fatty acid patterns, BMI and gastrointestinal symptoms. Further studies and trials are needed.
The drawbacks
Not all vegan diets are healthy since they may include a high consumption of ultra-processed vegan foods which are readily available nowadays. Vegan processed foods may be loaded with sugar, salt, fat and additives. Furthermore, a nutritionally unbalanced vegan diet, high in processed and refined foods can increase disease risk.
Protein - Vegans need to take care to eat sufficient protein. Protein is an essential nutrient that is required for enzymes, neurotransmitters, hormones, muscles, hair, skin, bone and many other organs and tissues in the body. It is also required for chemical reactions that fuel energy, carry oxygen, make antibodies to fight infection, as well as building and repairing cells. A daily intake of 0.75 g of protein per kilogram of body weight is recommended for adults, older-aged vegans may need even more protein. Animal protein is more bioavailable than plant proteins. There is a need to complement different plant foods across the day to get 'complete' proteins, since not all of the 9 essential amino acids are available in all plant foods. Quinoa, tofu, edamame, amaranth, spirulina, buckwheat, hemp, chia and nutritional yeast contain all the essential amino acids. However most grains and seeds are extremely low in lysine but are good sources of tryptophan and methionine, whereas beans, pulses and most nuts are rich in lysine, but are not good sources of tryptophan or methionine. Therefore, it is very important to plan ahead and combine a variety of proteins such as: rice and beans, hummus and pita, peanut butter on bread, to create complete protein meals and snacks.
Anti-nutrients - Not all micronutrients are quite as bioavailable in plant foods as in animal foods due to anti-nutrients such as: oxalates (e.g. leafy veg, nuts), phytates (.e.g. wholegrains, legumes), lectins (legumes) and tannins (e.g. tea, coffee) which reduce the body's ability to absorb nutrients especially minerals such as calcium, iron, zinc. Appropriate food preparation can reduce their impact eg. soaking, sprouting, steaming, fermentation. peeling and boiling.
There is a higher risk of fractures and lower bone health in vegans; possible explanation could be a lower intake of protein, vitamin D, B12, and calcium, which are potentially limited in vegan diets.
A vegan diet may have adverse effects on HDL-cholesterol and triglyceride levels. This could be due to a higher refined carbohydrate intake, processed foods or a sedentary lifestyle.
Nutrient deficiencies - common nutrient deficiencies in vegans include:
Vitamin B12 - This is the only nutrient that is totally absent from a vegan diet, as no plant foods contain a reliable amount of B12 naturally. B12 is needed for energy, metabolism, red blood cells, immune function, the nervous system and homocysteine recycling. Vegans can get B12 from fortified foods but many may be processed i.e. breakfast cereals, plant milks etc or they can take a supplement daily. Humans can store several years' supply of B12 in the liver.
Iron - Iron contributes to normal energy metabolism, red blood cell formation, haemoglobin, cognitive function, oxygen transport and fatigue reduction. Plants contain iron but in the non-haeme form which influences its absorption. Vegans can increase intake of iron rich plant foods such as beans, pulses, dark green leaves and nuts/seeds. In addition, they can optimise their stomach acid for better absorption of non-haeme iron. Also, they can include a source of vitamin C at the same meal to help absorption. Tannins (in tea and coffee) and phytates, lectins (pulses/grains) should be avoided during iron rich meals as they decrease iron absorption. Using cast iron pans may be helpful because a small amount of iron may transfer to food during cooking. Vegans may need up to 1.8 times more iron than meat eaters since plant sources are less bioavailable. Supplementation should be considered if ferritin (stored iron) remains low after 3 months.
Calcium - Calcium is needed for bones, teeth, regulating muscle contractions, blood clotting, cardiac and nerve health. Dairy and sardines contain the most amount of calcium, there is much less in plant foods. In addition, anti-nutrients may compromise calcium absorption. Therefore, vegans can be at risk of calcium insufficiency. Calcium fortified foods, watercress, kale, cabbage, broccoli, soya, nuts (especially almonds), fennel and okra are plant sources. An online calcium calculator can help work out how much you are getting from your diet. Calcium supplements should be used cautiously, dietary calcium is a better source. It is important to note that calcium is not as effective without vitamins D3 and K2.
Selenium - Contributes to sperm formation, oxidative stress and inflammation protection, supports immunity, thyroid, skin, hair and nails. Soil content of selenium in agricultural land varies and most locations, especially Europe, have naturally low selenium. Eating Brazil nuts from Brazil provides sufficient selenium but lower levels are in most other plants. Other vegan sources of selenium include mushrooms, sunflower seeds, sesame seeds, tofu and brown rice. Taking a selenium supplement is recommended however overdosing should be avoided.
Iodine - Essential for thyroid hormones, brain health, immune system, breast and skin health. Seaweed is a good plant source of iodine. Iodised salt is available in some countries, but is not often accepted in a strict vegan diet. Supplementation can meet iodine requirements if deficient, however care should be taken, as too much iodine can cause thyroid disorders.
Vitamin D - Vitamin D is needed for immune function, inflammation reduction, neuro-muscular function, calcium & phosphorus utilisation in the body and bone mineralisation. Growing evidence suggests a role for vitamin D in disease prevention including cancer, diabetes and heart disease. Vegan sources of vitamin D include sunlight in the summer, fortified foods, mushrooms exposed to ultraviolet light when growing (although mushrooms contain vitamin D2, which is not as bioavailable as D3 from animal products) and tofu. Lower serum 25-hydroxyvitamin D levels have been reported in vegans compared to omnivores, especially those living in northern latitudes, where sunlight exposure is low especially in winter months. Vegan friendly supplements are either D2, or D3 from lichen. (Note - Lanolin (sheeps wool) is a non-vegan source in some supplements).
Vitamin K2 - Vitamin K is important for bone, heart and overall health and works in synergy with vitamin D, calcium and magnesium. Vitamin K2 may have a more protective effect on bone than K1. Since plants (especially dark green leafy veg) are a rich source of Vitamin K1, vegans are unlikely to be deficient in Vitamin K since gut bacteria can convert Vitamin K1 into Vitamin K2. Main dietary sources of vitamin K2 are animal foods however a fermented food called natto is the best vegan source. Vitamin K tends to be stored in the liver for future use.
Omega 3 [EPA & DHA] - We cannot make omega-3 fatty acids in our bodies. Omega-3 is essential for cell membrane health, immune, cognitive, cardiac, hormone, skin and joint health. Research indicates that vegans have lower amounts of DHA in their blood. Plant derived a-linolenic acid (ALA) can be converted to EPA and DHA but the rate of conversion can be low. Vegans should optimise food sources of ALA i.e. Flax, chia, hemp, seaweed and walnuts. However, supplementation may be needed, algae oil is vegan.
Choline - Choline is important for liver function, supporting energy levels, muscle movement, normal brain development and the nervous system. Mainly found in eggs and beef liver, therefore diets with no eggs, fish or meat may have insufficient choline. Wholegrains, nuts, seeds, brassicas and soy are plant based options which should be eaten regularly.
Co-enzyme Q10 - This is a fat soluble, vitamin like natural substance found in every cell in the body. It is essential for mitochondrial energy, heart health, healthy ageing, fibromyalgia and those taking statins. We make this compound in our bodies, but it reduces with age. The main food source is organ meats. Plant based sources include: extra virgin olive oil, soybeans, peanuts, spinach, broccoli and cauliflower. Plasma concentrations of CoQ10 were found to be lower in vegans and therefore supplementation may be required.
Zinc - Zinc is essential for immune cells, hair, skin, nails, fertility, gut health, reproduction and enzymes. Vegan diets usually have enough zinc, however zinc rich plants often contain phytate which lowers absorption during digestion, making zinc less bioavailable in vegan diets. Therefore vegans need about 50% more zinc to ensure absorption. Vegans should try to include 2mg of zinc from foods per meal. Sources include sourdough bread, oats, dark green leafy veg, seeds, lentils and tofu.
The Drawbacks in Autoimmunity
Nutrient deficiencies can be a trigger in autoimmune diseases, especially since many of the nutrients mentioned above are important for the immune system. Selenium for example, is known for its immunomodulatory and anti-inflammatory properties. Iron provides oxygen to cells, without which hypoxia may occur which can cause an autoimmune - inflammatory loop. Furthermore, Vitamin D receptors are found on all immune cells, highlighting its importance for effective functioning of the immune system. One of the first things to try for autoimmune remission is correcting nutrient deficiences, as they can cause much imbalance. Furthermore, protein deficiency also affects hormones, neurotransmitters and blood sugar levels which are all inflammatory drivers in autoimmunity.
How to optimise a vegan diet
A well-planned and balanced plant-based diet may be protective since eating more plants is certainly very beneficial for health. However, the nutrition of each person is an individual matter and an adequate supply of vitamins and minerals is essential. It is important to:
Cook from scratch using fresh ingredients and avoid unhealthy ultra-processed foods, making sure you check food labels for added unhealthy ingredients.
Include nutrient dense, colourful and varied plant foods.
Plan all meals carefully to ensure all daily nutrient requirements have been understood and are included in each meal.
Consider soaking, germinating and fermenting grains and legumes to increase bioavailability and absorption of micronutrients.
Avoid eating large quantities of foods with anti-nutrients at one meal and alter timing of eating anti-nutrient foods e.g. drink tea between meals instead of with a meal.
Ensure you are meeting your protein needs on a vegan diet, try incorporating a variety of complete amino acid sources or combinations of nearly complete sources into your plant-based diet. Consume higher levels of proteins to compensate for poor bioavailability. Maybe consider protein powders.
A vegan diet doesn't mean you don't need to exercise, since a sedentary lifestyle may negate any benefits gained from a vegan diet.
Consider supplementation where necessary under professional guidance.
Vegan diets for Autoimmunity?
It is important to understand the implications of a deficient or 'unhealthy' vegan diet if you have autoimmunity. Nutrient deficiencies can add fuel to the fire in chronic inflammation and add to the autoimmune 'symptom load' e.g. fatigue, cognitive issues and hormone imbalances. Even though a vegan diet is perceived as 'healthy', if done wrong, it can have implications for inflammation and autoimmunity. Testing for, and supplementing nutrient deficiencies may be helpful, this can be done with your doctor or a nutrition practitioner. Furthermore, in autoimmunity dietary proteins such as gluten or lectins can be pro-inflammatory and for some may be a trigger in their autoimmunity. Vegan diets may include a higher amount of these proteins which can be a problem for some and may be required to be eliminated. It is also important to mention that emerging evidence on the gut microbiome and it's positive role in autoimmune diseases suggests we should certainly all... EAT MORE PLANTS!
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