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Part 2: The Veganuary nutrient guide

Have you switched to a vegan diet in January? Read our in-depth nutrient guide to ensure your plant-based diet remains nutritious.

A well-planned vegan diet is high in fibre, low in energy and saturated fat, and therefore may reduce your risk of type 2 diabetes and cardiovascular disease [1,2]. But as with all diets, you must prepare sufficiently for a vegan diet. So, what nutrients should you think about, and why isn’t vegan food automatically healthy?

Are you planning to continue a vegan diet after January? In part two of our Veganuary series, we explore the essential nutrients which you need to think mindfully about if switching to a vegan diet.

Iron 

Iron has countless roles in the body from energy metabolism to oxygen transport [3]. There are two types of iron in our food: haem iron (from meat foods) and non-haem iron (from plant foods). Haem iron is more bioavailable than non-haem iron - this means that our bodies can absorb and use more of it.  

So, what does this mean for a vegan diet? It means that a vegan diet should be full to the brim of good non-haem iron sources – it’s a matter of iron-quantity over iron-quality this time! Good sources of plant iron include whole grain cereals (such as wheat, rye and brown rice), nuts and seeds, dark green vegetables and dried fruit. As you can tell, these are all healthy foods, packed full of fibre and healthy fats, so your body will only thank you for eating more of them! 

What’s more, the UK fortifies wheat flours with iron* so it is easy to up your intake by including bread in your diet. Wholemeal wheat flour is not fortified as it naturally contains iron, so want a natural boost? Choose wholemeal. *Surprisingly, gluten-free flours are not fortified by law (you can check whether yours is on the ingredients list).

Females have the highest daily needs of iron (14.8 mg/day), due to menstruation, followed by adolescent males (11.3 mg/day). Once over the age of 19, male recommendations fall (8.7 mg/day), but females maintain their higher requirements up until 50+ years, when they then decrease (8.7 mg/day). 

This table gives you an idea of how to get your daily iron requirements from plant foods:

Food (100g portion) Iron content (mg)
Baked beans (in tomato sauce) 1.4
Chickpeas 2
Sunflower seeds 6.4
Figs (dried) 3.9
Broccoli (boiled) 1
Spinach 1.6
Almonds 3

Certain ingredients present in plant foods can bind to minerals such as iron, reducing their bioavailability. Anti-nutrients are present in grains as phytates, in vegetables such as spinach as oxylanates and in tea as tannins.

These ingredients are well known opponents to iron, but foods containing them can offer you a huge host of health benefits, so it is crucial that you don’t cut them out. Instead, there are some handy tips and tricks to enhance the quantity of iron you absorb from your foods:

  • Vitamin C can improve the absorption of non-haem iron [4], in addition vitamin C can counteract the negative effects of phytate [5]. Try squeezing lemon juice on salads or pairing your breakfast cereal with a small glass of orange juice. 
  • Cooking vegetables thoroughly can reduce the amount of oxylanates in foods. Steaming vegetables, rather than boiling, can reduce oxylanates without the loss of other healthy nutrients into cooking water [6].
  • Choosing grains which have sprouted, or soaking grains over-night, can reduce the action of phytates [7].
  • Wait an hour or two after finishing your evening meal to enjoy your evening cuppa. This will help you to reap the highest possible benefits of iron from your meal.  

Consuming too much iron through supplements can lead to adverse effects in the body so iron supplements should only be taken for a limited time under the advice of your doctor.

If you think you may be at risk of iron deficiency, or you are experiencing symptoms such as tiredness which may suggest iron deficiency, then the Iron Deficiency Blood Test will give you an in-depth look at your iron levels. Our doctors will advice you on whether supplementation is needed, and whether a low iron level should be discussed with your GP. After supplementation, retesting your blood will reveal whether your iron levels are in the healthy range.

Calcium 

We need calcium in our diet for many essential reasons, including healthy bones, muscle and nerve function. Bones are constantly remodelled throughout our lives, so we must eat enough calcium to support our bodies to rebuild them. 

Between the ages of 18-30 years, calcium intake is particularly important as this is when you are building peak bone mass (the greatest bone density you will achieve in your lifetime). In older age, especially in the post-menopausal life stage, calcium loss from bones increases. So, it is particularly crucial to ensure you have enough calcium in your diet.

It is well known that the richest sources of calcium are dairy products. Plant foods also contain calcium but in lower amounts. In addition, many vegan food products, such as plant-based milks are now available which are fortified with calcium. Although, surprisingly, not all plant-milks are fortified, so always check this on the packet!

There is debate over the bioavailability of different types of fortified calcium which are used in the food industry. For example, tricalcium phosphate may not be a like-for-like replacement for dairy calcium, and may over-estimate calcium by over 50%, but calcium carbonate may be more equivalent to the calcium in dairy foods [8, 9].

Unfortunately, calcium is also prone to the effects of anti-nutrients (such as phytate) which are present in plant foods and can decrease its availability when in our bodies.  

Adults are recommended to have 700 mg of calcium a day. The table below outlines some food sources of calcium in a vegan diet:

Food Amount of calcium (mg)
10 almonds 50
1 slice of white bread 50
Steamed broccoli (110g) 50
Watercress (40g) 50
2 dried figs 100
1 small tin baked beans (200g) 100
200 ml calcium-fortified soya milk 200
Tofu (calcium set, 120g) 200

Unfortunately, there is no dependable way to test whether you are obtaining enough calcium from your diet because the body corrects plasma levels of calcium with calcium from our bones. However, optimal vitamin D levels are needed to absorb sufficient calcium from your foods, so assessing your vitamin D levels through a Vitamin D (25 OH) Blood Test can be informative.

Vitamin B12

Vitamin B12 is involved in many essential roles in the body, including energy metabolism, psychological function and in the regulation and functioning of the immune system [4]. 

Vitamin B12 is only found in animal foods [3]. A large European study found significant difference in blood levels of vitamin B12 between vegans and non-vegans, and in addition, that 15% of vegans had plasma concentrations consistent with a deficiency [10].

As a vegan, it is good practice to always opt for vegan food products which are fortified with vitamin B12 (look for cyanocobalamin on the label). Common foods fortified with vitamin B12 include breakfast cereals and non-dairy milks [3]. Fortified nutritional yeast is an excellent source of vitamin B12 and can add delicious savoury flavours to your dishes. 

In the UK adults are recommended to consume 1.5 ug of vitamin B12 a day.

Food Amount of vitamin B12 (ug)
1 tbsp nutritional yeast 2.2
40g iron fortified bran flakes 0.9
200ml iron fortified soya milk 0.8
1 tbsp iron fortified yeast extract 1.3
200 ml fortified oat milk 0.8

If you think you are not getting enough vitamin B12 through foods, or you have identified a deficiency, speak to your health professional about taking supplement. A vitamin B12 supplement of 10 ug/day is currently advised for vegans [1]. This requirement is set higher than the recommended daily requirement as the absorption may not be as high as that from animal foods. 

Symptoms of not getting enough vitamin B12 include tiredness, breathlessness and depression [12]. A Vitamin B12 (Active) Blood Test can tell you whether your body is getting enough vitamin B12 to stay healthy. Vitamin B12 deficiency can be difficult to detect with blood tests, as it exists in several forms within the blood. Vitamin B12 (Active) Blood Test looks at the biologically active form and, compared to a Total Vitamin B12 test (serum cobalamin), it is thought to give a better indication of whether deficiency is likely. You can read more about this here

Iodine

Iodine is needed to produce thyroid hormones which control important bodily functions including metabolism and growth. 

Not eating enough iodine for a prolonged time may lead to deficiency. One of the most visible signs of severe deficiency is goitre, where the thyroid gland in the neck becomes enlarged. Milder deficiencies may affect your ability to think clearly. Iodine is particularly important during pregnancy as deficiency can permanently harm the developing foetus by stunting growth and mental development.

Current UK recommendations state we should obtain 150 ug of iodine per day in our diets. 

Iodine is found in dairy products, fish, and eggs…So where can vegans find iodine in their diet? Plant foods are dependent on the iodine levels in soil and often this is low. Seaweed or kelp is a very rich source of iodine, but the iodine content is highly variable which may be toxic, so it is not recommended to eat seaweed regularly.

Some foods have iodine added, such as salt that is labelled as ‘iodised’. However, current recommendations suggest we cut back on salt, so we shouldn't overconsume it. Fortunately, some plant-based milks are fortified with iodine; look for varieties with potassium iodide on the ingredients list.

The table below outlines some vegan food sources of iodine:

Food source Amount of Iodine (ug)
200ml iodine fortified soya milk 45
200ml iodine fortified oat milk 45
1.5 g iodised salt* 30

*Current UK guidelines recommend adults eat no more than 6g of salt per day (and 2.4g sodium). Salt is already present in many foods, so always read the label.

Severe iodine deficiency is uncommon in the UK. However, research suggests that those following vegan and vegetarian diets have a higher risk of mild iodine deficiency [11].

Excess iodine is harmful, so before taking iodine supplements, it is strongly advised you discuss this with a health professional. An Iodine Home Urine Test can be a valuable way to assess your body levels of iodine, and whether you should try to increase your intake of iodine-containing foods. 

Fats and Omega-3

We need fat in our diet for organ protection, energy storage, absorption of vitamins, and healthy brain and nerve development… and much more.

Fat is high in energy, so it is easy to overeat and within the western world it is well known that we consume too much. But there are many different types of fat. 

Fat can be saturated or unsaturated. Eating too much saturated fat is a risk factor for cardiovascular disease [13], so we need to be mindful of the amount that we eat.

Most plant foods contain slightly less fat (g for g) than animal foods, so vegan diets rich in fresh fruit and vegetables, can be lower in calories [14]. In addition, healthy vegan diets are more likely to contain greater amounts of unsaturated fat than saturated fat [14]. However, it is a common misconception that all plant fats are unsaturated – palm oil and coconut oil are also high in saturated fat so we should be mindful of the quantities we eat. Many processed vegan food products contain high levels of palm and coconut fat, so always check the labels. The lower down the ingredients list, the better. 

There are certain types of unsaturated fat, which our bodies cannot make, so they are essential to have in our diet (unsurprisingly, they are called essential fatty acids). a-linolenic acid (ALA) is an omega-3 essential fatty acid found in chia seeds, walnuts, linseeds (flax) and rapeseed oil. Once in the body, ALA can be converted to other important fatty acids: Docosahexaenoic acid (DHA) and Eicosapentaenoic acid (EPA). These fatty acids are essential for brain and nerve development and are believed to be anti-inflammatory.  

The conversion of a-linolenic acid to DHA and EPA is not very efficient, occurs slowly, and can vary significantly from person to person. We can obtain DHA and EPA directly from our diet more readily, but these compounds are not present in plant foods. 

Thankfully, special types of microalgae have been produced which can generate EPA and DHA. Vegans who are looking to increase their levels of omega-3 fats can purchase supplements containing algae-generated EPA and DHA. 450 mg EPA and DHA is recommended per daily adult dose.

You can test your blood levels of essential fatty acids with an Omega 3 and 6 Blood Test.

All-in-all, a well-planned and diverse vegan diet can offer a host of benefits, but we should be mindful about whether our diet contains sufficient nutrients to stay nutritious!


We thank Elizabeth Eveleigh for her contribution to the Iodine section. If you are interested to hear the most up-to-date research from a vegan-diet researcher, in part three Elizabeth Eveleigh (ANutr) helps answer some of our questions around all things Veganuary.

In part one, you may also be interested to read about our recent Veganalysis study. Does the science match up with reality? The results reveal all!


References

[1] https://www.bda.uk.com/resource/plant-based-diet.html

[2] Benatar, J.R. and Stewart, R.A., 2018. Cardiometabolic risk factors in vegans; A meta-analysis of observational studies. PloS one13(12), p.e0209086.

[3] Geissler, C. and Powers, H.J. eds., 2017. Human nutrition. Oxford University Press.

[4] EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA), 2014. Scientific Opinion on the substantiation of a health claim related to vitamin C and increasing non haem iron absorption pursuant to Article 14 of Regulation (EC) No 1924/2006. EFSA Journal12(1), p.3514.

[5] Siegenberg, D., Baynes, R.D., Bothwell, T.H., Macfarlane, B.J., Lamparelli, R.D., Car, N.G., MacPhail, P., Schmidt, U., Tal, A. and Mayet, F., 1991. Ascorbic acid prevents the dose-dependent inhibitory effects of polyphenols and phytates on nonheme-iron absorption. The American journal of clinical nutrition53(2), pp.537-541.

[6] Chai, W. and Liebman, M., 2005. Effect of different cooking methods on vegetable oxalate content. Journal of agricultural and food chemistry53(8), pp.3027-3030.

[7] Luo, Y. and Xie, W., 2014. Effect of soaking and sprouting on iron and zinc availability in green and white faba bean (Vicia faba L.). Journal of food science and technology51(12), pp.3970-3976.

[8] Zhao, Y., Martin, B.R. and Weaver, C.M., 2005. Calcium bioavailability of calcium carbonate fortified soymilk is equivalent to cow's milk in young women. The Journal of nutrition135(10), pp.2379-2382.

[9] Heaney, R.P., Rafferty, K., Dowell, M.S. and Bierman, J., 2005. Calcium fortification systems differ in bioavailability. Journal of the American Dietetic Association105(5), pp.807-809.

[10] Selinger, E., Kühn, T., Procházková, M., Anděl, M. and Gojda, J., 2019. Vitamin B12 Deficiency Is Prevalent Among Czech Vegans Who Do Not Use Vitamin B12 Supplements. Nutrients11(12), p.3019.

[11] Eveleigh, E.R., Coneyworth, L.J., Avery, A. and Welham, S.J., 2020. Vegans, Vegetarians, and Omnivores: How Does Dietary Choice Influence Iodine Intake? A Systematic Review. Nutrients12(6), p.1606.

[12] https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/symptoms/

[13] Mozaffarian, D., Micha, R. and Wallace, S., 2010. Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Med, 7(3), p.e1000252.

[14] Benatar, J., 2017. Cardiometabolic Risk Factors in Vegans–A Meta-Analysis of Case Control Studies. Heart, Lung and Circulation26, pp.S344-S345.

[15]  https://www.bda.uk.com/resource/iodine.html