Recommended Blood Tests for Vegans

People on vegan and plant-based diets often ask me 'how often do I need to get blood tests?' and 'what do I need to test for?'

These are valid questions, and are actually quite difficult to answer in general terms, as your nutrient needs and status depends on a number of factors, such as your gender, your medical history, your stage of life (whether you're planning a pregnancy, for example), or whether you're on any medications. One thing I can't recommend highly enough is forming a relationship with a good GP who knows you and your medical history, as they will be the one who orders and interprets your blood tests.

To begin with, there’s a lot of confusion about which nutrients tested in the blood are actually reflective of your dietary intake and/or the body's stores. As a prime example of this, many people assume that if their calcium levels in their blood are within the range, that their dietary calcium intake is adequate. This is unfortunately untrue, as the body maintains your calcium levels between narrow limits by way of a mechanism known as homeostasis, so if your dietary calcium intake is low, your body will draw on its calcium stores (i.e. the skeleton) in order to maintain calcium levels in the blood. To some extent, other nutrients are subject to this same regulation, including the minerals zinc and magnesium.

So, how often should you have a blood test? 
If you’re otherwise fit and healthy, I wouldn’t recommend having a blood test any more frequently than once per year.  If you’ve been diagnosed with a condition such as vitamin B12 deficiency or iron deficiency anaemia, your GP will recommend testing more regularly to ensure that the treatment is working. 
 
What to test for:
1. Full blood examination/count  
This provides detailed information about your red and white blood cells, and is usually done with all blood tests. It can be used to detect things such as an anaemia caused by iron and vitamin B12 deficiency.

2. Vitamin B12
As this vitamin is only found in animal products (including meat, dairy and fish), it’s absolutely essential that anyone on a plant-based diet ensure they are taking supplemental vitamin B12 on a regular basis (which you can read more about here).

Your GP will order 'total vitamin B12’, and if this test result is low or borderline low (<260pmol/L), the pathologist will also perform an ‘active vitamin B12’ (holotranscobalamin) test, which measures how much of the biologically active form of the vitamin you have in your blood. Serum methylmalonic acid (MMA) and homocysteine (HC) are metabolites which can also be used to assess vitamin B12 status, but these are not covered by Medicare bulk-billing, so you'll need to pay out of pocket if you'd like these tests conducted.

3. Iron studies
Firstly, there is no greater risk of iron deficiency if you’re vegan or vegetarian (in fact, most people on plant-based diets actually get more dietary iron), though people on plant-based diets usually have lower ferritin levels, which is a marker of how much iron is stored in the body. 

As low iron is a relatively common problem for women of childbearing age, it's definitely worth keeping an eye on your levels, particularly if you have heavy periods, are a long distance runner, or are feeling tired and depressed. 

If you're interested in reading more about iron and plant-based diets, have a read of this post I published earlier in the year on my blog, or this article published in the Medical Journal of Australia in 2012.

4. Vitamin D
Medicare have recently clamped down on 'unnecessary vitamin D testing' (as it was costing them tens of millions of dollars every year), so under new guidelines, only individuals 'at risk' of vitamin D deficiency are eligible for a bulk-billed blood test (e.g. people with Coeliac Disease, Inflammatory Bowel Disease, or a 'chronic lack of sun exposure’, which just sounds like ‘living in Melbourne’ to me, ha ha).

Vitamin D testing is at the discretion of the GP, so ask them if they think it’s medically necessary for you to have your level tested. As I (and the majority of my clients) live in Melbourne, I routinely recommend vitamin D supplements through the cooler months (May-September) anyway, so for some people it makes more sense to just start on a supplement rather than go out and have their levels tested. In saying this, if your levels are very low, you will need a much higher dose of vitamin D than I recommend for the general population to correct the deficiency, so please have a chat with your GP to see what they recommend for you. 

Other tests:

Iodine: 
Iodine is something I harp on about a LOT about with clients, as it is required for thyroid function and critically important for pregnant and breastfeeding women. Dietary surveys show that Australians get the majority of their iodine from dairy products, which leaves vegans (and some vegetarians) without a decent dietary source. Unfortunately the soil in which we grow plant food in in Australia are depleted in iodine, which means fruit, vegetables, grains and legumes don't contain much iodine. Brown seaweeds (such as arame and wakame) are very rich sources of iodine, but not many people routinely consume them (and there is a risk of getting too much iodine from them, so I don't recommend starting eating them if you haven't grown up doing so, as dramatically increasing your iodine intake can cause problems). In my opinion, the easiest way to ensure you're getting 100% of the RDI for iodine is by taking a daily multivitamin. The simplest way to assess your regular iodine intake is to do a urinary iodine test.

In summary: your GP is the best person to determine whether you need additional tests depending on your health status. For example, if you've been feeling tired and gaining weight, your GP may want to test your thyroid function, as an underactive thyroid gland could be causing those symptoms. Your GP may also want to test your cholesterol levels (depending on your age, and family history of heart disease) or your glucose tolerance if you are at risk of type 2 diabetes. 

One final thing: as a dietitian I can’t order blood tests to be bulk-billed through Medicare, so please ask your GP to fill out a pathology request form for you, which you will then present to the pathology collector. 

Vitamin B12 for Vegans

If you are vegan (or follow an entirely plant-based diet), taking a vitamin B12 supplement is non-negotiable, unless you're having 3 serves of fortified foods every day*, which means the manufacturer has added vitamin B12 to the product (which is a form of supplementation in itself).

Whether or not you need to take additional dietary supplements as a vegan depends on a number of factors such as your age, gender, stage of life (for example, whether you're pregnant or breastfeeding), your dietary intake (i.e. whether you're getting the nutrients your body needs from your food), where you live (which determines the food supply you have access to), and environmental factors (such as sun exposure), but in this post I'll just focus on vitamin B12.

I've edited this post many times in the past two years since I originally posted it to make sure it's up-to-date and accurately reflects the current scientific knowledge, and will continue to tweak things here and there as new research is published. 

The main reasons I'm so passionate about vitamin B12 for vegans is that there are so many myths and misconceptions about it in the vegan community, and as it is only found in animal-based foods, vitamin B12 deficiency remains prevalent in vegan populations, despite it being eminently preventable by appropriate supplementation. A recent review found that rates of vitamin B12 depletion and deficiency in vegetarian populations (including 'strict' vegetarians, or vegans) around the world is 'high', and one population study found deficiency rates of 52% in male vegans.

Vitamin B12 is required for DNA synthesis, cell division and maintaining the myelin sheath which surrounds nerve cells. Vitamin B12 deficiency is incredibly serious, and not something to be taken lightly. Vitamin B12 deficiency can result in irreversible nerve damage, psychiatric conditions such as psychosis, and is absolutely devastating for babies born to vitamin B12 deficient mothers. Symptoms of vitamin B12 deficiency include fatigue, shortness of breath, pale/yellow skin, depression, and numbness or tingling in fingers and toes, but some people don't report any symptoms at all, even with overt deficiency. 

Dietary sources of vitamin B12

Vitamin B12 is produced by bacteria which live in the soil and in animal guts, and is only found in animal products including meat, fish and dairy products, unless it has been added to foods designed for vegans and vegetarians, such as certain brands of soy milk*. As soon as I say this, people will start to argue that some plant-based foods do contain biologically-active vitamin B12, and although this is true, I would argue that the levels in these foods cannot be relied on to meet your vitamin B12 requirements. As an example, a study from the University of Western Sydney (link) found that mushrooms do contain biologically-active vitamin B12, however, one serving of mushrooms only contains 2-4% of the RDI (which is the amount of vitamin B12 you need on a daily basis). 

Other vegan foods (such as spirulina) which are often touted as good sources of vitamin B12 have been shown to contain inactive analogues of vitamin B12, which means the compounds detected in the lab 'look' like vitamin B12, but are not biologically active within the human body.

Common myths and misconceptions about vitamin B12:

'Vitamin B12 deficiency takes years, maybe even decades to develop, so it's not something vegans need to worry about'

Nutrition textbooks say a person *should* have enough vitamin B12 stored in their body (in the liver) to last 2-5 years without a dietary source, but as a dietitian reading lots of blood test results, I've seen clients with vitamin B12 deficiency after only a few (3-6) months on a vegan diet, so it's something to start supplementing with as soon as you make the decision to go vegan, vegetarian or plant-based.

'I eat organics and don't wash my vegetables, so I don't need to worry about vitamin B12'

Yes, soil contains vitamin B12-producing bacteria, but the issue here is again the reliability of the amount of vitamin B12 you're getting from unwashed vegetables. It's not worth the risk, so always take a supplement.

'Vitamin B12 deficiency is only a problem for vegans'

Vitamin B12 deficiency is certainly not only a vegan deficiency - one study of 302 female University students in Sydney found that 11% had serum vitamin B12 levels below the lower cut-off for the reference range (which was set particularly low at 120pmol/L, which is far lower than the standard cut-off of 180-200pmol/L). If you are vegetarian, or even a meat-eater who is actively reducing how much meat and dairy you're eating (which many people are), I would urge you to consider supplementing with vitamin B12.

Older adults are also at risk of vitamin B12 deficiency, as stomach acid levels decline as we age, which makes it difficult to cleave the vitamin from its protein-bound form in food.

Certain medications also reduce vitamin B12 levels, such as Metformin (a drug indicated for Type 2 Diabetes) and proton pump inhibitors (used to reduce stomach acid levels), so please ask your GP whether any medications you are on could affect your nutritional status.

'Cyanocobalamin (a type of vitamin B12 commonly used in supplements) contains cyanide, which is toxic'

There are two forms of vitamin B12 available as a supplement: cyanocobalamin and methylcobalamin. The most well-studied in treating deficiency states is cyanocobalamin. Cyanocobalamin does contain cyanide, but the quantity in a supplement is so small (compared to what you take in through food each day) that there's no need to be concerned. Data from a Norwegian study showed that the average dietary intake of cyanide was around 95mcg/person/day, compared to 20mcg in a 1,000mcg cyanocobalamin tablet. You can read more about cyanide and cyanocobalamin here. However, if you are a vegan smoker, it is recommended that you take a non-cyanocobalamin form of vitamin B12, such as a combination of both adenosylcobalamin and methylcobalamin, or hydroxocobalamin as an intramuscular injection (talk to your GP about the frequency required for the injections). 

'I've been vegan for X number of years and never taken a supplement, and my vitamin B12 levels are fine'

This one is difficult to explain, but I would recommend having your homocysteine and methylmalonic acid (MMA) levels tested by blood test (which will more accurately assess your vitamin B12 stores than a serum vitamin B12 assay), and to start taking supplements regularly, as it's not worth risking deficiency. Total vitamin B12 levels can also be falsely elevated by inactive analogues of vitamin B12 found in foods such as mushrooms and tempeh, which may be the reason why some vegans who don't supplement appear to have adequate levels on a blood test.

'I sprinkle nutritional yeast on my meals so I don't need to supplement with vitamin B12'

Although most brands of nutritional yeast (also known as savoury yeast flakes, or 'nooch') do contain vitamin B12 (as the yeast is grown on vitamin-enriched media), the levels vary from brand to brand and most don't provide anywhere near enough to be adequate as a once-daily source. Fortified foods need to be consumed 3 times per day and each serving should provide a minimum of 1mcg of vitamin B12. 

'Methylcobalamin is the active form of vitamin B12; cyanocobalamin is synthetic' 

There are two active coenzyme forms of vitamin B12 in the body: methylcobalamin and 5-deoxyadenosylcobalamin. Each coenzyme form facilitates a discrete metabolic reaction - methylcobalamin is required by methionine synthase to catalyse the conversion of homocysteine to methionine, and adenosylcobalamin is required by methylmalonylcoA-mutase to convert methymalonyl-CoA to succinyl-CoA. Cyanocobalamin is readily converted to both coenzyme forms, is the most well-studied, and is the most stable (chemically). For these reasons, I recommend cyanocobalamin over the other types of vitamin B12 available as supplements. There is no evidence that methylcobalamin is superior in any way to cyanocobalamin, and higher doses may be required to prevent deficiency (if you're particularly interested, you can read more about the issue here).

Vitamin B12 testing

You can test your vitamin B12 levels with a simple blood test, which your GP can order. If your total vitamin B12 levels are low or borderline, the pathologist will do a further test for 'active B12' (holotranscobalamin) level, which is a more sensitive test. You can also test your serum methylmalonic acid (MMA) or homocysteine (HC) (which are metabolites of vitamin B12-dependent enzymes), but please check with your GP as to whether these tests are covered by Medicare, or whether there will be an out of pocket expense.

DOSAGE RECOMMENDATIONS

The following dosage recommendations are based on cyanocobalamin-containing vitamin B12 supplements only. 

Provided they don't contain any lactose (and aren't in a gelatine capsule), vitamin B12 supplements are vegan.

You'll notice that the quantities I have recommended are much larger than the Recommended Dietary Intake (RDI) of 2.4mcg for adult men and women because at low doses, the absorption of vitamin B12 from the intestines is limited to approx. 1mcg at a time, which means you either need to take a small dose 3x per day (which is how people who eat meat and dairy meet their vitamin B12 requirements), or a much larger dose less frequently (from which much less will be absorbed).

If you are an adult aged between 18 and 50 years**, choose one of the following options:

-A once daily dose of at least 250mcg cyanocobalamin as a vitamin B12-only supplement, such as the Nature's Own 250mcg chewable

OR

-1,000mcg of cyanocobalamin as a vitamin B12-only supplement which you can dissolve under your tongue, chew, or spray into your mouth 2-3x per week, such as the Thompson's Ultra B12 1000mcg cyanocobalamin tablets 

OR

-2,000mcg cyanocobalamin which you can dissolve under your tongue, chew, or spray into your mouth 1-2x per week

How much vitamin B12 is too much?

At present, there is no upper level of intake for vitamin B12 set by the NHMRC (which you can read more about here), but in my opinion, there is no need to exceed 1000mcg (1mg) per day if you do not have a vitamin B12 deficiency and are just aiming to maintain your levels. 

*In Australia, there are a limited number of foods which are permitted to be fortified with vitamin B12 (which means the manufacturer has added vitamin B12 to the product). Examples include certain brands of soy milk (such as Sanitarium So Good) and vegetarian meat alternative products such as the Vegie Delights range (which includes products such a sausages and burgers). One serving of a B12-fortified food should provide a minimum of 1mcg of vitamin B12. 

**If you are over 50 years of age a daily dose of 500-1000mcg is recommended. If you are pregnant or breastfeeding, please speak with your GP, Obstetrician or Dietitian for individual advice.

Plant-Based Diets & Iron

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After 'where do you get your protein?', the second most common question I'm asked as a woman on an entirely plant-based (vegan) diet is probably 'where do you get your iron?'. 

Let me just clarify one important point: it is a myth that vegans get less iron than meat-eaters and are at greater risk of iron deficiency anaemia. From a study on the EPIC-OXFORD cohort of over 65,000 people, the vegans in the study actually had the highest daily iron intakes (15.3mg) compared to the omnivores (13.4mg) . This observation was confirmed in an Australia study on male omnivores, vegetarians and vegans. Despite having a higher iron intake, a position paper from the Academy of Nutrition and Dietetics in the US reported that vegetarians tend to have lower iron stores as assessed by serum ferritin levels (though still within the normal range), but are not at a greater risk of iron deficiency anaemia (characterised by low haemoglobin and ferritin levels)

Why do we need iron?
Iron has many functions in the body, the most well-known being at the centre of haemoglobin, the protein which transports oxygen in the blood. A similar protein (myoglobin) is also found transporting oxygen in the muscle tissue. Iron is also required for numerous (93) enzymes, and cytochromes involved in cellular energy production (e.g. cytochrome C) and detoxification (cytochrome P450 family). Iron is also required for the production of the thyroid hormones, and has a role in the metabolism of neurotransmitters such as serotonin.

Causes of low iron levels:

  • inadequate dietary intake
  • decreased intestinal absorption due to a chronic condition, e.g. Crohn's Disease, Coeliac Disease
  • blood loss, e.g. surgery
  • heavy menstruation
  • pregnancy
  • strenuous exercise. Long-distance runners are at particular risk due to the destruction of red blood cells (haemolysis) that occurs with repetitive heel strikes against hard pavement
  • frequent blood donations

Iron deficiency vs. Iron deficiency Anaemia
It's important to note that there is a difference between being iron deficient (low stores of iron in the body which if severe enough will affect red blood cell production), and having Iron Deficiency Anaemia (characterised by low haemoglobin levels and very low/absent iron stores). 

Symptoms of Iron Deficiency Anaemia include:

  • shortness of breath
  • thin, flat, or spoon-shaped nails (koilonychia) 
  • hypersensitivity to cold temperatures
  • frequent headaches
  • loss of appetite
  • pica (craving to eat dirt or other non-nutritive substances)
  • restless legs
  • glossitis - inflammation of the tongue 
  • hair loss
  • pale skin and conjunctiva (inside of the eyelids)
  • heart palpitations
  • reduced work productivity
  • impaired memory
  • impaired concentration
  • fatigue
  • apathy and depression
  • low exercise tolerance (feeling exhausted after not much physical activity)
  • reduced resistance to infections (i.e. more frequent colds and other illnesses)

Haem vs. non-haem Iron
There are two types of dietary iron: haem iron and non-haem iron. Haem iron - as it is derived from blood and muscle - is only found in animal-based foods (meat, eggs, fish) whereas non-haem iron is found in both animal and plant-based foods. Because we're all herbivores here, this discussion will focus on dietary non-haem iron.

Iron requirements:
Recommended Dietary Intake (RDI) for adult men= 8mg
RDI for adult women (aged 19-51 years) = 18mg

It is recommended that vegans and vegetarians consume 80% more iron than omnivores, which brings the RDI for adult women up to a whopping 32mg per day (virtually unachievable without supplementation). However, this recommendation was based on only one study from 1991 which looked at iron absorption in two groups: one containing maximal enhancers of iron absorption, and the other containing maximal inhibitors of iron absorption (which they used as the basis for the vegetarian diet). As this study doesn't accurately reflect a balanced, nutrient-rich plant-based diet, I'd take this recommendation with a grain of salt, and instead of focusing on hitting an arbitrary number of milligrams of iron each day, follow my Practical Recommendations below.

Non-haem Iron absorption is regulated by:
-How much iron you have stored in your body, i.e. if you have lower stores, absorption from the gut is up-regulated, so you will absorb more iron from your food to try and boost your stores
-Dietary enhancers of iron absorption, and
-Dietary inhibitors of iron absorption

Enhancers of iron absorption:

  • Vitamin C (ascorbic acid) - found in foods such as capsicum, tomatoes, broccoli, cauliflower, oranges, kiwi fruit, Brussels sprouts. Just 50mg of vitamin C (the amount in 1/2 a large orange) will enhance absorption by 3-6 times
  • Beta-carotene (pro-Vitamin A) from orange and yellow vegetables such as pumpkin, sweet potato and carrots has been found to increase the absorption of iron from grains
  • Other organic acids (e.g. citric acid) in fruits and vegetables  
  • Fermented vegetables (e.g. sauerkraut, kimchi) 
  • Lysine, an amino acid found in legumes and quinoa
  • Garlic and onion - both were found to enhance the iron absorbed from whole grains and legumes (read more here)

Inhibitors of iron absorption:

  • Phenolic compounds in coffee, black tea, herbal teas (such as chamomile and peppermint), red wine and cacao 
  • Calcium (in amounts greater than around 50mg), found in large quantities in fortified plant-based milks and calcium-set tofu
  • Soy protein in soy milk, tofu and tempeh. However, because of the high iron content of soy foods, the net effect on iron absorption is positive

Phytic acid (found in legumes and whole grains) is also also considered an inhibitor of iron absorption, but the effect is overcome by the addition of some vitamin C to a meal. Phytic acid is also reduced by yeast or sourdough fermentation of breads, soaking and cooking, and soaking and sprouting of grains and legumes. Phytic acid is certainly not an anti-nutrient - it has antioxidant activity and is associated with a reduced risk of numerous chronic diseases.

The top plant-based sources of iron:

  • Legumes & Lentils (approx. 2-3mg per 3/4 cup/125g cooked)
  • Tofu (2.9mg per 100g)
  • Tempeh (2.2mg per 100g)
  • Green vegetables, particularly broccoli (1mg per 1/2 cup cooked), spinach (3.9mg per 100g cooked), bok choy (2mg per 100g stir-fried without oil), silverbeet (2.8mg per 100g boiled)
  • Sweet potato (1.25mg per 250g raw), potato (1.65mg per 300g raw)
  • Nuts, particularly cashews (1.3mg per 25g) and almonds (1mg per 25g)
  • Seeds, particularly pepitas/pumpkin seeds (2.5mg per 25g) and sunflower seeds (1.2mg per 25g)
  • Tahini (1mg per 20g)
  • Whole grains, particularly amaranth (5.2mg iron per 1 cup cooked), quinoa (2.8mg per 1 cup cooked), rolled oats (1.9g per 50g), brown rice (1mg per 1 cup cooked) and wholewheat pasta (3mg per 75g dry weight)
  • Molasses (1mg per 20g)
  • Fresh fruit, particularly oranges (0.75mg per 200g orange), apricots (0.6mg per 200g), and figs (0.6mg per 200g)
  • Dried fruit, such as dried apricots (1.5mg per 50g), dates (1.3mg per 50g) and figs (0.7mg per 50g). In saying this, dried fruit is no higher in iron than the equivalent amount (by kilojoules) of fresh fruit. Dried fruit is only higher in iron (gram for gram) than fresh fruit because it's had most of its water removed, which concentrates the iron
  • Iron-fortified breakfast cereals, e.g. Weet-Bix (3mg per 30g serve)
  • Dark chocolate (1.3mg per 30g serve)
  • Wheat germ (1mg per 10g)

    A note on greens powders:
    Although spirulina does contain a fair amount of iron (3.6mg per teaspoon), I wouldn't recommend it due to concerns over contamination with toxins from blue-green algae. Greens powders are certainly not necessary for a healthy diet - just eat your greens in their whole, unprocessed forms and you'll still get all the nutritional benefits. If you really want to add a greens powder to your morning smoothie, add chlorella instead - it's still a good source of iron and doesn't seem to have the same risk of toxin contamination

Practical recommendations:

  • Include a serve of a protein-rich plant foods (legumes, tofu or tempeh) with 2 meals each day 
  • Include vitamin C-rich fruits or vegetables (or 1/2 glass orange juice with pulp) with your iron-rich meals 
  • Include vegetables rich in beta-carotene with your iron-rich meals (e.g. carrot, pumpkin, sweet potato)
  • Choose iron-rich green leafy vegetables with meals, such as silverbeet, spinach and bok choy
  • Choose whole grains and whole grain products over refined grains and their products, as iron is concentrated in the outer layers of grains (germ and bran) which is removed to produce white grains
  • Avoid drinking tea, coffee, cacao or wine at meal times (1-2 hours after is okay)
  • Avoid drinking plant milk fortified with calcium with iron-rich meals 
  • Avoid taking calcium supplements with or shortly after iron-rich meals 
  • Include a small handful (20-30g) of nuts and/or seeds each day 
  • Have your iron levels tested annually

Don't self-diagnose iron deficiency!
If you're feeling tired, please see your GP and request a blood test before buying a bottle of iron supplements. Fatigue could be related to any number of things, e.g. lack of sleep, mental health conditions or other nutrient deficiencies such as vitamin b12 or zinc. High-dose iron supplements (e.g. Ferrograd-C) have numerous side effects (e.g. constipation, stomach upset, nausea) and excess iron within the cell reacts with reactive oxygen species, forming a highly reactive free radical (the hydroxyl radical), which has the potential to cause oxidative stress and cellular damage.  Another reason not to take iron supplements is that haemochromatosis is also a relatively common genetically-inherited condition which causes iron overload in the body, which will be made much worse by taking iron supplements, as our bodies have no mechanism to excrete excess iron.

If you are diagnosed with Iron Deficiency Anaemia:
It is likely you will be put onto a high-dose iron supplement (e.g. Ferro-grad C) or asked to have a series of iron injections to bring your haemoglobin back up until the normal range. Please make sure your GP investigates the underlying cause of your anaemia (rather than just assuming it's due to your vegan diet), as anaemia relatively uncommon and can be a symptom of a serious medical condition such as Coeliac Disease and Inflammatory Bowel Diseases such as Crohn's Disease.

Any questions? Feel free to comment below and I'll do my best to answer them. 

x Lucy 

 

Maple-Pepita Crisp

One of my favourite snacks is Mrs May's Naturals 'Pumpkin Crunch', which are little cubes of slightly-sweetened roasted pumpkin seeds (pepitas). Given they're from the US (think of the food miles!), quite expensive, and only have a few ingredients (pumpkin seeds (92%), sesame seeds, rice malt, evaporated cane juice, sea salt), I decided to recreate them. I made mine into shards rather than cubes, as it cooks much faster. 

Pepitas are such a great addition to a vegan/plant-based diet, as they're a good source of the minerals zinc and iron, and are also an excellent source of magnesium. 

Per 25g serve, pepitas contain:

  • 1.9mg zinc
  • 2.5mg iron
  • 135mg magnesium (40% of the RDI for a woman)
  • 6g protein

Maple-Pepita Crisp

This is such a simple recipe that is surprisingly moreish - I eat it as a snack by itself, but it's also delicious on a smoothie bowl or bowl of banana nice cream. 

Ingredients:
*If you'd like to make a larger batch, just double the recipe

  • 1 cup (160g) pepitas (pumpkin seeds)
  • 2 tsp maple syrup
  • 1 tbsp white sesame seeds
  • optional: a small pinch of salt

Method:

  1. Pre-heat the oven to 120 degrees Celcius (250 degrees Fahrenheit) fan-forced. Line a baking tray with baking paper
  2. Place the pepitas and sesame seeds in a mixing bowl. Stir to distribute the sesame seeds. Add the maple syrup and salt (if you're using it), then stir until well combined.
  3. Spread the mixture onto to the baking paper, roughly forming a double layer
  4. Bake for 20 minutes, then remove from the oven and leave on the bench (or a wire cooling rack, still on the baking paper) to cool. The mixture will still be soft when you take it out of the oven, but it will set hard as it cools.
  5. Break into large shards and store in an airtight container in the fridge. Enjoy!

 

Supporting your Thyroid on a Plant-Based Diet

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The thyroid is an endocrine (hormone-secreting) gland which sits at the base of the throat and regulates many metabolic processes, including body temperature and the metabolic rate.

In order to produce the thyroid hormones T4 and T3, the thyroid needs a reliable source of two key trace elements: iodine and selenium. Other nutrients (such as iron and zinc) are also required for optimal thyroid function, but in this post I'll focus on iodine and selenium, as they are directly involved in the synthesis of thyroid hormones, and without dietary planning, they are especially at risk of falling short in plant-based diets.

Iodine deficiency disorders are a major public health concern in Australia, as around half (43%) of the population don’t meet the RDI for iodine. The amount of iodine and selenium in plant foods depends on the soil concentration, and for iodine in particular, the soil in many areas of Australia where food is grown is notoriously low.

Dietary surveys show that for Australians, the main sources of these two nutrients are seafood, milk and eggs for iodine, and seafood, poultry and eggs for selenium, so where are we going to get our iodine and selenium on a plant-based diet?

Iodine

The only sources of iodine on a plant-based diet are iodised salt, seaweeds (also known as sea vegetables) or a daily multivitamin (which generally contain 100% of the RDI).

Bread is also a source of iodine as bread manufacturers are required by law to use iodised salt (in place of regular salt) as an ingredient. 100g of bread (3 thin slices) contains roughly a third of the RDI for iodine. (NB/ organic breads are exempt from this legislation, which means if you’re an organics consumer, you won’t be getting a significant amount of iodine from bread.) 

Iodised salt

Iodised salt used to be an efficient way of getting iodine to the masses, but most people have ditched it in favour of fancier boutique salts - such as pink salt flakes or Himalayan salt - which don’t contain appreciable amounts of iodine. If you don’t add salt to your food, I am certainly not recommending that you start doing so just to get the iodine - this is where a multivitamin containing 100% of the RDI for iodine would be appropriate. However, if you are a salt-user, switching to iodised salt can help you to get more iodine into your diet.

Seaweed/ Sea Vegetables

As a general rule, brown seaweeds, such as arame and wakame tend to be higher in iodine than red seaweeds such as nori and dulse. If you regularly eat brown seaweeds, I would advise limiting them to once or twice per week and only consuming them in small quantities, as excess iodine can be toxic to the thyroid gland. 

I have previously recommended using dulse flakes daily as a source of iodine, but have since calculated that you need quite a decent sprinkle on a meal to meet the RDI, so I now recommend either nori (2 sheets per day) or a multivitamin (containing 100% of the RDI for iodine) daily.

Seaweeds to avoid

Hijiki seaweed has been found to be high in naturally-occurring inorganic arsenic, and is not safe for human consumption (FSANZ, 2004). 

Dried kelp is also not a good idea as it is extremely high in iodine. The use of powdered kelp in Bonsoy (a brand of soy milk) between 2004 and 2009 resulted in extremely high levels of iodine in the milk and was responsible for ‘poisoning’ and causing extensive health problems in hundreds of consumers (who later won a massive class action law suit against the parent company). 

Is there any harm in having too much iodine?

Although it’s important to ensure you’re getting enough iodine it’s important to note that the safety margin for iodine is quite narrow – the upper safe limit is just 1,100mcg, which is only 7 times the RDI of 150mcg for adults. Although high intakes of iodine don’t cause thyroid problems, they can unmask hyperthyroidism (an overactive thyroid gland) and increase the severity of the condition. For this reason, I advise against kelp supplements for iodine, which have been shown to have varying levels of iodine and can be contaminated with heavy metals such as arsenic.

Selenium

The role of selenium in the functioning of the thyroid gland is less well understand than for iodine, but it is known that selenium is required by the an enzyme which convert the less active thyroid hormone (T4) to the more active form (T3), and is also a key component of an antioxidant enzyme glutathione peroxidase which function inside the cells of the thyroid gland.

As with iodine, the selenium content of plant foods depends on the soil the food is grown in, and is often low in areas low in iodine. Luckily, there are certain plants are particularly good at hoarding selenium (‘seleniferous’ plants). Brazil nuts fall into this category, as they are a particularly reliable source of selenium. Just 2 brazil nuts contains 74mcg, which is 100% of the RDI for selenium (70mcg for men and women). 

Multivitamins

Taking a daily multivitamin is an easy and reliable way to ensure you're getting the RDI for both iodine (150mcg) and selenium (70mcg), so if you're already one then there's no need to be concerned about food sources of these nutrients. 

References:

For further reading on iodine levels in seaweeds: 
http://www.foodstandards.gov.au/science/surveillance/pages/surveyofiodinelevels5369.aspx