In short
- Vitamin B12 is the key value: it comes almost exclusively from animal products.
- Iron from plants is absorbed less well, so iron stores can fall unnoticed.
- A deficiency often develops months to years before you notice anything.
- Measuring is mainly useful with complaints, after a longer period eating plant-based, or around conception.
What you can measure
Not every cause is visible in blood. These are the values that most often explain something.
Recommended test
Recommended with a plant-based diet
Vitamins, minerals & electrolytes
9 markersThis test measures in a single draw the values that a plant-based diet calls for attention to: vitamin B12, ferritin, vitamin D, folate, zinc, magnesium, calcium, sodium and potassium. That way you see where you stand now and can adjust deliberately instead of supplementing on instinct. Ideally measure before you start taking supplements, otherwise you are mainly measuring the supplement.
- Personal assessment by a registered doctor
- Clear laboratory report, in plain language
- No referral needed
- 1000+ blood draw locations
€159
Plus 29,- blood draw fee per order, free from 225,-.
Complete pictureBloodworks Premium
36 markers in one appointment
Why a plant-based diet needs attention
A well-composed plant-based diet supplies most nutrients amply. There are, however, a few nutrients that occur mainly in animal products or are absorbed less well from plants.
That is not an argument against eating plant-based, it is a matter of knowing what to watch. Those who drop meat and dairy without replacing anything run into the same handful of deficiencies over time.
Blood testing is a tool here, not a goal. It shows where you stand now, so you can adjust deliberately instead of supplementing on instinct.
Vitamin B12: the most important one
Vitamin B12 in a usable form comes almost exclusively from meat, fish, eggs and dairy. Plant sources such as seaweed or fermented products do not supply a reliable amount.
Your liver holds a substantial store, so a deficiency only shows after months to years. That explains why people sometimes eat plant-based for years without complaints and still turn out to be deficient.
Complaints that can fit a deficiency are fatigue, tingling in hands or feet, trouble concentrating, a sore tongue and low mood. Because a deficiency builds up over months to years, a measurement is the way to spot it in good time.
If you eat fully plant-based, supplementing B12 is the starting point. Vegetarians who use dairy and eggs sit in between and benefit more from a measurement to see whether their intake is enough.
Have vitamin B12 measured
Your B12 value measured in a certified laboratory, all-in including the blood draw fee, with doctor interpretation and a personal PDF report. No referral required.
Iron and ferritin: absorption is the bottleneck
Iron is plentiful in pulses, wholegrains, nuts and green vegetables. The issue is not the amount but the absorption: iron from plants is taken up less well by your gut than iron from meat.
What improves absorption is vitamin C with the meal, for example peppers, citrus or kiwi. What hinders it is tea, coffee and large amounts of dairy close to the meal.
Ferritin is the value reflecting your iron stores and the first to fall. Menstruating women, athletes and growing teenagers carry the greatest risk, because their consumption is higher.
Watch one thing: ferritin rises temporarily with inflammation or infection. A result taken just after flu or a hard training session can therefore mask a deficiency.
Vitamin D, zinc, iodine and calcium
Besides B12 and iron, these values deserve attention:
- Vitamin D: comes mainly from sunlight and oily fish. In the Netherlands the value comes out low for many people in winter, plant-based or not.
- Zinc: found in pulses, nuts and seeds, but absorption is hindered by phytates in those same foods. Soaking, sprouting and sourdough help.
- Iodine: in the Netherlands iodine comes mainly from iodised bakery salt and dairy. Anyone baking their own bread without iodised salt and using no dairy misses an important source.
- Calcium: without dairy you need fortified plant drinks, tofu, nuts and green vegetables. A blood value says little about your intake here, because your body regulates it tightly.
- Omega 3: for the long-chain fatty acids, algae oil or oily fish are the sources. This is not a standard test.
Iodine, copper and selenium are available at Bloodworks as separate additions through Bloodworks Select. For calcium and omega 3, a blood measurement tells you less than a critical look at your diet.
| Nutrient | Where it pinches | Where you get it |
|---|---|---|
| Vitamin B12 | virtually absent from plant foods | supplement or fortified products |
| Iron | less efficient absorption from plants | pulses and wholegrains, with vitamin C |
| Vitamin D | little sun in the winter months | sunlight and a supplement |
| Zinc | absorption hindered by phytates | nuts, seeds, pulses, sourdough bread |
| Iodine | no dairy and sometimes no iodised salt | iodised bakery salt, fortified products |
When should you measure?
Measuring is mainly useful at these moments:
- six to twelve months after switching to a fully plant-based diet
- with complaints such as persistent fatigue, breathlessness on exertion, tingling or hair loss
- around conception or during pregnancy
- if you use supplements and want to know whether your dose suits your situation
- periodically, for example once every one to two years, to follow trends
Practical: how to get a usable result
If you use supplements, you mainly measure their effect. If you want to know where you stand without them, discuss with your doctor whether you can pause them temporarily. Never do that during pregnancy or with an established deficiency without consulting first.
High-dose biotin, often found in supplements for hair and nails, can interfere with certain laboratory measurements. Always report what you take.
At Bloodworks you have this tested without a referral, at one of the more than 1000 affiliated collection points across the Netherlands. The Vitamins, minerals and electrolytes package measures nine values in one draw: vitamin D, vitamin B12, folate, magnesium, calcium, ferritin, zinc, sodium and potassium.
Frequently asked questions
Do I always need to supplement vitamin B12 as a vegan?
With a fully plant-based diet, supplementing is the starting point, because reliable plant sources are lacking. A measurement shows where you stand now.
Is one B12 test enough to rule out a deficiency?
It usually gives a good first picture. With doubt, or with complaints that persist, additional testing such as methylmalonic acid or homocysteine can add clarity. Discuss that with your doctor.
Do I need to fast for these tests?
Not strictly for most vitamins and minerals. Because several values are often measured in one draw, we advise fasting in practice. You receive clear instructions with your lab form.
My ferritin is low but my blood count is normal. What does that mean?
That can point to iron stores running down before anaemia develops. Our doctor interprets that in your context and advises whether adjusting your diet or supplementing makes sense.
Which values should I measure if I have just switched?
Start with vitamin B12 and ferritin, possibly with vitamin D alongside. If you want a broader picture including zinc, folate and calcium, a package is cheaper than adding up individual tests.
Where do you give blood?
You can give blood at collection points across the Netherlands, usually without an appointment.
Find a collection point near you or read how a blood draw works.