Vitamin Deficiency Testing: Are You Getting the Nutrients You Need?

Vitamins are essential micronutrients that your body needs in small quantities to function properly. They play critical roles in energy production, immune function, bone health, neurological function, and hundreds of enzymatic reactions. Despite living in a country with excellent food quality, vitamin deficiencies are surprisingly common in Sweden.

The most prevalent is vitamin D deficiency — due to our northern latitude and limited sunlight during autumn and winter, studies suggest that up to 40 percent of the Swedish population has insufficient vitamin D levels during the darker months. Vitamin B12 deficiency affects an estimated 5 to 15 percent of adults, particularly those following plant-based diets or taking certain medications.

Many people who contact us have taken supplements for years without knowing whether they need them. The challenge with vitamin deficiencies is that symptoms often develop gradually and are non-specific — fatigue, mood changes, poor concentration, and weakened immunity can all stem from low vitamin levels, but these symptoms are easily attributed to stress or poor sleep.

Blood testing provides a definitive answer, measuring your actual vitamin levels so you can take targeted action rather than guessing.

Key Biomarkers for Vitamin Status

Vitamin D

Vitamin D (25-hydroxyvitamin D) is the most commonly tested vitamin in Sweden. Levels below 50 nmol/L are considered insufficient, and below 25 nmol/L is classified as deficiency. Optimal levels for general health are typically between 75 and 125 nmol/L.

B12

Vitamin B12 (cobalamin) is essential for nerve function, red blood cell formation, and DNA synthesis. Deficiency can cause fatigue, numbness and tingling, cognitive difficulties, and anaemia. Serum B12 is the standard test, but Active B12 (holotranscobalamin) is a more sensitive marker of functional B12 status.

Folate

Folate (vitamin B9) works closely with B12 in cell division and red blood cell production. Low folate is particularly important to address before and during pregnancy to prevent neural tube defects.

Iron and magnesium

Iron studies (serum iron, ferritin, transferrin saturation) are often included alongside vitamin panels because iron deficiency is the most common nutritional deficiency globally and its symptoms overlap significantly with vitamin deficiencies. Magnesium is another frequently low mineral that affects muscle function, sleep quality, and energy production.

Vitamin & Mineral Panel →Vitamin D Test →Vitamin B12 Test →

Signs You May Have a Vitamin Deficiency

  • Persistent tiredness that does not improve with rest
  • Frequent colds, infections, or slow wound healing
  • Muscle weakness, cramps, or bone pain
  • Mood changes, irritability, or depression
  • Tingling or numbness in hands or feet
  • Pale skin or unexplained bruising
  • Poor concentration and brain fog
  • Hair loss or brittle nails
  • Mouth ulcers or a sore tongue
  • Following a restrictive diet (vegan, vegetarian, or eliminating food groups)

What Your Results Might Show

Low vitamin D

Low vitamin D is extremely common in Sweden, especially between October and April. If your level is below 50 nmol/L, supplementation is typically recommended. If you book an appointment, your practitioner can talk through a suitable dose with you, based on how low your levels are.

Very low levels (below 25 nmol/L) are worth discussing with a practitioner or your doctor.

Low B12

Low vitamin B12 can indicate dietary insufficiency (especially in vegans and vegetarians), malabsorption conditions such as pernicious anaemia or coeliac disease, or medication effects (metformin and proton pump inhibitors can reduce B12 absorption). If your B12 is low, that is worth raising at an appointment, and may warrant further investigation.

Low folate

Low folate often occurs alongside B12 deficiency and is addressed with dietary changes or supplementation.

Your report

Your health report shows each vitamin level against both the standard reference range and the optimal range. What to do about it is something to discuss at an appointment.

Absorption

Low levels are not always down to diet. Metformin and stomach-acid tablets, for example, both reduce how much B12 the body absorbs. In our clinic we would rather measure than guess before suggesting a supplement.

Order a Vitamin Panel

Frequently Asked Questions

How often should I test my vitamin levels?
For most people, testing once or twice a year is sufficient — ideally once in late winter (when vitamin D is lowest) and once in summer. If you are supplementing to correct a deficiency, retesting after 3 months helps confirm that your levels have improved.
Should I stop taking supplements before a vitamin blood test?
For the most accurate baseline reading, we recommend not taking supplements on the morning of your test. However, do not stop long-term supplementation without consulting your practitioner — the goal is often to see whether your current supplementation is achieving adequate levels.
Can I get all the vitamins I need from food?
In theory, a varied and balanced diet can provide most vitamins. However, vitamin D is very difficult to obtain through food alone in Sweden due to limited sunlight, and B12 is only naturally found in animal products. Individual factors like gut health, medication use, and genetic variations can also affect how well you absorb nutrients from food.
Is it possible to have too much of a vitamin?
Yes. While water-soluble vitamins (B and C) are largely excreted if consumed in excess, fat-soluble vitamins (A, D, E, K) can accumulate in your body. Excessive vitamin D supplementation, for example, can cause hypercalcaemia. This is why testing before and during supplementation is important rather than taking high doses without monitoring.
Can I have B12 deficiency even if my B12 result is normal?
Yes. Serum B12 measures the total amount in your blood, and a result in the lower part of the reference range can still be too low for some people. Active B12 (holotranscobalamin) and homocysteine show more clearly whether your cells are getting enough. They are worth measuring when you have symptoms and a normal B12. We often see people with B12 in the lower part of the range who have clear symptoms.
What are the symptoms of B12 deficiency?
Common symptoms include tiredness, numbness or tingling in the hands and feet, poor memory, low mood and a sore or smooth tongue. Deficiency is more common in older people, in people who eat little or no animal food, and in people taking metformin or medicines that reduce stomach acid. Because the symptoms develop slowly, many people live with them for a long time before they are tested.
Do I need vitamin D in winter in Sweden?
From roughly October to March the sun in Sweden is too weak for your skin to make vitamin D, so your levels depend on food and on what you stored over the summer. Oily fish, eggs and foods with added vitamin D help, but many people still drop below recommended levels by late winter. A blood test tells you whether you need more, and how much.
What are the symptoms of magnesium deficiency?
Muscle cramps, twitching, tiredness, poor sleep and headaches are commonly linked to low magnesium. It is hard to measure accurately in blood, because most of your magnesium is stored inside cells and bone, so a normal result does not always rule out low stores. Alcohol, some medicines and long-term stress can all increase how much your body loses.
Can a vitamin deficiency cause hair loss?
Yes. Low iron stores, vitamin D, B12 and zinc have all been linked to thinning hair, and more than one can be low at the same time. It is worth testing before taking supplements, because too much of some nutrients, such as vitamin A and selenium, can also cause hair loss.
NW

Reviewed by

Wellth Team

Wellth

Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.

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Important to know

Wellth does not diagnose or treat disease. We work with diet, lifestyle and preventive health, alongside the care you already have.

Our reports and sessions do not replace medical advice, and a test result should not be read as a diagnosis. We use both standard healthcare reference ranges and optimal ranges. A value can therefore be normal by healthcare standards and still fall outside the range associated with good health. That does not mean disease, but it can be a chance to act early.

Supplements are only recommended by a nutritional therapist as part of a consultation, never automatically from a test result.

If anything in your results needs to be looked at by a doctor, we will tell you clearly. Contact your healthcare provider if you are worried about your health. Call 1177 for advice, or 112 in an emergency.