Vitamin D

• Keeping bones and teeth strong. Vitamin D helps the body use calcium and phosphate from food. Long-term serious deficiency can weaken bones. [1] [3]
• Normal muscle function. Severe deficiency-related bone disease can also involve weakness and trouble walking. Tiredness alone cannot diagnose low vitamin D. [1] [3]
• Preventing shortage in risk groups. Dutch daily advice depends on age and circumstances. Extra vitamin D is not proven to prevent colds. [1]

For most people in the Netherlands, sunlight is the principal source. Winter sunshine there does not support adequate production, so stores made earlier also matter. Production varies with outdoor exposure, clothing and skin tone. Do not treat a presumed deficiency by prolonged unprotected sun exposure; protect skin from damage during longer exposure.[1][2]

Oily fish such as herring and salmon supplies vitamin D, while eggs and meat contain smaller amounts. Dutch margarine and other fat spreads or cooking fats are fortified, but plain oil generally is not. Read the label rather than assuming every product in a category contains the same amount. People in a group advised to supplement may not meet their needs through food alone.[1]

Voedingscentrum advises a daily 10-microgram supplement for children through age 3, pregnant people, women aged 50–69 and people aged 4–69 with darker skin or limited daylight exposure. From age 70 the advice is 20 micrograms per day. These are prevention recommendations, not a treatment dose for established deficiency. [1]

Check whether your multivitamin already contains vitamin D. The UK NHS gives a broader autumn/winter recommendation; that is not Dutch policy. Discuss bone pain, substantial weakness or uncertainty about your situation with a clinician. [1] [2] [3]

Long-standing deficiency can cause rickets in children and soft, painful bones in adults (osteomalacia); weakness can also occur. Tiredness on its own can have many causes. Bone pain, difficulty rising or walking, or bowed legs in a child need assessment because low calcium or other conditions may also be involved. [1][3]

A clinician may order a blood test measuring 25-hydroxyvitamin D and consider symptoms, food and individual risks together. See vitamin D deficiency for the difference between prevention and treatment. A daily prevention supplement does not replace investigating lasting bone pain or marked weakness. [1][3]

Prolonged excess from supplements can raise calcium levels and damage the kidneys. Voedingscentrum gives an adult upper limit of 100 micrograms daily; it is a safety ceiling, not a target, and children's limits are lower. Normal food and sunlight are not typical causes of vitamin D overdose in healthy people.[1][2]

Consider all products you take before adding doses. Clinicians may choose and monitor different regimens for diagnosed disease; do not copy a treatment dose from someone else's experience. Discuss high-dose use, kidney problems or possible adverse effects with a health professional rather than increasing the dose yourself.[1][2]

Check if Dutch preventive advice applies to you, then read the daily vitamin D amount on the label and include any multivitamin. Eat a varied diet including foods such as oily fish, and spend time outdoors responsibly. Prolonged unprotected sun exposure is not a deficiency treatment. [1]

Recurrent bone pain, fractures with little injury, difficulty getting up or bowed legs in a child needs clinical assessment. Bring a supplement list; do not improvise a high treatment dose. [3]