Natural Ways to Increase Vitamin D Besides Sunlight

Taking a daily vitamin D supplement of 15 μg (600 IU) is the most reliable way to increase vitamin D levels when sunlight exposure is limited. 1

Dietary Sources of Vitamin D

Vitamin D naturally occurs in limited food sources. Here are the best natural dietary options:

Fatty fish - One of the richest natural sources of vitamin D3 (cholecalciferol), including salmon, mackerel, and tuna 2
Fish liver oils - Particularly cod liver oil, which contains high concentrations of vitamin D (250 μg/100g) 2
Eggs - Especially egg yolks, though the vitamin D content is lower than in fish (1.3-2.9 μg/100g) 2
Mushrooms - Some varieties contain significant amounts of vitamin D2 (ergocalciferol), particularly those exposed to UV light (21.1-58.7 μg/100g) 2
Beef liver - Contains moderate amounts of vitamin D (1.3-2.9 μg/100g) 2

Since natural food sources are limited, fortified foods can be an important source of vitamin D:

Fortified dairy products - Including milk and yogurt that have been fortified with vitamin D 3
Fortified breakfast cereals - Many cereals are fortified with vitamin D and can contribute significantly to daily intake 3
Fortified plant-based beverages - Such as soy, almond, or oat milk alternatives 2
Fortified orange juice - In some countries, orange juice is fortified with vitamin D 2
Fortified fat spreads - Including some margarines and butter alternatives 2

When dietary sources and sunlight exposure are insufficient, supplementation becomes necessary:

Daily supplementation - A daily vitamin D supplement of 15 μg (600 IU) is recommended for adults when sunlight exposure is limited 1
Higher doses for older adults - Adults over 70 years may need higher doses, around 20 μg (800 IU) daily 1
Year-round supplementation - For older adults, taking a vitamin D supplement all year round is recommended, not just during winter months 1

Absorption factors - Vitamin D is fat-soluble, so consuming it with some dietary fat can improve absorption 1
Individual variations - Factors such as skin pigmentation, geographic location, and genetic variations in vitamin D binding protein can affect vitamin D status 1
Avoiding excessive doses - Single large doses of 300,000-500,000 IU should be avoided 4
Toxicity threshold - Vitamin D levels above 180 nmol/L (72 ng/mL) can be toxic 1

Maintaining sufficient vitamin D levels is crucial for:

Bone health - Vitamin D is essential for calcium absorption and bone mineralization 1
Muscle function - Adequate levels help maintain muscle strength and balance 1
Immune system support - Vitamin D plays a role in immune function 1
Potential cardiovascular benefits - Some evidence suggests associations with cardiovascular health 1

Relying solely on diet - It's difficult to achieve adequate vitamin D intake through diet alone; most people need either sufficient sun exposure or supplementation 5
Seasonal variations - In northern/southern latitudes (>35th parallel), winter sunlight may not provide sufficient UV-B for vitamin D synthesis 1
Overestimating sun exposure benefits - Factors such as sunscreen use, clothing coverage, and time of day significantly affect vitamin D synthesis from sunlight 1
Ignoring individual risk factors - People with darker skin, indoor lifestyles, or who cover their skin extensively have higher risk of deficiency 1