The sun is believed to be the primary source of vitamin D, thus the nickname "the sunshine vitamin". When your skin is exposed to sunlight, the ultraviolet B rays, or UVB, can transform cholesterol in the skin cells to vitamin D through synthesis.

Vitamin D is essential for the body, just as much as the other vitamins are. One of its main roles is instructing cells to absorb calcium and phosphorus, essential minerals to maintain strong and healthy bones. Strong bones can protect you from various conditions, such as rickets — a disorder that causes children to have weak and soft bones. The condition is called osteomalacia in adults.

Vitamin D deficiency has been linked to various health problems, including osteoporosis, heart disease, high blood pressure, diabetes, infections, immune system disorders, multiple sclerosis, cancer, and many more.

As Indonesia is currently in the rainy season, the sun doesn't come out of behind the clouds as often. To keep your vitamin D intake in check, you can always consume food that contains a significant amount of vitamin D. 

Here are some food and drinks to keep your vitamin D levels sufficient. Please note that health professionals use international units (IU) to measure the levels of vitamin D. One microgram of vitamin D is equal to 40 IUs.

Pescetarian heaven

There are several types of fish and their products that can provide you with high vitamin D levels.

One product that is the source of high vitamin D is cod liver oil. One tablespoon of cod liver oil can contain 1360 IU. Originally derived from Atlantic cod, the oil is purified and encapsulated in pills. It is a known supplement for bone health, but it can also reduce inflammation in the body.

Other notable fishes that contain high levels of vitamin D are swordfish with 566 IUs (per 3 ounces), cooked salmon with 447 IUs (per 3 ounces), canned tuna with 154 IUs (per 3 ounces), and sardines with 46 IUs (per 2 pieces).

Aside from vitamin D, salmon is one of the best sources of omega fatty acids and vitamin B-12. It is good to reduce inflammation, promote heart health and maintain skin elasticity. Following right behind it is canned tuna that is also high in omega fatty acids and iron. 

Other types of food

If you are not a fan of fish, vitamin D is also attainable from other types of food, such as egg yolks and beef livers.

Although small, egg yolks contain essential minerals, vitamins, and proteins. They can help promote immune system health, keep your blood pressure low, and reduce the risk of macular degeneration and cataracts.Beef liver isn't only naturally high in vitamin D, but also protein, other vitamins, nutrients, and minerals.

According to Nutrition Advance, it is lower in calories compared to 90 percent of lean beef. It generally contains more vitamins than any fruits and vegetables. However, it is high in cholesterol, so moderate consumption is recommended.

Refreshing options

Some people prefer to drink their vitamin D instead of cooking and munching. That's why fortified milk and orange juices exist.

Fortified milk and milk products are essentially ordinary milk with additional nutrients such as calcium, phosphorus, and potassium. One cup of vitamin-fortified milk can contain 115 to 124 IUs of vitamin D.

While most people associate orange with vitamin C. While this is true, oranges are also rich in vitamin D and calcium. It can promote the production of collagen for youthful and radiant skin. 

If you'd like more nutrients in your orange juice, grab a carton or a bottle of fortified orange juice from your local supermarket. A cup of fortified orange juice can contain up to 137 IUs of vitamin D.