A few ways to naturally increase your vitamin D and calcium levels include:
Including more foods in your diet that are high in these nutrients like dairy and fish
Use fortified dairy-free milk
Eat other fortified foods such as bread and cereal
Spend more time in the sun (where this is not possible UV lamps are a good alternative)
Maintain a healthy weight and balanced diet
You can take Adcal-D3 as a vitamin and calcium supplement if you are struggling to effectively increase your levels to a healthy standard naturally. However, you should consult with your GP or prescriber to make sure that Adcal-D3 is the correct supplement for you and your condition.