In other words, you might boost vitamin D absorption with magnesium, but you need adequate magnesium first. In one trial with 180 adults, those with low baseline vitamin D levels saw an increase ...
Good sources of vitamin A (retinol) to eat to increase your intake include: cheese, eggs, oily fish, fortified low-fat spreads, milk, yoghurt, liver, yellow, red and green fruit and leafy vegetables.
Supplements come in various dosages, each featuring different combinations of vitamins and ingredients, making it hard to determine which collagen powder is best when shopping in-store or online.