Vitamin D, following activation in the skin, is converted to the hormone calcitriol by enzymes in the liver and kidneys. People in northern climates who may not get adequate sun exposure can become deficient in vitamin D. What mineral would be especially affected by this?

Calcium

Explanation:

The Vitamin D is an important vitamin and it is related with the element calcium in the body. The Vitamin D is responsible for the absoprtion of calcium in the body present in the food. In the deficiency or depletion of the Vitamin D in the body is likely to affect the calcium levels. The calcium is the main element present in the bones and the teeth. Calcium helps to build bones. In the condition which involves the depletion of Vitamin D levels the calcium levels will also deplete. This will result in conditions like oesteoporosis, rickets and other bone deformities.

Thus people in the northern climates receiving low sunlight, will likely to receive low Vitamin D and will likely to develop bone related problems due to low calcium levels.