any disease that produces malabsorption can bring about deficiencies of vitamins a, d, e, and k.

fat

Explanation:

Vitamin's A, D, E and K are fat-soluble vitamins and mostly provide most benefit when consumed together with foods that are rich in fat. Fat-soluble vitamins don not dissolve in water, but instead absorb best when taken with higher-fat foods. Once absorbed into the body, fat-soluble vitamins are stored in fatty tissues and liver.Therefore; any disease that produces fat malabsorption can bring about deficiencies of vitamins a, d, e, and k.

It would be the equator