Looking at these facts one can Easily Explain :

Lower haemoglobin levels:

Iron deficiency anemia occurs when your body doesn't have enough iron to produce hemoglobin. Hemoglobin is the part of red blood cells that gives blood its red color and enables the red blood cells to carry oxygenated blood throughout your body. If you aren't consuming enough iron, or if you're losing too much iron, your body can't produce enough hemoglobin, and iron deficiency anemia will eventually develop.

Calcium defeciency or Blood Pressure Issues:

Calcium is a vital mineral that our body uses to stabilize blood pressure and build strong bones and teeth. Everyone should consume the recommended amount of calcium per day through the food they eat or, if necessary, by taking calcium supplements.

When you don't get enough calcium, you increase the risk of developing diseases such as osteoporosis and calcium deficiency disease, also known as hypocalcemia.

And not so known Deficency of Magnesium:

Magnesium is involved with over 300 metabolic processes in our bodies, leading to the mineral being called the 'master mineral'.

Magnesium is necessary for the proper transportation of calcium across cell membranes along with vitamin D, vitamin K. Excessive calcium intake has been linked to heart health issues by staying in the blood long enough to calcify into arterial plaque.

Modern monoculture farming methods that rely heavily on using chemical fertilizers, pesticides, and insecticides that are absorbed into the soil causes heavy depletion of its mineral content.

Since magnesium operates on a cellular magnesium deficiency it is difficult to indentify with Serum or blood level measurements