For most minerals on this page Calk counts the days when a food carrying that mineral appeared in the diary — source days, not amounts. Each section below says which question it answers.
Absorption can vary with the chemical form, the rest of the meal, health, medication and individual physiology. Blood tests and clinical assessment answer questions that a food log cannot.
Iron Sources#
What Calk calculates. Calk counts the days a recorded food carried a worthwhile amount of iron and names those sources: meat, seafood, legumes, tofu, leafy greens and fortified foods. Heme iron from animal foods and non-heme iron from plant and fortified foods absorb differently on average NIH 2024 Hurrell 2010.
What you can do. Pair a plant iron source with a vitamin C source, such as beans with peppers or lentils with tomatoes. Tea, coffee and high-phytate foods can reduce non-heme iron absorption when consumed in the same meal. If deficiency is a concern, have it tested and take clinical advice rather than raising your iron intake blindly.
Calcium Sources#
What Calk calculates. Calk counts the days a calcium source appeared - dairy, fortified alternatives, calcium-set tofu, some greens, fish eaten with bones NIH 2024.
What you can do. Check that a calcium source appears regularly. Fortified products vary, so use the current label. Absorption and requirements vary, and a count of source days cannot assess bone health or replace medical advice.
Magnesium Sources#
What Calk calculates. Calk counts the days a magnesium source appeared and names which ones: nuts, seeds, whole grains, legumes, leafy greens. Milligrams are not part of it, and neither are the adult reference intakes, which vary by age and sex NIH 2022.
What you can do. Add one familiar source to a repeated meal: seeds on oats, beans in a bowl, nuts with fruit or a whole grain in place of a refined one. Supplements can interact with medicines and can cause adverse effects at high doses.
Zinc Sources#
What Calk calculates. Calk counts the days a zinc source appeared: meat, shellfish, dairy, legumes, nuts and seeds. Zinc from plant-heavy diets can be less bioavailable, because phytate binds it NIH 2024.
What you can do. Use a range of food sources. Soaking, sprouting, fermenting and leavening can reduce phytate in some foods. Persistent concern about intake or absorption belongs with a clinician.
Iodine & Selenium Sources#
What Calk calculates. Calk counts source days for iodine and for selenium separately. Iodine sources include iodized salt, dairy, seafood and seaweed; selenium sources include seafood, meat, eggs, grains, seeds and Brazil nuts NIH 2024 NIH 2024.
The amounts in seaweed and Brazil nuts can vary greatly. Too much iodine or selenium can do harm.
What you can do. Check whether a normal source appears in the recorded pattern. Do not use high-dose supplements to correct a diary estimate, especially when thyroid disease, kidney disease, pregnancy or medication changes the context.