Can You Overdo Vitamins or Minerals?

Fat-soluble vitamins include Vitamins A, E, D, and K. Fat-solubility means that the body can store these vitamins in fat deposits and can use them over longer terms. It also means that these stores of fat-soluble vitamins can increase and sometimes lead to toxicity, sometimes even after a single high dose!

Vitamin A supports the vision and the immune system. The measurement of Vitamin A can be confusing—it is measured by micrograms (mcg) of retinol activity equivalents (RAE) because many pro-forms of Vitamin A—such as beta carotene—come in the form of both foods and supplements. Vitamin A toxicity can show as vision changes, headaches, dizziness, bone pain, nausea, and skin irritation, along with patches of peeling skin, reddening, and irritation. This usually occurs at levels above 3000 mcg RAE or 10,000 IU. Vitamin A toxicity can lead to liver and bone damage. Excess beta carotene intake can turn the skin a funky yellow-orange color but is not dangerous—but it CAN be a sign that there is a problem with the amounts of vitamins in general you are taking!

Vitamin E consists of 8 related substances—including 4 tocopherols and four tocotrienols. The only form of Vitamin E used in the body is alpha-tocopherol which acts as an important antioxidant, soaking up naturally produced free radicals. These free radicals can damage cellular proteins and DNA, leading to an increased risk of damaging gene mutations. Overall, Vitamin E is important for vision, fertility, the nervous system, the blood, and the skin. High doses are thought to increase the risk of prostate cancer, strokes, and hemorrhages. High doses can also result in diarrhea, nausea, fatigue, blurry vision, rash, and other symptoms.

Vitamin D or calciferol(1) is produced by the skin and “finalized” by the liver and kidneys. Vitamin D acts as a steroid hormone and plays a role in bone, intestinal, immune, and cardiovascular health. It also plays a role in cellular reproduction, muscle function, and nervous system health. Vitamin D is central to the control of calcium and phosphate levels in the bone and blood. Amounts over 10,000 IU are considered excessive and may result in high levels of calcium in the blood—further(2) leading to “nausea, vomiting, muscle weakness, neuropsychiatric disturbances, pain, loss of appetite, dehydration, polyuria, excessive thirst, and kidney stones.”

Vitamin K may be among the least known vitamins—it is a generic name for related substances, phylloquinones (Vitamin K1) and menaquinones (Vitamin K2). Vitamin K(3) plays a role in blood clotting and, as we are learning, may play a role in bone and heart health.

Vitamin K has no known toxic effects, but can interact with anticoagulants (blood thinners like warfarin (Coumadin®)), antibiotics, bile acid sequestrants (e.g., cholestyramine (Questran®) and colestipol (Colestid®)), and weight loss medications such as OTC product (orlistat (Alli®)) and prescription medications (Xenical®).

Humans require quite a list of minerals for health—these include calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, zinc, iodine, chromium, copper, fluoride, molybdenum, manganese, and selenium. These are usually divided into two groups—macrominerals, where the minerals are required in significant amounts and trace (or micromineral) minerals, which are required but only in quite small (trace) amounts.(4)

The four macrominerals are calcium, phosphorus, magnesium, sodium, potassium, chloride, and sulfur. The trace minerals are iron, manganese, copper, iodine, zinc, cobalt, fluoride, and selenium.

Macrominerals

Sodium is needed for fluid balance, nerve transmission, and for muscles to contract. Higher sodium levels are often associated with high blood pressure and risk of heart disease. High sodium intake is also associated with osteoporosis and kidney stones. Sodium(5), if taken in high amounts, can be associated with nausea, vomiting, diarrhea, and abdominal cramps.

Calcium is needed for strong bones and teeth, cell signaling, and protein function regulation. Calcium levels are tightly controlled by the parathyroid glands, bone, small intestine, and kidney. Mild calcium excess is associated with nausea, vomiting, appetite loss, constipation, abdominal pain, fatigue, frequent urination, and high blood pressure. More severe calcium excess (hypercalcemia) can result in confusion, delirium, coma, and death.

Phosphorus is distributed throughout the body and helps to form cell membranes and essential biochemical substances that store energy. It is also needed for bones and cell signaling. Phosphorus toxicity is most commonly seen in those with kidney disease and may cause further kidney dysfunction and death.

Magnesium functions as a co-factor in hundreds of enzyme reactions in the body, including those involved in energy production and the synthesis of proteins and nucleic acids. Excess intake of magnesium can induce diarrhea, low blood pressure, lethargy, confusion, and muscle weakness. These usually occur at levels greater than 350mg of magnesium a day.

Potassium is needed for maintaining the charge difference across a cell membrane and as a co-factor for multiple enzyme systems. Most people are at risk for low potassium levels, but excess potassium (hyperkalemia) can occur, especially in those with poor kidney function. Hyperkalemia is associated with abnormal heart rhythms, tingling of the hands and feet, muscle weakness, and paralysis.

Chloride, along with sodium, is a major electrolyte and helps control blood volume, blood pressure of the volume of the fluid bathing the cells. High levels of chloride are often associated with high levels of sodium and may result in fatigue, weakness, dry mouth, excessive thirst, and high blood pressure.

Sulfur is rarely associated with toxicity—but it can be caused by some medications and some pesticides. High levels of sulfur can cause blindness, seizures, brain damage, and death. Sulfur is necessary for proper protein structure.

Trace Minerals

Of the trace minerals— playing various roles in the body—the main ones that can cause toxicity are iron, zinc, selenium, and iodine—but ALL trace minerals can be toxic at high enough doses!

Iron toxicity is a major cause of childhood poisoning. Iron toxicity can present(6) as “nausea, vomiting, abdominal pain, tarry stools, lethargy, weak and rapid pulse, low blood pressure, fever, difficulty breathing, and coma”. Iron functions to help carry oxygen to cells, in energy production, as an antioxidant, and in DNA replication and repair.

Zinc is needed in several different enzyme systems, for protein structure and for regulation of, for example, gene expression. Excess zinc can result in abdominal pain, nausea, vomiting, and diarrhea. Intranasal zinc, as found in a few OTC cold treatments, can cause loss of smell.

Selenium toxicity can result in brittle hair and nails, skin rashes, GI distress, breath smelling like garlic, fatigue, and neurological symptoms. These usually occur with the use of over 400 mcg a day over relatively long periods of time. Selenium functions as part of enzyme systems important in thyroid function, DNA replication, and reproduction.

Iodine is mainly important for thyroid function—the prohormone, T4, contains 4 iodine atoms, while the active hormone, T3, contains 3 iodine atoms. Excess iodine is associated with an overactive thyroid. The symptoms of this form of hyperthyroidism are loss of weight, high heart rates, warm skin, diarrhea, and muscle weakness.