Is it possible to overdose on vitamin and minerals?

There’s no question that vitamins and minerals are necessary for good health. Found abundantly in various food sources, these nutrients are essential but only in small amounts. Generally most healthy people likely have adequate stores of these micronutrients and would not necessarily gain much additional benefit by taking a supplement.

Besides, in recent year many food companies have voluntarily “beefed-up” levels of vitamins and minerals in several food products. From breakfast cereals, energy bars, juices, enriched breads and pastas, and even margarines, the majority of us are likely easily over the recommended daily intake of a host of nutrients.

But is it possible to overdose on these nutrients? The answer is definitely yes if a person is taking a mega-dose of a particular nutrient in a supplement form. It is nearly impossible to get too much of any vitamin or mineral from eating foods. The nutrients within food are in a much less concentrated form as what is found in a supplement plus they are mixed in with many other nutritional components like phytochemicals which they work together with synergistically.

Rather, the problem stems from taking large doses of single based vitamin and/or mineral supplements for long lengths of time such as for months or years on end.

Many people view taking nutrient supplements as all good – they don’t realize there is no real advantage to taking more than the recommended amounts of vitamins and minerals required. One problem is there is rarely any scientific reason to take massive amounts of any vitamin or mineral (unless under the guidance of your doctor). Secondly, there can be real health problems if you mega-dose with some nutrients with certain symptoms that develop. Usually the symptoms can be reversible if you stop taking the high dosage but not always.

Which vitamins and minerals are unsafe in large doses?

To protect the public from mega-dosing of large amounts of vitamins and minerals, the Food and Nutrition Board of the Health and Medicine Division of the National Academies of Science, Engineering and Medicine has established Tolerable Upper Intake Levels (UL) for most vitamins and minerals. If a vitamin or mineral does not have a UL listed, it does not mean a person can take that nutrient in whatever amount they want; rather the UL has not yet been established as of this time.

The purpose of the UL is to warn consumers that there is an increased risk of an adverse health risk if they exceed that limit. To remind everyone, it is almost impossible to mega-dose of any nutrient with food – the danger comes from taking a dietary supplement, especially of a single nutrient in a high dose. Here are just a few vitamins and minerals which have a UL limit set and what possible health consequences could happen if you take too much:

Vitamin A

This fat-soluble vitamin is essential for normal vision, cell development, and healthy immune system functioning. Each day, adults require between 700 to 900 micrograms (mcg). Best food sources include fish, liver, meat, dairy foods, and brightly colored fruits and vegetables.

Because it is a fat-soluble vitamin, it is stored in the fatty tissues of our body accumulating over time. The UL for vitamin A for adults is 3,000 mcg or 10,000 IU (International Units). If a person is taking a dietary supplement for vitamin A exceeding these amounts long-term, it can lead to liver damage, joint and bone pain, rash, dizziness and nausea. Pregnant women should never take a vitamin A supplement as it can result in severe facial abnormalities of their newborn baby.

Vitamin D

This fat-soluble vitamin also stored in the body, aids in absorbing and utilizing calcium. If your intake is inadequate, you run the risk of developing weak bones leading to osteoporosis. Most adults require 600-800 IU a day. The sun is our biggest source of vitamin D as there are few natural food sources of it. The primary food sources include egg yolks, liver, fatty fish, and cod liver oil.

The UL for vitamin D is 4,000 UL. Excessive sun exposure does not cause or increase any toxic levels of vitamin D to occur. The main way is from taking a high-dose supplement of it. Too much vitamin D can lead to a buildup of calcium in your blood (hypercalcemia) which can cause poor appetite, nausea and vomiting. Weakness, frequent urination, and kidney problems may also occur.

Folate

Folate is a water-soluble vitamin which is not stored in the body. Folic Acid is the synthetic or man-made form of folate and which is used to fortify foods. This B-complex vitamin is essential for making DNA, cell division, and for preventing neural tube defects such as spina bifida. Both men and women require 400 mcg each day with the best food sources being fruits and green leafy vegetables. The UL for folate is 1,000 mg a day for adults.

If folate is taken in mega-dose amount, it can mask a person who has a vitamin B12 deficiency and not a folate deficiency causing irreversible neurological damage.

Calcium

The most abundant mineral in the human body is calcium. This mineral is a must for building and maintaining strong bones and to carry out other important functions in the body. Almost all calcium is stored in bones and teeth, where it supports their structure and hardness. Dairy foods such as milk, cheese, and yogurt are the best dietary sources along with some plant-based foods such as broccoli.

Each day, adults require 1,000 to 1,200 mg of calcium. The UL for this mineral is 2,000 (for individuals ages 51 and older) to 2,500 mg (for individuals ages 19-50). Going above the UL can result in constipation, possible increase in the risk of kidney stones, and may interfere with the body’s ability to absorb iron and zinc.

Iron

The essential mineral of iron is a crucial part of hemoglobin, a protein found in red blood cells. Hemoglobin is responsible for delivering oxygen to all of the body’s cells. Adult men need 8 mg of iron daily while adult women require 18 mg but that amount drops to just 8 mg after menopause. Iron rich foods include red meat, liver, beans, and spinach.

When it comes to taking a supplement of iron, more is not better. Adults should not take any more than 45 mg of iron (UL) a day unless they are being treated with iron under close supervision. Children can overdose from iron toxicity and adults who have an inherited condition called hemochromatosis can have trouble regulating their iron absorption. As a result, this can lead to dangerous levels of excess iron deposited in organs such as the liver, heart, and pancreas which can lead to condition such as cirrhosis, heart failure and diabetes.