What Is Manganese and What Foods Are High in It?

The mineral manganese is essential for your health but is only needed in very small amounts. Foods high in manganese include shellfish, nuts, whole grains, and other foods.

The mineral manganese is essential for your health but is only needed in very small amounts. You probably get all the manganese you need without trying. Still, it's helpful to know something about the fruits of ongoing manganese research and what foods are high in this mineral. 

Manganese is a metallic element listed on the periodic table. It is brittle but has many industrial uses. Additionally, all living things need manganese to survive. The human body contains about 12 milligrams of manganese. We usually take in about 4 milligrams a day. 

People often confuse manganese with magnesium, another metallic element that is essential for health. You need magnesium in fairly large amounts, though, instead of the tiny amounts you need of manganese. Nutritionists classify manganese as a trace mineral or a micronutrient. 

Manganese performs several important functions:

• Coenzyme function. Manganese is necessary for some enzymes to function properly. It helps the body break down and use carbohydrates, cholesterol, and amino acids. 
• Bone and cartilage health. Manganese helps the body form healthy cartilage and bone. In at least some animals, low manganese levels result in malformed bones.
• Wound healing. Collagen promotes healing, and manganese is necessary for the formation of collagen. 

Manganese also forms part of an enzyme called superoxide dismutase (SOD). This enzyme is an important antioxidant. Antioxidants fight cell damage caused by free radicals, which can speed up aging and contribute to health conditions like heart disease and cancer. SOD breaks the free radical superoxide down into smaller molecules that do less damage.  

Scientists are currently studying the connection between manganese and multiple disorders. One is osteoporosis, a condition that weakens bones. Some studies have indicated that those with higher levels of manganese have stronger bones and experience fewer fractures. Other studies, though, did not show this link. More research is needed. 

Another area of interest is diabetes because manganese affects how the body handles glucose. Researchers have looked for a connection between low levels of manganese and type 2 diabetes, but so far, studies have been inconclusive.

The Food and Nutrition Board (FNB) of the National Academies sets recommended levels for vitamins and minerals. The board found insufficient evidence to establish recommended levels for manganese, though. Instead, board members looked at how much manganese healthy individuals get and determined Adequate Intakes (AIs). 

Your age and gender determine your AI for manganese. Most adults need from 1.6 milligrams to 2.6 milligrams. Women who are pregnant or lactating need slightly more.

Experts say that most humans get enough manganese from their diets. They haven't identified any groups at risk for manganese deficiency. 

If you were to have a deficiency, though, symptoms could include:

• For men: skin rashes and hair color changes
• For women: premenstrual symptoms such as pain and moodiness
• For children: slowed growth and weak bones

Although doctors can measure manganese levels in the blood or urine, it's uncertain how relevant those levels are. The skeleton contains much of the manganese in the human body, and more resides in the kidneys, pancreas, brain, and liver. 

Sources of manganese include:

• Shellfish, especially clams, oysters, and mussels
• Nuts, especially hazelnuts and pecans
• Whole grains, such as brown rice and oatmeal
• Legumes, a food group that includes peas, beans, lentils, and peanuts
• Leafy vegetables, especially spinach and kale
• Some fruits, including pineapples and blueberries
• Many spices, especially black pepper
• Tea

If you take a multivitamin with minerals, you may get extra manganese. Many supplements contain from 1.0 to 4.5 milligrams of manganese. You can also take manganese separately or combined with other minerals. Vitamin manufacturers use different compounds to add manganese to their products. No research shows that one compound is better than others.  

If you are considering taking a dietary supplement such as manganese, though, you should know:

• Most people can get all the nutrition they need through their diets.
• Taking supplements can cause you to get too much of a substance.
• Supplements may have side effects.
• The Food and Drug Administration does not regulate supplements in the same way it regulates medicines.  
• Supplement manufacturers may describe their products as natural, but they can still harm your health, especially at high doses.

The FNB has set upper limits for manganese intake. Taking in more can damage your health. Upper limits range from 2 milligrams to 11 milligrams, depending on your age and whether you are pregnant or lactating.

Even so, it would be quite difficult to get a toxic amount of manganese from your diet. On the other hand, people who work in certain industries such as mining, though, can encounter toxic quantities of manganese through exposure. 

Additionally, some factors affect the way your body handles manganese. If you are low on iron, your body will absorb manganese more readily. If you have liver disease, your body can't eliminate manganese easily. Both of these conditions could elevate your manganese levels.

People who eat mostly plant-based foods such as grains and nuts may also have higher-than-normal manganese levels. The same is true of those who drink a lot of tea. Without other contributing factors, though, these levels of manganese are unlikely to prove toxic.  

The chances that you need to worry about manganese are slim. Eating a healthy diet is the best way to get adequate manganese and other vitamins and minerals, though, so be sure to eat plenty of whole grains, vegetables, and legumes. 

If you have concerns about your manganese level, talk to your doctor.