Teens who skip their breakfast will have weaker bones, smaller brains and slower metabolism for life

It's something nutritionists have been banging on about for years. 

But now a study has provided even clearer evidence: breakfast really is the most important meal of the day.

The research by King's College London found that starting the morning with a meal is particularly important for teenagers and children.

Young people who skip breakfast could leave themselves open to severe issues with development, that could affect them later on in life.

Specifically, they do not get enough iron, folate, calcium or iodine - which can leave them with low brain function and lacking in energy, among other health problems.  

The researchers who conducted the study, published by the British Journal of Nutrition, chronicled the eating habits of kids between ages four and 18 everyday from 2008 to 2012.

They found that a quarter of kids between ages 11 and 18 skipped breakfast everyday and seven percent of those between four and 10 did the same.

A third of those kids who skip it are not getting enough iron while about a fifth are not getting enough calcium or iodine. And about 7 percent do not get enough folate.

Study researcher Dr Gerda Pot said: 'This study provides evidence that breakfast is key for parents to ensure that their children are getting the nutrition they need.'

Iron, folate, calcium and iodine deficiencies can translate to a host of medical issues.

If a child does not get enough iron - which circulates oxygen throughout the body - their body cannot produce enough oxygen-carrying red blood cells that are healthy.

When they do not have enough oxygen, they become fatigued.

The exhaustion that ensues from not having enough oxygen can affect how well their brain functions as well as their immune system's ability to keep the body healthy and infection-free.

Iron is also essential in maintaining healthy cells, hair and skin.

The amount of iron that a child needs depends on their age but it decreases as they get older.

For example, they need 10 mg each day from ages four to eight - because iron is essential to healthy growth - but only eight mg from ages nine to 13.

Calcium is necessary for strong bones and teeth but also helps with other important bodily functions.

In addition to causing brittle bones, a calcium deficiency can also result in problems with a child's hormone release and their muscle contractions. 

Children need more calcium as they get older. From ages four to eight they need 1,000 mg daily while from nine to 18 they need 1,300 mg.

Iodine is important for good thyroid health. While most people in the US consume enough iodine, a deficiency can result in a goiter, which is an enlargement of the thyroid gland.

Children who do not get proper amounts of iodine can also experience slow mental development.

From ages one to eight, children need about 90 mcg of iodine daily. From nine to 13 they need 120 mcg and from 14 to 18 they need 150 mcg.

The researchers also found that some children who did not eat breakfast everyday had a low folate intake.

Folate is important because it helps the bowel absorb nutrients properly and betters your metabolism.

Children aged one to three need 150 mcg of folate each day; from from four to eight they need 200 mcg; from nine to 13 they need 300 mcg and from 14 on they need 400 mcg.

While the study provides hard evidence that children and teenagers should be eating breakfast every day, Dr Pot said more research needs to be done to provide a fuller picture of what a healthy breakfast entails.

'Further studies that investigate specific foods and dietary quality would help to identify if the differences are due to the different types of breakfast being eaten by different age groups, as well as provide more insight into the impact of breakfast on dietary quality overall.'

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