All About Micronutrients

online nutrition coaching, free radicals, antioxidants

Micronutrients are better known as vitamins and minerals. As a personal trainer in London I train my clients to get healthy, fit and strong, but I also educate them about the importance of good nutrition. You can’t out-train a bad diet, however hard you try.

In order for your body to function optimally, you require the right balance of macro-nutrients (carbohydrates, protein, fats, water) as well as micro-nutrients (vitamins and minerals). In this blog post I’ll focus on the micro-nutrients. There are a lot of them!


Vitamin A

The main vitamin for healthy eyesight. Food sources include liver, kidneys, eggs, milk, butter, dark leafy vegetables, carrots. The most famous one is carrots, for their magic property of being able to see in the dark if you eat enough of them.

Vitamin B

This is not a single vitamin, but a whole family of vitamins, as you’ll see below. The main food sources are red meat and grains. Their main function is to help enzymes metabolize the macro-nutrients (fats, proteins, carbs). The B vitamins help unlock the energy from food, getting energy to both body and brain. Pregnant women require more B vitamins, particularly B9 (folic acid).

Vitamin B1 (Thiamine)

Helps metabolize carbohydrates, energy production, keeps your heart healthy. Anyone who drinks more than around 10 units a week are likely to be deficient in B1, as alcohol limits its absorption. Alcohol damages many functions of the body as it is toxic to every organ and cell. (If you’ve read that red wine is good for you, it’s the grape juice that’s beneficial, not the alcohol, so if you want the goodness without the toxicity of alcohol, drink red grape juice. or simply eat red grapes.)

Vitamin B2 (Riboflavin)

Acts as a catalyst in the mitochondria, the energy factories of your cells. Good sources of B2 are natural yoghurt, chicken and fish.

Vitamin B3 (Nicotinic acid)

Vital for processing fats in the body and regulating your blood sugar levels. Best food sources are fish, chicken, turkey, pork, liver. Symptoms of  B3 deficiency are apathy, poor concentration, low energy, depression.

Vitamin B6 (Pyridoxine)

Helps metabolize amino-acids (the building-blocks of protein). Good food sources: pork, fish, chicken, turkey, eggs. Deficiency in B6 and B9 (folic acid) can cause serious conditions such as osteoporosis, heart disease, and certain forms of cancer. Vegetarians and vegans are recommended to take vitamin B supplements.

Vitamin B9 (Folic acid)

Vital for DNA and RNA synthesis. Good sources are dark green vegetables (don’t overcook!), lentils, eggs (yolk). One of my personal training clients in central London thought that egg yolks were bad for you because of the cholesterol. I explained that this health scare was a myth, and that egg yolks are full of nutrients, including this vitamin.

Vitamin B12 

When you eat fats, they’re broken down into fatty-acids. Vitamin B12 helps metabolize fatty-acids. Other roles include red blood cell production, healthy nervous system, and processing folic acid (B9). Foods rich in vitamin B12 (such as eggs) help relieve the symptoms of rheumatoid arthritis. Vegetarians and particularly vegans are in danger of being deficient in B12, so I recommend edible seaweeds such wakame, the only non-animal source of B12.

Vitamin C 

Promotes healing of wounds, and regulates cholesterol levels. Best sources are citrus fruits such as lemons and limes, and oranges. Also rich in vitamin C are fruits like blackcurrants and blackberries. There is vitamin C in vegetables, but boiling vegetables depletes the bio-availability of this vitamin, as it’s water-soluble. (If you suffer from IBS, avoid eating too much raw veg, as it can aggravate the bowels, particularly the insoluble fibre raffinose, found in vegetables such as Brussel sprouts. In contrast, cooked artichoke can relieve the symptoms of IBS).

Vitamin D

Exposure to sunlight is vital for vitamin D production. Good food sources are eggs, dairy, and oily fish. Vitamin D is essential for strong bones and a strong immune system.

Vitamin E

Fights free radicals and delays the signs of ageing. Good food sources include fresh vegetables, olive oil, nuts and sunflower seeds. Brussel sprouts are rich in vitamin E, and cooking them increases the bio-availability of this vitamin. Avocados are another great source of vitamin E.

Vitamin K 

Controls blood clotting and helps bone-building. Good sources: spinach, broccoli, sprouts and avocados.


In addition to vitamins, your body needs the full range of minerals to function effectively. These minerals are divided into major minerals (there are 7 of them) and  the 10 trace minerals, which as the name suggests, you only require in tiny amounts.

The Major Minerals:

Calcium is the most abundant mineral in the body, as it forms the bulk of your bones and teeth, but it easily depletes so you need 1,000mg a day to keep your calcium levels topped up. You also need calcium for many functions such as muscle contraction, nerve transmission, and regulating lactic acid levels after intense activity. Best food sources: milk, yoghurt, cheese (particularly romano cheese, swiss cheese, and ricotta cheese, in that order). Excessive calcium intake could lead to kidney stones. One way to boost absorption of calcium is to eat beetroot, which contains silica. Vegetarian sources of calcium include broccoli, chick peas and dried figs.

Chloride is one of the four electrolytes, which regulates fluid levels in the body.

Magnesium is another electrolyte (fluid balance). It also helps your muscles to work harder, by enhancing oxygen delivery to working muscles. Magnesium also activates many enzymes in the body. If you train intensively, make sure you top up your magnesium stores by eating plenty of fish.

Phosphorus together with calcium is an essential component of bones and connective tissue.

Potassium One of the electrolytes, vital for fluid regulation. Good food sources include potatoes, mushrooms, celery, and in particular artichokes.

Sodium is one mineral we are rarely deficient in, as it’s in all processed foods and also occurs naturally in fish. Athletes who sweat heavily might become sodium deficient, but this can be remedied with an electrolyte drink. Sodium is an electrolyte: it helps retain fluid balance in the body, between cells and bloodstream.

Sulphur is needed for cartilage production.  Cartilage is flexible connective tissue found in your joints, and in structures such as your outer ear. Good food sources include sprouts.

The Trace Minerals:

Boron helps bones absorb calcium. Best food sources: fruit and vegetables.

Chromium helps reduce excess body fat, regulates blood sugar, and promotes lean muscle growth. Exercise depletes it, so keep your chromium levels topped up by eating wholegrains, mushrooms, nuts. However, excessive chromium intake can impede iron and zinc metabolism, as I explained to one of my personal training clients in Holland Park who was addicted to snacking on nuts between meals. Eggs and chicken are also good sources of this mineral.

Cobalt helps iron absorption, and nerve function (particularly myelin sheath formation). Good food sources include seafood, fish, red meat (particularly liver), spinach, and nuts.

Fluoride is vital for healthy teeth and bones. Tap water contains fluoride, so you don’t need other food sources.

Iodine Vital for thyroid hormone production (thyroxin), to regulate metabolic rate and therefore bodyweight. Best food sources: sea vegetables (particularly kelp), scallops, cod. Kelp contains pretty much the full spectrum of essential minerals.

Iron is needed to make haemoglobin, which enables your red blood cells to carry oxygen around your bloodstream to feed all the muscle cells of your body. Iron deficiency anaemia causes low energy and poor physical performance. Red meat (particularly liver) is the best source of iron, but too much iron can impede absorption of zinc. For vegetarians, spinach is a good source, but you need to eat a lot, and combine it with some lemon juice to aid absorption, otherwise the oxalates in spinach bind with the iron and prevent absorption. Other good vegetarian sources are pumpkin seeds and lentils.

Drinking too much tea/coffee can hinder iron absorption, so cut back on these. Switch to mint tea or green tea instead.

Manganese is vital for healthy bones, connective tissue, and calcium absorption. Best food sources: green veg, brown rice, coconut oil/milk, almonds.

Selenium is a key component of the enzyme glutathione, a vital antioxidant. Together with vitamin E it helps combat free-radicals, and boosts recovery time after physical exercise. Best food sources are meat, seafood, whole grains.

Zinc helps build and repair muscle after intensive workouts, so I’m always telling my personal training clients in London to eat more red meat, the single best food source of zinc. However, you only need 2-3 small portions of red meat a week to keep your zinc levels topped up. Zinc is also vital for a healthy immune system, and for converting food into energy. For vegetarians and vegans, sunflower seeds are a good source of zinc, although vegetarian sources of zinc are not as bioavailable (in other words, they don’t absorb as easily into the body). If sunflower seeds are soaked overnight and then added to your breakfast next morning, the zinc will be better absorbed.

Dominic Londesborough is a personal trainer in London and online nutrition coach.