B vitamins play a role in energy metabolism and help to fight fatigue. Vitamin C is also known to boost energy, while iron helps to transport oxygen in the body.

In one study 97 healthy women were randomly assigned to placebo or treatment with multivitamins/minerals. They were assessed on cerebrovascular blood flow, total and fat oxidation and oxygen consumption using indirect calorimetry of exhaled pulmonary gas after supplementing with either lower or higher (3RDA) dose for eight weeks.

B Vitamins

The B vitamins – sometimes called “energy vitamins” – help the body turn the food you eat into energy to keep your brain and body working. They are water-soluble and can’t be stored in the body so you need to get them each day from your diet. They also act as coenzymes – they power enzymes that speed up chemical reactions in the body.

Without the B vitamins, your body would have trouble turning the energy-yielding nutrients in carbohydrates, fats and proteins into fuel for its cells and for making blood to carry oxygen throughout your body. The B vitamins also help your cells grow and multiply and aid in the production of red blood cell hemoglobin. You can find the eight B vitamins in many unprocessed foods including meat, fish, dairy products and leafy green vegetables. B-complex supplements often pack all of the essential vitamins into one pill.

Each of the B vitamins performs a slightly different function but they all work together to form the complex metabolic machinery that keeps your body running. They are involved in both catabolic metabolism – the breaking down of molecules to release energy – and anabolic metabolism – the building and transformation of bioactive molecules. The B vitamins are especially important for the brain because they play a role in the generation of neurotransmitters, help transport amino acids across the blood-brain barrier and help the brain make use of glucose (sugar) for energy.

Vitamin C

Vitamin C is known for its immune-boosting properties and may help prevent the dip in energy that can occur after intense exercise. It also helps with connective tissue repair, reduces oxidative damage and aids iron absorption. While research on vitamin C supplementation specifically for athletes is limited, there’s no doubt that it’s an important nutrient for your overall health and fitness. You’ll find a good amount of vitamin C in most multivitamins and can get plenty from eating a variety of whole foods including fruits, vegetables and dairy.

For most adults, the daily requirement for vitamin C is around 40mg.1 It’s also available as a standalone supplement and is found in a wide range of nutritional products from multiple brands. When trying to maintain a balanced diet, it can sometimes be challenging to get all the essential nutrients from food alone. In such cases, multivitamins can help fill potential gaps in your nutrition. They provide a convenient way to ensure you’re getting the right vitamins and minerals, especially if your diet is lacking in certain areas.

Vitamin D

Vitamin D, the “sunshine vitamin,” is best known for its contribution to bone health but it also may improve energy levels. The researchers behind a new study from Newcastle University believe that the reason for this lies within mitochondrial efficiency – the power stations inside every cell that use glucose and oxygen to create energy in the form of a molecule called ATP. Muscle cells need large amounts of ATP for movement and it is thought that Vitamin D helps them to work more efficiently by increasing the speed at which they replenish their stores after each contraction.

The research gave 120 fatigued (but otherwise healthy) people a single megadose of vitamin D or a placebo and found that those given the Vitamin D experienced improved energy levels. This is in line with other studies that have found low energy and fatigue to be linked to Vitamin D deficiency.

While a dietary deficiency of vitamin D is common, there are a number of things you can do to make sure your levels are optimal. You can add fish, cod liver oil, salmon, trout, mackerel and fortified milk to your diet as well as take a supplement.

The Vitamin D you get from food and sun exposure is biologically inert and must undergo two hydroxylations in the body to become active Vitamin D. These hydroxylations are carried out in the liver and kidneys. The first hydroxylation converts Vitamin D into 25-hydroxy Vitamin D, or 25(OH)D, which is commonly known as calcidiol. The second hydroxylation takes place in the kidney and forms the physiologically active 1,25-dihydroxy Vitamin D, or 1,25(OH)2D, more commonly known as calcitriol. The resulting Vitamin D can be used by the body to regulate calcium, phosphorous and magnesium – essential nutrients for bone health.

Iron

Iron is necessary for the production of healthy red blood cells, and plays a key role in oxygen transport. It is a component of hemoglobin, which is an erythrocyte (red blood cell) protein that delivers oxygen from your lungs to all parts of your body. Iron is also a component of myoglobin, which transports oxygen to muscle tissue. Insufficient intake of iron can result in anemia, which can affect both physical and mental fatigue.

Many foods provide a significant source of iron. However, many people are unaware of the amount of iron they eat and may not be able to meet their daily needs through diet alone. Food labels are regulated to indicate the amount of iron a product contains and provide a guide to help consumers identify dietary sources of iron. Foods that provide 20% or more of the Daily Value (DV) of iron are considered to be high in this nutrient.

Over-the-counter supplements are available in a variety of forms, including ferrous sulfate, ferrous fumarate and ferrous gluconate. When choosing a supplement, it is important to note whether the two number amounts on the label refer to the chemical compound form or the elemental, pure iron, as the latter is more easily absorbed by the body.

Magnesium

Magnesium is a mineral that aids hundreds of metabolic reactions in your body. In addition, it’s known to help prevent muscle cramping and improve sleep quality. It’s also important for the active transport of potassium and calcium across cell membranes, which is necessary for nerve transmission and normal heart rhythm (5). Dietary surveys show that half of all Americans don’t consume enough magnesium in their diets, causing deficiency and potentially setting the stage for a host of chronic diseases, including diabetes, high blood pressure and heart disease.

A magnesium-rich multivitamin and a balanced diet are your best bet for getting the magnesium you need to feel and perform your best. Leafy vegetables are packed with magnesium, as are whole grains, nuts and seeds and many breakfast cereals. A few teaspoons of Epsom salt in your bath may also boost your intake.

The form of magnesium found in supplements, magnesium glycinate, is easily absorbed and doesn’t have the laxative effects that are associated with other forms of the mineral, such as magnesium citrate (a popular type of antacid) and magnesium oxide (which is sometimes used as an ingredient in milk of magnesia and has a strong laxative effect). In one study, a combination of magnesium, potassium and vitamin B6 significantly improved glucose utilization during exercise by helping muscles use glycogen more effectively.

A 4-week magnesium supplement also improved exercise performance in the 20 m shuttle run test by decreasing lactate accumulation. Getting too much magnesium, however, can be harmful. It can interfere with the absorption of other vitamins and minerals, such as zinc and copper. Long-term or high-dose supplementation isn’t recommended, especially in people with kidney disease.