What is it? A chemical element and essential nutrient needed for optimal health.

Why you need it It’s required for 300 biological functions, including DNA synthesis. Modern farming and food processing method means there’s less magnesium in food than ever before.

1. Avocado

The favourite food of all food and fitness bloggers and the most photographed item on Instagram, one avocado contains about 15% of your daily magnesium requirement, alongside a decent dose of energy-releasing B vitamins.

2. Spinach

The NHS’s recommended daily intake of magnesium is 300mg for men and 270mg for women, and 100g of spinach contains around 80mg – or more than 25% of your daily intake needs. Spinach is also one of the few foods that’s very high in vitamin K.

3. Brazil nuts

A 25g portion of brazil nuts contains approximately 25% of your RDI of magnesium, as well as heart-helping unsaturated fats, appetite-suppressing fibre and protein, and a decent whack of potassium, which aids hormone production.

4. Mackerel

Most oily fish from cold-water environments contain magnesium, but mackerel has more than most: a typical 85g fillet provides around 22% of your RDI of the essential element. Pollock is another good option with around 18%, while tuna has 14%.