All you need to know about Magnesium foods, availability and absorption

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Magnesium is the eighth most abundant ground element and the fourth most abundant cation in human bodies. It has a crucial role in several body functions and participates in more than 300 biochemical reactions ! We need to receive magnesium regularly through diet. In the UK, the recommended daily intake for adults (19-64 years old) is 300 mg for men and 270 mg a day for women . Overall, best magnesium foods include leafy greens, nuts, seeds and legumes.

Magnesium is involved in :

• the activation of the insulin receptor
• Vitamin D activation and binding to its transport protein
• carbohydrate, protein and fat metabolism
• tissue sensitivity to parathyroid hormone
• bone and protein structure
• cell membrane functions
• DNA and RNA synthesis
• Blood vessel function
• heart rythm and muscle conraction
• the production of glutathione, a very important antioxidant

Low dietary magnesium intake has been associated with a higher incidence of cardiovascular disease and type 2 diabetes ^, . However, magnesium foods are also high in more nutrients that could protect again relevant diseases. For example, legumes can be high in both magnesium and fibre, which could also reduce the risk of cardiovascular disease. Thus, it is possible that the variety nutrients we find in a balanced diet is what results to cardiovascular and other metabolic health benefits .

Why is magnesium food content reduced these days ?

1. Intensive agriculture has modified mineral concentrations in soil

Plants receive Mg from the soil through the roots. From there, magnesium is transferred to the roots and sprouts and it ends up in chloroplasts. High Ca²⁺, K⁺ and ammonium ion concentrations in the ground reduce magnesium availability to the plants. This happens because these anions compete magnesium during the uptake from the plant root transporters.

During the past few decades, agricultural production has led to magnesium soil depletion and lower concentration in plant food sources for two main reasons:

• The use of pesticides, fertilizers and other techniques using K⁺ and not magnesium. Since K⁺ is a magnesium antagonist, plants absorb less magnesium from the soil.
• The growing population has resulted to an increase in food demand and intensive crop farming. Magnesium is required for the increased plant growth and crop yield. Consequently, magnesium in soil is absorbed by more plants and a smaller amount is available to each plant for absorption!

2. High CO₂ concentrations due to global warming

High soil pH (increased acidity) is another factor that reduces magnesium absorption from plant roots. Increased CO₂ in the atmosphere has increased the ground’s pH, resulting to lower magnesium absorption from the plant roots. Also, it has been shown that edible parts of the plants have a higher concentration of CO₂ and lower Mg and iron concentrations.

When plants contain less magnesium, herbivore animals, which are part of the human diet, may also consume less magnesium through plants. Magnesium is found in animal products in smaller amounts comparing to plant food sources, but still a big part of magnesium dietary intake comes from meat!

How can we increase absorption from magnesium foods ?

1. Soak your legumes overnight before cooking! Oxalate and phytates in plant food sources can reduce magnesium absorption. Soaking can activate phytase, an enzyme that could prevent phytates to reduce magnesium absorption.
2. Choose wholegrain cereals, rice and bread! Milling reduces magnesium concentrations.

 

Best Magnesium foods to include in your diet

Magnesium is found in animal products in smaller amounts comparing to plant food sources, but still a big part of food intake comes from meat. You can find the best magnesium foods per food category in the tables bellow. Nutrition information is provided by Nutritics!

Cereal/grains

Seafood

Food	Portion	Energy (kcal)	Magnesium (mg)	Magnesium % RI
Shrimps	80g, cooked	93	88	23
Tuna	120g, baked	164	49	13
Prawns	140g, cooked	98	50	13

Fruit and vegetables

Food	Portion size	Energy (kcal)	Magnesium (mg)	Magnesium %RI
Spinach	235g (boiled)	53	263	70
Banana	120g (1 large)	108	32.4	9
Dried mangoes	40g (1 snack size box)	155	27.4	7
Dried strawberries	12 g (1 tbsp)	33	7.9	2

Pulses

Food (80g, raw)	Energy (kcal)	Magnesium (mg)	Magnesium %RI
Soya beans	233	200	53
Butter beans	234	152	41
Red kidney beans	236	120	32
Mung dal	239	104	28
Green lentils	249	88	23
Tofu	67	27	6

Nuts/seeds

Food	Portion size	Energy (kcal)	Magnesium (mg)	Magnesium % RI
Chia seeds	20g (2 tbsp)	93	2	16
Almonds (flaked)	20g	131	54	14
Cashews	18g (10 whole)	119	54	14
walnuts	20g (5 whole)	142	32	9
Sunflower seeds	10 g (1 tbsp)	60	39	10
Pumpkin seeds	12g (1 tbsb)	71	32	9

Fun Magnesium foods:

Food	Portion size	Energy (kcal)	Magnesium (mg)	Magnesium % RI
Cocoa powder	10g (1bsp)	35	52	14
Dark chocolate (>70% cocoa)	25g	140	51	13
Pop corn	30g	122	43	12
Almond butter	15g 1 heaped tsp	98	40	11
Chocolate drink	18g (1 sachet)	68	33.5	9
Peanut butter	15g 1 heaped tsp	95	27	9

References