Why Spinach Is Called A Superfood?

Dark, leafy greens, such as spinach, are beneficial for skin, hair, and bone health. They also provide protein, iron, vitamins, and minerals.

Nutrition

A 100 g serving of spinach contains 28.1 milligrams mg of vitamin C, 34% of a person’s daily recommended amount. Spinach also contains iron, potassium, vitamin E, and magnesium. Different cooking methods can change the nutritional content of spinach. One cup of raw spinach contains:7 calories, 0.86 g of protein, 29.7 mg of calcium, 0.81 g of iron, 24 mg of magnesium, 167 mg of potassium, 141 mcg of vitamin A and 58 mcg of folate. Spinach also contains vitamin K, fiber, phosphorus, and thiamine. Most of the calories in this vegetable come from protein and carbohydrates.

Is Spinach a Good Source of Iron?

Spinach is a nutritious and plant-based source of iron, a mineral that is crucial in transporting oxygen in the blood. Iron is also important for maintaining healthy pregnancies, supporting the immune system, and aiding digestive processes. A person can increase their body’s iron absorption from plant-based products by consuming them alongside foods rich in vitamin C.

The two types of iron found in food are haem (found in animal products) and non-haem (found in plants). Bioavailability refers to the amount of nutrients that we can absorb from foods in the diet for metabolic use. The iron found in the majority of plant foods isn’t always fully absorbed due to the presence and influence of other dietary constituents. These dietary cofounders that inhibit iron uptake are phytic acid, (found in cereals & legumes), oxalic acid (found predominantly in vegetables) and polyphenols (which can be found in tea, coffee and vegetables). 

Spinach contains high levels of oxalic acid, which binds with iron and blocks absorption in the gut. The oxalic acid found in spinach appears to be higher than most other green vegetables, such as kale and broccoli. The majority of iron in spinach is not usable for the body and studies have shown that as little as 2% of iron from spinach is actually absorbed by the body! Other examples of foods that inhibit iron absorption include peas, lentils and chickpeas due to the high phytic acid content. 

It is possible to reduce the oxalic acid content of spinach through cooking - boiling spinach for around 15 minutes reduces the concentration of acid. Both cooked and raw spinach have plentiful nutritional benefits, including its rich fiber, vitamin, folic acid and calcium content. Understanding which foods to eat in combination with spinach can help promote the absorption of iron. 

Calcium

Spinach contains approximately 30 mg of calcium per cup. While milk and dairy products are the richest dietary sources of calcium, dark green, leafy vegetables such as spinach and rhubarb also contain a considerable amount of the mineral. However, the importance of spinach as a source of calcium is diminished by the fact that its bioavailability is poor.

Calcium bioavailability refers to the amount of the mineral present in spinach in relation to the amount that is absorbed and utilized by the body. Although rich in calcium, spinach also contains a high amount of oxalic acid, which forms an indigestible complex with calcium, thereby reducing the bioavailability of calcium from spinach. Calcium bioavailability from spinach is very low compared to its bioavailability from dairy products and other vegetables.

Magnesium

One cup of spinach contains 24 mg of magnesium. Magnesium is necessary for energy metabolism, maintaining muscle and nerve function, regular heart rhythm, a healthy immune system, and maintaining blood pressure. Magnesium also plays a part in numerous biochemical reactions in the body.

Spinach was evaluated for its bioavailability of magnesium in the experiment with magnesium-deficient rats. The effect of oxalic acid on absorption of dietary magnesium was also examined in the same experiment. Oxalic acid remained in spinach after cooking of boil or frizzle was not deleterious to magnesium availability and spinach is one of the most promising sources of magnesium.

Diabetes Management

Spinach contains an antioxidant known as alpha-lipoic acid, believed to reduce some of the symptoms of type 2 diabetes. Alpha-lipoic acid is shown to help lower blood sugar levels, improve insulin resistance and may also help to protect against damage to the body’s cells. Studies also demonstrated that alpha-lipoic acid supplements can help with neuropathy (nerve damage) caused by diabetes.

Cancer Prevention

Spinach and other green vegetables contain chlorophyll, a pigment that gives plants their green color. Research suggests chlorophyll may have anticancer properties and that people who eat diets rich in green vegetables may have a lower incidence of developing cancer.

Studies in rodents show that chlorophyll can reduce the occurrence of cancerous tumors. It was found that chlorophyll can form close bonds to carcinogenic chemicals called aflatoxins. When they bind, the chlorophyll helps to block the absorption of the aflatoxins (cancer-causing agents) in the intestines. Chlorophyll also helps to prevent damage done to genes by harmful aflatoxins.

Chlorophyll has antioxidant properties. Some studies show that regular intake of leafy, green vegetables helps to increase antioxidants in the bloodstream. Limited studies show that chlorophyll may also decrease oxidative damage done by harmful carcinogens. So far, these studies have only been tested on animals and await human trials.

Asthma Management

Eating a diet rich in fruits and vegetables may help reduce the severity of asthma symptoms and lessen the risk of attacks. Antioxidants, such as vitamin C, vitamin E, and beta carotene, may all assist lung function, and spinach contains all three. Vitamin A content found in spinach is said to strengthen the entry points in the human body such as respiratory, intestinal tracts and mucus membranes. 

Lowering Blood Pressure

Due to its high potassium content, spinach may help reduce or manage high blood pressure. Potassium can help reduce the effects of sodium in the body. Additionally, a low potassium intake might be as potent a risk factor for developing high blood pressure as a high sodium intake.

Bone Health

Scientists have found a link between low intakes of vitamin K and a higher risk of bone fracture. Adequate vitamin K consumption is important for good health. It acts as a modifier of bone matrix proteins, improves calcium absorption, and may reduce the amount of calcium that leaves the body in urine.

Leafy, green vegetables are some of the best foods to eat when your goal is to strengthen your bones. However, spinach can actually prevent your body from effectively absorbing calcium because it contains a high amount of oxalate. Oxalate interferes with the body's ability to absorb calcium. Spinach is best eaten cooked because cooking destroys much of the Oxalate. 

Fiber in Spinach

Spinach is high in fiber and water, both of which help prevent constipation and promote a healthy digestive tract. Spinach offers a plethora of nutritional benefits, including a good amount of fiber. One cup of cooked spinach contains 4 grams of fiber. While that may not sound like much, the nutritional density of spinach is displayed when you consider that 1 cup of spinach contains only 41 calories. In comparison, a 1 cup serving of corn also contains 4 grams of fiber, but also packs a hefty 177 calories.

Healthy Skin and Hair

Spinach features large quantities of vitamin A, which moderates oil production in the skin pores and hair follicles to moisturize the skin and hair. Spinach and other leafy greens high in vitamin C are crucial for building and maintaining collagen, which provides structure to skin and hair. Additionally, iron deficiency is a common cause of hair loss, which a person can help prevent with a diet of sufficient iron-rich foods, such as spinach.

Thanks a lot.

Dr Magdy Badran