Potatoes: What Are The Nutrients & Health Benefits

Article by Jenn Khoo, BSC

From roasted potatoes to fries and mash, which all play significant roles in the British’s diet, it simply shows the importance of humble potatoes in the country. Potatoes are the fourth most important crop in the world, coming after rice, wheat and maize.[1] They are eaten as a staple food all around the world due to their great nutritive values and affordability. Though potatoes can be easily accessed and incorporated in almost any dish, many still shy away from this wonderful root vegetable due to its label of being high in starch. However, potatoes are in fact much more than that and are a rich source of various nutrients such as dietary fibre, Vitamin C, B6 and potassium.

Types of potatoes:

There are over 500 types of potatoes grown around the world but only a few are commonly seen in supermarkets with amazing names such as Charlotte, Maris Piper and King Edward potatoes. They can be categorised into 2 main types- waxy and floury. Each type has their own distinctive qualities and are used for different dishes.[2] Waxy potatoes are known to contain less starch (16-18% starch) and are moister. Charlotte is one of the waxy varieties, which is great for steaming or boiling. On the other hand, Maris Piper and King Edward are floury potatoes which contain higher starch content (20-22%) and are more suitable for baking and mashing as they fluff well, but not boiling as they tend to fall apart.

Nutrients in potatoes:

Macronutrients are nutrients that are required in large quantities as sources of energy, namely carbohydrates, fat, protein and dietary fibre.

Carbohydrates:

Potatoes are high in starch, which is a type of complex carbohydrate made up of long chains of sugar molecules which are later broken down into glucose in the body for energy. These starchy potatoes are a good source of energy but they should be eaten in moderation as they fall in the high glycaemic index (GI) category. Glycaemic index is a rating system which reflects how quick a carbohydrate food breaks down in the body and increases one’s blood glucose level. Hence being a high GI food means that the consumption of potatoes could result in the spike in your blood glucose level. However, this does not mean that potatoes should be avoided. GI can be lowered by cooking potatoes with fat via condiments such as olive oil, or protein as this could slow the absorption of carbohydrates, hence slows the spike in blood glucose level.[3]

Besides the digestible starch which cause sugar spike, potatoes are also high in resistant starch. Resistant starch, also known as unavailable carbohydrate, acts as prebiotic which ferments in the large intestine and feed the good bacteria in the gut.[4] Resistant starch can also help to lower the blood sugar spike.[5] Research has found that resistant starch in potatoes can be better retained by baking and microwaving than boiling.[6]

Dietary Fibre:

Potato with skin is a good source of fibre, particularly insoluble fibre.[7] It contributes significantly to total fibre intake at 12% on average for UK adults.[8]As the name suggests, insoluble fibre is an indigestible carbohydrate that helps to pass solids more easily as it increases the stool weight by adding physical bulk.[9] The flesh of potatoes can also contain soluble fibre, which dissolves in the body but cannot be digested. Soluble fibre helps to slow the absorption of glucose, hence helps to control blood glucose levels.[10]

Protein and Fat:

Potatoes are low in fat and protein. They are often perceived to be associated with weight gain but in fact, fat content in potatoes when it is cooked on its own is only about 0.1% of its fresh weight. Fat content in potatoes only becomes concerning if they are processed heedlessly. For example, the fat content increases from 0.1g per 100g to about 15g when potatoes are made into chips.[11]

Vitamins and minerals:

Potato is a rich source of vitamin C, vitamin B6 and potassium.

• Vitamin C: Potatoes account for ¼ of the vitamin C intake of British people. Different processing and cooking methods can influence the vitamin C content in potatoes. Greatest vitamin C loss occurs with boiling (50%), followed by baking and roasting and least losses in frying. Frying can enhance the retention of vitamin C and this is hence crisps contain a large amount of vitamin C. As vitamin C cannot be synthesised or stored in the human body, we can only obtain vitamin C from a varied and balanced diet. Thus potatoes would be a great addition to your meals as a medium-sized potato (200g) would contribute to 48% of the RNI* for vitamin C.[12]

• Vitamin B6: Vitamin B6, also known as pyridoxine, plays a role in protein and carbohydrate metabolism and also cognitive development.[13] Potatoes are one of the richest sources for vitamin B6. According to the U.S. Food and Drug Administration (FDA), one cup of boiled potatoes provides 0.4 mg of vitamin B6 per serving[14] which is equivalent to about one-third of the RNI* for vitamin B6.[15]

• Potassium: Potatoes contribute to 15% of the daily potassium intake of the UK adults. Potassium is essential for the regulation of fluid balance, muscle contractions and nerve signals in our body.

*RNI: Reference Nutrient Intake is the amount of a nutrient which is enough for at least 97% of the population[16]

How to incorporate potatoes into your meals:

Potatoes are such a versatile ingredient that can be incorporated in almost any dish and every cuisine. As long as potatoes are prepared without adding too much salt or saturated fat, one medium-sized potato can be eaten a day as part of a healthy diet. Study has found that daily intake of non-fried potato is associated with a better diet quality compared to refined grains like white rice or pasta.[17]

Some of the recipes that we love and you may want to give a go include; potato pea curry, vegan moussaka and a veggie roast.

Things to look out for

Storage and spoilage:

• Store potatoes in a cool and dry area but not in the fridge as storing in the fridge can increase the amount of sugar they contain and increase the amount of a chemical compound known as acrylamide[18]

• Green colouration on the skin of potatoes is a useful indicator that there is an increase in the level of a toxin known as glycoalkaloid

• Having bitter flavour is the best indication that tubers are unsafe to eat[19]

Others:

• Potatoes do not count towards your 5 A Day[20]· ESFA has recommended that peeling, boiling and frying can reduce glycoalkaloid content in potatoes.[21]

This blog post was written by Jenn Khoo who is currently a final year Nutrition (BSc) student at King’s College London and is particularly interested in gut health and mental health. Jenn also loves experimenting on food and creating healthy recipes, which she occasionally posts on Instagram @khoojiayi_. She strongly believes that food can bring people together but also bring health to people and thereby wishes to create a space where people can enjoy nutritious food together.

References:

1. http://www.bbc.com/travel/story/20200302-the-true-origins-of-the-humble-potato

2) https://www.greatbritishchefs.com/features/potato-variety-guide

3) https://www.nhs.uk/common-health-questions/food-and-diet/what-is-the-glycaemic-index-gi/

4) https://hopkinsdiabetesinfo.org/what-is-resistant-starch/

5) https://onlinelibrary.wiley.com/doi/abs/10.1111/nbu.12244

6) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7023081/

7) https://www.nutrition.org.uk/nutritionscience/nutrients-food-and-ingredients/carbohydrate.html?start=2

8) https://www.nutrition.org.uk/attachments/708_PotatoResourceforHP.pdf

9) https://www.diabetes.co.uk/nutrition/insoluble-fibre.html

10) https://www.diabetes.co.uk/nutrition/soluble-fibre.html

11) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6267054