Top of the charts for popularity, Registered Nutritionist, Kerry Torrens explores why this family favourite deserves more of the health headlines.
What are potatoes?
A member of the nightshade family that includes tomatoes and aubergines, potatoes (solanum tuberosum) are the underground energy store (tuber) of the plant. There is a huge variety of different types of potatoes, but from a culinary perspective, they’re typically divided into ‘floury’, ‘waxy’ and ‘new’.
Floury potatoes, like Maris Piper, are packed with a type of starch called amylose. These starch granules swell and burst open when cooked to create a soft, fluffy texture, making these potatoes ideal for soft, creamy mash. Waxy potatoes, such as Charlotte, contain less amylose – this gives the cooked potatoes a firmer texture, ideal for roasting and gratins. New potatoes, on the other hand, are immature potatoes that are picked early in the season; they retain their structure when cooked, making them perfect for potato salads.
A medium portion (175g) of boiled potatoes (flesh and skin) provides:
- 119kcal / 509kJ
- 3.1g protein
- 0.2g fat
- 26.1g carbohydrate
- 1.9g sugar
- 3.1g fibre
- 12mg vitamin C
How you prepare and cook potatoes will impact their nutritional value. Cooking potatoes whole in their skins retains fibre and some important nutrients like potassium, magnesium, zinc and iron. Levels of vitamins C and B6 reduce during cooking, whereas carotenoids and some plant compounds called polyphenols increase. Roasting, frying or cooking in cream, such as in a classic dauphinoise, will significantly increase the fat and calorie count of the potato dish.
Regular potatoes do not count towards your five-a-day contribution, because we tend to include them on our plate as a starchy carb to replace foods like pasta or rice. They are also often associated with high-fat diets. Find out more about what counts as one of your five-a-day with our handy infographic.
Top 5 health benefits of potatoes
1. Nutritional value for money
Potatoes offer a more favourable nutrient-to-price ratio than many other vegetables, and are an important staple across the world. In the UK diet, they make a useful contribution towards our vitamin C, potassium, vitamin B6, folate and fibre intake. Given a growing global population, potatoes are a good choice because they provide food quickly on less land.
2. Low in fat
Many people including health professionals take a negative view of potatoes, but it’s worth remembering that when boiled or baked, potatoes are virtually fat-free. Tubers are rich in starch, but contribute fewer calories than the equivalent portion of pasta or rice. What’s more, unlike pasta and rice, they contribute useful micronutrients, such as vitamin C, folate and potassium.
Potatoes are low in protein, but the protein they do contribute is of excellent biological value – this means it provides a good spread of the amino acids needed for health.
3. Supports gut health
As well as being a good source of fibre, some of the starch in potatoes is particularly beneficial for our gut microbes. This is because it is ‘resistant starch’, meaning it’s resistant to our digestion but can be broken down by our gut bacteria, providing them with the fuel they need to function and thrive.
When we cook and cool potatoes, the starch granules lock together, making them more resistant to digestion. Studies suggest that when we include foods rich in resistant starch, we experience a host of health benefits, including more efficient digestion, less risk of some chronic diseases and a reduced risk of colon cancer.
4. May support blood sugar management
Being rich in resistant starch, potatoes may benefit blood sugar control and help manage appetite. Animal studies have linked resistant starch from potatoes with better insulin sensitivity, lower fat accumulation and less weight gain. A study looking at the effects of 30 grams of resistant starch each day over a four week period showed this appears to be replicated in healthy humans. It’s worth remembering that you can increase the resistant starch content of potatoes by boiling, cooling and storing them in the fridge before eating.
Potatoes are also a useful source of a type of fibre called pectin, which helps slow stomach emptying, keeps you fuller for longer and helps lower the blood sugar effects of a meal.
5. Source of protective antioxidants
Potatoes are a useful source of plant compounds that have a protective antioxidant effect. The flesh of the potato is a source of carotenoids including lutein and zeaxanthin, which are beneficial for the eye. Potatoes are also a source of polyphenols, including chlorogenic acid, and flavonoids, the predominant of which are catechin and epicatechin.
Are potatoes safe for everyone?
Potatoes are generally recognised as safe for most people. However, in rare circumstances some individuals may be allergic to both raw and cooked potato. If you have a potato allergy, you may also be allergic to other members of the solanaceae family, including tomatoes, bell peppers and aubergines.
Potatoes contain compounds called glycoalkaloids, which includes solanine. These compounds are toxic when eaten in large quantities. When preparing potatoes, look out for patches of green visible on the skin – this indicates higher levels of glycoalkaloids. Remove these parts of the potato before cooking. Store potatoes in a cool, dark place to avoid the accumulation of glycoalkaloids.
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Kerry Torrens is a registered nutritionist (MBANT) with a postgraduate diploma in personalised nutrition and nutritional therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications, including BBC Good Food.
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