Spud lovers rejoice! Once the mascot of the anti-carbs brigade, blamed for everything from weight gain to Alzheimer’s, potatoes are being allowed off the nutritional naughty step.
Scientists from Montefiore Medical Center in New York have investigated starchy carbohydrates – rice, bread and potatoes – to get to the bottom of widespread carb confusion. Amid concern that consumers are lumping all starchy carbs in the same basket in the belief they’re similarly unhealthy, researchers analysed the impact this has had on the nutritiousness of their diets.
By analysing typical American meals, they found that opting for rice or bread instead of potatoes could deprive people of key nutrients. In fact, researchers discovered that choosing potatoes over bread and rice twice a day could boost potassium intake by 21 per cent, vitamin B6 by 17 per cent, vitamin C by 11 per cent and fibre by 10 per cent.
The potential benefits of this are significant. For example, eating more fibre – few of us consume enough – is known to reduce the risk of serious conditions such as heart disease, Type 2 diabetes and bowel cancer.
“The humble potato has been given a bad rap,” says Dr Duane Mellor, a senior teaching fellow at Aston Medical School in Birmingham. White potatoes have been an affordable staple for hundreds of years, yet in recent times they’ve fallen out of favour amid the trend for low-carb diets and earned a reputation for being unhealthy. “The truth is that potatoes contain a lot of vitamins and other nutrients that are important for good health,” Dr Mellor says.
They’re particularly good sources of vitamin C, vitamin B6 and potassium, as well as a less talk-about nutrient called choline, which Dr Mellor says is vital for a healthy brain, nerves and muscles and especially important for pregnant women.
For genetic reasons, some of us don’t make as much choline as others, so it’s important to eat foods rich in the compound. Potatoes contain the second highest levels of choline after protein-rich foods such as meat and soya. “A jacket potato contains around 10 per cent of a person’s daily choline requirements,” Dr Mellor says.
Spuds also contain fibre, including the type known as resistant starch, which is formed when they’re cooked and then allowed to cool. Resistant starch can’t be digested in the small intestine, so it passes into the large intestine, where it ferments and produces compounds called short-chain fatty acids. These feed the gut bacteria known for having a wide range of health benefits, and also help lower our blood fat and blood sugar levels.
So, if potatoes are so good for us, why don’t they count towards our five-a-day? “In the UK, we don’t count potatoes as vegetables,” says Dr Mellor. Instead, they’re categorised as a starch. In contrast, they count as vegetables in Australia, where dietary guidelines recommend seven-a-day (five vegetables plus two fruit).
“This leaves space for potatoes alongside other vegetables, allowing for plenty of variety,” says Dr Mellor. In the US, potatoes are classed as starchy vegetables, and it’s recommended that while adults should consume two to three cups of vegetables a day, starchy vegetables should be limited to four to six cups per week.
Of course, the latest US research doesn’t give the green light to binge on crisps; the extent to which spuds are good for us largely depends on how they’re cooked. Given the British penchant for chips, we’re not exactly making the most of their nutritional potential. “Frying potatoes as either crisps or chips can increase their calorie content as well as their fat content by around 300 per cent,” Dr Mellor says.
Both the skin and the flesh of potatoes are good for us, which is why eating both is the healthiest way. “The skin is a great source of fibre, whereas most of the vitamins and minerals are found in the flesh,” Dr Mellor says. Overcooking potatoes (or storing them for a long time ) can lead to loss of vitamin C. “And chopping or dicing potatoes up small and boiling them in water can mean that they leach or lose minerals to the water, especially potassium,” he says.
The healthiest way to cook potatoes is to boil or bake them in their skins, says registered nutritionist Kerry Torrens, but there are pros and cons to both. “Boiled ones lose some of their potassium content in the cooking water and baked ones have a higher GI (glycaemic index).”
This refers to how quickly food affects your blood sugar level as spikes in blood sugar over the long term can potentially cause inflammation and metabolic disorders. If Torrens had to choose the best way to eat potatoes, it would be boiled in their skins and left to cool, in order to benefit from the resistant starch. “As long as you don’t coat the cooled potatoes in mayo, this way of eating them is good news for your waistline, blood sugar levels and gut health,” she says.
Is there any truth in the widely held belief that eating potatoes causes weight gain? It’s not altogether true, at least not according to some studies. In 2016, scientists at the University of Copenhagen in Denmark found no “convincing evidence” to link obesity, Type 2 diabetes and cardiovascular disease with mashed, boiled or baked potatoes.
Unsurprisingly, they did find that French fries “may be associated” with an increased risk of obesity and Type 2 diabetes, but added that further research would be needed.
Some research even suggests that eating potatoes can help with weight management. A study published last year in the Journal of Medicinal Food found that boiled potatoes are more filling than other starchy foods such as bread and rice and may actually be helpful in maintaining a healthy weight.
The bottom line is that potatoes contain nutrients that are good for us, and they can be enjoyed as part of a healthy diet. But remember to eat lots of other vegetables, too. “It’s always best to have a variety of plant-based foods, including starch rich foods such as potatoes, sweet potatoes, rice, pasta and cereals,” Dr Mellor says.
References:
New York starchy carbs study: ncbi.nlm.nih.gov
Reference values for recommended intake in the UK: nutrition.org.uk
Copenhagen study on potatoes and risk of obesity: pubmed.ncbi.nlm.nih.gov
Potatoes and weight loss: pbrc.edu
Nutrients in oven-cooked French fries: fdc.nal.usda.gov
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