The Health Benefits of Sweet Potatoes

You have probably noticed by now that there is one starchy root vegetable that seems to sneak its way into my recipes and recommendations often. The humble sweet potato. Do not overlook this gnarly orange object as it really does have quite an impressive array of health benefits and is worthy of inclusion.

Sweet potatoes (Ipomoea batatas) are a nutrient-dense root vegetable with a long history of culinary and medicinal use. The high beta-carotene content in orange-fleshed sweet potatoes contributes significantly to their health benefits, particularly for eye health and immune support (Tanumihardjo et al., 2010). Furthermore, purple-fleshed varieties are rich in anthocyanins, known for their antioxidant properties (Zhang et al., 2015). If you can find them, the purple ones really are something special. I will always pick up a few packs if I am lucky enough to stumble across them. Amazing with some hummus. I digress.

So, let’s have a look at exactly what makes them so special, and why I am such a fan.

Glycemic Index and Blood Sugar Regulation

Despite their naturally sweet taste, sweet potatoes have a moderate glycemic index (GI), typically ranging from 44 to 94, depending on preparation methods (Atkinson et al., 2008). Boiled sweet potatoes have a lower GI (~46-61) compared to roasted or baked ones (~82-94), which makes them a preferable carbohydrate source for individuals with type 2 diabetes (Ludwig, 2002).

The presence of resistant starch and soluble fibre in sweet potatoes helps regulate postprandial glucose levels, improving insulin sensitivity (Jiang et al., 2020). Studies indicate that consuming sweet potatoes may lower HbA1c levels and reduce fasting blood glucose in diabetic individuals (Ludwig et al., 2008). They fall perfectly into my recommendation of a low glycemic high fibre carbohydrate source. Slow burning and versatile.

Antioxidant and Anti-Inflammatory Properties

This is probably the most obvious benefit. Sweet potatoes contain polyphenols, flavonoids, and carotenoids (that vivd orange colour in the orange variety), which exhibit strong antioxidant and anti-inflammatory effects (Zhang et al., 2015). The purple-fleshed varieties are particularly high in anthocyanins, which have been shown to inhibit oxidative stress and reduce markers of inflammation such as C-reactive protein (CRP) (Li et al., 2021).

Carotenoids in sweet potatoes also play a role in modulating inflammatory pathways by reducing nuclear factor kappa B (NF-κB) activation, a key regulator of inflammation in chronic diseases (Tanumihardjo et al., 2010).

Gut Health and Digestive Benefits

Sweet potatoes are an excellent source of prebiotic fibre, which nourishes beneficial gut microbiota. The resistant starch and soluble fibre content promote the growth of Bifidobacteria and Lactobacilli, beneficial bacteria associated with improved digestion and enhanced gut barrier function (Slavin, 2013).

The sweet flavour that sweet potatoes have, is given by these oligo saccharides - similar to the common dietary supplement ‘FOS’.

Studies suggest that sweet potato-derived fibre can alleviate symptoms of irritable bowel syndrome (IBS) and constipation, likely due to its effect on increasing stool bulk and reducing transit time (Eswaran et al., 2013).

Cardiovascular Health Benefits

Regular consumption of sweet potatoes has been linked to cardiovascular protection, primarily due to their high potassium content, which helps regulate blood pressure and counteracts the effects of dietary sodium (He & MacGregor, 2008). It does this by relaxing the blood vessel walls allowing the vessels to dilate, and also reducing overall plasma volume.

Carotenoids as an antioxidant group help to reduce the oxidation of cholesterol. When cholesterol oxidises it causes damage to the endothelium (blood vessel lining) and that sets the stage for heart disease. Minimising this oxidation provides vital cardiovascular benefit.

Furthermore, anthocyanins in purple sweet potatoes have been shown to reduce LDL cholesterol levels and improve endothelial function, both of which are critical factors in heart disease prevention (Zhang et al., 2015).

Immune System Support

Beta-carotene, the precursor of vitamin A, is crucial for immune function. Deficiency in vitamin A impairs T-cell differentiation, increasing susceptibility to infections (Semba, 2012). Sweet potatoes provide an abundant and bioavailable source of this essential nutrient, particularly in populations at risk of vitamin A deficiency.

Additionally, vitamin C in sweet potatoes contributes to immune defence by enhancing phagocytic activity and lymphocyte proliferation, crucial for fighting infections (Carr & Maggini, 2017).

There is also a unique storage protein fund in sweet potatoes that acts primarily as a food source for the plant as it is growing. This appears to have a unique ability to increase the numbers of white cells such as macrophages. This early stage research out of China still has a long way to go, but this benefit will be something to watch.

Cancer Prevention Potential

Research suggests that the phytochemicals in sweet potatoes may contribute to cancer prevention by inhibiting tumour growth and inducing apoptosis in cancerous cells. Anthocyanins in purple sweet potatoes have demonstrated anticarcinogenic effects, particularly in colorectal and breast cancer models (Wang et al., 2016).

Beta-carotene has been extensively studied for its role in reducing the risk of lung and skin cancers, although excessive supplementation in high-risk groups (e.g., smokers) has yielded mixed results (Tanumihardjo, 2010). Dietary intake on the other hand, appears to be a different story.

My big caveat always though - as interesting as these benefits are, no one food is a magic bullet for cancer. If only!

Cognitive and Neurological Benefits

Emerging research suggests that sweet potatoes may support cognitive function and neurological health. The high antioxidant content protects neurons from oxidative damage, potentially reducing the risk of neurodegenerative diseases such as Alzheimer’s disease (Wang et al., 2016). It is also worth bearing in mind that more and more evidence is now linking neuro-inflammation with issues such as depression too, and these antioxidant compounds will assist in reducing inflammatory load.

Animal studies indicate that anthocyanins in purple sweet potatoes can improve memory and learning abilities, though further human trials are needed (Zhang et al., 2015).

Nutritional Composition of Sweet Potatoes

A 100g serving of cooked sweet potato contains approximately:

• Energy: 86 kcal
• Carbohydrates: 20.1g (including 4.2g sugar and 3.0g dietary fibre)
• Protein: 1.6g
• Fat: 0.1g
• Vitamin A (as beta-carotene): 19,218 IU (384% of the recommended daily intake, RDI)
• Vitamin C: 2.4mg (4% RDI)
• Vitamin B6: 0.2mg (10% RDI)
• Potassium: 337mg (9% RDI)
• Manganese: 0.3mg (13% RDI)

Conclusion

So you see, there is a good reason that these brightly coloured roots always take a starring role in my books and recipes. They deliver a lot of benefit for a cheap and humble ingredient. Sweet potatoes deliver multtiple benefits, including blood sugar regulation, antioxidant and anti-inflammatory properties, gut health promotion, cardiovascular protection, immune enhancement, cancer prevention, and cognitive support. Their nutritional value and bioactive compounds make them a winner in my eyes.

References

• Atkinson, F.S., Foster-Powell, K. and Brand-Miller, J.C., 2008. International tables of glycemic index and glycemic load values. Diabetes Care, 31(12), pp.2281-2283.
• Carr, A.C. and Maggini, S., 2017. Vitamin C and immune function. Nutrients, 9(11), p.1211.
• Eswaran, S., Muir, J. and Chey, W.D., 2013. Fiber and functional gastrointestinal disorders. The American Journal of Gastroenterology, 108(5), pp.718-727.
• He, F.J. and MacGregor, G.A., 2008. Beneficial effects of potassium on human health. Physiologia Plantarum, 133(4), pp.725-735.
• Jiang, Y., Lönnerdal, B. and Kim, K., 2020. Resistant starch and diabetes management. Nutrients, 12(6), p.1774.
• Semba, R.D., 2012. The role of vitamin A and related retinoids in immune function. Nutritional Immunology, pp.47-63.
• Wang, Q., Han, Y., Zhang, X. and Tian, W., 2016. Anthocyanins from purple sweet potato protect against cancer. Molecules, 21(11), p.1436.
• Zhang, Z., Yang, R., Zhou, X. and Gao, W., 2015. Nutritional and bioactive compounds of purple sweet potato. Food Chemistry, 173, pp.1192-1200.