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Sweet potato vs Yam - Health impact and Nutrition Comparison

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Article author photo Zvart Movsisyan by Zvart Movsisyan | Last updated on November 29, 2020
Education: Medical biochemistry MD
Yam
vs
Sweet potato

Summary

Yams and sweet potatoes are entirely different vegetables. In nutritional comparison, yam is richer in fiber and has a lower glycemic index, sodium and sugar content than sweet potatoes.

There isn’t an obvious winner in mineral comparison because of the extremely high potassium and sodium levels in yam and fairly higher content of calcium and zinc in sweet potato.

Yam is also richer in most vitamins compared to sweet potato, with the exceptions of vitamin A, vitamin B2, and vitamin B5.

Both of them have anti-diabetic, antioxidant, and anti-proliferative effects. Besides, sweet potatoes contribute to good eyesight, while yams can be useful for women’s hormonal health.

Introduction

Most people have at least once seen a tuberous root vegetable named yam in US supermarkets, but oftentimes it is actually a type of sweet potato. Furthermore, there’s a chance you’ve never tasted or even seen real yam unless you bought it in specialized ethnic or international markets. So, as you can already guess from what has been said, sweet potatoes and yams are completely different vegetables, although they have some similarities and their names are sometimes used interchangeably. Let’s deal with this confusion.

Main Differences

Both sweet potato and yam are tuber vegetables.

Sweet potatoes are tapered and prolonged vegetables, covered with smooth skin, the color of which varies from beige, yellow, orange, or red to purple or brown. The flesh also varies depending on the type, from purple and orange to white. The flavor of the flesh is sweet, and the texture is moist and juicy. Sweet potatoes originated in South and Central America.

On the other hand, yams are bigger. The skin is rough and bark-like, while the flesh is white, yellow, purple or pink, starchy, dry, and less sweet. Yams originated in Asia and Africa; nowadays, they are common in the Caribbean and Central America.

There are a few reasons for the sweet potato and yam confusion. It first started in the 30s of the 20th Century, when Louisiana farmers had marketed their sweet potatoes as “yam” to differentiate them from the other types of sweet potatoes growing in other states.

According to another version, enslaved Africans in the US had called the local sweet potatoes “nyami,” which became yam, owing to the resemblance with the true yams they had known in Africa.

Nutritional Comparison

It seems essential to emphasize that sweet potatoes and yams are also different in terms of nutrition.

Yam is higher in fiber and lower in sugars, sodium, and glycemic index, while sweet potato is lower in saturated fat. Thus, in macronutrients content, yam is the winner.

Minerals

As you can easily see from the charts of comparison below, in this section, it’s a tie between these two vegetables.

Yam is significantly higher in potassium, somewhat higher in sodium, slightly higher in phosphorus, and lower in sodium.

On the other hand, sweet potato is relatively higher in calcium and slightly higher in zinc, magnesium, and iron.

Mineral Comparison

Mineral comparison score is based on the number of minerals by which one or the other food is richer. The "coverage" chart below show how much of the daily needs can be covered by 300 grams of the food
Contains more Phosphorus +17%
Contains more Potassium +142.1%
Contains less Sodium -83.6%
Contains more Copper +17.9%
Contains more Calcium +76.5%
Contains more Iron +13%
Contains more Magnesium +19%
Contains more Zinc +25%
Calcium Iron Magnesium Phosphorus Potassium Sodium Zinc Copper 6% 21% 15% 24% 72% 2% 7% 60%
Calcium Iron Magnesium Phosphorus Potassium Sodium Zinc Copper 9% 23% 18% 21% 30% 8% 9% 51%
Contains more Phosphorus +17%
Contains more Potassium +142.1%
Contains less Sodium -83.6%
Contains more Copper +17.9%
Contains more Calcium +76.5%
Contains more Iron +13%
Contains more Magnesium +19%
Contains more Zinc +25%

Vitamins

From the viewpoint of vitamins, yam wins hands down again.

Yam is greatly richer in vitamin C and reasonably higher in vitamin E, vitamin K, vitamins B1 and B6.

Sweet potato, on the other hand, is significantly higher in vitamin A, as well as vitamins B2 and B5.

Vitamin Comparison

Vitamin comparison score is based on the number of vitamins by which one or the other food is richer. The "coverage" chart below show how much of the daily needs can be covered by 300 grams of the food
Yam
6
:
Contains more Vitamin E +34.6%
Contains more Vitamin C +612.5%
Contains more Vitamin B1 +43.6%
Contains more Vitamin B6 +40.2%
Contains more Folate +109.1%
Contains more Vitamin K +27.8%
Contains more Vitamin A +10180.4%
Contains more Vitamin B2 +90.6%
Contains more Vitamin B5 +154.8%
Equal in Vitamin B3 - 0.557
Vitamin A Vitamin E Vitamin D Vitamin C Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B5 Vitamin B6 Folate Vitamin B12 Vitamin K 9% 7% 0% 57% 28% 8% 11% 19% 68% 18% 0% 6%
Vitamin A Vitamin E Vitamin D Vitamin C Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B5 Vitamin B6 Folate Vitamin B12 Vitamin K 852% 6% 0% 8% 20% 15% 11% 48% 49% 9% 0% 5%
Contains more Vitamin E +34.6%
Contains more Vitamin C +612.5%
Contains more Vitamin B1 +43.6%
Contains more Vitamin B6 +40.2%
Contains more Folate +109.1%
Contains more Vitamin K +27.8%
Contains more Vitamin A +10180.4%
Contains more Vitamin B2 +90.6%
Contains more Vitamin B5 +154.8%
Equal in Vitamin B3 - 0.557

Health Impact

Yam is higher in fiber and resistant starches, contributing to our digestive health. Fiber prevents constipation, feeds our healthy gut bacteria, and reduces the risk of colorectal cancer and inflammation. Besides, fiber helps with weight loss since it turns into a gel, filling up the stomach and keeping us full for a long time.

On the other hand, sweet potatoes help gain weight since they are a good source of complex starches, vitamins, minerals, and proteins and are easy to digest.

Sweet potato is higher in vitamin A and carotenoids, which ensure the light-detecting function of the eyes. A vitamin A deficiency may lead to xerophthalmia – pathologically dry eyes that can, in turn, lead to night blindness. Purple sweet potatoes are also beneficial to our eyesight due to special antioxidants, anthocyanins, which protect the eyes.

In vitro and in vivo studies on mice claim that anthocyanins extracted from purple sweet potatoes have slowed the growth of stomach, bladder, colon, colorectal, and breast cancer cells (1, 2, 3). These antioxidants have expressed significant anti-proliferative and anti-metastatic effects, preventing different types of cancer. Besides, studies on mice show that anthocyanins extracted from purple sweet potatoes can improve learning and memory by contributing to brain function improvement (7, 8).

It is worthy to note that both sweet potato and yam possess anti-diabetic effects. Studies demonstrate that white-skinned sweet potatoes and yams improve glucose and lipid metabolism by decreasing insulin resistance (9, 10, 11, 12).

It is worth mentioning that yams have specific compounds called saponins, such as dioscorin, diosgenin, and dioscin. One study has discovered immunomodulatory, blood pressure-lowering, and antioxidant activities of dioscorins extracted from different types of yams (4). Diocsorins can also protect airway epithelial cells from allergen destruction. According to research, diosgenin in yam contributes to improving the status of sex hormones, antioxidants, and lipids, reducing the risk of cardiovascular diseases and breast cancer in postmenopausal women (5, 6).

References

  1. https://www.ncbi.nlm.nih.gov/pubmed/23784800
  2. https://www.ncbi.nlm.nih.gov/pubmed/29749527
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609785/
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943009/
  5. https://www.ncbi.nlm.nih.gov/pubmed/11428178
  6. https://www.ncbi.nlm.nih.gov/pubmed/16093400
  7. https://www.ncbi.nlm.nih.gov/pubmed/14609130
  8. https://www.ncbi.nlm.nih.gov/pubmed/19863544
  9. https://www.ncbi.nlm.nih.gov/pubmed/10706405
  10. https://www.ncbi.nlm.nih.gov/pubmed/17645559
  11. https://www.ncbi.nlm.nih.gov/pubmed/19629697
  12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4632431/
Article author photo Zvart Movsisyan
Education: Medical biochemistry MD
Last updated: November 29, 2020

Infographic

Yam vs Sweet potato infographic
Infographic link

Comparison summary table

Pay attention to the most right column. It shows the amounts side by side, making it easier to realize the amount of difference.
Yam Sweet potato
Lower in Sugar ok
Lower in Sodium ok
Lower in glycemic index ok
Lower in Saturated Fat ok
Lower in Cholesterol Equal
Lower in price Equal
Rich in minerals Equal
Rich in vitamins Equal

All nutrients comparison - raw data values

Nutrient Yam Sweet potato Opinion
Net carbs 23.78g 17.12g Yam
Protein 1.53g 1.57g Sweet potato
Fats 0.17g 0.05g Yam
Carbs 27.88g 20.12g Yam
Calories 118kcal 86kcal Yam
Starch g 12.65g Sweet potato
Fructose g 0.7g Sweet potato
Sugar 0.5g 4.18g Yam
Fiber 4.1g 3g Yam
Calcium 17mg 30mg Sweet potato
Iron 0.54mg 0.61mg Sweet potato
Magnesium 21mg 25mg Sweet potato
Phosphorus 55mg 47mg Yam
Potassium 816mg 337mg Yam
Sodium 9mg 55mg Yam
Zinc 0.24mg 0.3mg Sweet potato
Copper 0.178mg 0.151mg Yam
Vitamin A 138IU 14187IU Sweet potato
Vitamin E 0.35mg 0.26mg Yam
Vitamin D 0IU 0IU
Vitamin D 0µg 0µg
Vitamin C 17.1mg 2.4mg Yam
Vitamin B1 0.112mg 0.078mg Yam
Vitamin B2 0.032mg 0.061mg Sweet potato
Vitamin B3 0.552mg 0.557mg Sweet potato
Vitamin B5 0.314mg 0.8mg Sweet potato
Vitamin B6 0.293mg 0.209mg Yam
Folate 23µg 11µg Yam
Vitamin B12 0µg 0µg
Vitamin K 2.3µg 1.8µg Yam
Tryptophan 0.012mg 0.031mg Sweet potato
Threonine 0.054mg 0.083mg Sweet potato
Isoleucine 0.052mg 0.055mg Sweet potato
Leucine 0.096mg 0.092mg Yam
Lysine 0.059mg 0.066mg Sweet potato
Methionine 0.021mg 0.029mg Sweet potato
Phenylalanine 0.071mg 0.089mg Sweet potato
Valine 0.062mg 0.086mg Sweet potato
Histidine 0.034mg 0.031mg Yam
Cholesterol 0mg 0mg
Trans Fat 0g 0g
Saturated Fat 0.037g 0.018g Sweet potato
Monounsaturated Fat 0.006g 0.001g Yam
Polyunsaturated fat 0.076g 0.014g Yam

Which food is preferable for your diet?

ok
ok
is better in case of low diet
Yam Sweet potato
Low Fats diet ok
Low Carbs diet ok
Low Calories diet ok
Low glycemic index diet ok

People also compare

Vitamin and Mineral Summary Scores

The summary score is calculated by summing up the daily values contained in 300 grams of the product. Obviously the more the food fulfills human daily needs, the more the summary score is.
Vitamin Summary Score
19
Yam
85
Sweet potato
Mineral Summary Score
25
Yam
21
Sweet potato

Macronutrients Comparison

Macronutrient comparison charts compare the amount of protein, total fats, and total carbohydrates in 300 grams of the food. The displayed values show how much of the daily needs can be covered by 300 grams of food.
Protein
9%
Yam
9%
Sweet potato
Carbohydrates
28%
Yam
20%
Sweet potato
Fats
1%
Yam
0%
Sweet potato

Comparison summary

Which food is lower in Sugar?
Yam
Yam is lower in Sugar (difference - 3.68g)
Which food contains less Sodium?
Yam
Yam contains less Sodium (difference - 46mg)
Which food is lower in glycemic index?
Yam
Yam is lower in glycemic index (difference - 19)
Which food is lower in Saturated Fat?
Sweet potato
Sweet potato is lower in Saturated Fat (difference - 0.019g)
Which food contains less Cholesterol?
?
The foods are relatively equal in Cholesterol (0 mg)
Which food is cheaper?
?
The foods are relatively equal in price ($0.2)
Which food is richer in minerals?
?
It cannot be stated which food is richer in vitamins. See the charts below for detailed information. See the charts below for detailed information. See the charts below for detailed information.
Which food is richer in vitamins?
?
It cannot be stated which food is richer in vitamins. See the charts below for detailed information. See the charts below for detailed information. See the charts below for detailed information.

References

The source of all the nutrient values on the page (excluding the main article the sources for which are presented separately if present) is the USDA's FoodCentral. The exact links to the foods presented on this page can be found below.

  1. Yam - https://fdc.nal.usda.gov/fdc-app.html#/food-details/170071/nutrients
  2. Sweet potato - https://fdc.nal.usda.gov/fdc-app.html#/food-details/168482/nutrients

All the Daily Values are presented for males aged 31-50, for 2000 calorie diets.

Data provided by FoodStruct.com should be considered and used as information only. Please consult your physician before beginning any diet.