Discover the Nutritional Benefits of Japanese Sweet Potatoes
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Nutritional Facts for Japanese Sweet Potato

Nutritional Facts for Japanese Sweet Potato
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Updated on July 31, 2025
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Japanese sweet potatoes, with their reddish-purple skin, are an alternative to the common Beauregard, garnet, and jewel sweet potato varieties. Naturally low in fat and high in nutritional value, they’re packed with health benefits.

The sweet tuber is rich in antioxidants as well as heart-healthy minerals. Plus, as part of a balanced diet, the nutrients and fiber in Japanese sweet potatoes may help you maintain your weight, balance out your mood, and boost digestive health.

About Japanese Sweet Potatoes

Also known as satsumaimo, sweet potato varieties from Japan are small to medium in size. They’re long, slender, and irregularly shaped. Their semi-rough, textured skin is garnet-colored with a distinct purplish undertone. Once cooked, their mildly sweet-flavored, soft flesh deepens to a golden, cream-colored hue with a dry, starchy texture.

Japanese sweet potatoes, also called Japanese yams, are quite similar to American yams but possess a sweeter taste and softer flesh with a lighter yellow coloring. But all varieties of sweet potatoes belong to the morning glory family, while yams are tubers related to lilies native to Africa and Asia.

All types of sweet potatoes contain ‌similar nutritional profiles‌. But depending on their color, some have a higher content of certain phenols — plant compounds that have an antioxidant effect.

 Yellow and orange sweet potatoes have a higher content of carotenoids, while purple sweet potatoes have more anthocyanins.

Calories in a Japanese Sweet Potato

There are about 115 calories in one Japanese sweet potato that’s 151 grams (g); by comparison, the same amount of white potato has about 138 calories.

Japanese sweet potatoes contain only an insignificant amount of ‌fat‌ and ‌no cholesterol‌ (which is true of all potatoes).

 Of course, if you eat your baked potato with butter or sour cream, you’ll increase the fat content. Try using herbs or spices and a dollop of yogurt to add flavor instead.

Carbs in Sweet Potatoes for Energy

Carbohydrates are important for the production of energy needed for metabolic and physical processes. Carbs help fuel your brain, nervous system, cells, and heart.

The United States Department of Agriculture (USDA) guidelines recommend that your intake of carbs be 45 to 65 percent of your daily caloric intake.

 Eating a Japanese sweet potato provides 27 g or about 9 percent of your daily value.

Beneficial Fiber Content

One Japanese sweet potato offers 4 g of dietary fiber. Fiber has many benefits, including keeping ‌your digestive system‌ healthy. Fiber is the part of food your body cannot digest. By absorbing water and adding bulk to increase the size and softness of your stool, fiber promotes regularity and helps ‌prevent constipation.

Research has also shown that getting more fiber from food can lower the risk of long-term diseases, such as cardiovascular disease, type II diabetes, obesity, and colon cancer.

USDA Dietary Guidelines recommend getting between 25 and 34 g of fiber daily, depending on your gender and age.

The high fiber‌ content and lack of fat in Japanese sweet potatoes might also help you maintain or lose weight. Fiber is filling, without adding significant calories. This feeling of fullness is ‌satiating‌, and it may help you control how much food you eat and prevent overeating.

What’s more, you might think that the ‌high-carb content‌ of Japanese sweet potatoes would cause weight gain. But a study published in 2018 found that a plant-based, high-carbohydrate, low-fat (vegan) diet was linked with weight loss and beneficial effects on body composition. The study group had overall loss of body weight and body fat after 16 weeks. Plus, there was a decrease in insulin resistance. This effect happened without adding any exercise.

Healthy Vitamins

Japanese sweet potatoes contain ‌many of the B vitamins‌ your body needs to make energy, including:

  • ‌Thiamine‌
  • ‌Riboflavin‌
  • ‌Niacin‌
  • ‌Vitamin B6‌
  • ‌Folate‌
  • ‌Pantothenic acid‌
  • ‌Biotin‌
Each Japanese sweet potato also contains two potent antioxidants: vitamins C and E. These play a major role in controlling and reducing oxidative stress (which leads to cell damage).

Essential Minerals for Heart Health

Japanese sweet potatoes are packed with healthy minerals, especially potassium, calcium, and magnesium.

 Some important nutrients in Japanese sweet potatoes may help lower your risk of cardiovascular disease. The heart-healthy DASH diet — which includes the intake of calcium, magnesium, and potassium — may result in ‌lower blood pressure.‌

Potassium

The ‌potassium‌ content in Japanese sweet potatoes helps maintain the fluid and electrolyte balance and cell integrity in your body. You also need potassium for the development and maintenance of your ‌nervous system and muscles,‌ including your heart.

By regulating the relaxation of the walls of your blood vessels, potassium helps lower or maintain your ‌blood pressure‌. Potassium manages the conduction and transmission of electrical signals in your nervous system, which protects against ‌irregular heartbeats, according to Harvard Health Publishing.

Calcium

Calcium binds fatty acids, so it can reduce the body’s absorption of fat. In theory, this could lower cardiovascular disease risk, but the research on this subject has been mixed.

 One Japanese sweet potato provides 4 percent of your daily calcium.

Magnesium

‌Magnesium‌ in Japanese sweet potatoes can help regulate blood pressure and blood sugar, as well as maintain muscle and nerve function. Your blood vessels need magnesium to relax and to ‌transport calcium and potassium‌. The combination of magnesium, calcium, and potassium contributes to lessening your chance of developing ‌high blood pressure.

Tryptophan for Mood and Sleep

Eating sweet potatoes might just help you chase away the blues. One of the important amino acids that make up the protein in Japanese sweet potatoes is a compound called ‌tryptophan‌. A medium Japanese sweet potato contains 30 milligrams (mg) of tryptophan.

Tryptophan is the precursor of both serotonin and melatonin.

 Serotonin is a brain chemical that plays a role in ‌regulating mood, sleep, appetite, and pain‌.

 Melatonin is a hormone in your body involved in sleep. Melatonin supplements are commonly used as a sleep aid.

Research has found that tryptophan supplementation can improve mood

 and sleep quality.

The Takeaway

  • Japanese sweet potatoes are rich in antioxidants and essential vitamins such as B vitamins, C, and E — potentially providing various health benefits including weight management and mood improvement.
  • Their minerals, like potassium and magnesium, support heart health by aiding in the maintenance of healthy blood pressure and vascular function.
  • Japanese sweet potatoes also contain tryptophan, which has mood-boosting and sleep-promoting effects. But more research is needed to fully understand the extent of these benefits.
  • Including this low-calorie, high-fiber variety of sweet potato in a healthy, balanced diet may help protect against chronic illnesses, though balance and moderation are crucial to maintaining overall health.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
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  8. Fiber. Harvard T.H. Chan School of Public Health. April 2022.
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  10. Dietary Guidelines for Americans 2020-2025. United States Department of Agriculture. December 2020.
  11. Kahleova H et al. A Plant-Based High-Carbohydrate, Low-Fat Diet in Overweight Individuals in a 16-Week Randomized Clinical Trial: The Role of Carbohydrates. Nutrients. September 2018.
  12. B Vitamins. MedlinePlus. September 23, 2021.
  13. Japanese Sweet Potatoes. Calorie Slism.
  14. Caruso F et al. Interaction Between Vitamins C and E When Scavenging the Superoxide Radical Shown by Hydrodynamic Voltammetry and DFT. Biophysica. June 18, 2024.
  15. Calcium. National Institutes of Health Office of Dietary Supplements. July 11, 2025.
  16. Key Minerals to Help Control Blood Pressure. Harvard Health Publishing. May 3, 2019.
  17. L-Tryptophan. National Library of Medicine: National Center for Biotechnology Information.
  18. Serotonin. Cleveland Clinic. September 11, 2024.
  19. Melatonin. Mayo Clinic. August 13, 2025.
  20. Kikuchi AM et al. A Systematic Review of the Effect of L-Tryptophan Supplementation on Mood and Emotional Functioning. Journal of Dietary Supplements. April 10, 2020.
  21. Sutanto CN et al. The Impact of Tryptophan Supplementation on Sleep Quality: A Systematic Review, Meta-Analysis, and Meta-Regression. Nutrition Reviews. May 3, 2021.
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Lynn Grieger, RDN, CDCES

Medical Reviewer

Lynn Grieger is a registered dietitian-nutritionist, certified diabetes care and education specialist, certified personal trainer, and certified health and wellness coach. She completed requirements to become a registered dietitian at Valparaiso University in 1987 and completed a dietetic internship at Ingalls Memorial Hospital in Harvey, Illinois, in 1988. 

Lynn brings her expertise in nutrition, exercise, and behavior change to her work in helping people reach their individual health and fitness goals. In addition to writing for Everyday Health, she has also written for websites and publications like Food and Health Communications, Today's Dietitian, iVillage.com, and Rodale Press. She has a passion for healthy, nutrient-dense, great-tasting food and for being outdoors as much as possible — she can often be found running or hiking, and has completed a marathon in every state.

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Gordon Kerr has worked in the health care industry for the past 15 years. He holds a diploma in Food and Nutritional Science from CSNN, Canadian School of Natural Nutrition, Vancouver. With his passion for a healthy lifestyle and the desire to help others benefit from proper nutrition and natural remedies, Gordon accepted the international position with CARICOM Regional Food and Nutrition in the Caribbean and moved to Barbados. As well as educating the under-nourished people in the region, Gordon formulated dietary plans to help manage medical conditions including chronic nutrition-related diseases, such as diabetes and hypertension. Now retired, Gord enjoys a quiet life on a small island in the Gulf Islands of B.C.

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