Home Ingredients Sweet Potato (Ipomoea batatas)
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Sweet Potato (Ipomoea batatas)

Ipomoea batatas
Evidence Level
Limited
8 Clinical Trials
6 Documented Benefits
2/5 Evidence Score

Sweet potato (Ipomoea batatas) is a starchy root; its leaves are also eaten as a cooked green. Orange-fleshed roots are rich in beta-carotene, which the body converts to vitamin A: in USDA data, 100 g of baked sweet potato supplies about 961 mcg RAE of vitamin A, 3.3 g of fiber and 475 mg of potassium. Orange-fleshed sweet potato improved a vitamin A store marker in children compared with white-fleshed sweet potato and raised vitamin A intake in community programs, but did not raise body vitamin A stores in a 60-day trial in women. In a Cochrane review, Caiapo, a white-skinned sweet potato extract, lowered HbA1c versus placebo in two pooled trials in people with type 2 diabetes; all three of its trials came from one group and were rated very low quality. A purple sweet potato beverage lowered liver enzymes versus placebo in two small trials. Baked or roasted roots had a higher glycemic index than boiled.

Studied Dose Orange-fleshed root 125 g a day, boiled and mashed (children, 53 school days), or about 600 mcg RAE a day (women, 60 days); Caiapo extract 4 g a day for 3 to 5 months; purple sweet potato beverage 2 to 3 bottles (125 mL each) a day for 8 weeks; purple leaves within a 7-day high-polyphenol diet.
Active Compound Whole sweet potato root (orange-, white- or purple-fleshed) or leaves, supplying beta-carotene (provitamin A; 12 mcg dietary beta-carotene = 1 mcg RAE), fiber, potassium and, in purple-fleshed types, acylated anthocyanins. Caiapo is a separate extract of white-skinned sweet potato.

Benefits

Vitamin A status in children eating orange-fleshed sweet potato

In a randomized trial in 180 South African children aged 5 to 10, 125 g a day of boiled, mashed orange-fleshed sweet potato on school days improved a liver vitamin A store marker compared with white-fleshed sweet potato, which has no beta-carotene. The share of children with normal status rose from 78% to 87%, a trend that was not formally tested.

Supported by Trial 1, Trial 3

Vitamin A intake in households growing orange-fleshed sweet potato

In randomized programs in rural Uganda and Mozambique that promoted growing and eating orange-fleshed sweet potato, vitamin A intake rose in young children and women compared with control areas. In Uganda, low blood retinol fell by 9.5 percentage points in children. In Bangladeshi women, 60 days of the root raised blood beta-carotene but not total body vitamin A.

Supported by Trial 2, Trial 3

Blood sugar markers with white-skinned sweet potato extract (Caiapo)

In a Cochrane review, 4 g a day of Caiapo for 3 to 5 months lowered HbA1c by about 0.3 percentage points versus placebo in two pooled trials of 122 adults with type 2 diabetes managed by diet. The review's three small trials all came from one research group and were judged very low quality. This extract is not a substitute for medical care.

Supported by Trial 4, Trial 2

Glycemic response to boiled versus baked or roasted sweet potato

In a glycemic index test of ten Jamaican sweet potato varieties in ten healthy adults, boiled sweet potato had a glycemic index of 41 to 50, while baked (82 to 94) and roasted (79 to 93) sweet potato were much higher. Cooking method mattered more than variety. This was a single-meal test, not a long-term trial.

Supported by Trial 1, Trial 3

Liver enzyme levels with a purple sweet potato beverage

In two placebo-controlled trials of a purple sweet potato beverage rich in anthocyanins, 8 weeks lowered the liver enzyme GGT in 38 Japanese men, and GGT, AST and ALT at some time points in 37 Europeans, compared with a low-anthocyanin placebo drink. Participants had mildly raised liver enzymes. The second, a pilot trial, included authors from Yakult, which supplied the beverage in a related study.

Supported by Trial 7, Trial 6

Oxidative stress markers after exercise with purple sweet potato leaves

In a crossover trial in 15 untrained young men, 7 days of a diet including purple sweet potato leaves, compared with a low-polyphenol diet, raised plasma polyphenols and antioxidant power and lowered oxidative damage markers and the inflammatory signal IL-6 after an hour of running. Heat shock protein 72 did not differ. These are blood markers, not performance.

Supported by Trial 8

Mechanism of action

1

Beta-carotene converted to vitamin A as needed

Orange flesh owes its color to beta-carotene, which the gut converts to vitamin A. NIH counts 12 mcg of dietary beta-carotene as 1 mcg RAE, and conversion falls when vitamin A stores are adequate. Plasma beta-carotene rose in women eating the root even when body vitamin A stores did not, so higher blood carotene does not by itself show better status.

2

Cooking changes how fast the starch is digested

Boiled sweet potato produced a much lower blood sugar rise than baked or roasted sweet potato of the same varieties in a glycemic index test. The study measured blood glucose responses only and did not test why cooking method mattered; within each method, variety made a smaller difference.

3

Anthocyanins absorbed from purple-fleshed roots and leaves

Purple-fleshed sweet potato is rich in acylated anthocyanins, and purple sweet potato leaves were used as a high-polyphenol food in trials. In the leaf trial, a diet with the leaves raised plasma polyphenols compared with a low-polyphenol diet. How these compounds might act on liver enzymes is not established in people; that work is mainly in cells and animals.

Clinical trials

1
Orange-fleshed vs white-fleshed sweet potato and vitamin A stores in school children: randomized trial
PubMed

Randomized controlled feeding trial: 125 g of boiled, mashed orange-fleshed sweet potato (1031 mcg RAE a day as beta-carotene) or the same amount of white-fleshed sweet potato with no beta-carotene, on 53 school days. All children were dewormed. Vitamin A stores were assessed with the modified relative dose response test. Funding is not detailed in the abstract (van Jaarsveld et al. 2005, Am J Clin Nutr)

180 primary school children aged 5 to 10 in South Africa (90 per group).

The vitamin A store marker (DR:R ratio) improved more with orange-fleshed sweet potato than control (intervention effect -0.008, 95% CI -0.015 to -0.001, P = 0.02). Children with normal vitamin A status rose from 78% to 87% in the treatment group (P = 0.096) and changed from 86% to 82% in controls; these proportions were not used to test the effect.

2
Orange sweet potato promotion in rural Uganda: randomized effectiveness study
PubMed

Randomized controlled effectiveness study of two 2-year programs (intensive and reduced) promoting household growing and eating of orange sweet potato, compared with control areas, by a HarvestPlus team at the International Food Policy Research Institute (Hotz et al. 2012, J Nutr)

Farming households in Uganda: intake measured in children aged 6 to 35 months (265) and 3 to 5 years (578) and women (573); vitamin A status measured in children aged 3 to 5 and women with low serum retinol at baseline.

Orange sweet potato intake rose in both program groups (P < 0.01) and supplied 44 to 60% of vitamin A intake at follow-up. Inadequate vitamin A intake fell by more than 30 percentage points in young children and more than 25 points in women versus control. Low serum retinol fell by 9.5 percentage points in children with complete data (396, P < 0.05); the abstract reports a status result for children only.

3
Orange-fleshed sweet potato and vitamin A pool size in Bangladeshi women: randomized trial
PubMed

Randomized controlled trial, 6 days a week for 10 weeks: boiled white-fleshed sweet potato (0 RAE), boiled orange-fleshed sweet potato (600 mcg RAE a day), fried orange-fleshed sweet potato, or white-fleshed sweet potato plus a retinyl palmitate capsule, added to home diets (Jamil et al. 2012, J Nutr)

Women with low initial vitamin A status in a resource-poor community in Bangladesh (30 per group).

Final plasma beta-carotene was higher in the orange-fleshed groups (P < 0.0001), and marginally higher with fried than boiled (P = 0.07). Plasma retinol and total body vitamin A pool size did not differ by group, including the retinyl palmitate group. The authors concluded the impact on vitamin A status appeared limited in this population.

4
Caiapo white-skinned sweet potato extract vs placebo for 12 weeks in type 2 diabetes
PubMed

Randomized, placebo-controlled multicenter trial: 4 g Caiapo (an extract of white sweet potato) or placebo once daily for 12 weeks, with oral glucose tolerance tests monthly. The abstract does not state funding or who supplied the extract (Ludvik et al. 2004, Diabetes Care)

61 adults with type 2 diabetes treated by diet alone (30 Caiapo, 31 placebo), mean age about 55.

HbA1c fell from 7.21% to 6.68% with Caiapo (P < 0.001) and was unchanged with placebo (7.04% to 7.10%). Two-hour glucose fell more with Caiapo than placebo (P < 0.001), and end-of-study cholesterol was lower than placebo (P < 0.05). Body weight fell in both groups. Triglycerides and blood pressure did not change, and no significant adverse effects were reported.

5
Caiapo extract vs placebo for 5 months: insulin sensitivity and inflammation markers
PubMed

Randomized, placebo-controlled multicenter trial: 4 g Caiapo daily or placebo for 5 months. The abstract does not state funding or who supplied the extract (Ludvik et al. 2008, Diabetes Obes Metab)

61 adults with type 2 diabetes on diet only (27 Caiapo, 34 placebo).

With Caiapo, insulin sensitivity (OGIS, P = 0.0072) and adiponectin rose, and fibrinogen, HbA1c (6.46% to 6.25%), fasting glucose and triglycerides fell compared with baseline; in the placebo group HbA1c rose from 6.25% to 6.50%. Body weight, cholesterol and the inflammation marker hs-CRP did not change. The abstract reports mainly within-group changes.

6
Purple sweet potato beverage vs placebo and liver enzymes in Japanese men: randomized trial
PubMed

Randomized, double-blind, placebo-controlled parallel trial for 8 weeks: two 125 mL bottles a day of a purple sweet potato beverage (200.3 mg anthocyanins per bottle) or a placebo drink (1.7 mg). Funding is not stated in the abstract (Suda et al. 2008, Eur J Clin Nutr)

Healthy men aged 30 to 60 in Kumamoto, Japan, with one or more liver enzymes (GGT, AST, ALT) above normal and no viral hepatitis; 38 of 48 enrolled completed.

GGT, AST and ALT showed group by time interactions (P < 0.05). GGT was lower than placebo at 2 weeks (-14.1 IU/L, P = 0.017), 6 weeks and 8 weeks (-27.9 IU/L, P = 0.014), but not significantly at 4 weeks (P = 0.081). Other measures were not affected.

7
Purple sweet potato beverage vs placebo and liver enzymes in Europeans: placebo-controlled pilot
PubMed

Double-blind, placebo-controlled pilot trial for 8 weeks: three 125 mL bottles a day of a purple sweet potato beverage (177 mg anthocyanins per bottle) or placebo (1.3 mg). Three authors were affiliated with Yakult, which supplied the beverage in this group's 2016 study (Oki et al. 2017, Eur J Clin Nutr)

40 healthy Caucasian adults aged 41 to 69 with mildly raised liver enzymes; 39 completed and 37 were analyzed.

Compared with placebo, GGT was lower on day 43 (P = 0.038; day 15 P = 0.077), AST was lower on days 29 and 43, and ALT was lower on day 43 (P = 0.037). Results were reported by time point; other blood and clinical chemistry values showed no clinically relevant changes.

8
Purple sweet potato leaves vs low-polyphenol diet and exercise oxidative stress: crossover trial
PubMed

Controlled crossover trial: 7 days of a high-polyphenol diet with purple sweet potato leaves or a low-polyphenol control diet, 14-day washout, then 1 hour of treadmill running at 70% of VO2max. Funding is not stated in the abstract (Chang et al. 2010, J Appl Physiol (1985))

15 healthy, untrained young men in Taiwan.

Compared with the control diet, the leaf diet raised plasma total polyphenols and antioxidant power (FRAP) and lowered the oxidative damage markers TBARS and protein carbonyl and plasma IL-6 around exercise. Heat shock protein 72 did not differ between diets. Exercise performance was not an outcome.

Side effects and drug interactions

Common Potential side effects

Large, regular intakes of orange-fleshed sweet potato can tint the skin yellow-orange (carotenodermia). NIH describes this as harmless and reversible, and dietary beta-carotene is not known to cause birth defects, unlike high-dose preformed vitamin A.
Sweet potato contains calcium oxalate crystals, with more in the shoots than the roots, and in a lab study of eight varieties grown under drought stress, six exceeded maximum calcium oxalate levels for raw eating. People told to limit oxalate because of kidney stones should ask a clinician how sweet potato and its leaves fit their diet.
Potassium: USDA lists about 475 mg of potassium per 100 g of baked sweet potato and about 508 mg per 100 g of raw leaves. People told by a doctor to limit potassium, for example because of kidney problems, should count them.
Baked and roasted sweet potato produced a high glycemic index (79 to 94) in a single-meal test, compared with 41 to 50 for boiled. People watching blood sugar may notice larger rises with baked or roasted forms.
In the Caiapo extract trials, a Cochrane review found no serious adverse effects; reported effects were mostly mild abdominal distension and pain. In an uncontrolled 4-week study of the purple sweet potato beverage, ALT rose over time; the placebo-controlled trials found no clinically relevant safety changes.

Important Drug interactions

Glucose-lowering medicines: the Caiapo extract was tested for lowering blood sugar in people managed by diet alone, not with diabetes drugs. Anyone taking glucose-lowering medicine should ask a doctor before adding it, since effects could add up.
Warfarin: USDA lists about 302 mcg of vitamin K per 100 g of raw sweet potato leaves, while the root has very little (about 2 mcg). People on warfarin should keep leafy green intake, including sweet potato leaves, consistent and tell their clinician about changes.
Potassium limits: if a medicine or a kidney condition requires limiting potassium, count sweet potato roots and leaves.
No drug interaction studies of sweet potato foods were found.

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Frequently asked questions about Sweet Potato (Ipomoea batatas)

Is orange sweet potato a good source of vitamin A?

Yes. NIH lists one whole baked sweet potato at about 1,403 mcg RAE, more than the adult Daily Value, all from beta-carotene. The body converts beta-carotene to vitamin A as needed, so beta-carotene from food is not known to cause vitamin A toxicity. In trials, the root improved vitamin A measures in children, but 60 days did not raise body vitamin A stores in Bangladeshi women.

Does cooking method change the blood sugar effect of sweet potato?

In a test of ten Jamaican varieties in healthy adults, boiled sweet potato had a glycemic index of 41 to 50, while baked and roasted sweet potato scored 79 to 94. So the same root can act like a low or high glycemic food depending on how it is cooked. Portion size and what it is eaten with also matter.

What is Caiapo and is it the same as eating sweet potato?

Caiapo is a concentrated extract of white-skinned sweet potato taken as 4 g a day in trials. It is not the same as eating the root, and the trial results do not transfer to sweet potato meals. A Cochrane review of three small placebo-controlled trials in people with type 2 diabetes, all from one research group, found lower HbA1c in two pooled trials but judged the trials very low quality.

Are purple sweet potatoes and sweet potato leaves different?

Purple-fleshed roots are rich in anthocyanins and purple leaves supply polyphenols, while orange roots are the beta-carotene source. A purple sweet potato beverage lowered liver enzymes versus placebo in two small trials, and the leaves lowered exercise oxidative stress markers in a 15-person trial. The leaves are also high in vitamin K.

What is Sweet Potato?

Sweet potato (Ipomoea batatas) is a starchy root; its leaves are also eaten as a cooked green. Orange-fleshed roots are rich in beta-carotene, which the body converts to vitamin A: in USDA data, 100 g of baked sweet potato supplies about 961 mcg RAE of vitamin A, 3.3 g of fiber and 475 mg of potassium.

What is Sweet Potato used for?

Sweet Potato is researched primarily for Liver Health and Antioxidant. In a randomized trial in 180 South African children aged 5 to 10, 125 g a day of boiled, mashed orange-fleshed sweet potato on school days improved a liver vitamin A store marker compared with white-fleshed sweet potato, which has no beta-c…

What is the recommended dosage of Sweet Potato?

The clinically studied dose is Orange-fleshed root 125 g a day, boiled and mashed (children, 53 school days), or about 600 mcg RAE a day (women, 60 days); Caiapo extract 4 g a day for 3 to 5 months; purple sweet potato beverage 2 to 3 bottles (125 mL each) a day for 8 weeks; purple leaves w… Always follow the product label and check with a healthcare provider for personal advice.

Is Sweet Potato safe, and does it have side effects?

Side effects and cautions reported for Sweet Potato include: Large, regular intakes of orange-fleshed sweet potato can tint the skin yellow-orange (carotenodermia). NIH describes this as harmless and reversible, and dietary beta-carotene is not known to cause birth defects, unlike high-dose preformed vitamin A. It may also interact with some medications. Sweet Potato is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Sweet Potato interact with any medications?

Possible interactions include: Glucose-lowering medicines: the Caiapo extract was tested for lowering blood sugar in people managed by diet alone, not with diabetes drugs. Anyone taking glucose-lowering medicine should ask a doctor before adding it, since effects could add up. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Sweet Potato?

NutraSmarts rates the evidence for Sweet Potato as Limited (2 out of 5). It is backed by 8 study summaries and 15 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(15 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. van Jaarsveld PJ, Faber M, Tanumihardjo SA, Nestel P, Lombard CJ, Benadé AJ. Beta-carotene-rich orange-fleshed sweet potato improves the vitamin A status of primary school children assessed with the modified-relative-dose-response test. Am J Clin Nutr. 2005;81(5):1080-7. doi: 10.1093/ajcn/81.5.1080.PubMedUsed to support: Randomized controlled trial in 180 South African children aged 5 to 10: 125 g a day of boiled, mashed orange-fleshed sweet potato (1031 mcg RAE as beta-carotene) or white-fleshed sweet potato for 53 school days. The vitamin A liver store marker (DR:R) improved more with orange-fleshed sweet potato (effect -0.008, P = 0.02); the change in children with normal status (78% to 87%, P = 0.096) was not formally tested.
  2. Hotz C, Loechl C, Lubowa A, Tumwine JK, Ndeezi G, Nandutu Masawi A, Baingana R, Carriquiry A, de Brauw A, Meenakshi JV, Gilligan DO. Introduction of β-carotene-rich orange sweet potato in rural Uganda resulted in increased vitamin A intakes among children and women and improved vitamin A status among children. J Nutr. 2012;142(10):1871-80. doi: 10.3945/jn.111.151829.PubMedUsed to support: Randomized controlled effectiveness study in rural Uganda of 2-year programs promoting orange sweet potato. Intake rose versus control, supplying 44 to 60% of vitamin A intake; inadequate vitamin A intake fell by more than 30 points in children aged 6 to 35 months and more than 25 points in women. Low serum retinol fell by 9.5 percentage points in children with complete data (n = 396, P < 0.05).
  3. Hotz C, Loechl C, de Brauw A, Eozenou P, Gilligan D, Moursi M, Munhaua B, van Jaarsveld P, Carriquiry A, Meenakshi JV. A large-scale intervention to introduce orange sweet potato in rural Mozambique increases vitamin A intakes among children and women. Br J Nutr. 2012;108(1):163-76. doi: 10.1017/S0007114511005174.PubMedUsed to support: Randomized controlled effectiveness study in rural Mozambique comparing a 1-year and a nearly 3-year program to promote orange sweet potato. With the first program model, net vitamin A intake rose by 263, 254 and 492 mcg RAE a day in younger children, older children and women, and the impact was similar with both models; orange sweet potato provided 80% of vitamin A intake in reference children. Blood vitamin A was not reported in the abstract.
  4. Jamil KM, Brown KH, Jamil M, Peerson JM, Keenan AH, Newman JW, Haskell MJ. Daily consumption of orange-fleshed sweet potato for 60 days increased plasma β-carotene concentration but did not increase total body vitamin A pool size in Bangladeshi women. J Nutr. 2012;142(10):1896-902. doi: 10.3945/jn.112.164830.PubMedUsed to support: Randomized controlled trial in Bangladeshi women with low vitamin A status (30 per group) comparing white-fleshed sweet potato, boiled or fried orange-fleshed sweet potato (600 mcg RAE a day) and a retinyl palmitate capsule for 60 days. Plasma beta-carotene rose in the orange-fleshed groups, but plasma retinol and total body vitamin A pool size did not differ by group.
  5. Ludvik B, Neuffer B, Pacini G. Efficacy of Ipomoea batatas (Caiapo) on diabetes control in type 2 diabetic subjects treated with diet. Diabetes Care. 2004;27(2):436-40. doi: 10.2337/diacare.27.2.436.PubMedUsed to support: Randomized placebo-controlled trial in 61 adults with type 2 diabetes treated by diet: 4 g a day of Caiapo (white sweet potato extract) for 12 weeks. HbA1c fell from 7.21% to 6.68% with Caiapo and was unchanged with placebo; 2-hour glucose fell more than with placebo, and final cholesterol was lower than placebo. Body weight fell in both groups. Funding and extract supplier are not stated in the abstract.
  6. Ludvik B, Hanefeld M, Pacini G. Improved metabolic control by Ipomoea batatas (Caiapo) is associated with increased adiponectin and decreased fibrinogen levels in type 2 diabetic subjects. Diabetes Obes Metab. 2008;10(7):586-92. doi: 10.1111/j.1463-1326.2007.00752.x.PubMedUsed to support: Randomized placebo-controlled trial in 61 adults with type 2 diabetes on diet only: 4 g a day of Caiapo (27) or placebo (34) for 5 months. Insulin sensitivity and adiponectin rose and fibrinogen, HbA1c, fasting glucose and triglycerides fell within the Caiapo group; HbA1c rose with placebo. Body weight, cholesterol and hs-CRP did not change.
  7. Ooi CP, Loke SC. Sweet potato for type 2 diabetes mellitus. Cochrane Database Syst Rev. 2013;2013(9):CD009128. doi: 10.1002/14651858.CD009128.pub3.PubMedUsed to support: Cochrane review of sweet potato for type 2 diabetes: three placebo-controlled trials (140 participants, 6 weeks to 5 months), all by the same trialist, with unclear or high risk of bias; the plain language summary calls all three very low quality. 4 g a day for 3 to 5 months lowered HbA1c versus placebo (mean difference -0.3%, 95% CI -0.6 to -0.04; 2 trials, 122 people). The authors concluded the evidence is insufficient. Adverse effects were mostly mild.
  8. Suda I, Ishikawa F, Hatakeyama M, Miyawaki M, Kudo T, Hirano K, Ito A, Yamakawa O, Horiuchi S. Intake of purple sweet potato beverage affects on serum hepatic biomarker levels of healthy adult men with borderline hepatitis. Eur J Clin Nutr. 2008;62(1):60-7. doi: 10.1038/sj.ejcn.1602674.PubMedUsed to support: Randomized, double-blind, placebo-controlled trial in 38 Japanese men with mildly raised liver enzymes: two bottles a day of a purple sweet potato beverage (200.3 mg anthocyanins per bottle) or a placebo drink for 8 weeks. GGT, AST and ALT showed group by time interactions; GGT was lower than placebo at 2, 6 and 8 weeks (about -28 IU/L at 8 weeks) but not significantly at 4 weeks.
  9. Oki T, Kano M, Ishikawa F, Goto K, Watanabe O, Suda I. Double-blind, placebo-controlled pilot trial of anthocyanin-rich purple sweet potato beverage on serum hepatic biomarker levels in healthy Caucasians with borderline hepatitis. Eur J Clin Nutr. 2017;71(2):290-292. doi: 10.1038/ejcn.2016.153.PubMedUsed to support: Double-blind, placebo-controlled pilot trial in 40 Caucasian adults aged 41 to 69 with mildly raised liver enzymes: three bottles a day of a purple sweet potato beverage (177 mg anthocyanins per bottle) or placebo for 8 weeks. GGT, AST and ALT were lower than placebo at some time points (day 43 for all three). Three authors were affiliated with Yakult.
  10. Oki T, Kano M, Watanabe O, Goto K, Boelsma E, Ishikawa F, Suda I. Effect of consuming a purple-fleshed sweet potato beverage on health-related biomarkers and safety parameters in Caucasian subjects with elevated levels of blood pressure and liver function biomarkers: a 4-week, open-label, non-comparative trial. Biosci Microbiota Food Health. 2016;35(3):129-36. doi: 10.12938/bmfh.2015-026.PubMedUsed to support: Open-label, single-arm (uncontrolled) 4-week study in 20 overweight Caucasian adults with raised blood pressure and liver enzymes, drinking two cartons a day of a purple sweet potato beverage (117 mg anthocyanins each). Systolic pressure was lower after 4 weeks than before (P = 0.0125) and rose again after washout; ALT rose over time. With no control group, the changes cannot be attributed to the beverage. The beverage, a commercial Japanese product obtained from Yakult Honsha, was concentrated purple sweet potato juice with enzymatically degraded starch and fiber, lemon juice and flavorings (full text read).
  11. Chang WH, Hu SP, Huang YF, Yeh TS, Liu JF. Effect of purple sweet potato leaves consumption on exercise-induced oxidative stress and IL-6 and HSP72 levels. J Appl Physiol (1985). 2010;109(6):1710-5. doi: 10.1152/japplphysiol.00205.2010.PubMedUsed to support: Controlled crossover trial in 15 untrained young men: 7 days of a high-polyphenol diet with purple sweet potato leaves or a low-polyphenol diet before 1 hour of running. Compared with control, the leaf diet raised plasma polyphenols and antioxidant power and lowered TBARS, protein carbonyl and IL-6; HSP72 did not differ.
  12. Bahado-Singh PS, Riley CK, Wheatley AO, Lowe HI. Relationship between Processing Method and the Glycemic Indices of Ten Sweet Potato (Ipomoea batatas) Cultivars Commonly Consumed in Jamaica. J Nutr Metab. 2011;2011:584832. doi: 10.1155/2011/584832.PubMedUsed to support: Glycemic index test in 10 healthy adults of ten Jamaican sweet potato cultivars cooked four ways. Boiled sweet potato had the lowest glycemic index (41 to 50) and baked (82 to 94) and roasted (79 to 93) the highest; cooking method mattered more than cultivar.
  13. Gouveia CS, Ganança JF, Lebot V, Pinheiro de Carvalho MÂ. Changes in oxalate composition and other nutritive traits in root tubers and shoots of sweet potato (Ipomoea batatas L. [Lam.]) under water stress. J Sci Food Agric. 2020;100(4):1702-1710. doi: 10.1002/jsfa.10185.PubMedUsed to support: Laboratory analysis of eight sweet potato accessions from Madeira, the Canaries and Guinea-Bissau under drought. Soluble and insoluble (calcium) oxalate were higher in shoots than tubers, and six accessions were above maximum calcium oxalate levels for raw consumption. Not a human study.
  14. U.S. Department of Agriculture, Agricultural Research Service. Sweet potato, cooked, baked in skin, flesh, without salt (FDC ID 168483, NDB 11508); Sweet potato, cooked, boiled, without skin (FDC ID 168484, NDB 11510); Sweet potato leaves, raw (FDC ID 169303, NDB 11505). FoodData Central, SR Legacy. USDA FoodData Central. 2019;Food records published April 2019; accessed 2026..SourceUsed to support: Not PubMed-indexed; official USDA food composition data (read). Per 100 g baked sweet potato: 90 kcal, fiber 3.3 g, potassium 475 mg, vitamin C 19.6 mg, vitamin A 961 mcg RAE, beta-carotene 11,509 mcg, vitamin K 2.3 mcg; a medium root is 114 g. Per 100 g boiled without skin: 76 kcal, fiber 2.5 g, potassium 230 mg, vitamin A 787 mcg RAE. Per 100 g raw leaves: 42 kcal, fiber 5.3 g, potassium 508 mg, vitamin A 189 mcg RAE, lutein plus zeaxanthin 14,720 mcg, vitamin K 302.2 mcg.
  15. National Institutes of Health, Office of Dietary Supplements. Vitamin A and Carotenoids: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. 2025;Updated March 10, 2025; accessed 2026..SourceUsed to support: Not PubMed-indexed; official NIH fact sheet (read). One mcg RAE equals 12 mcg dietary beta-carotene or 2 mcg supplemental beta-carotene. Lists one whole sweet potato baked in its skin at 1,403 mcg RAE (156% of the Daily Value). Beta-carotene is not known to be teratogenic, and the most common effect of long-term excess is carotenodermia, a harmless, reversible yellow-orange skin color.