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Table 3 Studies of nutritional interventions involving individuals living with sickle cell disease in Africa

From: Nutritional perspectives on sickle cell disease in Africa: a systematic review

Authors and year of publication

Location

Ages

No. of subjects

Intervention

Nutrient intervention type

Design

Outcome

Comments

Afolabi et al., 2012 [85]

Lagos State and Ogun State, Nigeria

15–48 years

Not reported

Seed oils from Solenostemon monostachyus, Ipomoea involucrate and Carica papaya plants

Plant extract/ seed oil

In vitro comparisons using blood from SCD patients; comparison groups were controls, cells treated with glutathione, and cells treated with a known anti-sickling plant extract

• All plant extracts studied led to reduction in sickled red blood cells, reduction in Fe+ 2/Fe+ 3 ratios, and reduction in lactate dehydrogenase activity when compared with controls

• Individual extracts also showed varying improvements in hemoglobin concentration, sickle cell polymerization inhibition, and catalase activity

Some gender dependent differences were noted; specific bioactive compounds within each plant extract were not isolated

Imaga et al., 2013 [86]

Lagos State, Nigeria

15–28 years

4 (2 treated, 2 controls)

Oral ingestion for two weeks of a commercial product made from Cajanus cajan plant extract

Plant extract/ seed oil

Non-blinded in vitro comparison study

• Treatment group reported to have anti-sickling effect, but no statistical analyses performed

• Treatment group reported to have increased fetal hemoglobin, but no statistical analyses performed

• No effect reported on packed cell volume, hemoglobin, or mean corpuscular hemoglobin

Statistical analyses lacking for main outcomes

Kaddam et al., 2019 [87]

Khartoum, Sudan

5–42 years

47

Acacia Senegal (gum Arabic) supplementation as a lipid-lowering agent

Plant extract/ seed oil

Single-arm trial

Treatment led to significantly decreased total cholesterol, triglycerides, and low-density lipoprotein; no effect on high-density lipoprotein

Gum Arabic is a dried, gummy substance obtained from the acacia Senegal tree

Adegoke et al., 2013 [88]

Ekiti State, Nigeria

1 year to “adolescent” (upper range not specified)

125 (65 treated, 60 controls)

Oral ingestion for 6 months of freshly squeezed lime juice; dose was weight- dependent (range: 10–30 ml daily)

Micronutrient

Open label, randomized study

• Treated group had significantly fewer pain episodes, febrile illness, and admission rate

• Treated group had significantly increased mean hematocrit

• No change in transfusion rate, organomegaly, or jaundice

Effect hypothesized to result from vitamin C, amino acids (especially phenylalanine) and flavonoids

Adegoke et al., 2017 [67]

Ile-Ife, Nigeria

Mean age

7 years

170 (95 treated, 75 controls)

Oral ingestion for 3 months of vitamin D supplementation in children with SCD that had low 25-hydroxyvitamin D (25-OHD) levels

Micronutrient

Age- and gender-matched controlled study

• Children with SCD and low 25-OHD levels had enhanced levels of pro-inflammatory cytokines

• Treatment with vitamin D in children with SCD that had low 25-OHD levels led to an improved pro-inflammatory cytokine profile

Effect hypothesized to result from anti-inflammatory influence of supplemental vitamin D

Daak et al., 2013 [89]

Khartou, Sudan

2–24 years

128 (67 treated, 61 controls)

Oral ingestion for 1 year of Omega-3 capsules containing EPA and DHA fatty acids; dose was weight-dependent

Macronutrient

Double-blinded, placebo-controlled, randomized study

• Treatment group had improved primary outcome: significantly fewer clinical vaso-occlusive events

• Treatment group also had reduced severe anemia, reduced blood transfusions, reduced white blood cell counts, and reduced school absences due to disease

• No change in rates of stroke, sequestration crisis, or vascular necrosis

The study was not powered to detect changes in rates of stroke, sequestration crisis, or vascular necrosis

Cox et al., 2018 [90]

Dar-es-Salaam, Tanzania

8–12 years (mean 10 years)

119

Oral ingestion of ready-to-use supplementary food (RUSF) with and without arginine and citrulline

Macronutrient

Double-blind, random order crossover trial

• RUSF increased the global arginine bioavailability ratio and improved measures of endothelial function, and led to improvements in growth

• RUSF fortified with arginine and citrulline did not additionally increase the plasma global arginine bioavailability ratio or improve endothelial function

Arginine is the sole substrate of endothelial nitric oxide synthase and has been implicated in pathophysiology of SCD complications

Onalo et al., 2019 [91]

Abu, Nigeria

5–17 years (mean 11 years)

68 (35 treated, 33 controls)

Oral arginine therapy every 8 h until discharge in SCD patients hospitalized with severe vaso-occlusive events

Macronutrient

Double-blind, randomized, phenotype included placebo-controlled trial

• Plasma arginine levels increased by 125% (arginine arm) vs 29% (placebo arm)

• 54% of children treated with arginine were discharged compared to 24% in placebo arm by day 5

• Arginine treatment appeared to ameliorate some measures of pain

• No significant differences in adverse events but arginine arm trended more towards vomiting compared to placebo

Arginine had previously been shown to have benefits in individuals with SCD in studies performed in the Unite States