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This peer-reviewed article has been accepted for publication but not yet copyedited or
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considered published and may be cited using its DOI
10.1017/S0007114520003815
The British Journal of Nutrition is published by Cambridge University Press on behalf of The
Nutrition Society
Vitamin C Improves Healing of Foot Ulcers; A Randomised, Double-Blind,
Placebo-Controlled Trial
Running Title: Vitamin C Improves Healing of Foot Ulcers
Authors
Jenny E. Gunton 1-3, Christian M. Girgis 1-2,4, Timothea Lau 1, Mauro Vicaretti 1, Lindy Begg
1, Victoria Flood 1,5,6
1 Westmead Hospital, Sydney Medical School, Faculty of Medicine and Health, The
University of Sydney, NSW. Australia
2 Centre for Diabetes, Obesity and Endocrinology Research (CDOER), The Westmead
Institute for Medical Research, The University of Sydney, NSW, Australia.
3 Garvan Institute of Medical Research, Darlinghurst. NSW. Australia.
4 Department of Endocrinology and Diabetes, Royal North Shore Hospital
5 Westmead Hospital, Research and Education Network, Western Sydney Local Health
District
6 Sydney School of Health Sciences, Faculty of Medicine and Health, The University of
Sydney
Corresponding author (lead contact):
Professor J. Gunton,
Room 2040, Clinical Sciences Corridor,
Westmead Hospital,
Westmead, NSW, 2145, Australia.
Tel: 61 2 8089 8089
Fax: 61 2 9295 8404
Email: jenny.gunton@sydney.edu.au
Word counts – abstract 240 text 3386
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Abstract
Chronic foot ulcers are associated with a high risk of osteomyelitis, poor quality of life,
amputations and disability. Few strategies improve their healing, and amputation rates in
high-risk foot services are usually over 30%.
We conducted a randomised, inactive-placebo controlled, double-blind trial of 500mg of
slow-release vitamin C in 16 people with foot ulcers conducted in the foot-wound clinic at
Westmead Hospital. Nine were randomised to control and 7 to vitamin C. When serum
vitamin C results become available at 4 weeks, all people with deficiency were offered both
vitamin C and glucosamine tablets for the next 4 weeks. Patients without baseline deficiency
continued their original assigned treatment.
The primary outcome was percent ulcer healing (reduction in ulcer size) at 8 weeks.
Fifty percent of subjects had baseline vitamin C deficiency, half having undetectable levels.
Healing at 8 weeks was significantly better in the vitamin C group (median 100% versus –
14%, p=0.041). Healing without amputation occurred in all patients in the vitamin C group.
In contrast, 44% of controls had not healed their ulcer at the end of the study period..
Vitamin C improved healing of foot ulcers. Further studies are needed to determine whether
there is a threshold effect for serum vitamin C above which therapy is ineffective and
whether there are better or lesser responding subgroups. Because of its low cost and ease of
access and administration we recommend offering vitamin C therapy to all people who have
chronic foot ulcers and potentially suboptimal vitamin C intake.
Funding: The study was funded by a Research and Education Network (REN) Grant, from
REN, Westmead Hospital.
Trial registration number: ACTRN12617001142325
Keywords; foot ulcer, vitamin c, ulcer healing, amputation, diabetes, vascular disease
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Scurvy is the clinical manifestation of severe vitamin C deficiency. Hippocrates (460 BC–
370 BC) described scurvy in the ancient Greek army in men with leg pain, and bleeding gums
with gangrene (1). It is estimated that more than 2 million sailors died of scurvy between 1500
and 1800 AD, with common final causes of death including infection, bleeding and fractures.
Lind’s treatise on scurvy in 1753 described treating 6 pairs (12 subjects) with potential
remedies. Five pairs were given treatment with vinegar, cider, elixir of vitriol, mustard and
garlic purges, or drinking 2 pints of seawater daily. These 5 treatments were ineffective. One
pair received oranges and lemons and only these 2 subjects recovered (2). Vitamin C itself was
not discovered until 1933 and Albert von Szent‐Györgyi received the 1937 Nobel prize for
this and other work.
In current times, vitamin C deficiency and scurvy are usually presumed to be rare in the
absence of famine or eating disorders. However, we reported a case series of people with
diabetes and poorly healing lower limb ulcers (3) in whom there was prompt ulcer healing
with vitamin C replacement. A report published during the period in which our study was
conducted identified a 59% rate of vitamin C deficiency in a high-risk foot ulcer clinic (4).
Foot ulceration can be defined as erosion of tissue or a breach in skin below the ankle.
Conditions that increase the risk of foot ulceration include diabetes, peripheral vascular
disease, any disease associated with sensory peripheral neuropathy, and conditions affecting
foot structure or architecture. Foot deformity, past foot ulcers and amputation are the most
significant risk factors for future ulcers (5). These ulcers are often complicated by infection,
including osteomyelitis, and/or impaired blood supply (vascular disease). Chronic foot ulcers
carry a high risk of amputation.
Vitamin C is required for collagen formation, and for proper function of the immune system
to decrease and control infections. We hypothesised that vitamin C may improve foot ulcer
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healing, and tested this with a randomised, double-blind, glucosamine-placebo-controlled
trial of vitamin C supplementation in people attending the High-Risk Foot Clinic (now called
Foot Wound Clinic) at a tertiary referral hospital.
METHODS
This was a pragmatic, investigator-initiated, randomised, double-blind, inactive-placebo-
controlled trial. No commercial support was provided for the trial, which was funded by a
grant from the Research and Education Network of Westmead Hospital. Ethics approval was
given by the Human Research Ethics Committee (HREC) of Western Sydney Local Health
District (WSLHD).
Patients
People were eligible to participate if they were adults who presented as a new patient to the
High-Risk Foot Clinic at Westmead Hospital and had a current foot ulcer. No patients
required exclusion for healing between booking their first clinic visit and attending. Other
exclusion criteria were inability to give informed consent for cognitive issues (n=3 excluded)
or language issues (0), and a decision being made at that first visit that the subject would
proceed to amputation (n=1). One additional patient was excluded because their serum
vitamin C level had been measured before clinic presentation and they were already being
treated with vitamin C supplements. Two patients declined to consent after learning that a
blood test was involved. Patient flow is detailed in the Consort Diagram (Figure 3).
After signing informed consent, subjects completed a brief dietary survey and underwent a
venipuncture for measurement of serum vitamin C. They were then randomised to vitamin C,
500 mg daily in a slow-release capsule, or the inactive comparator which was identical-
appearing glucosamine sulfate capsules (1000mg). The vitamin C was a commercial product
made by Blackmores purchased from the local pharmacy. The slow-release formulation was
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chosen because it is safer in people with renal impairment, giving lower risk of oxaluria and
also, because it isn’t flavoured / chewable as most vitamin C formulations are, it was easier to
obtain a matching appearing control. Glucosamine was a commercial product made by
BioOrganics also purchased from the local pharmacy. Neither Blackmores nor BioOrganics
had any role in the trial design, funding, analysis or preparation of this report. These
medications were delivered to the trials-pharmacy at Westmead Hospital for dispensing.
Patients were recruited from January 2018 to March 2019. Numbers of subjects were
estimated using PowerStat (Vanderbilt), α 0.05, power 0.8, assuming a 25% standard
deviation in ulcer healing and a 40% improvement in ulcer size with vitamin C. This
recommended 7 patients per group. The trial was stopped at 16 subjects.
Randomisation and treatment
Randomisation was carried out by computerised random number generation (Excel) and the
clinical trials pharmacists dispensed 4 weeks of the assigned medication. Patients were
instructed to take 1 tablet daily, and continue normal clinical attendance and all usual care as
determined by the High-Risk Foot Clinic Team. Only the clinic trials pharmacist had access
to the treatment assignment information, all other staff and patients were blinded.
At our institution, the serum vitamin C result takes approximately 4 weeks to return. The
vitamin C result was available to the treating team in the clinic from that time. When the first
28 days of medication were completed, if the patient was vitamin C deficient, they were
dispensed both vitamin C and glucosamine tablets by the clinical trials pharmacist for the
second 28 days. If the baseline serum vitamin C was normal, they continued their original
medication for a further 28 days. This was done so that all deficient people were offered
treatment with vitamin C while original treatment assignment remained blinded. As stated
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above, all other care was provided as ‘usual care’ at the clinic; there were no other study-
interventions.
Outcome measures
The primary endpoint of the study was percent ulcer healing at 8 weeks (percent reduction
compared to initial ulcer volume). Ulcer size was estimated using a silhouette 3D camera, or
if unavailable (e.g. at home visits), by measuring ulcer dimensions. Ulcers were presumed to
be ‘punched out’ at uniform depth for this purpose. If ulcers became larger, percent ulcer
healing was negative. The closest visit to 8 weeks was used for the primary endpoint. This
occurred at a median of 63 days for the glucosamine group and 55 days for the vitamin C
group. This time point was chosen based on clinic experience and data indicating that early
heal is a good predictor of final healing (20, 21) . People who underwent amputations before 8
weeks (N=2) had the ulcer size at the date of amputation used for their 8-week value for the
primary endpoint.
Complete ulcer healing was considered to have occurred when the epithelium was intact (i.e.
100% healing with no ongoing drainage). People who underwent amputations were
considered to not have healed ulcers. Secondary outcomes included time to 50% ulcer
healing, time to complete ulcer healing and rate of healing of ulcers. Data was collected for
amputation rates, which were a prespecified secondary outcome although when we planned
the study, we considered that it was not powered to assess this outcome.
Serum vitamin C measurement
The blood test request forms included instructions to wrap samples in foil and place on ice
immediately. Serum vitamin C was measured following precipitation of proteins, followed by
separation on a reverse-phase HPLC column (lab-packed LiChrosorb RP-18 (5 micron) 150 x
3.0mm) and measurement using an amperometric (BAS) electrochemical detector. Intra-
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assay CV at a vitamin C level of 45μmol/L is 6.9% and at 87μmol/L is 6.5%. The detection
limit is 5μmol/L, and the assay is linear to at least 200μmol/L. Normal range is 40-
100μmol/L. People with undetectable levels returned a result of <5μmol/L and 4μmol/L was
used for analysis.
Statistical analysis
SPSS version 21 or GraphPad Prism version 8 were used for analysis. Analysis was by
intention to treat. Where people had amputations, their ulcer was considered to not have
healed and the ulcer size prior to amputation was used. Where values were not normally
distributed (e.g. percent ulcer healing) as indicated by skewness values >1 (calculated in
SPSS), non-parametric testing was used. Two tailed p-values were used. A p-value of <0.05
was considered statistically significant.
RESULTS
Demographic and baseline characteristics of the trial subjects are shown in Table 1. Nine
people were randomised to control and 7 to vitamin C. Four subjects in each group had
known vascular disease, and 4 subjects in each group had diabetes mellitus. All subjects had
at least one of vascular disease, diabetes, neuropathy or deformed foot architecture. There
was a wide age-range, with the younger adult patients (18-44, N=3) all having long-standing
type 1 diabetes.
Baseline ulcer size was non-significantly larger in the people assigned to vitamin C, and was
not normally distributed (Figure 1A, note log-scale for y-axis). Baseline vitamin C levels
were not measured in 2 people as they did not attend the venipuncture service after
consenting to participate in the study, and being randomised (1 control, 1 vitamin C) and
having medications dispensed. They were considered to be vitamin C sufficient for intention-
to-treat purposes. Median vitamin C in the study population was 30.5 μmol/L (interquartile
range 4-52). Eight of the 16 subjects were vitamin C deficient, with 4 subjects having
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undetectable levels (Figure 1B). Four people in each treatment group had baseline deficiency.
The shaded grey box indicates the normal range.
The primary endpoint, as pre-specified in the clinical trial registry, was percent ulcer healing
at 8 weeks (percentage reduction in ulcer volume). This was significantly better in people in
the vitamin C group at median 100% compared to –14% in the glucosamine group (p=0.041,
Figure 1C, yellow-filled symbols indicate people who were deficient at baseline). Median
time to 50% ulcer healing was significantly faster in the vitamin C group at a median of 20
days compared to a median of 48 days in the 5 of 9 subjects who achieved 50% ulcer healing
in the glucosamine group (Figure 1D, p=0.028).
Kaplan-Meier analysis of 50% healing showed significantly improved results in the vitamin
C group (Figure 2A, p=0.004, deficient-at-baseline subjects have yellow symbols).
All 7 vitamin C subjects went on to complete ulcer healing at a median of 77 days (range 21
to 190 days), Figure 2B. Five of 9 subjects in the glucosamine group went on to complete
ulcer healing at a median of 77 days (range 26 to 146 days).
Serum vitamin C was positively correlated with serves of cooked vegetables eaten per day
(r=0.558, p<0.05). Unexpectedly, neither reported fruit nor fruit juice intake correlated with
vitamin C. As expected, meat, fish, nut and water consumption did not correlate with vitamin
C. Baseline ulcer size was negatively correlated with baseline serum vitamin C (r= -0.622,
p<0.05 by Spearman testing). In the whole group, ulcer size at first and second follow-up
visits also correlated negatively with vitamin C (r= -0.656, and -0.754 respectively, both
p<0.05). The relationship between follow-up ulcer size and baseline vitamin C disappeared in
the vitamin C group but strengthened in the glucosamine group (r= -0.735 (p<0.05), and -
0.927 (p<0.01), respectively).
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Discussion
Guidelines in Australia for treatment of diabetes-related foot complications are overdue for
review (11). Similar guidelines for people without diabetes are not available but overall the
European Wound Management Association (EWMA) guidelines describe wound care and the
International Working Group on the Diabetic Foot (IWGDF) guidelines describe prevention,
assessment and interventions. In general, people without diabetes are treated similarly.
Management for both groups includes pressure off-loading (removing physical pressure from
the wound) which speeds wound healing (12) and protects from further injury. For people with
no contraindications (such as impaired vascular supply or active infection), this should be in
the form of a non-removable, full-contact individualised boot or cast. Appropriate, removable
footwear should be used for people with vascular compromise or infection.
For people with impaired vascular supply, improving blood flow when possible assists
healing (11). There is some evidence that hydrogel dressings may assist in selected wounds (13).
In 2018, a multi-centre randomised controlled trial (RCT) of topical epidermal growth factor
spray showed significant benefit in diabetes-related foot ulcers (14). Ulcers in people without
diabetes were not studied.
Most other strategies have not proven beneficial (13). Many were not tested in RCTs or the
results were inconclusive. IWGDF updated their previous review in 2016, and concluded
that: “with the possible exception of negative pressure wound therapy in post-operative
wounds (15), there is little published evidence to justify the use of newer therapies. Analysis of
the evidence continues to present difficulties in this field as controlled studies remain few and
the majority continue to be of poor methodological quality (13, 16).”
Perhaps surprisingly, there are no trials showing that improved blood glucose control in
people with diabetes hastens ulcer healing (17). Since high blood glucose levels are
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detrimental to immune cell function, it is still reasonable to aim for glucose levels
< 11 mmol/L (200mg/dL). In addition, long-term better glycaemic control decreases the risks
of amputations, so this should be the aim for people with foot ulcers because they are at
increased risk of amputation (17).
The remainder of the treatment recommendations are necessarily primarily based on expert
opinion and recommend debridement, control of exudate (fluid leak from the wound) and
consideration of patient comfort and costs to guide dressing selection (18, 19). The 2019
IWGDF guidelines state on page 164 in relation to wound healing interventions, “do not use
interventions aimed at correcting the nutritional status (including supplementation of protein,
vitamin and trace elements, pharmacotherapy with agents promoting angiogenesis)”.
In the USA, there was a decrease in non-traumatic lower limb amputations in people with
diabetes between 2000 and 2009 but this worsened by 50% in the subsequent years to 2015
(6). It is of particular concern that the increases in amputation rates were greatest in young and
middle-aged adults (18–44 and 45–64 years). In 2010, the USA reported rates of amputations
in people with diabetes were ~3 times higher than Australia, per head of population (7). In
2015, there were approximately 115,000 non-traumatic lower limb amputations in the USA in
people with diabetes (6). These figures may be underestimates as minor amputations may be
performed in the outpatient setting. In Australia there are approximately 8000 lower limb
amputations yearly. Most of these are non-traumatic, below the ankle amputations, and relate
to foot ulcers (8, 9). As stated in a ‘call to action’ editorial in the Medical Journal of Australia,
this is one amputation about every 3 hours (10).
In this study, vitamin C treatment improved ulcer healing in the high-risk foot clinic subjects.
This was a pragmatic trial with few exclusion criteria; patients had to be able to give written
informed consent and not be planned for amputation on their first visit. We excluded one
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additional person who had pre-clinic testing of their vitamin C, was deficient, and was
already taking supplements (Consort diagram, Figure 3). With the intention of making the
results as widely applicable as possible, the high-risk foot clinic staff were instructed to
continue to give usual standard of care in all other regards. All investigators were blinded to
treatment assignment, so all therapeutic decisions were made according to usual care.
Most animals can synthesise vitamin C, but humans, primates, guinea pigs and bats do not
have the necessary rate-limiting enzyme. This makes study of scurvy difficult, because
animal models are expensive, ethically challenging and / or unfamiliar to most researchers.
Data shows improved wound healing in guinea pigs treated with vitamin C (22), but the
published human trial data does not answer the question of whether vitamin C is useful for
healing foot ulcers.
One randomised controlled trial studied 49 people undergoing elective surgery for tattoo
removal. They were supplemented with both vitamin C and pantothenic acid. The trial found
no differences in healing (23). However, these people had no reason to expect problems with
wound healing. The wounds were clean, electively-created surgical non-foot wounds, rather
than injury-related non-healing foot wounds which are the type seen at foot ulcer clinics.
A more relevant model to foot ulcers is pressure sores. A study of 16 people with pressure
sores tested 3 treatment groups: 1) control, 2) addition of high protein/energy supplements,
and 3) high protein/energy supplements + arginine + vitamin C + zinc supplements daily (24).
Group 3 had the fastest ulcer healing. The patient groups all had low baseline zinc levels, so
zinc supplementation has a likely benefit which is not possible to separate from vitamin C in
this study design. A second randomised controlled trial of 20 surgical patients with pressure
sores found significantly improved ulcer healing in the vitamin C group (25). In contrast, a
randomised trial of 88 nursing home residents with normal baseline nutrition did not find a
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benefit of vitamin C supplementation for pressure ulcers (26).
A review of the literature for ‘foot ulcer’, ‘randomised or randomised’ and ‘vitamin C or
ascorbate or ascorbic’ only identified 2 randomised studies of foot ulcers involving vitamin
C. One randomised Iranian study used topical kiwifruit application (27) and it reported
significantly better ulcer healing in the kiwifruit group. Their proposed mechanisms for
healing were vitamin C and actinidin, which is a proteolytic agent in kiwifruit. Baseline
vitamin C was not reported.
Ulcers in a randomised study of people with leprosy (a relevant model because of the
associated neuropathy) were treated with media conditioned with topical amniotic membrane
stem cells and supplemented with nothing, vitamin C or vitamin E. There was no control
group and all study groups showed significant healing. In both the vitamin C and E groups
there was 100% ulcer healing. The vitamin E group healed fastest (28). This suggests benefits
of vitamin C and vitamin E in people with leprosy.
The study presented here appears to be the first report of a randomised controlled trial of
vitamin C alone for treatment of foot ulcers.
Synthesis of mature collagen, a critical structural protein in skin-healing, requires vitamin C
(29) which is needed for hydroxylation of the synthesised collagen chains. Appropriate
hydroxylation is required for formation of the proper triple-helix structure of mature collagen.
In addition to the need for vitamin C for collagen formation, ascorbic acid is also needed for
normal immune function. Osteomyelitis is a common reason for amputations in people with
chronic foot ulcers. Inadequate vitamin C nutrition may therefore encourage development of
osteomyelitis in the absence of skin integrity. Many of the sailors in centuries past who died
from scurvy experienced bone fractures. It is interesting to speculate that lack of vitamin C
may further predispose people to osteomyelitis by impairing bone repair.
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This study has limitations, especially relating to the small sample size. The consistent results
across the study endpoints, biological plausibility and a recent report (4) finding similar rates
of vitamin C deficiency in a high-risk foot service increase the likelihood that these results
are correct . However, with small numbers, our study could not identify a cut-off point for
vitamin C, that is, a level above which supplementation is not beneficial. It was also not able
to identify any subgroups who benefited either more or less from supplementation. In
addition, the numbers are too few to conduct an economic analysis.
Work on vitamin C trials is unlikely to be funded by industry, due to the low cost and ready
availability of this vitamin. These additional studies will probably require larger-scale
funding from not-for-profit grant funders, such as NIH or NHMRC.
Vitamin C is cheap, and at 500mg per day of slow-release supplements, it is very safe. If
supplementation prevents only one amputation per 10 patients with chronic foot ulcers who
would otherwise eventually undergo amputation, treating all patients might prevent more than
10,000 amputations per year in the USA alone. In addition, as time to 50% ulcer healing was
significantly shorter in people receiving vitamin C, it is likely that costs of running the
service and costs to patients would be lower in people treated with vitamin C.
We recommend consideration of vitamin C supplementation, preferably with a slow-release
form, in all people attending for chronic foot ulcers who do not have exemplary dietary fruit
and vegetable intake. Ideally, given its very cheap cost to health services, and high likelihood
of favourable cost outcomes, this would be provided free to patients, to improve compliance.
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Acknowledgements
The authors declare they have no conflicts of interest.
This work was funded by the Research and Education Network of Westmead Hospital.
JEG receives funding from NHMRC Program Grant APPID 1149976 Complexity in
Nutrition.
The study was designed by JEG, CG, LB and VF. Patients were recruited by CG and TL and
vascular patients were reviewed by M.V. Data was collected from medical records by TL and
JEG. All authors assisted with manuscript preparation and review. The study was approved
by the Westmead Human Research Ethics Committee and all participants gave written,
informed consent. We would like to thank Ms Olivia Wroth and Dr Andrew Dwyer for
proofreading and helpful comments on the paper.
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REFERENCES
1. Ralli EP, Sherry S. (1941) Adult Scurvy and the Metabolism of Vitamin C. Medicine.20:251-
340
2. Lind J. Treatise of the Scurvy. Edinburgh: Sands, Murray and Cochrane for Kincaid and
Donaldson; 1753. 695-6 p.
3. Christie‐David D, Gunton J. (2017) Vitamin C deficiency and diabetes mellitus–easily missed?
Diabetic Medicine.34:294-6
4. Brookes JDL, Jaya JS, Tran H, et al. (2020) Broad-Ranging Nutritional Deficiencies Predict
Amputation in Diabetic Foot Ulcers. The International Journal of Lower Extremity Wounds.Online
ahead of print:27-33
5. Boyko EJ, Ahroni JH, Stensel V, et al. (1999) A prospective study of risk factors for diabetic
foot ulcer. The Seattle Diabetic Foot Study. Diabetes Care.22:1036-42
6. Geiss LS, Li Y, Hora I, et al. (2019) Resurgence of Diabetes-Related Nontraumatic Lower-
Extremity Amputation in the Young and Middle-Aged Adult U.S. Population. Diabetes Care.42:50
7. Carinci F, Massi Benedetti M, Klazinga NS, et al. (2016) Lower extremity amputation rates in
people with diabetes as an indicator of health systems performance. A critical appraisal of the data
collection 2000–2011 by the Organization for Economic Cooperation and Development (OECD). Acta
Diabetologica.53:825-32
8. Dillon MP, Fortington LV, Akram M, et al. (2017) Geographic Variation of the Incidence Rate
of Lower Limb Amputation in Australia from 2007-12. PloS one.12:e0170705
9. AIHW. Diabetes: Australian facts 2008. In: AIHW, editor. Foot complications. Canberra:
AIHW; 2008. p. 44-6.
10. AM B, JB A, Allard BP, et al. (2012) A limb lost every 3 hours: can Australia reduce
amputations in people with diabetes? Medical Journal of Australia.197:doi: 10.5694/mja10.10837
11. The George Institute BI, Adelaide Health Technology Assessment. Prevention, identification
and management of foot complications in diabetes: technical report. Melbourne: Baker IDI; 2011.
Downloaded from https://www.cambridge.org/core. University of Sydney Library, on 02 Nov 2020 at 23:10:20, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0007114520003815
Accepted manuscript
12. Bus SA, van Deursen RW, Armstrong DG, et al. (2016) Footwear and offloading interventions
to prevent and heal foot ulcers and reduce plantar pressure in patients with diabetes: a systematic
review. Diabetes Metab Res Rev.32 Suppl 1:99-118
13. Hinchliffe R, Valk G, Apelqvist J, et al. (2008) A systematic review of the effectiveness of
interventions to enhance the healing of chronic ulcers of the foot in diabetes.24:S119-S44
14. Park KH, Han SH, Hong JP, et al. (2018) Topical epidermal growth factor spray for the
treatment of chronic diabetic foot ulcers: A phase III multicenter, double-blind, randomized,
placebo-controlled trial. Diabetes research and clinical practice.142:335-44
15. Armstrong DG, Lavery LA. (2005) Negative pressure wound therapy after partial diabetic foot
amputation: a multicentre, randomised controlled trial. The Lancet.366:1704-10
16. Game FL, Apelqvist J, Attinger C, et al. (2016) Effectiveness of interventions to enhance
healing of chronic ulcers of the foot in diabetes: a systematic review. Diabetes Metab Res Rev.32
Suppl 1:154-68
17. Fernando ME, Seneviratne RM, Tan YM, et al. (2016) Intensive versus conventional
glycaemic control for treating diabetic foot ulcers. Cochrane Database of Systematic Reviews
18. Bergin SM, Gurr JM, Allard BP, et al. (2012) Australian Diabetes Foot Network: management
of diabetes‐related foot ulceration—a clinical update. Medical Journal of Australia.197:226-9
19. Lazzarini PA, van Netten JJ, Fitridge RA, et al. (2018) Pathway to ending avoidable
diabetes‐related amputations in Australia. Medical Journal of Australia.209:288-90
20. Sheehan P, Jones P, Caselli A, et al. (2003) Percent change in wound area of diabetic foot
ulcers over a 4-week period is a robust predictor of complete healing in a 12-week prospective trial.
Diabetes Care.26:1879-82
21. Sheehan P, Jones P, Giurini JM, et al. (2006) Percent change in wound area of diabetic foot
ulcers over a 4-week period is a robust predictor of complete healing in a 12-week prospective trial.
Plastic and reconstructive surgery.117:239s-44s
Downloaded from https://www.cambridge.org/core. University of Sydney Library, on 02 Nov 2020 at 23:10:20, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0007114520003815
Accepted manuscript
22. Krámer GM, Fillios LC, Bowler EC. (1979) Ascorbic Acid Treatment on Early Collagen
Production and Wound Healing in the Guinea Pig. Journal of Periodontology.50:189-92
23. Vaxman F, Olender S, Lambert A, et al. (1995) Effect of pantothenic acid and ascorbic acid
supplementation on human skin wound healing process. A double-blind, prospective and
randomized trial. Eur Surg Res.27:158-66
24. Desneves KJ, Todorovic BE, Cassar A, et al. (2005) Treatment with supplementary arginine,
vitamin C and zinc in patients with pressure ulcers: a randomised controlled trial. Clin Nutr.24:979-87
25. Taylor T, Rimmer S, Day B, et al. (1974) Ascorbic acid supplementation in the treatment of
pressure-sores. The Lancet.304:544-6
26. ter Riet G, Kessels AG, Knipschild PG. (1995) Randomized clinical trial of ascorbic acid in the
treatment of pressure ulcers. Journal of Clinical Epidemiology.48:1453-60
27. Mohajeri G, Safaee M, Sanei MH. (2014) Effects of topical Kiwifruit on healing of neuropathic
diabetic foot ulcer. J Res Med Sci.19:520-4
28. Prakoeswa CRS, Natallya FR, Harnindya D, et al. (2018) The efficacy of topical human
amniotic membrane-mesenchymal stem cell-conditioned medium (hAMMSC-CM) and a mixture of
topical hAMMSC-CM + vitamin C and hAMMSC-CM + vitamin E on chronic plantar ulcers in leprosy:a
randomized control trial. J Dermatolog Treat.29:835-40
29. Mandl J, Szarka A, Banhegyi G. (2009) Vitamin C: update on physiology and pharmacology.
British Journal of Pharmacology.157:1097-110
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Accepted manuscript
Table 1 Baseline characteristics of trial subjects
Data indicate mean± standard deviation or median (95% confidence interval (CI)). Excess alcohol was
considered ≥2 standard drinks per day. Those two people reported consuming ≥4 standard drinks
daily. HbA1c is reported for people with known diabetes.
Glucosamine-treated
(control)
Vitamin C-treated
Whole group
Number (N)
9
7
16
Male/female
9/0
5/2
14/2
Age (years)
57.7±13.8
63.9±22.2
60.4±17.5
Height (cm)
178 (95% CI = 5)
175 (6)
176 (5)
Weight (kg)
84 (6)
95 (11)
90 (9)
BMI (mg/m2)
26.1 (1.7)
29.9 (2.6)
26.5 (2.1)
Vascular disease
4
4
8
Diabetes (N)
4
4
8
Neuropathy (N)
4
5
9
Deformed foot (N)
2
1
3
Smoker (current/ex/never)
0/4/3
4/3/2
4/7/5
Excess alcohol
1
1
2
HbA1c (%)
9.5 (range 5.9–11.4)
9.5 (range 9.5–9.6)
9.5 (range 5.9–11.4)
eGFR <60mL/min/1.73m2
2 (44 and 58)
2 (27 and 59)
4 (range 27–59)
Baseline ulcer size (mm3)
100 (601)
180 (3890)
100 (816)
Known ulcer duration (wks)
9 (range 4–48)
9 (range 1–154)
9 (range 1–154)
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Accepted manuscript
Figure 1. Baseline ulcer and vitamin C, and healing of ulcers. A) Baseline ulcer size. Note
log-scale for y-axis. Individual values are shown. Symbols with yellow centers indicate
people with vitamin C deficiency. B) Baseline vitamin C levels. The shaded area indicates the
normal range. C) Percent healing at 8 weeks (% reduction in ulcer volume). 100% indicates
complete healing. Negative values indicate enlarged wounds compared to baseline. Symbols
with yellow centers indicate people with baseline vitamin C deficiency. D) Days from
baseline visit to 50% reduction in ulcer volume. Symbols with yellow centers indicate people
with baseline vitamin C deficiency.
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Accepted manuscript
Figure 2. Ulcer healing rates. A) Percent of people with 50% ulcer healing compared to
baseline volume (p<0.01). Yellow symbols indicate people with baseline vitamin C
deficiency B) Percent of people with completely healed ulcers. 4 subjects in the control group
did not achieve ulcer healing.
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