Debunking 10 nutrition myths: current evidence and understanding

Dr. Kahkasha, Deoghar

India has been celebrating the National Nutrition Week for the past forty years now. This year’s theme is – ‘Celebrate a World of Flavours’. We chose to celebrate the observance this year by addressing some common nutritional myths associated with cancer care, with the available scientific evidence.

1. Myth: Medical assisted Nutrition (MAN) is a must for palliative care patients

Evidence: MAN includes all tube based or intravenous catheter-based, mode of nutritional delivery. A Cochrane review yielded 5 prospective studies and one systematic review but no Randomised Control Trials (RCT) and showed no Quality of Life (QoL) benefit, no survival advantage, increased complications and tube related issues1. A qualitative prospective study found, HPN (Home Parenteral Nutrition) to be associated with multiple physical symptoms of nausea, vomiting, drowsiness and headache, and that HPN restricted one’s family life and social involvement2.

2. Myth: Parenteral Nutritional Support is beneficial for children undergoing chemotherapy

Evidence: There is limited evidence to suggest that whenever indicated parenteral nutrition (PN) may be beneficial in improving weight gain, serum albumin and caloric intake in well-nourished children undergoing chemotherapy when compared to enteral nutrition. The chemotherapy induced nausea, vomiting, mucositis, enterocolitis and diarrhea may be detrimental to the nutritional support and quality of life in these children. A Cochrane review further suggests that addition of novel substrates like glutamine (two RCTS) showed no benefit of glutamine in nutritional indices of children undergoing chemotherapy.3, 4

3. Myth: Home based Parenteral Nutrition is beneficial for palliative patients with Malignant Bowel Obstruction

Evidence: A 2018 meta-analysis of 13 studies and 721 pooled patients clearly seeks to prove that the benefit of Parenteral Nutrition was very low either in improving the QoL or the survival of patients with bowel obstruction5. Multiple “Choosing Wisely” groups have suggested the limited use of home based Parenteral Nutrition and strongly recommended against the use of the same.6

4. Myth: Naso-Gastric Tube (NGT) feeding is to be preferred over prophylactic Percutaneous Endoscopic Gastrostomy (PEG) in patients with Head and Neck Cancer (HNC) to undergo radiotherapy or chemoradiotherapy

Evidence: On the contrary, there is moderate evidence of PEG being superior to NGT feeding in head and neck cancer patients undergoing treatment. During the early phase i.e within six weeks of treatment, the NGT has shown to be inferior to PEG in terms of weight loss.7 Recent Meta-analysis in Clinical Nutrition ESPEN, pooled data of 298 patients (5 studies including 3 RCTs) suggest that prophylactic PEG may be better (moderate level of evidence) than reactive enteral feeding, for improved nutritional status, reducing treatment interruptions and short term QoL and disease-free-survival.8

5. Myth: Radiologically intervened percutaneous Gastrostomy is better than Endoscopic Gastrostomy

Evidence: Despite both methods reporting a high success rate, there is a slight difference in the indication and feasibility of both the techniques. Either of the methods used in endoscopic gastrostomy like pull type, push type or the introducer method, vs using USG-guided or fluoroscopic guidance for radiological gastrostomy may be safe and reliable, no RCTs were identified in the 2016 Cochrane review.9

6. Myth: Diet plans improve outcomes in cancer survivors

Evidence: Diet interventions show no difference to truly minor difference in the overall survival or risk of second malignancies. However, diet related interventions did show an increase in fruit and vegetable consumption (moderate level of evidence), dietary fiber and that the overall diet quality index do help cancer survival. Majority studies are focused on breast, colorectal and gynecological malignancies. Other malignancies have only been recently involved in ongoing trials with clear benefits are yet to be elucidated. Hence it would be wrong to generalize.10

7. Myth: Immuno-nutrition as supplement is core to cancer treatment

Evidence: Arginine, glutamine, omega 3 fatty acids [Eicosa Pentaenoic acid (EPA)] and nucleotides have been suggested to improve immune function with potential benefits seen in-vitro and some animal studies. Limited studies have shown to reduce infection related complications in critically ill patients with these immuno-nutrients.11 However, in a systematic review of HNC patients receiving immuno-nutrition perioperatively, there was no benefit in the length of stay, no effect on wound infections or mortality, with low-quality evidence established for halving of fistula forming rates which is a common surgical morbidity.12, 13, 14 In Gastrointestinal surgeries, some evidence of its advantage is seen, but largely in the Enhanced Recovery After Surgery (ERAS) era.15

8. Myth: Pharmacological interventions help improve cancer cachexia

Evidence: There has been no FDA approved medication for cancer cachexia and there is grossly inadequate evidence that any pharmacological agent improves cancer cachexia. Guidelines like the ASCO have recommended clinicians against offering any medications for the same.16, 17

InterventionType of RecommendationEvidenceBenefitsHarm
Progesterone analogsModerate in favorIntermediateModerateModerate
CorticosteroidsModerate in favorIntermediateModerateModerate
AnamorelinNo recommendation (not commercially available)IntermediateModerateLow
OlanzapineNo recommendationLowModerateLow
AndrogensNo recommendationLowModerateLow
ThalidomideNo recommendationLowLow Low
NSAIDs (Celecoxib)No recommendation Low Low Low
CyproheptadineNo recommendation LowNoneLow
CannabinoidsWeak againstLowNone Low
MelatoninModerate againstIntermediateNoneModerate
TNF inhibitors (Etanercept, Pentoxifylline, Infliximab)Moderate againstIntermediateNoneModerate
Anti-IL6 therapy (Selumetinib, Ruxolitinib)Moderate AgainstIntermediateLowModerate
Hydrazine sulfateStrong againstIntermediateNoneModerate
MirtazapineNo recommendation IntermediateNoneNone
GhrelinNo recommendationLowVery LowNone
ErythropoietinNo recommendation IntermediateNoneNone
ResiquimodPre-Clinical
MO-8503Pre-Clinical
AtorvastatinPre-Clinical
AR-42Pre-Clinical
FenofibratePre-Clinical
MetforminPre-Clinical
EtoxomirPre-Clinical
anti-PTHrPPre-Clinical

9. Myth: Vegetarianism can avoid all cancers

Evidence: Two recent UK Biobank studies have helped in clearing the conundrum about vegetarianism and the risk of cancer. Both studies which were published recently have a robust mean follow-up of 10.6-11.4 years, and they are now considered the largest databases forming evidence on the contentious area of vegetarianism and pescatarian diets. Low meat eaters (< 5times a week) had a reduced risk of colorectal cancer. Vegetarians had a lower risk of all cancers, prostate cancer and post-menopausal breast cancer. Pescatarians also showed lower risk of all cancers when compared to regular meat eaters (>5 times a week). Much of these can be attributed to low BMI of vegetarian post-menopausal women and attributed to other confounders like tobacco and alcohol. An informed conclusion to current evidence suggests that vegetarianism does reduce the risk of certain specific cancers and may have limited effect on other cancers.18, 19, 20

10. Myth: Sugar, Artificial Sweeteners cause Cancer

Evidence: There is a general fear and myth that sugar causes cancer. Although it is important to understand the effects of increased sugar consumption, absolute restriction was never warranted. The American Heart Association recommends daily 25 gm for women and up to 37 gm of sugar for men.21 Recent prospective French study of 1,01,279 participants showed that total sugar intake was a significant risk factor for development of cancer [Hazard Ratio (HR) of 1.17] and particularly breast cancer (HR 1.51). Increased sugar consumption in the form of sweet beverages and even 100% fruit juices, dairy based products, milk-based desserts also showed increased risk. It is also important to take note of the effects of artificial sweeteners on risk of cardiovascular diseases and risk of cancer. In the same study, published in BMJ, there was a significant risk of cardiovascular events noted with consumption of artificial sweeteners. The study also rebuked the benefit of substituting regular sugars with artificial sweeteners for risk reduction of cardiovascular diseases.22 Consumption of aspartame and acesulfame-K which are the commonly used artificial sweeteners have shown a significant increased risk of cancer with HR 1.15 and 1.13 respectively.23 In conclusion, the WHO recommendation of restricting free sugars to <5 % of total calorific requirement may be the safest practice.24

To conclude more evidence based nutritional recommendations should be made and followed, locally available food items should be preferred over exotic and costlier versions of the same. Let food be thy medicine!


References

  1. Good P, Richard R, Syrmis W, Jenkins‐Marsh S, Stephens J. Medically assisted nutrition for adult palliative care patients. Cochrane Database of Systematic Reviews 2014, Issue 4. Art. No.: CD006274. DOI: 10.1002/14651858.CD006274.pub3. Accessed 21 September 2022.
  2. Orrevall Y, Tishelman C, Permert J. Home parenteral nutrition: a qualitative interview study of the experiences of advanced cancer patients and their families. Clinical Nutrition 2005;24(6):961‐70.
  3. Ward EJ, Henry LM, Friend AJ, Wilkins S, Phillips RS. Nutritional support in children and young people with cancer undergoing chemotherapy. Cochrane Database of Systematic Reviews 2015, Issue 8. Art. No.: CD003298. DOI: 10.1002/14651858.CD003298.pub3. Accessed 21 September 2022.
  4. Cohen, J.E., Wakefield, C.E., Cohn, R.J., 2016. Nutritional interventions for survivors of childhood cancer. Cochrane Database of Systematic Reviews 2016.. doi:10.1002/14651858.cd009678.pub2
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  6. Choosing Wisely Accessed 21 September 2022.
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About the Author: Dr Kahkasha is the Associate Professor, Department of Biochemistry and Team palliative care, AIIMS, Deoghar.

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