Condition

General Cancer Care and Prevention

Cancer is a group of diseases in which cells ignore signals to stop dividing or die, multiplying unchecked and sometimes spreading. Vitamin D and omega-3 fatty acids carry the strongest evidence, rated moderate, and smaller studies found lower colorectal cancer risk with Korean ginseng and better immune measures with reishi. The ginseng and reishi findings are limited, and vitamin E and beta-carotene showed no clear benefit.

Sources: PMID 16428086

Updated 30 September 2026
How we grade
6 studies cited
General Cancer Care and Prevention protocol

Supplements studied: 13
Medicines and peptides: 1
Graded outcomes: 10
Trials: 20
People studied: 1,075,857

Evidence by supplement

Strong
Moderate
Limited
Very limited

13 supplements

Laughter

Laughter: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People
	Anxiety Symptoms Large Improvement	Improves (the measure goes down)	Large effect		128 people
	Stress Signs and Symptoms	Improves (the measure goes down)		1 study	177 people
Studies that measured stress signs and symptoms The Efficacy of Laughter Therapy on Psychological Symptoms in People With Cancer: A Systematic Review and Meta-Analysis of Randomized Controlled Studies.Psychooncology · PMID 39472305
	Depression Symptoms	Improves (the measure goes down)			304 people

Cannabis

Cannabis: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People
	Analgesic Use Small Decrease	Improves (the measure goes down)	Small effect	4 studies	1,333 people
Studies that measured analgesic use Smoked medicinal cannabis for neuropathic pain in HIV: a randomized, crossover clinical trialNeuropsychopharmacology · PMID 18688212 Nabiximols for opioid-treated cancer patients with poorly-controlled chronic pain: a randomized, placebo-controlled, graded-dose trialJ Pain · PMID 22483680 Sativex oromucosal spray as adjunctive therapy in advanced cancer patients with chronic pain unalleviated by optimized opioid therapy: two double-blind, randomized, placebo-controlled phase 3 studiesBr J Pain · PMID 28785408 and 1 more on the Cannabis page
	Pain	Improves (the measure goes down)		6 studies	1,333 people
Studies that measured pain An open-label extension study to investigate the long-term safety and tolerability of THC/CBD oromucosal spray and oromucosal THC spray in patients with terminal cancer-related pain refractory to strong opioid analgesicsJ Pain Symptom Manage · PMID 23141881 Comparison of the analgesic effects of dronabinol and smoked marijuana in daily marijuana smokersNeuropsychopharmacology · PMID 23609132 Multicenter, double-blind, randomized, placebo-controlled, parallel-group study of the efficacy, safety, and tolerability of THC:CBD extract and THC extract in patients with intractable cancer-related painJ Pain Symptom Manage · PMID 19896326 and 3 more on the Cannabis page
	Sleep Quality	Improves (the measure goes up)		4 studies	759 people
Studies that measured sleep quality Cannabinoids for adult cancer-related pain: systematic review and meta-analysisBMJ Support Palliat Care · PMID 31959586 A double-blind, randomized, placebo-controlled, parallel group study of THC/CBD spray in peripheral neuropathic pain treatmentEur J Pain · PMID 24420962 Sativex successfully treats neuropathic pain characterised by allodynia: a randomised, double-blind, placebo-controlled clinical trialPain · PMID 17997224 and 1 more on the Cannabis page
	Quality of Life	Improves (the measure goes up)		2 studies	24 people
Studies that measured quality of life The Effects of Dosage-Controlled Cannabis Capsules on Cancer-Related Cachexia and Anorexia Syndrome in Advanced Cancer Patients: Pilot StudyIntegr Cancer Ther · PMID 31595793 Comparison of orally administered cannabis extract and delta-9-tetrahydrocannabinol in treating patients with cancer-related anorexia-cachexia syndrome: a multicenter, phase III, randomized, double-blind, placebo-controlled clinical trial from the Cannabis-In-Cachexia-Study-GroupJ Clin Oncol · PMID 16849753
	Depression Symptoms	Improves (the measure goes down)		1 study	360 people
Studies that measured depression symptoms Evaluating the Suitability and Potential Efficiency of Cannabis sativa Oil for Patients with Primary Burning Mouth Syndrome: A Prospective, Open-Label, Single-Arm Pilot StudyPain Med · PMID 33123730
	Weight	Improves (the measure goes down)			24 people

Reishi

Immunity: improves
Natural Killer Cell Activity: improves
TNF-Alpha: improves

Reishi: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People
	Immunity Small Improvement	Improves (the measure goes up)	Small effect	3 studies	34 people
Studies that measured immunity Monitoring of immune responses to a herbal immuno-modulator in patients with advanced colorectal cancerInt Immunopharmacol · PMID 16428086 Safety and tolerability of Ganoderma lucidum in healthy subjects: a double-blind randomized placebo-controlled trialAm J Chin Med · PMID 17597499 Effects of ganopoly (a Ganoderma lucidum polysaccharide extract) on the immune functions in advanced-stage cancer patientsImmunol Invest · PMID 12916709
	Natural Killer Cell Activity	Improves (the measure goes up)			34 people
	TNF-Alpha	Improves (the measure goes down)			34 people

Spirulina

CD4 Lymphocytes: worsens
White Blood Cell Count: improves
CD8 Lymphocytes: improves

Spirulina: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People
	CD4 Lymphocytes Small Decrease	Worsens (the measure goes down)	Small effect		100 people
	White Blood Cell Count	Improves (the measure goes up)		1 study	100 people
Studies that measured white blood cell count The effects of Spirulina on anemia and immune function in senior citizensCell Mol Immunol · PMID 21278762
	CD8 Lymphocytes	Improves (the measure goes up)			100 people
	Complement Component 4	Improves (the measure goes up)			100 people
	Hemoglobin	Improves (the measure goes up)			100 people
	Immunoglobulin A	Improves (the measure goes up)			100 people
	Immunoglobulin G	Improves (the measure goes up)			100 people
	Immunoglobulin M	Improves (the measure goes up)			100 people
	Neutrophil Count	Improves (the measure goes up)			100 people
	Serum Platelets	Improves (the measure goes up)			100 people

Panax Ginseng (Korean Ginseng)

Colorectal Cancer Risk: improves
Overall Cancer Risk: changes; see studies
Ovarian Cancer Risk: changes; see studies

Panax Ginseng (Korean Ginseng): outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People
	Colorectal Cancer Risk Moderate Improvement	Improves (the measure goes down)	Moderate effect		3,974 people
	Overall Cancer Risk	Changes; see studies		2 studies	4,617 people
Studies that measured overall cancer risk Preventive effect of ginseng intake against various human cancers: a case-control study on 1987 pairsCancer Epidemiol Biomarkers Prev · PMID 7655337 Non-organ-specific preventive effect of long-term administration of Korean red ginseng extract on incidence of human cancersJ Med Food · PMID 20521975
	Ovarian Cancer Risk	Changes; see studies			3,974 people
	Pancreatic Cancer Risk	Changes; see studies			3,974 people

Vitamin E

All-Cause Mortality
Prostate Cancer Risk: improves
Stroke Risk: changes; see studies

Vitamin E: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People
	All-Cause Mortality No effect		NoneNo effect	2 studies	89,293 people
Studies that measured all-cause mortality Vitamin E in the primary prevention of cardiovascular disease and cancer: the Women's Health Study: a randomized controlled trialJAMA · PMID 15998891 Vitamin E supplementation and cataract: randomized controlled trialOphthalmology · PMID 14711717
	Prostate Cancer Risk	Improves (the measure goes down)		4 studies	45,074 people
Studies that measured prostate cancer risk Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT)JAMA · PMID 19066370 Prostate cancer and supplementation with alpha-tocopherol and beta-carotene: incidence and mortality in a controlled trialJ Natl Cancer Inst · PMID 9521168 Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT)JAMA · PMID 21990298 and 1 more on the Vitamin E page
	Stroke Risk	Changes; see studies		2 studies	89,293 people
Studies that measured stroke risk Effects of vitamin E on stroke: a systematic review with meta-analysis and trial sequential analysis.Stroke Vasc Neurol · PMID 33109618 Effects of vitamin E on stroke subtypes: meta-analysis of randomised controlled trials.BMJ · PMID 21051774
	Cardiovascular Disease Mortality	Improves (the measure goes down)		1 study	89,293 people
Studies that measured cardiovascular disease mortality Aspirin prevents stroke but not MI in women; vitamin E has no effect on CV disease or cancerCleve Clin J Med · PMID 16970138
	Breast Cancer Risk	Changes; see studies			89,293 people
	Cancer Mortality	Improves (the measure goes down)			49,417 people
	Colorectal Cancer Risk	Improves (the measure goes down)			89,293 people
	Esophageal Cancer Risk	Changes; see studies			9,541 people
	Heart Failure Risk	Changes; see studies			9,541 people
	Lung Cancer Risk	Changes; see studies			49,417 people
	Major Adverse Cardiac Events	Changes; see studies			9,541 people
	Melanoma Risk	Changes; see studies			9,541 people
	Risk Of Cardiovascular Disease	Improves (the measure goes down)			39,876 people

Whey Protein

Length of hospitalization
Strength: improves

Whey Protein: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People
	Length of hospitalization No effect		NoneNo effect	1 study	657 people
Studies that measured length of hospitalization Effect of Whey Protein Supplementation on Postoperative Outcomes After Gynecological Cancer Surgery: A Randomized Controlled Trial.World J Oncol · PMID 39850521
	Strength	Improves (the measure goes up)		2 studies	657 people
Studies that measured strength Effect of Whey Protein Supplementation on Perioperative Outcomes in Patients with Cancer-A Systematic Review and Meta-Analysis (PROSPERO 2020: CRD42020188666).Nutr Cancer · PMID 34961401 Whey Protein Supplementation with or without Vitamin D on Sarcopenia-Related Measures: A Systematic Review and Meta-Analysis.Adv Nutr · PMID 37196876

Beta-Carotene

Overall Cancer Risk

Beta-Carotene: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Overall Cancer Risk No benefit in 12-year Physicians' Health Study (50mg every other day) in non-smokers		NoneNo effect		50,000 people

Zinc

Dysgeusia: improves

Zinc: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Dysgeusia	Improves (the measure goes up)		2 studies	58 people
Studies that measured dysgeusia A randomized, placebo controlled trial of oral zinc for chemotherapy-related taste and smell disordersJ Pain Palliat Care Pharmacother · PMID 22764846 Efficacy of exogenous oral zinc in treatment of patients with carbonic anhydrase VI deficiencyAm J Med Sci · PMID 10616164

Senna

Constipation Signs and Symptoms: improves

Senna: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Constipation Signs and Symptoms	Improves (the measure goes down)		2 studies	91 people
Studies that measured constipation signs and symptoms Efficacy of senna versus lactulose in terminal cancer patients treated with opioidsJ Pain Symptom Manage · PMID 9436336 Safety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patientsPharmacology · PMID 8234438

S-adenosylmethionine

Liver Enzymes: changes; see studies

S-adenosylmethionine: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Liver Enzymes	Changes; see studies		1 study	50 people
Studies that measured liver enzymes S-adenosylmethionine (AdoMet) supplementation for treatment of chemotherapy-induced liver injuryAnticancer Res · PMID 14981985

Ginkgo Biloba

Overall Cancer Risk: changes; see studies
Breast Cancer Risk: worsens

Ginkgo Biloba: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People
	Overall Cancer Risk	Changes; see studies		1 study	3,069 people
Studies that measured overall cancer risk Ginkgo biloba and risk of cancer: secondary analysis of the Ginkgo Evaluation of Memory (GEM) StudyPharmacoepidemiol Drug Saf · PMID 20582906
	Breast Cancer Risk Small Detriment	Worsens (the measure goes up)	Small effect		3,069 people

Melatonin

Cancer Mortality: improves

Melatonin: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cancer Mortality	Improves (the measure goes down)		1 study	643 people

Prescription medicines and peptides studied, for context

These are not supplements. Most need a prescription, and some are research compounds with no approved use. They are listed so the supplement evidence above can be read against them.

1 medicine or peptide

Thymosin Alpha-1

Overall Survival (Adjuvant): improves
Chemotherapy Tolerance: improves

Thymosin Alpha-1: outcomes studied for General Cancer Care and Prevention
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Overall Survival (Adjuvant) Small Improvement	Improves (the measure goes up)	Small effect	6 studies	720 people
	Chemotherapy Tolerance Moderate Improvement	Improves (the measure goes up)	Moderate effect	2 studies	410 people

Key findings

Anxiety SymptomsLaughterImproves (the measure goes down)
Analgesic UseCannabisImproves (the measure goes down)
ImmunityReishiImproves (the measure goes up)

The General Cancer Care and Prevention protocol

2 primary supplements · 5 supporting supplements

Vitamin D2,000–4,000 IU daily (target 40–60 ng/mL)
Omega-3 Fatty Acids2–4 g EPA/DHA daily

See the full protocol

Studies cited

6 studies from PubMed

Kefir Is a Viable Exercise Recovery Beverage for Cancer Survivors Enrolled in a Structured Exercise ProgramMed Sci Sports Exerc · PMID 34519716
Effects of ketogenic diets on cancer-related variables: A systematic review and meta-analysis of randomised controlled trials.Nutr Bull · PMID 38923748
Oral nutritional supplementation in cancer patients: A systematic review and dose-response meta-analysis.Clin Nutr · PMID 39986175
Feasibility and preliminary efficacy of the effects of flavanoid-rich purple grape juice on the vascular health of childhood cancer survivors: a randomized, controlled crossover trialPediatr Blood Cancer · PMID 25175762
Bright light therapy has a positive effect on sleep quality in patients with cancer: A meta-analysis.Sleep Med Rev · PMID 38537515
Drinking of maté and the risk of cancers of the upper aerodigestive tract in Latin America: a case-control studyCancer Causes Control · PMID 20623173

Evidence by supplement

Prescription medicines and peptides studied, for context

Key findings

The General Cancer Care and Prevention protocol

Studies cited

Related conditions

Supplement stack for General Cancer Care and Prevention