Vitamin C (Ascorbic Acid)

Vitamin C (Ascorbic Acid): Overview

Alternative Names: Ascorbic Acid.

Vitamin C use has been an alternative therapy for many years.  Many doctors do not hesitate to recommend doses of 1 to 5gm or more per day.  The Third National Health and Nutrition Survey, also called NHANES III, showed that 11% of nonsmoking women and 21% of nonsmoking men in the United States do not get enough vitamin C.
One of the most talked about vitamins in recent decades, vitamin C activity was first identified hundreds of years ago for it's ability to prevent and treat scurvy.  There are few conditions for which Vitamin C has not been promoted for, and in many cases had some effect.  Essentially, ascorbic acid is the main water soluble anti-oxidant of the body.  It is considered a vitamin in man because we cannot synthesize it.  There are thousands of articles and hundreds of books describing the benefits of supplementation with ascorbic acid.

In contrast with the findings from epidemiologic studies based on foods, observational studies of nutrients consumed in supplements and recent experimental trials provide little support for a strong protective role for vitamins C or E against cancer.  If vitamins C or E are indeed protective against cancer, that protection may derive from their consumption in complex mixtures with other nutrients and with other bioactive compounds as found in the matrix provided by whole foods.

One of the main objections to mega-dose vitamin C use has been the possibility of developing kidney stones from elevated oxalic acid levels in the urine.  This myth has been slow to die.  It turns out that elevated levels of oxalic acid seen in some urine samples of people taking vitamin C were misleading.  The particular testing method used could not distinguish between oxalic acid and vitamin C, thus giving a false positive reading for oxalic acid.  More accurate testing methods have shown there are no oxalic acid elevations in vitamin C users.

Urinary oxalate excretion generally does not increase significantly for both normal subjects and stone-formers with ascorbic acid supplementation unless doses exceed 6gm daily; however, oxalate excretion even at those high doses is still usually in the range achievable by dietary influences alone.  The exceptions derive from anecdotal reports of a small number of cases and from one poorly controlled trial with unstated methodology and questionable assay techniques (Piesse JW.  Nutritional factors in calcium-containing kidney stones with particular emphasis on vitamin C.) [Int Clin Nutr Rev 5(3): pp.110-29, 1985] A study did not find a correlation between a high daily intake of vitamin C or vitamin B6 and the risk of stone formation, even when consumed in large doses.  [J Urol, 1996 Jun, 155:6, pp.1847-51]

Source

Most ascorbic acid is synthesized by the oxidation of l-sorbose (usually derived from corn).  High quality ascorbic acid will be 99% pure and contain no residues of corn.  To get the maximum effect of ascorbic acid supplements, one should combine them with plant flavonoids.  Flavonoids, the so-called vitamin P, have been shown to increase the effectiveness of ascorbic acid as well as direct its usage to the areas most needed.

The best sources of vitamin C are fruits and vegetables.  Citrus fruits such as oranges, grapefruit, and tangerines are excellent sources.  Other good natural sources of vitamin C are: broccoli, cabbage, brussels sprouts, tomatoes, green peppers, melons, cantaloupe, kiwifruit, strawberries, sweet peppers, potatoes with skin, and alfalfa sprouts.

Here are some guidelines for eating fruits and vegetables with a high vitamin C content: Choose fresh or frozen fruits and vegetables over canned products; cook vegetables only for a short time in a small amount of water; eat raw vegetables; eat sliced fruits and vegetables shortly after they're cut; keep fruits and vegetables refrigerated, and eat them while they're fresh.

Acerola is a small cherry-like fruit of the small shrub Malpighia glabra.  As one of the richest natural sources of vitamin C, fruits have between 1-4.5% vitamin C.  The dried extraction (usually about 10:1) of the fruit juice may have between 10-18% Vitamin C content, although many of the products on the market above 10% are adulterated with commercial asorbic acid.  Acerola also contains such other vitamins as vitamin A, thiamin, riboflavin and niacin in similar proportions as other fruits.

Why it is Recommended

It is not known for sure if mega doses of antioxidants, such as vitamin C, can help decrease the risk for chronic diseases.  Much of the current information is conflicting.  More research is needed.  In a review of recent studies, it was suggested that an intake of 90mg per day provides the optimal health benefits related to heart disease and cancer.

Instructions

High oral doses of vitamin C have been used safely for decades.  If the amount you are using causes diarrhea, the dosage needs to be reduced.  However, in some conditions, in order for vitamin C to be effective it has to be used in doses that come very close to causing diarrhea.  Unless this "bowel tolerance" dose is found and maintained, the condition for which the vitamin C was recommended may not resolve.  If you are consuming doses of vitamin C greater than perhaps 500mg per day, do not stop its use abruptly.  It is best to taper your dose down over several days.  A sudden reduction may result in a temporary deficit ("rebound scurvy") and a negative influence on your resistance to infection.

The RDA for vitamin C is 75mg for women and 90mg men.  The RDA for pregnant women is 85mg; women who breastfeed should consume 120mg per day.  Several groups are recommending that 120-200mg should be considered the recommended daily intake.

Side-Effects; Counter-Indicators and Warnings

Consuming more than 2,000mg per day of vitamin C can cause stomach upset and diarrhea and possibly other adverse effects.

Caution must be advised regarding any use of vitamin C in cases of renal failure or dialysis.

Vitamin C (Ascorbic Acid)

Information On This Page

Vitamin C (Ascorbic Acid) can help with the following:

Addictions

Vitamin C (Ascorbic Acid) may help with Cigarette Smoke DamageCigarette Smoke Damage
Smokers are advised to consume an extra 35mg daily because smoking depletes the body of some vitamin C.

Aging

Vitamin C (Ascorbic Acid) often helps with Parkinsons DiseaseParkinson's Disease
Supplementation with vitamin C and E markedly slows the progression of the disease in its early stages.

Parkinson's disease patients given large doses of oral vitamin C and synthetic vitamin E supplements (3000mg and 3200 IU daily respectively) delayed the progression of their disease to the point where they needed l-dopa 2.5 years later than a group of patients who were not taking supplements.  Later research has shown that synthetic vitamin E in itself does not retard the progression of Parkinson's disease.  Thus it is likely that it was vitamin C by itself or its combination with vitamin E that was the active component in Dr. Fahn's experiment.  This fits with a later finding that vitamin E, a fat-soluble vitamin, does not readily cross the blood-brain barrier nor does it accumulate in the cerebrospinal fluid that bathes the brain.  Vitamin C, on the other hand, while not crossing the blood-brain barrier does enter the cerebrospinal fluid and can be found there in concentrations proportional to dietary intake.  Inasmuch as vitamin C is a highly effective antioxidant and is particularly adept in quenching hydroxyl radicals (the main culprits in the dopamine-cell destruction), it is becoming increasingly clear that this vitamin may be an excellent protector against Parkinson's disease and can materially help in slowing down the progression of the disease.

Allergy

Autoimmune

Vitamin C (Ascorbic Acid) often helps with VitiligoVitiligo
See the links between Vitiligo and Vitamin B12, and between Vitiligo and Copper.
Vitamin C (Ascorbic Acid) may help with Ulcerative ColitisUlcerative Colitis
Vitamin C (unless it causes colon irritation) may be supportive.

Circulation

Vitamin C (Ascorbic Acid) is highly recommended for Coronary Disease / Heart AttackCoronary Disease / Heart Attack
Supplemental vitamin C can help heal injured arteries when used with L-lysine and proline for plaque prevention and possibly removal.  A typical prescription would be 3-6gm vitamin C, 3-6gm lysine and 0.5-2gm proline.  Furthermore, vitamin C deficiency (as indicated by low plasma ascorbate concentration) is a known risk factor for coronary heart disease.

One year of supplementation with vitamin C (500mg bid) and vitamin E (400 IU bid) retarded the early progression of
transplant-associated coronary arteriosclerosis in a study of 40 patients up to 2 years after cardiac transplantation.  [Lancet 2002;359(9312): pp.1108-13]

Vitamin C treatment has a possible role in benefiting patients with coronary heart disease by countering the adverse effects of a high-fat meal.  Researchers found that postprandial serum triglyceride concentration increased significantly at 2-5 hours after a high-fat meal in all groups.  The postprandial flow-mediated dilatation was significantly aggravated in people not taking vitamin C (both with and without heart disease), but this parameter in patients and subjects taking vitamin C showed no significant change.  [Clin Cardiol 2002;25: pp.219-224]
Vitamin C (Ascorbic Acid) is highly recommended for Poor/Slow Wound HealingPoor/Slow Wound Healing
Vitamin C is crucial for the proper function of the enzyme protocollagen hydroxylase which produces collagen, the primary constituent of the granulation tissue that heals a wound and the key component in blood vessel walls.  A published review stated that vitamin C plays a variety of roles in the prevention and treatment of cancer, including stimulating the immune system and enhancing wound healing [Head 1998].  Wound healing requires more vitamin C than diet alone can easily provide.  It must be replenished daily because it is water-soluble; any excess is excreted rather than stored.

In a topical solution, vitamin C has shown to be very effective in encouraging healing of the cornea in the wounded eye [Gonul et al.  2001].
Vitamin C (Ascorbic Acid) is highly recommended for Nutritional Deficiency AnemiaNutritional Deficiency Anemia
Vitamin C enhances the absorption of iron.
Vitamin C (Ascorbic Acid) often helps with Iron Deficiency AnemiaIron Deficiency Anemia
It has been well established that better iron absorption occurs from both plant and animal sources when vitamin C is taken at the same time, whether from foods or as a supplement.  75mg of vitamin C in a meal will cause about a six-fold increase in the absorption of heme iron.  It appears that vitamin C enhances non-heme iron absorption in individuals with low iron status, but does not increase iron status unnecessarily in iron-replete individuals.  [Effect of ascorbic acid on iron absorption from different types of meals.  Hum Nutr: Appl Nutr,1986 40A: pp.97-113]
Vitamin C (Ascorbic Acid) often helps with Carotid Artery DiseaseCarotid Artery Disease
Vitamin C protects artery linings by making them more resistant to the kind of injury that permits plaque formation.
Vitamin C (Ascorbic Acid) often helps with AtherosclerosisAtherosclerosis
Dosage: 1,000mg tid.
Vitamin C (Ascorbic Acid) may help with Hypertension (High Blood Pressure)Hypertension (High Blood Pressure)
A 1999 study found that in systolic and diastolic hypertension as well as elevated pulse rate, blood plasma vitamin C levels were reduced.
Vitamin C (Ascorbic Acid) may help with Bruising SusceptibilityBruising Susceptibility
Easy bruising is a symptom of low vitamin C levels, as seen in scurvy.  While very few people actually have scurvy, even minor deficiencies of vitamin C can increase bruising.

Digestion

Vitamin C (Ascorbic Acid) often helps with Atrophic GastritisAtrophic Gastritis
There may be a localized deficiency of Vitamin C in atrophic gastritis.  Recent evidence suggests that beta-carotene and/or vitamin C along with vitamin E may reverse or reduce the risk of atrophic gastritis and/or gastric cancer.  Another study showed vitamin C levels to be low in atrophic gastritis and Helicobacter Pylori infection.

Environment / Toxicity

Vitamin C (Ascorbic Acid) is highly recommended for Copper ToxicityCopper Toxicity
See link between copper toxicity and manganese.
Vitamin C (Ascorbic Acid) may help with Heavy Metal ToxicityHeavy Metal Toxicity
Helps to protect us from heavy metals, particularly lead and arsenic which can poison certain enzyme reactions in the body.
Vitamin C (Ascorbic Acid) may help with Tendency To Sunburn EasilyTendency To Sunburn Easily
Vitamins C and E, both anti-oxidants, help reduce the damage due to free radicals produced through exposure to UV light.  Taking a combination of vitamins C and E has been shown to reduce the sunburn reaction, which might in turn indicate a reduced risk for later consequences of UV-induced skin damage.  [J Am Acad Dermatol, 38(1): pp.45-8 1998 January]
Vitamin C (Ascorbic Acid) may help with Fluoride ToxicityFluoride Toxicity
See link between Fluorosis and Calcium.

Hormones

Vitamin C (Ascorbic Acid) often helps with Histapenia (Histamine Low)Histapenia (Histamine Low)
Zinc and manganese with vitamin C remove copper from the tissues.  Copper destroys histamine and therefore as copper levels decrease, histamine levels should return towards normal.
Vitamin C (Ascorbic Acid) may help with Low Adrenal Function / Adrenal InsufficiencyLow Adrenal Function / Adrenal Insufficiency
Taking 1-3gm of mineral ascorbates up to 3 times daily is supportive of adrenal gland function.

Immunity

Infections

Vitamin C (Ascorbic Acid) often helps with Urinary Tract Infection (UTI)Urinary Tract Infection (UTI)
The urine pH is often elevated in times of bacterial infection but can be lowered by some medications or unbuffered vitamin C.  This produces a less favorable growth environment for some bacteria.
Vitamin C (Ascorbic Acid) often helps with Helicobacter Pylori InfectionHelicobacter Pylori Infection
A study showed vitamin C levels to be low in atrophic gastritis and Helicobacter Pylori infection.
Vitamin C (Ascorbic Acid) may help with Yeast / Candida InfectionYeast / Candida Infection
One Osteopath (DO) is known to use intravenous vitamin C followed by intravenous flagyl with good results for candidal overgrowth.
Vitamin C (Ascorbic Acid) may help with Cold Or FluCold Or Flu
Many studies have been done to determine the effect vitamin C has on the common cold.  Review of these studies shows that even larger doses of vitamin C, such as 500-1,000mg per day, have no significant effect on preventing colds.  These doses may, however, reduce the duration and severity of a cold for some people.  This may be because at high doses, vitamin C may act like an antihistamine.
Vitamin C (Ascorbic Acid) may help with Herpes Simplex Type IHerpes Simplex Type I
Vitamin C, zinc, thymus extracts, TMG, monolaurin from coconut, and olive leaf extract have all been used with some success as reported by various doctors.

Inflammation

Vitamin C (Ascorbic Acid) may help with LaryngitisLaryngitis
Vitamin C is both antibacterial and anti-inflammatory.  Dissolve 1 teaspoon of buffered vitamin-C powder in 8 ounces of water and sip this throughout the day.  Do this for the first forty-eight hours.

Mental

Vitamin C (Ascorbic Acid) often helps with Poor MemoryPoor Memory
Vitamin C is a powerful antioxidant which inhibits free-radical damage of cells and improves circulation, both of which are necessary for mental activity.  Use vitamin C, with bioflavonoids, at 1,000mg daily.

Metabolic

Vitamin C (Ascorbic Acid) may help with Syndrome X / Metabolic SyndromeSyndrome X / Metabolic Syndrome
Vitamin C is a powerful antioxidant that protects against infection and boosts the immune system.  It also helps maintain normal insulin function and may decrease bad cholesterol levels.
Not recommended for:
Vitamin C (Ascorbic Acid) is often not recommended for Hemochromatosis (Iron overload)Hemochromatosis (Iron overload)
One study has indicated that excessive vitamin C intake may be a contributing factor in hemochromatosis.  Vitamin C increases intestinal iron absorption while at the same time it seems to have an effect in decreasing copper.  This copper decreasing effect could be the direct result of increasing iron absorption or it could be an independent effect.  [Int J Vitam Nutr Res 1999 Mar; 69(2): pp.67-82]

As a result, some suggest that one doesn't take vitamin C supplements at all, while others recommend limiting vitamin C supplementation to 500mg per day.  Eating natural (unfortified and unprocessed) foods which contain vitamin C is fine.

Musculo-Skeletal

Vitamin C (Ascorbic Acid) may help with Ochronosis / AlkaptonuriaOchronosis / Alkaptonuria
Some physicians prescribe high doses of ascorbic acid to prevent the interaction of the ochronotic pigment with the tissues.  Unfortunately, the progress of the disease is not interrupted by this treatment.

Nutrients

Organ Health

Vitamin C (Ascorbic Acid) is highly recommended for Gallbladder DiseaseGallbladder Disease
Sixteen patients with gallstones who were scheduled for surgery received 500mg of Vitamin C four times per day for two weeks prior to surgery.  Another sixteen patients who had their gallbladders removed did not receive Vitamin C (the control group).  During surgery, bile was taken from the gallbladder of each patient.  Vitamin C treatment resulted in a significant increase in the concentration of phospholipids in bile (phospholipids such as lecithin have been shown to prevent stone formation).  More importantly, it took seven days for the bile from Vitamin C-treated patients to form cholesterol crystals (the first step in stone formation), compared with just two days in the control group.  [Eur J Clin Invest 1997;27: pp.387-391]

Vitamin C also could help dissolve gallstones, although that probably would require several years of continuous treatment, combined with a strict diet.  It is noteworthy that birth-control pills have been shown both to reduce blood levels of Vitamin C and to increase the risk of gallstones.
Vitamin C (Ascorbic Acid) is highly recommended for Diabetes Type IIDiabetes Type II
Dr. Fred Klenner, MD has used large amounts of Vitamin C for many ailments, and says that diabetics are so deficient they should be considered as having scurvy.  10gm per day, according to Dr. Klenner, cures many diabetics and enhances their well being in other cases.
Vitamin C (Ascorbic Acid) often helps with HepatitisHepatitis
Vitamin C (1,000 to 1,500mg per day), beta-carotene (100,000 IU per day), vitamin E (400 to 800 IU per day), and zinc (30 to 50mg per day) strengthen your immune system.
Not recommended for:
Vitamin C (Ascorbic Acid) is NOT recommended for Chronic Renal InsufficiencyChronic Renal Insufficiency
The authors of the following study believe it shows that vitamin C supplementation leads to a significant increase in serum oxalate levels in dialysis patients.  In renal insufficiency, vitamin C levels were elevated, but not oxalate levels.  Caution is advised with regard to vitamin C and renal insufficiency.

"Relationship Between the Serum Concentration of Oxalic Acid and Ascorbic Acid in Chronic Renal Insufficiency", Gerold, M., et al, Nieren-Und Hochdruckkrankheiten, May 1992;21(Suppl.  1): pp.58-61.  (Address: Dr. G.  Stein, Erlanger Allee 101, O-6902 Jena-Lobeda, Germany)

Reproductive

Vitamin C (Ascorbic Acid) often helps with Pregnancy-Related IssuesPregnancy-Related Issues
Several studies imply that harmful free radicals called lipid peroxides contribute to preeclampsia [Khan KS, Chien Pl.  Brit J of Obst & Gyn 1997;104(10): pp.1173-9], and that women with this condition are low in the antioxidants that combat them.  [Ziari SA, et al.  Am Jl of Perinat 1996;13(5): pp.287-91]

In one study of over 300 consecutive births, the mothers were given 5gm of vitamin C in the first trimester, 10gm in the second and 15gm in the third.  Their babies were all born very healthy and the nurses often commented that the vitamin C babies and mothers were generally healthier than the non-vitamin C participants.

The U.S.  RDA is 70mg.  NOTE: Be very careful to avoid high doses.

Respiratory

Vitamin C (Ascorbic Acid) is highly recommended for AsthmaAsthma
Supplementation with 1gm of vitamin C per day reduces the tendency of the bronchial passages to go into spasm [Lung 1976;154: pp.17-24], an action that has been confirmed in double-blind research.  [Ann Allergy 1990;65: pp.311-4] This amount of vitamin C, while providing benefit, is not curative.  Beneficial effects of short-term vitamin C supplementation (i.e., less than three days) have been observed.  In one double-blind trial, 500mg of vitamin C per day for two days prevented attacks of exercise-induced asthma.  [Ann Allergy 1982;49: pp.146-51]

Both treated and untreated asthmatic patients have been shown to have significantly lower levels of ascorbic acid in both serum and white blood cells.  Ascorbic acid has a wide variety of pharmacological effects that appear important in asthmatic treatment.

Skin-Hair-Nails

Vitamin C (Ascorbic Acid) often helps with Hives (Urticaria)Hives (Urticaria)
High doses of vitamin C, such as mineral ascorbates, can help those with hives by lowering histamine levels.  Taking 2gm every hour in water may bring relief.
Vitamin C (Ascorbic Acid) may help with WartsWarts
Vit C 4-10gms per day for an antiviral action.
Vitamin C (Ascorbic Acid) may help with Concern Over Wrinkled SkinConcern Over Wrinkled Skin
Ascorbic acid reserves are often depleted in older people, who tend to need more vitamin C in their diet.  Ascorbic acid increases the synthesis of collagen more than five-fold in cultures of human skin.  By replenishing ascorbic acid in the skin, collagen synthesis may be stimulated, and the loss of dermal substance associated with aging might be delayed or even reversed.

The skin's natural defenses against the free radicals produced by UV light are vitamin C and vitamin E.  These two antioxidants intercept free radicals before they can damage your skin.  Vitamin C protects significantly better against UVA phototoxicity than vitamin E; vitamin E, on the other hand, is more efficient against UVB.

Uro-Genital

Vitamin C (Ascorbic Acid) often helps with Cervical DysplasiaCervical Dysplasia
Recent evidence suggests that beta-carotene and/or vitamin C may reverse or reduce the risk of cervical dysplasia.  Inadequate vitamin C intake is an independent risk factor for the development of premalignant cervical disease and carcinoma in situ.
Vitamin C (Ascorbic Acid) may help with Eclampsia / PreeclampsiaEclampsia / Preeclampsia
Several studies imply that harmful free radicals called lipid peroxides contribute to preeclampsia [Khan KS, Chien Pl.  Brit J of Obst & Gyn 1997;104(10): pp.1173-9], and that women with this condition are low in the antioxidants that combat them.  [Ziari SA, et al.  Am Jl of Perinat 1996;13(5): pp.287-91]

The U.S.  RDA is 70mg.  NOTE: Be very careful to avoid high doses.
Vitamin C (Ascorbic Acid) may help with Urinary Stress/Urge IncontinenceUrinary Stress/Urge Incontinence
Vitamin C at 500mg, 2-3 times daily with meals may provide some anti-inflammatory support.

Vitamin C (Ascorbic Acid) can help prevent the following:

Aging

Vitamin C (Ascorbic Acid) often prevents Alzheimers DiseaseAlzheimer's Disease
Both vitamin E and vitamin C supplements reduced the incidence of Alzheimer's disease in a 1998 study.  This study followed 655 individuals over 65 years of age for an average of over 4 years.  The anticipated rate of Alzheimer's did not occur in those individuals taking larger amounts of either vitamin.  The lower levels of vitamin C and E found in some supplements did not provide this protection in this study.  A reasonable protective benefit could be expected with 400 IU of vitamin E or 500mg or more of vitamin C.  [Alzheimer Dis.  Assoc.  Disord.1998:12(3): pp.121-126]
Vitamin C (Ascorbic Acid) often prevents CataractsCataracts
Several experimental and epidemiologic studies have shown that long-term consumption of vitamin C supplements may substantially reduce the development of age-related lens opacities.  [Am J Clin Nutr, 1997 Oct, 66:4, pp.911-6]

Organ Health

Vitamin C (Ascorbic Acid) may help prevent Macular DegenerationMacular Degeneration
Taking anti-oxidants such as vitamins C and E has beneficial protective effects against age-related macular degeneration (AMD).  Since oxidative damage of the eye can cause macular degeneration, taking antioxidants may lower the disease's occurrence.  People with high levels of vitamin C, vitamin E and selenium appear to have a 70% lower risk of developing macular degeneration.  [Arch Ophthalmol, December 1995:113(12, 15): pp.18-23; Arch Ophthalmol 1993:111: pp.104-9]

Long-term use of multiple antioxidants plus zinc and copper clearly reduced the risk of developing advanced AMD and the rate of visual acuity loss in a randomized, double-blind, placebo-controlled trial of 3,640 older adults (aged 55-80 years) with preexisting retinal abnormalities, advanced AMD or vision loss due to AMD who were followed for an average of 6.3 years.  [AREDS Report No.  8.  Arch Ophthalmol 2001;119(10): pp.1417-1436]

Tumors, Malignant

Vitamin C (Ascorbic Acid) usually prevents Stomach CancerStomach Cancer
Vitamin C supplementation may help reduce the risk to the development of gastric cancer by increasing ascorbate levels within the stomach and decreasing mucosal DNA damage.
Vitamin C (Ascorbic Acid) may help prevent Breast CancerBreast Cancer
In a 1991 review of 46 studies of the protective effect of vitamin C against cancer, 33 of those studies showed that vitamin C helped safeguard against the development of many cancers.  This included non-hormone-dependent breast cancer.  Vitamin C did not appear to confer any protection against hormone-dependent (including estrogen-dependent) breast cancers.
Vitamin C (Ascorbic Acid) may help prevent Non-Hodgkins LymphomaNon-Hodgkin's Lymphoma
The diets of 358 white men and women with non-Hodgkin's lymphoma and 1,432 controls living in Nebraska were compared.  When dietary vitamin C levels were low, the risk of non-Hodgkin's lymphoma in men increased.  This correlation was not found in women.  [Ward MH, Hoar ZS, Weisenburger DD, et al.  Dietary factors and non-Hodgkin's lymphoma]

KEY

May be useful: may help with; may help prevent
May be useful:
may help with; may help prevent
Moderately useful: often helps with; often prevents
Moderately useful:
often helps with; often prevents
Very useful: is highly recommended for; usually prevents
Very useful:
is highly recommended for; usually prevents
Often counterindicated: is often not recommended for
Often counterindicated:
is often not recommended for
Should be avoided: is NOT recommended for
Should be avoided:
is NOT recommended for