L-Cysteine 500 mg by Puritan's Pride Premium

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Cancer. Although there is interest in using oral L-cysteine for prevention of cancers of the upper gastrointestinal tract, there is insufficient reliable information about the clinical effects of L-cysteine for this purpose.
• Diabetes. Although there is interest in using oral L-cysteine for diabetes, there is insufficient reliable information about the clinical effects of L-cysteine for this condition.
• Erythropoietic protoporphyria (EPP). Although there is interest in using oral L-cysteine for EPP, there is insufficient reliable information about the clinical effects of L-cysteine for this condition.
• Hangover. Oral L-cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial shows that an immediate release product (Catapult Cat L-cysteine vitamin tablet) providing L-cysteine 1200 mg in combination with other ingredients, taken six times between 7 pm and midnight in conjunction with alcohol 1.5 grams/kg over 3 hours, modestly reduces symptoms of hangover, including nausea, headache, stress, and anxiety, when compared with placebo. Each L-cysteine tablet also contained thiamine 50 mg, riboflavin 1.4 mg, niacin 16 mg, vitamin B6 1.4 mg, biotin 50 mcg, folic acid 200 mcg, vitamin B12 2.5 mcg, and vitamin C 80 mg (109709). Other researchers have questioned the validity of the statistical methods used in this study and suggest that not all of the noted outcomes were statistically significant (109716).
• Photoreactive keratectomy. It is unclear if oral L-cysteine is beneficial for promoting wound healing after photoreactive keratectomy. Details: Preliminary clinical research shows that taking L-cysteine 100 mg twice daily for 14 days starting one week before photoreactive keratectomy reduces complete corneal healing time by about 2 days when compared with taking placebo (109727).
• Venous leg ulcers. Topical L-cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial shows that topical application of a cream containing L-cysteine 2 mg/gram, glycine 10 mg/gram, and D,L-threonine 1 mg/gram for 12 weeks modestly increases healing and decreases pain when compared with placebo. However, there was no difference in exudate, offensive smell, or granulation. The cream was used as part of a treatment regimen involving cleaning and bandaging, two to five days each week (10255).
• Smoking cessation. It is unclear if oral L-cysteine is beneficial for promoting smoking cessation. Details: Preliminary clinical research shows that use of a slow-release lozenge containing L-cysteine 3 mg (Acetiumlozenge; Biohit Oyj) with each cigarette for 6 months does not increase the odds of smoking cessation when compared with placebo (109714). However, this study may have been inadequately powered to detect a difference between groups. An adequately powered study by the same research group shows that using this lozenge increases the odds of smoking cessation by about 51% when compared with placebo (109710).
• Stroke. Although there is interest in using oral L-cysteine for stroke prevention, there is insufficient reliable information about the clinical effects of L-cysteine for this purpose. More evidence is needed to rate L-cysteine for these uses.

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LIKELY SAFE ...when used orally in amounts found in foods. There is insufficient reliable information available about the safety of L-cysteine when used orally in amounts greater than those found in foods or when used topically.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts found in foods. There is insufficient reliable information available about the safety of amounts greater than those found in foods; avoid use. Some research suggests that taking L-cysteine during lactation increases levels of free L-cysteine in breastmilk. However, these levels are lower than those found in some commercial hydrolyzed protein infant formulas (109718).

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking L-cysteine supplements with antidiabetes drugs might increase the risk of hypoglycemia.  Details Animal research suggests that L-cysteine can have hypoglycemic effects (109722).

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General ...Orally, L-cysteine is well tolerated in amounts found in foods. When used in higher doses or when applied topically, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.

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