Life Extension Magazine®

Issue: Feb 2002

Eye Health

On propylene glycol, green tea benefits in a drink?, plus…

Scientifically reviewed by: Dr. Gary Gonzalez, MD, on January 2021.


Q: I want to learn more about propylene glycol. What is it, exactly, and is it safe?

A: Propylene glycol is a lubricant that protects against dry eyes and other forms of irritation. This ingredient has been approved by the FDA for ophthalmic use and is found in many prescription and over the counter eye drop solutions. Many people confuse propylene glycol with its derivatives that often incorporate the base structure, but are altogether different molecules. For example, many people confuse propylene glycol with its derivative ethylene glycol, a radiator fluid. Propylene glycol is an antioxidant and in a recent study prevented the formation of cataracts in rabbits. Also, propylene glycol represses the decline of glutathione and the elevation of lipid peroxide in the lens. Finally, propylene glycol metabolizes to lactate and pyruvate producing NADH and has protective activities against X-ray irradiation. [Ophthalmic Res. 1995; 27(6):350-5.]

Q: I have been taking SAMe for depression and it has been working well. I just found out that my DHEA is low. I am 52 years old. Is it advisable to take SAMe and DHEA together?

A: Yes, you can take both simultaneously. In fact, DHEA has been shown to help alleviate depression, too. Researchers at the University of California, San Francisco conducted a double-blind, placebo-controlled study on DHEA's potential as an antidepressant. Eleven patients with major depression were given up to 90 mg/day of DHEA for six weeks, and 11 were given a placebo. After six weeks, psychological tests indicated that about half the participants responded to DHEA therapy, with an overall enhancement of mood scores by 30.5%. In another study conducted at the National Institute of Mental Health, middle-aged people with dysthymia, a chronic, low-grade depression were given 90 mg of DHEA a day for three weeks, then 450 mg a day for three more weeks. DHEA significantly alleviated the participants' depression. Seven symptoms in particular got much better: lack of pleasure, low energy, low motivation, emotional numbness, sadness, inability to cope and excessive worry. DHEA worked for most people within 10 days. If the supplement was stopped, the symptoms reemerged. Overall, the response rate was 60%, which is better than what antidepressants usually do for dysthymia. Ninety milligrams a day was sufficient. No extra benefit was provided by the 450 mg dose.

Q: I drink bottled green tea drinks that I buy at my local health food store. Do they contain the same good antioxidants that capsules do?


A: The benefits of taking green tea include catechins, such as epigallocatechin gallate (EGCG). EGCG is the most potent cancer cell suppressing polyphenols found in green tea. A study in the Journal of Agricultural and Food Chemistry [2001;49;1:477-482] suggests that there might be some degradation of catechins in canned and bottled tea drinks. This is due to the sucrose solutions containing citric acid and ascorbic acid affecting the stability of the catechins and also the process of bottling, canning, transporting and storing. The Foundation recommends taking a standardized capsule, which guarantees consistent potency. Super Green Tea contains 95% green tea extract, which is standardized to provide 35% EGCG.

Q: I have been taking Zoloft for depression and am now off of it. Can I use melatonin for sleep? I saw a warning on your website that it might make depression worse.

A: For many, melatonin relieves depression. A recent study in Neuropsychobiology [2001;44(3):113-7] indicated that low melatonin levels were closely related to melancholic depression. However, there are a few select people who might feel more depressed when using melatonin. If that occurs, discontinue use.

Q: If I have more than six drinks in an evening, should I take more than six Anti-Alcohol Antioxidants? Is it harmful to take more?

A: Anti-Alcohol Antioxidants contains specific antioxidants that help to suppress free radicals and neutralize acetaldehyde, which is a toxic metabolite of alcohol. You might also add GastroPro, which provides additional protection from heavy alcohol consumption. Polyenylphosphatidylcholine-the main ingredient in GastroPro-has been shown to provide total protection against certain forms of alcohol-induced liver injury [Adv Pharmacol 1997;38:601-28]. Another benefit to taking GastroPro is that it helps to reduce gastric irritation, which is a common side effect when consuming large amounts of alcohol.

Q: I recently had a blood test and was told my total cholesterol is perfect. My HDL is ok and so are my triglycerides. However, my LDL is over 140. Should I follow your general cholesterol reduction protocol? If not, what supplements should I take?


A: Low-density lipoprotein (LDL) is called the "bad" form of cholesterol. LDL carries most of the cholesterol in the blood, and the cholesterol from LDLs is the main source of damaging accumulation and blockage in the arteries. Thus, the more LDL cholesterol you have in your blood, the greater your risk of heart disease. The cholesterol reduction protocol lists supplements that not only help to lower LDL, but also help to reduce LDL oxidation, which causes atherosclerosis. These supplements include garlic, which helps protect the arterial lining against oxidation. The combination of garlic with omega 3 fish oils has shown a 10% decrease in LDL levels. Green tea extract also lowers LDL and inhibits the oxidation of LDL cholesterol in the arteries. Curcumin inhibits platelet aggregation and significantly decreases the level of lipid (LDL) peroxidation. The April 1998 issue of Molecular Cell Biochemistry reported, "Curcumin extract may be protective in preventing lipoperoxidation of subcellular membranes."

Q: Do you have any information on pulmonary fibrosis?

A: The Foundation has recently written a protocol for pulmonary fibrosis. The main action of the protocol is to suppress the inflammatory cytokines that attack the lungs and cause fibrosis. There are several supplements you can take to help lower pro-inflammatory cytokines. These nutrients include Super GLA/DHA-six capsules per day, DHEA-25 mgs/day (avoid this supplement if any hormone related cancer exists), vitamin K-10 mg/day and Life Extension Mix-9 tablets, 14 capsules or 3 scoops of powder per day. Also, ask your doctor to prescribe pentoxifylline (Trental). The recommended dose is 400 mgs per day for one week, then increase to 400 mg twice per day thereafter. Pentoxifylline will help to suppress pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-a), which is a dangerous chemical messenger that incites the immune system to attack healthy tissues throughout the body. Elevated TNF-a causes a systemic inflammatory cascade throughout the body. A recent study [Int. J. Radiat. Biol 2000 Apr:76(4):523-32] found that the drug Captopril, which is an ACE inhibitor, may also have protective effects on radiation-induced pulmonary injury. This drug was effective in protecting the lung parenchyma from inflammatory response and subsequent fibrosis.