Can Antioxidant Supplements Cause Cancer?

Written by Dr. Steve Chaney on . Posted in current health articles, Drugs and Health, Supplements and Health

The Truth About Vitamins C & E

Author: Dr. Stephen Chaney

mythsI am always amazed at how certain nutrition myths take on a life of their own. A single study gets sensationalized. The study may not be very good, but some nutrition guru publicizes it even though it may be contradicted by other studies that come to the opposite conclusion.

Other blogs and news feeds pick it up. It gets repeated over and over until it becomes generally accepted as true. It becomes what I call an “urban nutrition myth”. Once these myths become well established they are hard to correct. When contrary information is published, it is ignored because everyone already knows the “truth”.

Can Antioxidant Supplements Cause Cancer?

The risks of antioxidant supplements are a perfect example. Most web sites and health experts warn that you should be careful about using antioxidant supplements. You are told that they may just increase your risk of cancer. They may just kill you!

The antioxidant vitamins C and E have generated the most scrutiny in recent years. There were a number of reasons to suspect that they might decrease cancer risk:

1) They destroy free radicals.
2) They decrease cancer risk in animal studies.
3) Increase consumption of vitamins C & E is associated with decreased risk of cancer in human population studies.

Because there was so much circumstantial evidence that vitamins C & E might decrease cancer risk, there have been a number of double-blind, placebo controlled human clinical trials to test that hypothesis.

• 6 clinical studies showed no effect of vitamin C and/or E on cancer incidence.
• 1 study suggested that vitamin E might decrease prostate cancer risk, and another study suggested that vitamin E might decrease colon cancer risk.
• 1 study (Kristal et al, Journal of the National Cancer Institute, doi: 10.1093/jnci/djt456, 2014) suggested that vitamin E alone might increase prostate cancer risk, but when vitamin E was combined with selenium there was no increased risk. I have discussed a likely explanation of those confusing results in a previous “Health Tips From the Professor” (https://healthtipsfromtheprofessor.com/selenium-vitamin-e-increase-prostate-cancer-risk/).

That’s it. Six clinical studies show no effect of vitamins C & E on cancer risk, two studies suggest that vitamin E decreases cancer risk and one study suggests that vitamin E increases cancer risk. Yet all the “experts” are warning that antioxidant supplements might increase your cancer risk. It has become an urban nutrition myth.

You may remember that I said that the final characteristic of an urban nutrition myth is that when contrary information is published, it is ignored. In fact, an excellent study showing no effect of vitamins C and E on cancer risk has just been published – and it is being ignored because it doesn’t fit the “truth” that most experts have come to believe.

What Does the Latest Study Show?

antioxidant supplementsThe study in question (Wang et al, American Journal of Clinical Nutrition, 2014; doi: 10.3945/ajcn.114.085480) was a post-trial follow-up to the Physicians’ Health Study II. It followed 14,641 US male physicians (average age 64 at the beginning of the trial) for 10.3 years. The subjects were randomly assigned to receive 400 IU of vitamin E every other day, 500 mg of vitamin C daily, or their respective placebos.

The investigators in charge of the study recognized that cancer takes many years to develop and that the effects of supplementation might not be recognized until years later. Because of that, the subjects were followed for an additional 2.8 years after the close of the trial to allow additional time for cancers to develop.

The results were clear cut:

• Vitamin E supplementation had no effect on the incidence of prostate cancer or total cancers.
• Vitamin C supplementation also had no effect on the incidence of prostate cancer or total cancers.
• Vitamin C supplementation decreased the incidence of colon cancer during the post-trial period by 46%, which was marginally significant.

The Bottom Line:

1) Can antioxidant supplements cause cancer?  You can ignore the dire warnings that antioxidant supplements may increase your risk of cancer. The only case where this appears to be true is for high dose beta-carotene supplements in smokers. The weight of evidence for vitamins C and E suggests that they are unlikely to increase your risk of cancer.

2) As I have said previously if there is any risk of antioxidant supplements, it is most likely to arise from using high purity individual antioxidant supplements. I recommend vitamin E supplements containing the full spectrum of tocopherols and tocotrienols, carotenoid supplements containing all the naturally occurring carotenoids, and supplements that combine complementary antioxidant nutrients – vitamin E and selenium, for example.

3) That doesn’t mean that you should run out and stock up on antioxidant supplements in the hope that they will prevent cancer. The same clinical studies that showed no harm from vitamin C and E supplementation also showed no consistent benefit.

4) This is also consistent with my comments in previous “Health Tips from the Professor”. For example:

• It is very difficult to prove, and unreasonable to expect, that supplementation will have a measurable effect on risk of a particular disease like cancer for everyone. People who are healthy and have very low risk of cancer, may experience other benefits from supplementation but are unlikely to experience a measurable decrease in cancer risk.

• Supplementation is most likely to be advantageous in select populations, generally populations with increased need for a particular nutrient or at highest risk of disease. It is clinical studies looking at the effect of supplementation in these select populations that often show the greatest benefit of supplementation.

• Supplementation is just one component of a holistic approach for reducing disease risk. Diet, weight control, exercise, adequate rest and stress reduction all play a major role as well. You can’t weigh 250 pounds and eat all your meals at McDonalds and expect supplementation to save you from disease.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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High Protein Diets and Weight Loss

Posted October 16, 2018 by Dr. Steve Chaney

Do High Protein Diets Reduce Fat And Preserve Muscle?

Author: Dr. Stephen Chaney

Healthy Diet food group, proteins, include meat (chicken or turkAre high protein diets your secret to healthy weight loss? There are lots of diets out there – high fat, low fat, Paleolithic, blood type, exotic juices, magic pills and potions. But recently, high protein diets are getting a lot of press. The word is that they preserve muscle mass and preferentially decrease fat mass.

If high protein diets actually did that, it would be huge because:

  • It’s the fat – not the pounds – that causes most of the health problems.
  • Muscle burns more calories than fat, so preserving muscle mass helps keep your metabolic rate high without dangerous herbs or stimulants – and keeping your metabolic rate high helps prevent both the plateau and yo-yo (weight regain) characteristic of so many diets.
  • When you lose fat and retain muscle you are reshaping your body – and that’s why most people are dieting to begin with.

So let’s look more carefully at the recent study that has been generating all the headlines (Pasiakos et al, The FASEB Journal, 27: 3837-3847, 2013).

The Study Design:

This was a randomized control study with 39 young (21), healthy and fit men and women who were only borderline overweight (BMI = 25). These volunteers were put on a 21 day weight loss program in which calories were reduced by 30% and exercise was increased by 10%. They were divided into 3 groups:

  • One group was assigned a diet containing the RDA for protein (about 14% of calories in this study design).
  • The second group’s diet contained 2X the RDA for protein (28% of calories)
  • The third group’s diet contained 3X the RDA for protein (42% of calories)

In the RDA protein group carbohydrate was 56% of calories, and fat was 30% of calories. In the other two groups the carbohydrate and fat content of the diets was decreased proportionally.

Feet_On_ScaleWhat Did The Study Show?

  • Weight loss (7 pounds in 21 days) was the same on all 3 diets.
  • The high protein (28% and 42%) diets caused almost 2X more fat loss (5 pounds versus 2.8 pounds) than the diet supplying the RDA amount of protein.
  • The high protein (28% and 42%) diets caused 2X less muscle loss (2.1 pounds versus 4.2 pounds) than the diet supplying the RDA amount of protein.
  • In case you didn’t notice, there was no difference in overall results between the 28% (2X the RDA) and 42% (3X the RDA) diets.

Pros And Cons Of The Study:

  • The con is fairly obvious. The participants in this study were all young, healthy and were not seriously overweight. If this were the only study of this type one might seriously question whether the results were applicable to middle aged, overweight coach potatoes. However, there have been several other studies with older, more overweight volunteers that have come to the same conclusion – namely that high protein diets preserve muscle mass and enhance fat loss.
  • The value of this study is that it defines for the first time the upper limit for how much protein is required to preserve muscle mass in a weight loss regimen. 28% of calories is sufficient, and there appear to be no benefit from increasing protein further. I would add the caveat that there are studies suggesting that protein requirements for preserving muscle mass may be greater in adults 50 and older.

The Bottom Line:

1)    Forget the high fat diets, low fat diets, pills and potions. High protein diets (~2X the RDA or 28% of calories) do appear to be the safest, most effective way to preserve muscle mass and enhance fat loss in a weight loss regimen.

2)     That’s not a lot of protein, by the way. The average American consumes almost 2X the RDA for protein on a daily basis. However, it is significantly more protein than the average American consumes when they are trying to lose weight. Salads and carrot sticks are great diet foods, but they don’t contain much protein.

3)     Higher protein intake does not appear to offer any additional benefit – at least in young adults.

4)     Not all high protein diets are created equal. What some people call high protein diets are laden with saturated fats or devoid of carbohydrate. The diet in this study, which is what I recommend, had 43% healthy carbohydrates and 30% healthy fats.

5)    These diets were designed to give 7 pounds of weight loss in 21 days – which is what the experts recommend. There are diets out there promising faster weight loss but they severely restrict calories and/or rely heavily on stimulants, they do not preserve muscle mass, and they often are not safe. In addition they are usually temporary.  I do not recommend them.

6)    This level of protein intake is safe for almost everyone. The major exception would be people with kidney disease, who should always check with their doctor before increasing protein intake. The only other caveat is that protein metabolism creates a lot of nitrogenous waste, so you should drink plenty of water to flush that waste out of your system. But, water is always a good idea.

7)     The high protein diets minimized, but did not completely prevent, muscle loss. Other studies suggest that adding the amino acid leucine to a high protein diet can give 100% retention of muscle mass in a weight loss regimen – but that’s another story for another day.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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