Nutritional Advice El Mondo

Antioxidants

Scientific studies (review articles) on the relationship between antioxidants and disease prevention:
One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of randomized, placebo-controlled double blind clinical trials (RCTs) will answer the following question:
"Do taking dietary supplements make sense?" Yes for a positive conclusion and no for a negative conclusion.

One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of (prospective) cohort studies or case-control studies will answer the following question:
"Should I change my diet?".

  1. Higher intake of antioxidant-rich foods reduces Parkinson's disease
  2. Higher selenium and lower zinc level increase risk of vitiligo
  3. Diet with high total antioxidant capacity decreases cancer mortality
  4. Antioxidant supplements could increase sperm quality
  5. Higher circulating concentration of vitamin C, vitamin E and β-carotene reduce cardiovascular mortality
  6. A diet with high antioxidant properties reduces all-cause mortality risk
  7. Vitamin and antioxidant supplements have no overall preventive effect against bladder cancer
  8. Perioperative antioxidant vitamin therapy in patients undergoing cardiac surgery reduces the incidence of postoperative atrial fibrillation and duration of hospital stay
  9. Perioperative antioxidant supplementations with NAC, PUFA and vitamin C prevent atrial fibrillation after cardiac surgery
  10. High antioxidant dietary intake reduces Alzheimer's disease
  11. Dietary intakes of vitamin C and E lower risk of Alzheimer's disease

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  • Antioxidants are substances that protect human cells from the damage caused by unstable molecules known as free radicals.
  • Oxidative stress is often defined as an imbalance of pro-oxidants and antioxidants.
    Pro-oxidants are also called free radicals.
  • Antioxidants are comparable with a car with 1 or 2 spare wheels. They can lose a spare wheel without getting unstable. The ideal situation in humans is antioxidants giving spare wheels to free radicals.
  • Free radicals are comparable with a car with 3 wheels. It is not comfortable to ride on 3 wheels and therefore, free radicals are also looking for the 4th wheel or electron for stabilization.
    Free radicals are defined as molecules having an unpaired electron in the outer orbit of the electron shell.
  • Human cells are comparable with a car with 4 wheels. They are stable but when losing a wheel to free radicals they become in turn free radicals. This is an undesirable situation in human body.
  • Antioxidants are:
    1. Vitamin C
    2. Vitamin E
    3. Coenzyme Q10
    4. Carotenoids, such as lycopene, beta-carotene, astaxanthin and lutein.
    5. Flavonoids, such as quercetin and revestrol.
    6. Antioxidative enzymes, such as SOD, catalase and glutathione.
    7. Minerals, such as copper, zinc, iron and selenium.
  • Rich sources of dietary antioxidants are vegetables, fruit and nuts.
  • Free radicals are generated largely during the production of ATP in the mitochondria.
    The ultraviolet light that penetrate the skin, tobacco smoking and the air pollutant that is high in smog which we inhale generate also free radicals.
  • At present there are no public health recommendations for antioxidants.
  • At present there is no causal relationship between antioxidant intake and decreased risk of developing diseases. Therefore, taking antioxidant supplements is not advisable in disease prevention.
  • National and international authorities recommend antioxidant intake from diet and not from dietary supplements.
  • A good way to obtain sufficient amounts of antioxidant is 200-300 grams of vegetables, 2-5 servings of fruits and 2-3 glasses of wine per day.
  • DNA is a major target of free radical damage. Free radical damage of DNA can cause diseases such as cancer, COPD, chronic diseases and cardiovascular diseases.
  • The EFSA (European Food Safety Authority) has not approved any claims of antioxidants.
    In Europe, only approved claims of EFSA are allowed on packaging of a product or dietary supplement.
  • Chain reactions of free radicals:
    1. Initiation stage
      • (1) RH → R˙+ H˙
      • (2) R˙ → R˙ + O2 → ROO˙
      • (3) 2ROOH → ROO˙ + RO˙ + H2O
    2. Propagation stage
      • (1) R˙ + O2 → ROO˙
      • (2) ROO˙ + RH → ROOH + R˙
      • (3) RO˙ + RH → ROH + R˙
    3. Termination stage
      • (1) R˙ + R˙ → R – R
      • (2) R˙ + ROO˙ → ROOR
      • (3) ROO˙ + ROO˙ → ROOR + O2