Written by: Shirley Brugerie, Yad-Tech Inc
A look back at some definitions
First, let’s review a few definitions to familiarize ourselves with the subject.
Free radical:
A free radical is an unstable atom derived from oxygen, highly reactive to surrounding molecules, whose primary objective is to return to a stable form. To achieve this, the free radical “attacks” our cells by “stripping” electrons from other atoms in its environment, thus restoring its original form and stability. The attacked atom then becomes a free radical, an unstable atom with radical potential. Free radicals are involved in the chemical reactions that accompany cellular life, but in excess they are potentially harmful as they can alter the proper functioning of our cells.
Certain factors, mainly linked to our lifestyle, can considerably influence the production of free radicals. Below are the main ones.
- Smoking
- Medication
- Drugs
- Alcohol
- Pollution
- Unbalanced diet
- Intense sport activity
- Stress
Antioxidant:
An antioxidant, a natural shield, is a molecule whose function is to neutralize the effects of free radicals by slowing down or preventing the oxidation chain process (electron transfer from one substance to another) by transferring electron to them directly, thus preventing them from reaching their target. Antioxidants trap electrons in existing free radicals, making them less active. Their function is to protect our cells against the damaging effects of free radicals.
Many antioxidants, a natural defense system, are either synthesized by the body or supplied by our diet.
Antioxidants are real allies in slowing or limiting the aging of our cells. They have great benefits for our cognitive functions, protecting our heart and vision, reducing the risk of cancer, keeping us energized and much more.
Oxidative stress:
Oxidative stress refers to an imbalance between the quantity of free radicals and the quantity of antioxidants present and usable in the body. This imbalance, to a greater or lesser degree, leads to numerous cellular disturbances, causing fatigue, premature aging, eye, circulatory and joint problems, to name but a few.
What about reproductive health?
Reproductive health is a subject rarely addressed when talking about oxidative stress, and yet fertility is experiencing a worldwide decline that is unfortunately accelerating.
Today, there are established and indisputable links, notably that the environment and certain lifestyles generate free radicals and thus greater oxidative stress (imbalance between free radicals and antioxidants). This oxidative stress is said to have a significant impact on the reproductive functions of both men and women. Indeed, the disturbances caused by this imbalance, and hence the presence of oxidative stress, affect the cells of our entire organism, and therefore our health in general. But it also plays a decisive role in the health of our precious gametes, oocytes and spermatozoa, our reproductive cells. Today, health professionals and fertility experts are increasingly aware of these consequences.
Gametes affected by oxidative stress lose quality, quantity and efficiency, leading to reduced fertility in both men and women.
Excellent news! Oxidative stress can be corrected!
The 3 main factors to consider when talking about oxidative stress are lifestyle, diet and physical activity. Here, we’re going to take a closer look at diet.
Indeed, although our bodies are capable of synthesizing antioxidants on their own, it’s essential to understand that food is also an important source of them, in addition to providing many other micronutrients and certain trace elements. So, by adopting healthy eating habits, we can play a significant role in our oxidative stress and therefore our reproductive health.
However, it is well known that the quality of our food has declined considerably over the last few decades. Poor soils (low in nutrients) and food processing (radical effect on our organism) are factors largely responsible for this phenomenon, to name but a few. Therefore, it’s very important to keep this in mind and opt for judicious food choices (fresh, organic, unprocessed products) and supplementation. In fact, the combination of a healthy, high-quality diet and supplementation can reduce oxidative stress more effectively, thereby increasing the chances of conception.
The ORAC index (free radical absorption capacity) is used to assess a food’s antioxidant capacity. The higher the ORAC index, the more antioxidant properties the food possesses, and therefore the more interesting it is. Thus, according to the following table, cloves have a much higher antioxidant capacity than curry powder.
Overview of the benefits of the best-known antioxidants on reproductive health and some dietary sources
Coenzyme Q10 (CoQ10):
CoQ10 is a powerful antioxidant molecule protecting cell membranes and preventing oxidation of lipoproteins, lipids, proteins and DNA. It also stimulates the release of anti-inflammatory factors.
It is an important molecule for male fertility. CoQ10 deficiency is known to be correlated with low sperm motility. Restoring its levels in the sperm significantly increases sperm motility.
CoQ10 also activates energy production at the cellular level (mitochondria) and can help improve ovarian response in women with ovulation disorders or polycystic ovary syndrome (PCOS). Its antioxidant and anti-inflammatory properties help combat cell damage and thus support oocyte quality.
A few food sources:
- Meat (heart, liver and muscle)
- Soy, corn and olive oil
- Oily fish such as tuna, salmon, mackerel and herring
- Eggs
Lycopene:
Lycopene is one of the most powerful antioxidants present in plants, responsible for the reddish-orange color of certain fruits and vegetables. It also belongs to the carotenoid family, which is recognized for its synergistic action with vitamin E. Lycopene is said to prevent the onset of cardiovascular disease, notably atherosclerosis, and plays an important role in protecting spermatozoa against oxidative stress. Normally present in large quantities in the testicles and seminal fluid, its content appears to be reduced in men suffering from infertility of unknown origin. In addition, a clinical study has validated that dietary supplementation with Lycopene can improve sperm motility and increase fertility potential in men.
A few food sources:
- Papaya
- Pink grapefruit
- Watermelon
- Red tomato
β-carotene (precursor of vitamin A):
β-carotene is a vitamin precursor, which means it can be converted into vitamin A in the body. Vitamin A plays a few roles in the body, most notably in vision and dark adaptation, cell multiplication and maturation, and oxidative stress.
The various stages of sperm maturation require vitamin A, which plays an essential role in the normal production of sperm by the testicles. Vitamin A deficiency has been observed in men with low sperm motility. It is important to note that carotenoids work in synergy with vitamin E.
Vitamin A also promotes egg quality through its role in ovarian hormone synthesis and prevents malformations. It is involved in cell division from the moment of fertilization and thus promotes embryonic development. And finally, it supports the implantation and formation of the placenta.
A few food sources:
- Sweet potato
- Carrots
- Red bell pepper
- Pumpkin
- Apricot
- Dandelion
- Parsley
- Lettuce
- Spinach
Vitamin B:
All B vitamins are essential for enzymatic activity and are therefore vital during the preconception period. Folic acid (B9) helps to promote conception and fetal health in women who are vegetarians or who eat little animal products (meat, fish, eggs, dairy products). Combined with prenatal vitamins such as B6 and B12, folic acid intake from the preconception period reduces the risk of congenital diseases, including neurological abnormalities. Studies have shown that giving vitamin B6 to women who have difficulty conceiving increases fertility. Vitamin B6 and B12 levels naturally decrease during pregnancy. Also, the absence of a nutritional intake rich in vitamins B6 and B12 increases the risk of anemia and pre-eclampsia in the mother, and skeletal and neuromotor abnormalities in the child.
A few food sources:
- Leguminous (lentils, chickpeas, etc.)
- Green leafy vegetables (spinach, broccoli, Brussels sprouts)
- Liver
- Wheat sprouts
- Nuts and seeds
Vitamin C :
Vitamin C is involved in the synthesis of collagen, neurotransmitters and hormones, amino acid metabolism and is also an antioxidant that has been shown to protect sperm DNA from oxidative damage. Clinical studies have shown that vitamin C significantly improves sperm motility and morphology.
A few food sources:
- Citrus fruits
- Guava
- Red fruit
- Yellow and red peppers
- Broccoli
- Brussels sprouts
Vitamin D:
Vitamin D is a non-essential dietary vitamin recognized for its important role in the development and maintenance of bone structure, calcium and phosphorus absorption, immune function and general health.
In men, vitamin D status is associated with sperm quantity, quality, morphology and motility. Vitamin D supplementation has been shown to enhance sperm quality, improving the chances of conception.
Vitamin D has also been shown to have beneficial effects on female reproduction, including in vitro fertilization (IVF) results, polycystic ovary syndrome (PCOS) and endometriosis. In addition, vitamin D may influence the synthesis of sex hormones (estradiol and progesterone) in healthy women. Vitamin D supplementation is therefore indicated from the pre-conceptional period onwards.
Food sources
- Cod liver oil
- Halibut
- Swordfish
- Herring
- Pink salmon
- Trout
- Eggs
- Shiitake mushroom
- Pork
- Vitamin D-fortified dairy products (e.g. soy)
Vitamin E:
Vitamin E is an antioxidant linked to the presence of lipids. It accumulates in adipose tissue, in the lipids making up cell membranes and in lipoproteins.
Vitamin E maintains the viability of immature spermatozoa and contributes to their maturation along the epididymis. In addition, clinical studies have confirmed that vitamin E improves the ability of sperm to fertilize the egg.
A few food sources:
- Wheat germ
- Almonds
- Hazelnuts
- Pine nuts
- Sunflower seeds
- Sunflower, rapeseed, olive, soybean oil
- Avocados
- Spinach
Selenium:
Selenium is involved in thyroid metabolism and is a cofactor (component) of one of the most important antioxidant enzymes in spermatozoa. It is also a structural component of the spermatozoa.
A few food sources:
- Eggs
- Poultry
- Beef
- Brazil nuts
- Mussels
- Chicken liver
- Pale-fleshed tuna
- Lobster
- Pork
- Sardines
- Sole
- Wheat germ