Cola is a highly popular summer beverage, and the success of the two major cola companies underscores its widespread appeal. However, in recent years, some men have become hesitant to drink cola due to persistent claims that it kills sperm. Is there scientific basis for this claim? Does cola truly kill sperm? What are the real culprits behind sperm reduction?
Rumor: Drinking cola reduces sperm count and lowers fertility.
Truth 1: Between 2001 and 2006, Danish physician Tina Kold Jensen studied the sperm quality and caffeine intake of 2,554 young men. The findings revealed that daily coffee consumption (with total caffeine intake below 800mg) and cola consumption (two 500ml bottles per day) had no impact whatsoever on sperm count, motility, or morphology.Do you really consume at least two bottles of cola and seven cups of coffee daily? If not, there's no need to obsess over rumors about coffee or cola killing sperm.
For the very small minority (3%) of young men who consume "massive" amounts of cola or caffeine, some do exhibit reduced sperm quality.Dr. Jensen believes these individuals not only consume more cola but also have other unhealthy dietary habits. In other words, drinking "massive amounts" of cola is merely one aspect of poor nutrition. Therefore, there is no evidence that heavy cola consumption causes reduced sperm quality. It's important to note that even though these heavy cola drinkers experienced a 30% drop in total sperm count, their levels still fell within the normal range defined by the World Health Organization.
Fact 2: In 1985, Dr. Sharee A. Umpierre and colleagues from Harvard Medical School's Department of Obstetrics and Gynecology mixed sperm with cola in vitro and measured surviving sperm counts, concluding that cola exhibits some spermicidal effects.In 1987, Hong Chuan-Yueh and colleagues at Taipei Veterans General Hospital examined whether sperm retained transmembrane migration activity in the presence of cola, concluding that cola does not affect sperm motility.
These two contradictory studies jointly received the 2008 Ig Nobel Prize in Chemistry.Regardless of these in vitro laboratory findings, the practice of using cola for vaginal douching as a contraceptive method is highly unscientific. By the time douching occurs, approximately 100,000 sperm may have already reached the uterus. Moreover, the sugar content in cola can easily cause bacterial infections in the genital area.
Even if cola does not kill sperm, it can still cause other health issues.
The carbon dioxide in cola stimulates gastric acid secretion. Excess stomach acid can cause bloating, reduce appetite, and decrease daily food intake. Inadequate nutrient intake from diet can impair normal growth and development, learning outcomes, athletic performance, work productivity, and overall health.
A 355 ml can of cola contains approximately 35 grams of sugar, equivalent to 140 calories—roughly the same as half a bowl of rice.However, while the calorie count is comparable, the nutritional value differs significantly. Sugar provides only calories and no other nutrients, making it an empty-calorie food or junk food. Regular consumption can lead to gradual weight gain and foster unhealthy eating habits, such as a preference for sweetened beverages over plain water. Additionally, sugar negatively impacts dental health.
The Real Culprits Behind Sperm Damage
1. Smoking and Alcohol Abuse
Studies reveal that men who smoke over 31 cigarettes daily or have smoked for more than 10 years experience significant declines in sperm count and motility, with abnormal sperm rates increasing exponentially.Alcohol is a gonadal toxin. Excessive drinking can poison the gonads, causing testicular damage, testicular atrophy, weakened reproductive function, decreased blood testosterone levels, and resulting in sperm damage, abnormalities, reduction, underdevelopment, and reduced motility. It can also induce ED and anejaculation.
2. Human Obesity
In recent years, the incidence of obesity has shown a year-on-year upward trend, becoming a societal issue affecting people's physical and mental health.Initially, obese individuals may not experience noticeable symptoms, but multiple hidden risks lurk, particularly in male obesity, which can impair the development of reproductive systems like the testes and penis. The underlying mechanism involves adipose tissue converting androgens into estrogens, reducing male hormones and increasing relative estrogen levels in the body. This disrupts sperm production and compromises sperm quality.Obesity can also trigger hypertension and diabetes, conditions that may lead to physiological dysfunction. 3. Environmental Pollution Our environment contains numerous chemicals in air, water, and soil that affect human reproduction. These include harmful metals like lead, mercury, and cadmium; a wide variety of pesticides and insecticides; and certain medications consumed by people—all posing threats to sperm.Experts indicate that male sperm reduction is primarily caused by chemicals produced from environmental factors. These substances can lead to degeneration and atrophy of the male reproductive system, abnormal mating behaviors, and disruptions to hormone receptor functions. This, in turn, affects the development of the embryonic reproductive system, resulting in feminization of male embryos, smaller testes, and further reduced sperm counts in subsequent generations.
4. Rampant Sexually Transmitted Diseases
In recent years, sexually transmitted diseases have spread widely, with the proliferation of drugs further fueling their spread. This represents a major biological threat to human reproduction.Most sexually transmitted diseases not only cause inflammation, damage, and structural alterations in the reproductive system, but many pathogens can also directly affect germ cell formation. They may induce genetic mutations, sperm abnormalities, or trigger immune responses that produce anti-sperm antibodies, leading to sperm destruction and infertility.
5. Nuclear Radiation
Nuclear radiation poses significant damage to the testes, as they are among the most radiation-sensitive organs in the human body. Even low doses can reduce sperm quality and may cause temporary azoospermia.Experts estimate that radiation doses of 200–300 roentgen can impair spermatogenesis. X-rays can cause sperm abnormalities and reduced quality; low-dose X-ray exposure may damage the genetic material of spermatogenic cells or result in abnormal sperm heads, leading to fetal malformations, miscarriage, premature birth, or mental retardation. Thermal radiation is also a significant cause of diminished sperm quality.Experts indicate that when testicular temperature exceeds 45°C, sperm production and motility can be impaired within two hours. Activities such as saunas, bathing in excessively hot water, working in high-temperature environments, and wearing tight-fitting pants can all damage the testes' ability to produce sperm and reduce sperm motility.
6. Electromagnetic Effects
In today's society, as living standards rise, the use of various electrical appliances—such as computers, color TVs, air conditioners, refrigerators, electric blankets, mobile phones, laser typesetting equipment, and dense radio transmitters—generates electromagnetic waves of different wavelengths and frequencies.Though invisible, these waves silently affect human reproductive cells, mercilessly damaging sperm in ways that are difficult to guard against.
Friendly reminder: Men need not worry about cola killing sperm, but cola-related conditions like high blood pressure can indirectly impact fertility. Therefore, it's best not to drink too much cola.