Written by Team MD
21 January 2015


12 of the Most Important Sex Studies from 2014



1) The Push for More Pleasurable Condoms

 Condoms prevent pregnancy and sexually transmitted diseases, and play an important role in promoting world health. The Gates Foundation, in an attempt to increase condom use, has vowed to fund projects that develop more user-friendly condoms. They have challenged manufacturers to make condoms that transfer more heat and sensation, are easier to apply, don’t break as often, and are more readily available. Decreased pleasure from condom use is the number one reason for unprotected sex in both genders. New condom design should address pleasurable sensations in men and women. (Journal Sexual Medicine, 10:3151-3154, 2013)


2) Elevated Uric Acid Linked to Erectile Dysfunction

 Erectile dysfunction (ED) is an excellent early marker of coronary artery disease, heart attack and stroke. Elevated blood uric acid is a risk factor of heart disease and a marker of poor metabolic health in the cells lining the blood vessels. These endothelial cells are vital for regulating blood flow to the penis and other tissues around the body. Turkish researchers found that elevated uric acid levels were common in older men with erectile dysfunction. This is probably not a causal relationship because of the link between ED and coronary artery disease. (Journal Sexual Medicine, December 2013)


3) Low Testosterone Levels Increase the Risk of Cardiovascular Disease

 Low testosterone (T) levels are linked to poor sexual performance, premature death, decreased muscle and bone mass, poor blood sugar regulation, obesity and cardiovascular disease. Spanish researchers, in a study of nearly 1,300 older men (average age 58), found that 33 percent had low testosterone levels. These men showed a higher risk of cardiovascular disease as indicated by high blood fats, high blood pressure, erectile dysfunction and obesity. The researchers concluded that obesity and severe erectile dysfunction were the best predictors of testosterone-related cardiovascular disease. They concluded that T levels below 12 nanomoles per liter increased the risk of disease. (Journal Sexual Medicine, published online June 5, 2014)


4) Viagra Increases the Risk of Melanoma

 Melanoma is a deadly form of skin cancer that develops in the melanocytes— cells that give color to the skin. In 2014, about 76,100 people will be diagnosed with melanoma and 9,710 people will die from the disease. Nearly 1,000,000 people in the United States have melanoma. Previous severe sunburn and excessive use of tanning beds are leading risk factors of the disease. A Harvard Medical School study showed an 84 percent increased risk of melanoma in men who used of sildenafil (Viagra). In contrast, sildenafil was not related to the development of squamous cell cancer (a less dangerous type of skin cancer). (Journal American Medical Association Internal Medicine, 174: 964•970, 2014)


5) Do High-Fat Diets Cause Erection Problems?

 A Brazilian study (Age 36: 597-611, 2014) linked high-fat diets to erection problems. High-fat diets are related to lower levels of nitric oxide, which is an important chemical for regulating blood flow in the penis. These “relationship studies” do not tell the whole story. Good tissue blood flow, while influenced by diet, reflects overall metabolic health. Regular exercise— particularly intense exercise— improves metabolic health and blood flow control. Unfit people tend to eat less healthy foods. The quality of the daily exercise and diet program, as well as smoking, stress and sleep habits, are more important for sexual health than analysis of isolated factors such as fat intake. (Journal Sexual Medicine, 11: 1620-1625, 2014)


6) Counterfeit Sex Supplements

 Many erection-promoting drugs sold on the Internet contain counterfeited, mislabeled and illegal substances. The drugs can have serious side effects such as decreased blood pressure, headache and dizziness. Drugs used to treat erectile dysfunction (ED), such as Viagra and Cialis, are expensive and available only through prescription. This has popularized knock-off drugs sold widely on the Internet. Pfizer scientists evaluated products from 22 different websites and found that most contained less of the active ingredient than advertised. The U.S. Food and Drug Administration (FDA) has not approved the use of these drugs, and they could be dangerous. (Journal of Sexual Medicine, 11(suppl. 2): 133-135, 2014)


7) Psychological Stress Damages Testicular Cells

 Chronic stress suppresses sexual desire and saps energy levels. Chinese researchers, in a study on rats, found that five weeks of chronic stress interfered with normal mating behavior and decreased the size and number of Leydig cells in the testes. Leydig cells produce testosterone when stimulated by luteinizing hormone. Stress also caused abnormal sperm cells and decreased tissue density in the testes. Chronic stress is bad for your sex life. It clouds the mind with worry and doubt, and triggers significant tissue damage in the testes. (Journal Sexual Medicine, 11: 653-663, 2014)


8) The Autoblow 2: A Sex Toy for Men

 More than 95 percent of men and 90 percent of women masturbate regularly. Curiously, more women use masturbation toys than men. Vibrators for women have been around since the invention of the Tremoussoir in France in 1734. Today, more than 50 percent of women use vibrators to help them get off. High-quality masturbation toys have been almost non-existent for men, but things are changing. The Autoblow 2 ($160) is an industrial-grade, hands-free masturbator that incorporates realistic artificial skin and a high quality motor that will give you hundreds of hours of self-pleasure. It is just one of a series of new high tech sex machines for men that include the Venus 2000 ($1,000) and the Fleshlight LaunchPad ($29.95) that links a Fleshlight masturbator to an iPad and makes it easier to watch porn as you get off. (The Daily Dot, April 24, 2014)


9) Viagra Improves Muscle Oxygen Levels in Men with Blood Vessel Disease

 Intermittent claudication (IC) is leg pain, numbness and fatigue occurring in lower body muscles during exercise, particularly the calf muscles, due to blood vessel disease. The inner lining of the blood vessels produce a chemical called nitric oxide, which increases muscle blood flow during exercise. IC is partially caused by inadequate nitric oxide production. Brazilian scientists from the Federal University of Sao Paulo found that sildenafil (Viagra) improved skeletal muscle oxygenation during exercise in men with intermittent claudication but did not improve pain-free walking time or walking endurance capacity. Other studies have found that long-term use of Viagra improves nitric oxide metabolism in skeletal muscle, so the drug might have a training-like effect on muscle blood flow. (American Journal Physiology: Regulatory, Integrative, Comparative Physiology. 307: R396-R404, 2014)


10) Economic Hard Times for Hookers

 Prostitution was more lucrative in 1911 than it is today— according to an analysis in The Economist. Expressed in 2007 dollars, street prostitutes made $25,000 per year in 1911 but only 18,000 per year in 2007. High-end escorts made $430,000 in 1911 but only $200,000 in 2007. The root of the problem is supply and demand. In 1911, 69 percent of men paid for sex, but only 15 percent did so in 2007. The Internet or the hook-up culture didn’t exist 100 years ago. Most men prefer girlfriends, which are a lot easier to get in modern times. Working girls commanded more money in years past because of the negative stigma attached to the profession— they had to get paid for the social disgrace. On a positive note, prostitution is more business-like than before because escorts can set up dates and negotiate prices. (The Economist, March 22, 2014)


11) ADHD Medicines Can Cause Prolonged Erections

 Attention-deficit hyperactivity disorder (ADHD) is a common childhood problem in which kids have trouble concentrating, paying attention in school, and getting along with others. The problem is typically treated with drugs such as Ritalin, Concerta and Daytrana containing stimulants such as methylphenidate or amphetamines. Physicians are often reluctant to treat kids with these drugs because of the long-term danger of dependence. The U.S. Food and Drug Administration issued a warning that the drugs can also cause prolonged erections, a condition called priapism, which can cause permanent damage to the penis. The average age of kids experiencing drug-linked priapism was 12½. (Pharmaceutical Processing, published online December 17, 2013)


12) Chronic Stress Damages Cells in the Testes

Chronic stress decreases sexual motivation and desire. Chinese researchers, in a study on rats, found that five weeks of chronic stress exposure impaired the health of the Leydig cells, which secrete testosterone. Examination of the tissues with an electron microscope showed abnormalities in the cell membranes and evidence of cell death. Chronic stress damages critical cells of the testes that are responsible for normal sexual function. (Journal Sexual Medicine, published online December 20, 2013)