There is no shortage of speculation about the causes of infertility and declining birth rates in industrialized countries. Although the Mayo Clinic says that most fertility problems aren't preventable, there are some lifestyle factors that put you at risk for low sperm count. For example, a high-sugar diet can contribute to obesity, which is linked to fertility problems.
In 1992, a study in the British Medical Journal, titled "Evidence for Decreasing Quality of Semen During Past 50 years," earned a lot of attention and plenty of disagreement, but its main idea was that men in industrialized nations have generally been producing fewer sperm, and the ones they are producing aren't quite as good as they used to be. The study did not attempt to explain the cause of the decrease.
According to the Mayo Clinic, there are a range of possible causes for low sperm counts, including poor health and obesity. Consuming excessive amounts of sugar contributes to many health issues, including obesity and type 2 diabetes. No one knows for sure whether high sugar is a direct cause of low sperm counts, or if it just contributes to other issues affecting fertility.
A 2009 study in Pharmacogenomics found a link between a sugar-mimic compound and reduced sperm counts. This compound is called an imino sugar, which has a different chemical structure from normal table sugar. It is so frequently tested that it is known to make rats and mice infertile. In 2002, the Proceedings of the National Academy of Sciences published a study suggesting that this sugar could have potential as a male contraceptive.
These highly controlled laboratory studies involved rats and mice, not people. Although imino sugars are the frequent subject of laboratory studies -- including human studies -- the research does not address regular table sugar and its effects on sperm count and fertility.
If you are trying to conceive a child, the Mayo Clinic advises following a healthy lifestyle. If you are struggling with excessive weight, which is a risk factor for infertility, look for ways to cut back on your refined-sugar intake. The research doesn't say for certain that eating less sugar will immediately increase your sperm count, but it will reduce your calorie intake to help manage weight. Even if it doesn't help your sperm count, reducing table sugar and managing weight will improve many other aspects of your health -- from blood pressure to diabetes risk.