Niki Bezzant: Bacon and eggs don't mix

The consumption of too much processed meat can increase the risk of low fertility and cancer. Photo / iStock

Could your weekend breakfast be affecting your ability to conceive? It's possible, according to researchers at the Harvard School of Public Health, who say that bacon and ham might be best kept off the menu for men looking to boost their fertility.

The Harvard researchers released the results of a study that found that frequent consumption of processed meats may harm a man's ability to fertilise an egg.

The researchers found a link between frequent processed meat consumption and lower fertilisation among men participating in IVF. Among this group, men who ate the least amount of processed meats (fewer than 1.5 servings a week) had a 28 per cent better chance of achieving pregnancy compared to men who ate the most (4.3 servings a week).

That doesn't mean to say that your Sunday brunch is causing lowered fertility. Often studies like this are reported that way, and this was no exception — cue images of sizzling bacon and headlines like "Put that bacon down, blokes!"

But as with all research, we need to understand what is really being studied. This particular finding is an association only — more research would be needed to establish a cause-and-effect relationship between bacon and fertility. And scientists would need to look at other factors in the diet.

It could be that men who eat less bacon also eat more vegetables and drink less alcohol, for example. But the study raises interesting questions to add to what scientists already know about processed meat and our health. It is known that processed meats — bacon, ham, salami, cured sausages — are not great for us. They tend to harbour high amounts of salt and saturated fat. Even more concerning is the link between processed meat and cancer. The World Cancer Research Fund says there is "strong evidence" that processed meats are a cause of bowel cancer. That's because when meat is preserved by smoking, curing, salting or preservatives, cancer-causing substances (carcinogens) can be formed. These substances can damage cells, leading to the development of cancer. They recommend eating processed meats "as little as possible".

That means choosing meat in its fresh, unprocessed form is better. But it is also recommended that for cancer prevention, we keep our overall intake of red meat reasonable. The cancer research fund also says eating a lot of red meat is linked with bowel cancer. Here, though, the recommendation is to cut down rather than cut out the meat completely. Red meat is a good source of protein, iron and zinc, so meat-lovers can be assured they are getting benefits from their steak and chops.

It may be worth having a look at your portions, though. Meat-loving Kiwi blokes used to steaks that cover half the plate could be eating more meat than is healthy.

The fund says it's fine to include up to 500g of red meat a week as part of a healthy, balanced diet. That's cooked weight; the equivalent in uncooked meat would be about 750g, or just over 100g a day. Kiwis on average eat less than this and if we stick to a pattern of plant-based eating with some meat, a couple of fish meals and a couple of meat-free meals in our week, we're likely to stay within healthy limits.

A serving size of 125-150g (raw weight) of meat is about right, and fits with the "ideal plate" model, too. The size and thickness of the palm of your hand is about right.

As for the bacon butty: swapping chicken — or even better, vegetables — for bacon is a good idea. Keep the mixed grill for an occasional treat.

• Niki Bezzant is editor-in-chief of Healthy Food Guide magazine.