Ask the Doc: Does eating nuts help male fertility?

The timing of this question couldn’t be better. A systematic review and meta-analysis of nut consumption and fertility has just been published in the medical journal ‘Advances in Nutrition’. A systematic review is a good way of collecting and examining all the research evidence about a particular topic, and a meta-analysis uses the published data from those studies to get an overall result.

There’s not a lot of research specifically about eating nuts and their effects on fertility, but it makes sense that there would be a beneficial effect. Nuts contain plenty of monounsaturated and polyunsaturated fats (think of these as ‘good’ fats) and not a lot of saturated fats (these are the ‘bad’ fats). They also have lots of protein, fibre, vitamins and minerals. Nuts are also part of a ‘Mediterranean diet’, which is associated with higher semen quality (see here and here) in male partners of couples seeking help for fertility.

The systematic review found only four studies, with two suitable for meta-analysis. These two studies (see here and here) involved participants either eating their usual diet, or their usual diet supplemented with nuts (either: 75g of walnuts per day for 12 weeks; or 30g of walnuts, 15 g of almonds and 15 g of hazelnuts per day for 14 weeks).

The studies didn’t actually measure fertility (the ability to conceive a pregnancy). They measured things like sperm counts, sperm movement and shape from semen analysis. These measures are almost always used to judge fertility, even though we know that “none of the measures, alone or in combination, can be considered diagnostic of infertility”. Ideally, researchers studying male fertility would measure whether men’s partners get pregnant or have children, but they hardly ever do that.

Men who had nuts added to their diets had more live sperm, with normal shape and movement than men who just ate their usual diets.

So, it looks like eating nuts can help male fertility.

When you think about the health benefits of eating nuts (especially if you eat them instead of less healthy foods), it’s probably a good idea to eat them regardless of whether you’re trying to become a dad. Unless you’re one of the 1-2% of people who have an allergy to nuts, of course.