How does diet affect fertility?

Nutrients and fertility 

A wide range of nutrients are important for your reproductive health and fertility. But there are a few nutrients that are particularly important, including:

• folate (folic acid)
• vitamin B12
• omega-3 fats

Folate (folic acid) and fertility

Folate is a type of B vitamin (vitamin B9). It’s often referred to as folic acid — the synthetic form of folate found in fortified foods and supplements. 

Folate plays an essential role in:

• making and repairing your DNA
• producing red blood cells — which carry oxygen around your body
• developing your baby’s brain and spinal cord during pregnancy — if there’s a problem with this development it’s called a neural tube defect (NTD)

A high intake of folate, particularly in supplemental form, has been linked to a lower rate of infertility and miscarriage in females. It’s also linked to:

• a better environment for a developing egg
• more successful infertility treatment 

In males, low folate levels have been linked to lower sperm count and motility.

Your body can’t build up a store of folate so you can become deficient in a matter of weeks. So it’s important to continuously get enough from your diet or from supplements.

Food sources of folate

Even if you take folic acid supplements, including folate-rich foods in your diet is a good idea. These foods are full of other nutrients and are good for your overall health. Foods high in folate include:

• leafy, green vegetables — for example, spinach, kale, broccoli, cabbage, and Brussels sprouts
• beans, peas, and lentils
• eggs
• shellfish
• beetroot
• oranges
• whole grains

Should you take a folic acid supplement?

A folate deficiency in the first few weeks of pregnancy (when many people don’t know they’re pregnant) can lead to a NTD. As a result, national guidelines recommend women take a daily 400 mcg folic acid supplement if trying for a baby and up until 12 weeks of pregnancy.

If there’s a higher risk of NTDs developing, a daily dose of 5 mg might be recommended by your doctor.

Note that folic acid supplements can mask a vitamin B12 deficiency — another key nutrient for fertility. This is because it can improve your symptoms so much that they’re not noticeable. Speak to your doctor if you’re concerned about this or check folate levels at home with a vitamins blood test.

Vitamin B12 and fertility

Vitamin B12 is essential for:

• red blood cell production
• DNA synthesis
• a healthy nervous system and heart
• the development of a baby’s brain and nervous system during pregnancy

Research shows that a higher intake of vitamin B12 is linked to a lower risk of ovulatory infertility — when issues with ovulation prevent you from getting pregnant.

A vitamin B12 deficiency can sometimes lead to temporary infertility in females. But this usually resolves itself if you treat the deficiency. In males, vitamin B12 might help support your sperm quality. 

Food sources of vitamin B12

Foods rich in vitamin B12 include:

• organ meats — but avoid too much organ meats if actively trying to get pregnant (contain a lot of vitamin A which can cause miscarriage or birth defects)
• beef
• fish — like clams, sardines, salmon, and tuna
• milk and dairy products
• eggs

Vitamin B12 is only naturally available in meat, fish or dairy. But there are fortified plant-based sources of vitamin B12 like:

• fortified milk alternatives
• fortified cereals
• fortified nutritional yeast

Should you take a vitamin B12 supplement?

If you’re at risk of developing a vitamin B12 deficiency like if you’re vegan or have coeliac disease, you might need to consider a supplement. 

Omega-3 fats and fertility

Omega-3s are are a type of unsaturated fat. They’re essential for brain development, cell structure, and hormone production.

Along with supporting hormone production, omega-3s might:

• improve egg quality
• delay ovarian ageing
• improve sperm motility
• reduce the risk of pregnancy complications — like preterm birth 

During pregnancy, omega-3s also help to build the structure of your baby’s cells. And if you’re not getting enough omega-3s from your diet, your stores will drop in order to provide it for your developing baby. So it’s important to make sure you’re getting enough before and during pregnancy.

Food sources of omega-3s

Oily fish, like salmon, trout, mackerel, tuna, and sardines, is one of the best sources of omega-3s. It’s recommended that you aim to eat 2 portions a week. 

During pregnancy, you should avoid certain types of fish as they’re high in mercury, including:

• shark
• swordfish
• king mackerel
• marlin
• bigeye tuna 

There are some plant sources of omega-3, like flaxseeds, chia seeds, walnuts, and hemp seeds. But your body finds it harder to use this type of omega-3 (ALA). 

Should you take an omega-3 supplement?

If you’re vegan, vegetarian, or don’t eat a lot of fish you might consider taking an omega-3 supplement. Aim to get an omega-3 supplement with both EPA and DHA — the most important forms of omega-3.

If you have a bleeding disorder or take blood-thinning medication, like warfarin, talk to your doctor before taking an omega-3 supplement.

Diet and fertility

Looking at whole foods, oily fish, whole grains, and vegetables seem to have a positive effect on your fertility. The Mediterranean diet is particularly high in these foods — which is likely why this diet is linked to improved fertility.

While eating too much-saturated fats and foods high in processed sugars might have a negative impact on fertility.

Should you take a fertility supplement? 

Eating a wide range of nutritious foods is the best way to get the nutrients you need — with folic acid being the exception if actively trying to get pregnant. But, if you’re worried you’re not getting enough of the nutrients that support your fertility, a supplement might help. 

It’s a good idea to speak to a health professional who can guide you on the best supplement for you.

Supplements for female fertility

A prenatal supplement will usually include a range of nutrients that are important for both fertility and the early development of your baby in pregnancy, like:

• folic acid
• vitamin D — all adults should consider a 10 mcg vitamin D supplement from October to April
• vitamin C
• omega-3 fats
• iron
• calcium 

It’s best to find a supplement that doesn’t contain more than your recommended daily amount — so you don’t have too much of a nutrient. Also, make sure the supplement doesn’t contain high doses of vitamin A (which can be harmful to a developing baby).

Supplements for male fertility

Some evidence suggests that antioxidant supplements, like vitamin C and E, might be beneficial for males who are having fertility issues.

If you have a build-up of harmful molecules called free radicals it can lead to oxidative stress — causes damage to your cells. Antioxidants help prevent these free radicals from damaging your cells.

Because sperm have been shown to be highly susceptible to oxidative damage, there has been a lot of interest in antioxidant supplements and sperm quality. And early research indicates that they might improve sperm motility. 

There are also a lot of foods rich in antioxidants — like fruit, vegetables, nuts, and whole grains.