Jump to: Three ways to have the best fertility diet | Eating a whole food lower-carb diet | Losing weight | Boosting your intake of vitamins C, E, and B | Take home message
Many factors influence your fertility levels, your chances of pregnancy, and your likelihood of having a successful live birth; some key factors include the level of exposure to chemical pesticides, the state of your mental health, genetics, and whether you’re living with chronic conditions like polycystic ovarian syndrome (PCOS).
While there are many factors outside of your control, there are changes to your lifestyle you can make that may increase your fertility and your chances of a successful pregnancy. Two main issues facing women with infertility are insulin resistance and higher levels of oxidative stress.
Insulin is a hormone that plays a crucial role in our metabolism; when our body is insulin resistant, the levels of insulin in the body rise, which can disrupt the balance of reproductive hormones in females.
Oxidative stress is an imbalance of molecules known as ‘free radicals’ and antioxidants in the body. When the levels of free radicals are too high and antioxidants too low, this can harm your fertility.
Fortunately, there are ways you can lower your insulin resistance and oxidative stress and improve your fertility through diet and nutrition.
Three ways to have the best fertility diet
1) Eating a whole food lower-carb diet
There’s good evidence that diets based on whole foods and lower in carbohydrates (around 30-40% of your intake) can reduce insulin resistance and improve the balance of hormones essential in supporting the health of your ovaries.
Find an NHS-backed low-carb meal plan here.
2) Losing weight
While a whole-food diet can lead to improvements in health without weight loss, there’s good evidence to suggest that losing excess body fat – particularly the fat stored in and around your internal organs – can help improve the health of your ovaries and fertility by reducing chronic inflammation, oxidative stress, and insulin resistance.
Click here for our tips on weight loss.
3) Boosting your intake of vitamins C, E, and B
One of the clinical signs of infertility is higher levels of inflammation and oxidative stress in the body, particularly within the reproductive system. Vitamins C and E are potent antioxidants that help reduce oxidative stress in the body. Consuming food such as peppers, broccoli, sunflower seeds, and almonds can help to boost your intake.
Your body also produces anti-oxidants through various chemical pathways requiring B vitamins to function correctly. Consuming foods rich in B vitamins, such as salmon, dark leafy greens, and liver, will help boost your body’s antioxidant capacity, which has been associated with better ovarian function.
At Second Nature, you’re supported by a registered nutritionist or dietitian to provide you with personalised support on your nutrition. While we can’t guarantee this will boost your chances of conception, we can ensure it will improve your overall health and well-being.
Click here to take our health quiz and join over 150,000 members like Carla, who’s hopeful that the changes she’s made on Second Nature will boost her chances of pregnancy.
Otherwise, keep reading as we delve into the science of how nutrition can help reduce insulin resistance and potentially increase your fertility.
1) Eating a whole-food lower-carb diet
Lower-carbohydrate diets have become more popular over the past decade as evidence has shown they can positively affect type 2 diabetes and lead to sustained weight loss. One of the underlying reasons lower-carb diets can be beneficial is their role in reducing insulin resistance.
Insulin resistance promotes the excess production of hormones known as androgens, like testosterone. When these levels are too high, it can harm fertility and the likelihood of a successful pregnancy.
A clinical study compared the effect of a lower-carb diet (which contained 41% of total energy from carbohydrates) to a standard high-carbohydrate diet (where carbohydrate intake was 55% of total energy intake) on markers of insulin resistance and reproductive hormones such as testosterone.
Both groups lost a small amount of weight (1.3kg & 1.66kg) and saw improvements in insulin resistance. Interestingly, the lower-carb group was almost twice as effective at lowering insulin resistance and decreased testosterone levels by 24.5%. Compared to the high-carb diet, which did not affect testosterone levels.
Similarly, a meta-analysis (a study comparing many studies on the same topic) looking at the impact of lower-carb diets on women living with PCOS found a positive effect of lower-carb diets on insulin resistance and testosterone compared to low-fat diets. Particularly those lasting more than four weeks.
Another meta-anaylsis showed similar positive results but acknowledged that most studies in this area had been conducted on women living with PCOS, so it’s difficult to know whether the positive effects of a lower-carb diet will translate to women without PCOS who have low fertility.
Still, there are positive signs that a whole-food diet lower in carbohydrates improves insulin resistance and other health markers linked to our reproductive system.
Key points
- Whole food lower-carb diets have been shown to have a positive effect on reducing insulin resistance.
- Insulin resistance can lead to excessive release of testosterone, which can lower fertility.
- Clinical studies have shown that lower-carb diets improve insulin resistance and markers of reproductive health in women with PCOS.
- However, less research has been conducted on women with low fertility who aren’t diagnosed with PCOS.
2) Losing weight
While there’s good evidence that a healthy diet will improve your health and fertility without weight loss, there’s also evidence to suggest that losing excess body fat can positively impact your health and fertility.
Observational studies have shown an association between weight and rates of pregnancy, live birth rates, and time to pregnancy during IVF treatment. There’s also an association between BMI and the levels of a hormone called AMH, which predicts the number of ovarian follicles – a key marker of fertility.
This might be due to the relationship between our fat cells, insulin resistance, and inflammation. Insulin resistance can lead to excess visceral fat levels (the fat stored in and around our internal organs), which releases pro-inflammatory proteins into the bloodstream, promoting more insulin resistance and disrupting our hormonal balance.
Insulin resistance can also increase fat cell size in your subcutaneous fat (the fat stored beneath your skin). When this happens, these fat cells become dysfunctional and release pro-inflammatory proteins into the bloodstream, worsening insulin resistance and disrupting hormone balance.
This was demonstrated in a randomised controlled trial in 49 women comparing the effect of a weight loss intervention before fertility treatment to a control group where the participants completed the fertility treatment only.
The participants in the weight loss group underwent 6 weeks of a low-calorie diet to induce weight loss, followed by 6 weeks on a weight maintenance diet.
The study showed that participants in the weight loss intervention – who achieved an average weight loss of 6.6kg compared to 1.1kg in the control group – had higher pregnancy rates (48% vs 14%), live birth rates (44% vs 14%), and fewer cycles of IVF to pregnancy (two vs four) compared to the control group.
Contrastingly, two large randomised controlled trials with over 800 women have shown very different results. The participants in both trials underwent a lifestyle programme lasting between 12-16 weeks before undergoing fertility treatment; whilst following a very low-calorie diet (1200/day).
Despite significant weight loss in both trials, the results showed no difference in pregnancy and live birth rates compared to the control groups who completed fertility treatment only.
This seems counterintuitive. However, it’s possible that as there was no period of weight loss maintenance in the larger trials, the participant’s bodies were under more stress due to the strict dieting regime. This may have had an impact on their ovarian function.
During severe caloric restriction, the body enters into a phase known as ‘metabolic adaptation’ that lowers energy expenditure, disrupts the balance of our reproductive hormones, and can affect ovarian function.
Animal research has found that calorie restriction can reduce fertility by affecting ovarian follicle development. However, after a period of weight maintenance, there’s an improvement in ovarian function compared to the baseline (before weight loss).
It’s possible that losing excess body fat and improving insulin resistance in the long term enhances fertility and your chances of conception, but trying to conceive during or immediately after a period of rapid weight loss and strict calorie restriction may harm your chances of pregnancy.
So losing weight sustainably can help your body burn off excess visceral fat and reduce the size of your subcutaneous fat cells, lowering your insulin resistance and likely helping your hormonal balance return to healthy levels.
Three ways to help you lose weight sustainably
- Eat a whole food lower-carb diet: see above.
- Eat until you’re comfortably full: find our hunger scale here.
- Eat three balanced meals a day: find an NHS-backed meal plan here.
Key points
- Observational research has shown an association between weight and pregnancy rates, live birth rates, and time to pregnancy. There’s also an association between weight and markers of ovarian health.
- Losing excess body fat can improve your health by reducing the amount of visceral fat, and reducing the size of your fat cells in your subcutaneous fat, which lowers insulin resistance.
- Small clinical trials looking at weight loss and maintenance show improvements in pregnancy, live birth rates, and time to pregnancy during IVF treatment.
- Two large trials showed no impact of weight loss on pregnancy and live birth rates, but this might be due to the strict weight loss regime prior to IVF treatment.
- Losing weight sustainably may increase your chances of pregnancy, while going on a strict diet and trying to lose weight too quickly may harm your chances.
3) Boosting your intake of vitamins C, E, and B vitamins
While eating a healthy balanced diet will naturally lead to increased levels of these vitamins and improve your body’s anti-inflammatory and antioxidant pathways, research suggests that boosting your intake of these micronutrients can increase your body’s antioxidant defences and help to regulate the female reproductive system.
Vitamins C and E are natural antioxidants that help support the body reduce levels of oxidative stress.
A clinical trial in women living with endometriosis (a condition of excess tissue growth in the ovaries and fallopian tubes) found that a daily supplement of vitamins C and E for 4 months reduced levels of oxidative stress and increased pregnancy rates compared with the control group (19% vs 12%).
As this study was small and in a population of women with a specific condition, it’s unclear what impact supplementing vitamins C and E would have on women without a chronic illness with low fertility. However, as it’s unlikely to cause harm, it could be a safe and viable option for women looking to conceive.
B vitamins play an important role in what’s known as the ‘one-carbon cycle’. The one-carbon cycle is the process by which the body produces antioxidants to maintain a healthy balance of oxidative stress within the body’s cells, particularly those in our reproductive system.
Observational studies have shown an association between higher folate (vitamin B9) intake – particularly from supplements – on ovarian function and the number of ovarian follicles. Folate also seems vital in ensuring the quality of your ovarian eggs (oocytes).
Correspondingly, a clinical trial investigated the impact of a supplement rich in B vitamins on the levels of AMH (a hormone linked to ovarian function) in infertile women who’d previously failed to conceive despite two cycles of fertility treatment.
The results showed average AMH levels rose by 40%. Surprisingly, 8 of the 49 women in the study became pregnant for the first time. This suggests that a high intake of B vitamins, particularly through the support of supplementation, may improve fertility and lead to a higher chance of conception.
If you’re a vegan or vegetarian, you may already have a low vitamin B12 intake, which has been shown to positively impact fertility and chances of pregnancy. We’d recommend a daily B12 supplement if you’re eating a plant-based diet.
How to boost your intake of vitamins C, E, and B vitamins
- Vitamin C: Peppers, broccoli, strawberries, citrus fruits, or supplements.
- Vitamin E: Sunflower seeds, almonds, hazelnuts, rainbow trout, or supplements.
- B vitamins: Salmon, dark leafy greens, liver and other organ meats, milk, eggs, and supplements.
Key points
- There’s good evidence showing an increased intake of vitamins C, E, and B vitamins can help fertility.
- They work by reducing oxidative stress that supports the reproductive system function.
- Vitamins C and E act as natural antioxidants to reduce oxidative stress.
- B vitamins support the body’s ‘one carbon cycle’ which produces antioxidants and lowers oxidative stress.
- Folate (B9) supports the production of healthy eggs.
- Boost your intake of these vitamins through your diet or through supplementation.
- Supplementation is a safe and affordable option alongside a healthy diet.
- Vegans and vegetarians should be taking a daily B12 supplement.
Take home message
Female fertility is a complicated puzzle, and many more factors will determine your chances of getting pregnant than your diet alone.
However, there’s good evidence to show that improving your diet and nutrition can reduce your insulin resistance, lower oxidative stress in the body, and enhance the function of your reproductive system.
While there are many uncontrollable factors during your attempts to conceive, this is one area you can own to give yourself the best possible chance for a successful pregnancy.
