Diet and lifestyle to support immune function during the COVID-19 crisis

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  • Diet and lifestyle to support immune function during the COVID-19 crisis

I have been working with the Department of Reproductive Medicine at Leeds Fertility for a number of years and, together with Professor Adam Balen, I have developed a diet and lifestyle programme to support couples and individuals with fertility problems. When patients follow this programme, we see significant improvements in general health and clinical outcomes for those who are trying to conceive. This means improvement in symptoms such as regularisation of the menstrual cycle or reduced PMS, improved semen parameters so that men who have previously needed ICSI can undergo standard IVF treatment, improved outcomes from IVF, or natural conception following long struggles trying to conceive including miscarriage.

The interesting thing with fertility is that, unlike with illnesses such as cancer and cardiovascular disease, we have a relatively short-term outcome so that we can discover more quickly whether an intervention is working. These diseases also share common areas of biological dysfunction that can be a target for dietary and lifestyle interventions. Fertility problems in both men and women can be seen as a red flag for other health concerns later in life as the consequences of these impaired processes accumulate throughout life to the point they can cause life-threatening illnesses such as cancer. One example is chronic inflammation implicated in numerous conditions ranging from endometriosis, PCOS, obesity, diabetes and cardiovascular disease.

One important component of a woman’s ability to conceive is immune function. A woman’s immune function is altered during pregnancy in order for her to tolerate something genetically different growing inside her – something the immune system would normally reject. About a week after the egg is fertilised, a key event that is critical for a pregnancy to progress happens – implantation. Implantation is where the embryo embeds itself in the lining of the womb so the process of forming the placenta that links mother and baby throughout gestation can begin. It is also a point where immune function is particularly important in determining the fate of the pregnancy. In order for an embryo to implant in the lining of the womb, the endometrium functions selectively in order to allow good quality embryos to implant and reject those with chromosomal abnormalities. For this to happen, the immune system needs to be balanced in a state known as immune tolerance. When the immune system isn’t functioning optimally, the endometrium either fails to allow good quality embryos to implant or allows poor quality embryos in, leading to miscarriage. A hyper-inflammatory response is associated with implantation failure whilst a hypo-inflammatory response is associated with overly permissive implantation and recurrent miscarriage.  It is certainly possible that similar factors play a role in the Covid-19 in that the immune response needs to be strong enough to fight infection but without ravaging on full-throttle such that it starts to damage the body. You may have heard of the hyper-inflammatory “cytokine storm” that leads to multiple organ failure in some patients who suffer serious illness with Covid. Certain drugs targeting these pro-inflammatory cytokines are being trialled. Steroid drugs that suppress immune function to prevent healthy embryos being rejected are also the subject of ongoing research into treating recurrent miscarriage. We therefore may be able to draw on other parallels with fertility and pregnancy in terms of optimising the immune response and we believe our findings in terms of our patients is particularly relevant at this time.

In terms of our patients, when testing these young, usually fit couples, we invariably find a number of nutrient deficiencies. For example, almost everybody is deficient in vitamin D, which is essential not only for reproductive health but also many other aspects of general health including immune function. Most also have either a deficiency or sup-optimal zinc status. The ratio between zinc and copper is important in terms of preventing inflammation, with higher levels of copper compared to zinc being pro-inflammatory. Almost every patient we test has an impaired zinc:copper ratio. In additional to testing and monitoring response to supplementation, we also draw on the UK Annual Diet and Nutrition Survey, which repeatedly finds that a significant percentage of the population has poor intake and low serum levels of key nutrients. Where there are deficiencies and poor dietary intake across a range of nutrients, the cumulative effects are likely to compromise ability to fight infection. It is therefore likely that many could benefit from improving nutritional health, particularly at this current time of increased stress and limited access to fresh air and exercise.

We believe that focussing on diet and lifestyle during lockdown will not only help optimise fertility in both men and women but also will reduce the chances of becoming seriously ill with Covid-19. Optimising health whilst trying to conceive is also vitally important in order to protect the future health of the baby, as both male and female preconception health have been shown to have an impact. Life-long health starts before conception via environmental influences on the sperm and egg. Mothers’ diets in particular before and during pregnancy have long-term effects on the child’s development and the health risks of poor maternal diet later in life to the babies born include cardiovascular disease, obesity and mental health disorders. In terms of Covid, whilst improvements to diet and lifestyle won’t prevent you becoming infected, they will help you get in the best health possible for you to fight infection. We don’t have any evidence that particular diets or nutrients have specific benefits in terms of Covid because this is such a new virus, but we can draw on studies on other coronaviruses such as cold and flu and also our own work in Leeds in terms of the benefits of improving diet, lifestyle and nutrient status for general health. Deficiencies do increase the risk of becoming more ill with other infections and this is likely to be the case with Covid. Often studies look at individual nutrients or assess whether high doses of particular vitamin or mineral improves outcomes, but what we have found is that you simply need to ensure sufficiency of all nutrients to allow the body to function optimally. This is best achieved through diet but where there are deficiencies, especially if these have persisted over long periods, supplements are often needed to restore levels. This means that it takes a bit of detective work to figure out what you may need in the absence of testing. Repeated data from annual UK Diet & Nutrition Surveys show poor dietary intake of key nutrients, including the latest study (published in 2019), with a significant percentage of the population consuming below the Lower Reference Nutrient Intake (LRNI) value for the 11 nutrients surveyed (including zinc, iron and selenium) and a decrease compared to previous surveys including lower folate and vitamin A intakes and much lower blood folate levels. If you know you have been eating unhealthily for some time therefore, you are likely to benefit from short-term supplementation to give nutrient levels a boost and it may be that, at this time, a multivitamin and mineral is a good place to start.

Given the significant variation between individuals in terms of genetics, the microbiota (the “good” bacteria in the gut) and differing responses to the same foods, it is impossible to be prescriptive and offer exactly the same dietary advice to everyone. We can, however, apply certain principles that are likely to be helpful for most people in supporting underlying health and optimising immune function. The idea is that, if you take steps in a number of different areas, it allows you to fine tune the various biological systems so that the combined effects of individual changes build up to produce a bigger effect. Whilst some of these things may sound quite basic, taken together, they may make a difference and ensure the body is in the best health to be able to fight and recover from any infection.

  1. Vitamin D – official advice is to supplement with vitamin D during the winter months in the UK as our bodies can’t produce enough from sunlight and diet tends to be a poor source as food contains only low levels. Vitamin D is an important immune function regulator and being deficient may make you more at risk. A recent meta-analysis also showed that vitamin D protected against acute respiratory tract infection ( It is believed that seasonal fluctuations of vitamin D contributes to seasonality of other coronavirus outbreaks (cold and flu). Everyone should be supplementing with vitamin D at this time (we find our patients usually need at least 1,000 units/day during winter months depending upon starting levels – we test and monitor response to supplementation via re-testing). Various factors affect serum vitamin D status and uptake including gastrointestinal malabsorption and certain gene variants. These variants are likely to be subject to ethnic variation and, as well as vitamin D status itself, may contribute to the increased prevalence of severe infections in ethnic minorities in the UK and internationally. Our data shows that patients are more likely to respond to oral spray supplementation, with several patients including those of South Asian origin being resistant to high-dose oral vitamin D tablet supplementation prescribed by GPs but responding well to the oral spray we recommend. Only one or two individuals from a significant data set have failed to respond to the spray and a good compromise if you do not know you have responded to standard vitamin D tablets via repeat testing is to alternative daily between a spray and a tablet. This means you should be covered by one means or the other. Long-term vitamin D supplementation also needs vitamin A and vitamin K2 as co-factors for vitamin D to work effectively in the body. Vitamin D supplementation can reduce vitamin A in the body, which is also important for immune function, so intake of vitamin A-rich foods is important whilst supplementing with vitamin D (eg eggs, cheese, liver, oily fish, cod liver oil). Vitamin A plays a significant role in numerous aspects of immune function but excessive intake may be detrimental and should be avoided when trying to conceive and during pregnancy.
  2. Zinc – zinc is also important for immune function and everyone that we test is either deficient or has sub-optimal levels. Zinc deficiency causes humoral and cell‐mediated immune dysfunction and increases susceptibility to infectious diseases. Requirements tend to increase with age. A short-term course of 15mg/d ideally of zinc picolinate is likely to be beneficial for most people during viral outbreaks and/or prior to lockdown exit. It is not advisable to supplement with minerals in the long-term without professional supervision as with zinc, for instance, high doses can drive down copper and iron. Zinc is best taken with protein to improve absorption and away from carbohydrate and fat (eg chicken salad).
  3. Fruit and vegetable intake and the Mediterranean diet – the Mediterranean diet with good intake of vegetables, fish, lean meat, nuts, beans, olive oil and whole grains is most associated with good health. Junk food diets and western-style breakfasts have been shown to increase circulating pro-inflammatory compounds (including one called interleukin – IL-17), whilst the Mediterranean diet and plant-based foods boost anti-inflammatory interleukin 10 levels. Highly processed foods should therefore largely be avoided. Brassica vegetables (eg broccoli, cabbage, cauliflower, sprouts and kale) have been shown to reduce levels of F2-isoprostane (F2-iP) in urine, which is an indicator of oxidative stress in the body, and constitute a particularly healthy inclusion with significant evidence accumulating for their diverse protective effects. Berries have also been shown to contain active polyphenolic compounds that have numerous health benefits including immunomodulatory properties and capacity to positively affect composition and immune activity of the gut microbiota. Brazil nuts and chia seeds may also be beneficial as they are high in selenium and the Annual Diet and Nutrition Survey shows that many in the UK have a very low intake. Selenium deficiency affects the immune response and increases oxidative stress. Oxidative stress can result in viruses becoming more virulent in somebody who is deficient. Eat 2-3 brazil nuts daily or regular chia seed portions for sufficiency of dietary selenium intake. These are just some examples of the benefits of fruit, vegetables and nuts to our health, and there are similar benefits with most plant-based foods. Aim for 8 portions (3 portions of fruit and 5 portions of vegetables) daily – 5 a day is a basic minimum, not something to aspire towards.
  4. Dietary diversity – a diverse diet increases microbiota (“good” bacteria in the gut) diversity and research shows this is associated with improved markers of health including lower inflammatory markers and frequency of infection. The aim should be to eat 30 different types of vegetables per week and vary sources of protein (meat, fish, beans, pulses, eggs, dairy etc), fat and carbohydrate as much as possible. Whilst food availability has been affected recently, but we recommend as much variety as is possible within the constraints of the current circumstances.
  5. Probiotic foods – 70% of immune function resides in the gut and a healthy digestion is important for a healthy immune system. Probiotic foods may be beneficial in boosting the “good” bacteria and include plain live yoghurt, kefir, sauerkraut, fermented soya and kimchi. High intake of prebiotic foods (dietary fibre in vegetable form) and polyphenols (colourful foods) also supports a healthy microbiota.
  6. Vegetarians and vegans – usually need to supplement with B12, iodine, omega 3 and often zinc and iron to avoid deficiency.
  7. Stress – it is important to take steps to mitigate stress and worry where possible as stress can affect immune function – yoga, meditation and breathing exercises can all help. Being outdoors and in nature has also been shown to have positive effects, so seek out nature where you can, even if it’s via an open window.
  8. Exercise – if there is one wonder drug that improves all aspects of health, including mental health, exercise would be it. Moderate exercise supports good immune function with inactivity and excessive exercise both being potentially detrimental. The aim should be to get outdoors and exercise if at all possible, being aware of course of the current restrictions.
  9. Sleep – poor quality sleep impacts immune function so everyone should aim to get adequate, good quality sleep. Having a good sleep hygiene routine in place including having a cool, dark bedroom, avoiding stimulants such as caffeine after midday and excessive alcohol, avoiding screen-time 2 hours before bed and similar sleep-wake times each day will all help improve sleep quality. Your body loves routine and having set meal-times as well as sleep-wake times also supports the workings of your body clock, which is known to impact all areas of health.
  10. Vitamin C – although not conclusive, vitamin C supplementation has some evidence to support its use with studies showing reduced incidence of pneumonia in vitamin C supplemented groups, for instance. Certainly, short-term supplementation of around 500mg of vitamin C daily during viral outbreaks will not cause harm.

We believe that improving the diet and lifestyle of the nation is an important component of the national strategy until a vaccine is developed and will reduce the number of people becoming seriously ill and dying with Covid-19. We hope you can see this time as an opportunity to focus on your general health and fertility that will reap dividends in so many ways, not least in helping reduce the impact of any negative consequences on mental health if you are finding lockdown difficult.

If you’re trying to conceive naturally, we hope it will also help you to get pregnant. Do let us know, we would love to hear.

Love and best wishes from us all at Balance Fertility

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