Globally, approximately 15% of couples of reproductive ages are seen as infertile
and rather more show fertility problems. The extent to which
nutrition can play a role in this has been investigated in many studies.
However, studies in this field are often of low-quality. The randomized
clinical trials were often carried out with small groups of
participants and had different designs - partly with nutritional supplements
and partly with different nutritional questionnaires.
In recent years, more dietary factors have been studied more specifically.
But here, too, more comprehensive data and more complex analyses are needed to
be able to make precise statements.
Generally, it can be said that the dietary
recommendations, which are also made for the prevention of “civilization diseases”
and for the promotion of
health, in the same sense improve some fertility conditions of women and men.
In the following, I highlight a few points that showed a clearer
correlation in positive or negative context. In general, however, it must be
emphasized that there are certainly always several factors interacting, just as these topics have already been dealt with in previous
lesson units – e.g., the quality and combination of food, the
pollution and production conditions, etc. – see previous teaching
letters)
Since one knows that the healthy and optimal conditions cannot be achieved
by single nutrients or supplements, but in numerous studies the effects
regarding fertility relationships, in both women and men, have been
investigated by looking on single substances or dietary supplements, such study
designs are not suitable from the outset to cover all important aspects. Such
study concepts cannot analyze the natural food conditions, since many thousands
of substances interact with the diet and there are thus so many variables that
do not allow it to define precisely, which particularly promotes the desired
effect.
In prospective case-control studies with the use of defined doses of a
selection of nutrients (to maintain clarity and correlation determination), one
can better guess possible interactions, but even these cannot capture the complex
interaction of the thousands of nutrients of a healthy diet. The studies are based on pharmacological
concept, on a design that wants to determine and define effects on specifically
used mono substances or only few interacting substances. Nature, however, does not work in this way.
Despite these immanent difficulties, I give in this teaching letter an
insight into data obtained on the question of better pregnancy planning or
reduction of infertility in the context of nutrition. However, you should
always be aware that, as mentioned, many more factors can play decisive
roles and that the supplementation of single substances or also multivitamin
preparations is generally not a solution and may have at most occasionally only
a limited support.
Generally, and with limited expressiveness (reduced
significance), the following can be observed about better fertility: A
healthy diet that provides a good supply of omega-3 fatty acids and
phytochemicals (secondary plant substances) as well as vitamins (more
frequently were studied, cryptoxanthin, lycopene, β-carotene, vitamin E,
vitamin C, vitamin D, vitaminB9 (folate) selenium and zinc,) In
contrasts fertility was reduced by: diets
rich in processed meat (e.g. sausage products) and especially red meat, as
well as full-fat dairy products, fast carbs (rapidly
absorbable sugars) especially
sugar-sweetened beverages and sweets, and alcohol. |
In the
past, soya and dairy products were described as detrimental to fertility.
Better research does not prove this link. In the contrary soya
and soybean products seem to have benefits in women
in therapeutic infertility treatment.
Also, the consumption of moderate doses of coffee
as well as even small doses of alcohol does not seem to have any disadvantages
in terms of fertility. Here, too, attention should always be paid
to the entire diet and consumption of semi luxury food, since, if the diet is
already poor and other risk factors, even a small dose of alcohol can cause
disadvantages. It should always be thought and analyzed more
"holistically".
Antioxidants, Omega-3 fatty acids, Vitamin D
It is commonly written that antioxidants improve fertility. The administration of antioxidants as food supplements was
occasionally seen to improve sperm quality; for the better fertility of
the woman, this did not show a significant benefit.
Note: Also,
with regard to antioxidant effects (e.g., by foods containing
abundant phytochemicals and thus also antioxidant vitamins in the natural
matrix of foods) the benefit cannot be limited to the biochemical antioxidant
effects; these nutrients always develop many other important functions at the same
time. In addition, based on the study results it is not possible to define
which antioxidants are responsible for the benefit or which doses are responsible for this benefit.
This is explained by the fact that the synergic interaction of the many
substances is needed, and individual substance analyses are not so meaningful.
Thus, antioxidant preparations are partly helpful, but partly not. Biology
shows the need of the natural matrix and complex biochemical reactions
catalyzed by many different substances!
If one nevertheless wants to make statements about individual substances,
one can determine the omega-3 fatty acids and the folic acid as a
mono-substance with a probable benefit in terms of fertility.
The extent to which omega-3 fatty acids can potentially benefit from
the consumption of fish and seafood must be considered as a benefit-risk
assessment if there is a risk of higher heavy metal pollution (e.g.,
mercury in some marine animals). The risk here does not only concern successful
fertilization, even after that there is a significantly higher risk for e.g. an
abort (heavy metals such as mercury pass through the placenta and develop on
the fetus a 5-10times higher toxic effect compared to adults).
The additional folic acid intake (also as a supplement), which is
above the dose of 400-450 g/day, as it is an evident recommendation for the
prevention of spinal malformation (Spina Bifida with neural tube defects),
seems to increase fertility in women.
Since folic acid doses up to 800 g/day are recommended
anyway, if the early enough supplementation for the prophylaxis has been missed
at least with 400 g folic acid /day minimum one month before pregnancy, and the
higher dose did not show increased risks *, an intake approximately of 600
µg folate/day (in total from food and supplementation) can certainly be
recommended in pregnancy planning.
*a link with increased cancer risks, as in animal
experiments, could not be substantiated in humans.
Although vitamin D is known to have much more important functions
than previously researched mainly in terms of "bone health"; and although
animal studies have seen links to better fertility, for humans studies vitamin
D no benefits for better fertility were shown if there is no deficiency for
vitamin D.
In the case of vitamin D deficiency, which in any case comes only to a small proportion from the usual diet, but via the production in the skin during sun contact, vitamin D should be supplemented.
Of course, there should also be no insufficient supply of other nutrients (e.g.,
proteins, fatty acids, long-chain carbohydrates, phytochemicals, vitamins, fiber,
etc.), as there may always be disadvantages for various organ functions from
the deficiency situations, which also play a role in fertility. Just as the slogan about nutrition during
pregnancy is true “not twice as much, but twice as good” applies, so does this
already apply to better fertility.
The many effects of nutrition and the consumption of luxury foods are far
from being fully analyzed, but many points can nevertheless show plausible,
which can be rather disadvantageous or rather beneficial. In the same sense,
this can be explained in the context of fertility.
Orientated, the so-called “Mediterranean Diet” (lots of vegetables
and fruits, fish, legumes, herbs, whole grains, healthy vegetable oil such as
olive oil) is good!
The intake of excessively high vitamin doses should also be avoided
(especially vitamin A and especially isolated high dose vitamins in
preparations or nutritional supplements), as these can damage the fetus. An
exception to supplementation is folic acid (folate or Vitamin B9). To
ensure adequate folic acid supply and to avoid spina bifida malformation in the
child, a higher intake of folic acid should take place at least already one
month before fertilization (for safety as a supplement of at least 400µg/day).
As mentioned above, a higher intake of folic acid may also increase fertility.
In addition to nutrition, other lifestyle factors, such as sufficient
physical activity, avoidance of pollutants, reduction of stress and increasing
resting time periods (work life balance) should promote health and thus fertility.
Avoiding obesity and achieving normal weight even before
pregnancy is another especially
important factor, as with greater overweight, many risk factors for the mother
and child can increase during pregnancy and persist beyond that (see the
article about Gestational Diabetes).
At least, women who are planning a pregnancy should be very careful when
taking medication (always consult your gynecologist or other doctor).
Summary
In summary, it can be said and plausibly explained that, also in context of better
fertility for both women and men, is important
• a balanced,
healthy diet, as recommended in the food pyramid.
• The good
composition with a clearly predominant vegetable content.
• Vegetable foods
with a great variety of flavors and colors (great diversity - goal: at
least red-yellow-green fruits and vegetables daily), which ensures the supply
of phytochemicals (secondary plant substances), plays an important key role.
• Plenty of
pulses and salads as well as culinary herbs complement the recommendation
of at least “5 servings of vegetables and fruit a day” (3 vegetables and 2
fruit).
• In addition, there
should be a supply of good fatty acids and good protein sources, which
is why white, low-fat meat (poultry meat) and even better fish
(especially the smaller sea fish that come from non-polluted seas) -
via such cold sea fish (herring, salmon, cod), the bioactive forms of omega-3
fatty acids (DHA and EPA) are well supplied - if supplementation is
required, oils from special microalgae are good vegan DHA and EPA
sources.
• In all these
points, attention should always be paid to the quality, which concerns
the avoidance or reduction of pollutants (the dose makes the poison) and
the hygienic, transport and storage conditions.
• Sufficient
physical activity and avoidance of obesity (with its higher risk of
diabetes and other diseases) must always be considered; the nutritional effects
(risk factors or protective factors) cannot be seen separately from physical
activity and weight management.
As we can see, it
is always the same multifaceted interacting factors that are naturally
important for the human organism and that play important key roles when
considering special functional areas - such as better fertility ratios here.
For some people, therefore, only single areas need to be optimized (with low deficits or a few unfavorable conditions); for others, several interventions or optimizations are required, some of which can only be achieved with extended therapeutic measures.
In addition to lifestyle factors, success can always
depend on individual genetic constitutions. The lifestyle factors play
important roles for the basic requirements of well-functioning organs and
homeostasis (balance of physiological body functions) e.g., blood flow and
metabolic conditions as well as immune reactions and numerous protective
mechanisms.
Lifestyle factors, such as the diet and physical
activity, even have epigenetic effects (they can modify gene functions -
i.e., for example, mute some “risk genes” (gene silencing) or strengthen
"repair genes").
Prof. Dr. Werner Seebauer is Dean of Studies – Association of German Preventologists, Head of Preventive Medicine Department of Institute of Transcultural Health Sciences (European University Viadrina) and Head of Preventive Medicine – NESA (The New European Surgical Academy). Since 2000, prof. dr. Werner Seebauer worked only in preventive medicine, after ten years spent at the Frankfurt University Hospital. He is also involved in the medical professionals training for nutrition and prevention.