You can give your libido a boost by choosing the right foods for breakfast. Photo / Getty Images
Many factors can affect sex drive, including relationship issues, stress or tiredness.
Diet too can have a direct effect on the hormones which drive whether you're in the mood for intimacy.
According to a nutritionist, you can give your libido a boost by choosing the right foods for breakfast and ensuring they're packed with vitamin D.
Studies show that people across the UK are chronically deficient in this nutrient – which can cause low oestrogen in women and reduced testosterone in men, reports the Daily Mail.
It's estimated that a staggering one in five British adults do not have adequate levels of "the sunshine vitamin".
Rob Hobson, head of London-based Healthspan Nutrition, recommends eating mushrooms, fortified breakfast cereals, mackerel and eggs for breakfast to help boost vitamin D levels.
He said: "I usually say diet comes first when it comes to getting all your nutrients. But vitamin D is actually very difficult to get from diet alone.
"Very few foods contain vitamin D. The main source is oily fish and a little can be found naturally in eggs and mushrooms.
"You can also find vitamin D in fortified foods such as breakfast cereals and margarine spreads.
"Additionally, our recent research found that Britons are living a mole-like existence – seeing an average of less than 10 hours of daylight a week during the winter months.
"So it's difficult to get vitamin D from diet and sun exposure alone, especially in the winter, so taking vitamin D supplements is recommended.
"Public Health England recommends everyone gets a daily intake of 10mg."
Below explains why these breakfast foods are good for you.
Oily fish like mackerel
Fish has been touted as an excellent source of vitamin D, especially oily fish including salmon and mackerel.
According to nutritional databases, mackerel provides 360IU per serving while salmon has up to 685IU of vitamin D.
But be aware that farming methods can impact on how much the fish contains.
A study by Boston University Medical Cente in 2009 found that farmed salmon had approximately 25 per cent of the vitamin D content as wild salmon.
Fortified breakfast cereals
Some popular cereals such as Kellogg's Special K are fortified with vitamin D.
You can boost your levels further by having your cereal with fortified dairy or soy milk and a glass of orange juice.
Eggs – go for free range
While most of the protein in an egg is found in the egg white, the vitamins and minerals are found primarily in the yolk.
A typical egg yolk contains around 18 to 39IU of vitamin D, which isn't very high.
However, eggs from chickens that roam outside in the sunlight have three to four times the amount, according to 2014 research by Martin Luther University of Halle-Wittenberg in Germany.
Furthermore, those from chickens fed with vitamin D-enriched feed have levels up to an astounding 6,000IU of vitamin D per yolk, Iowa State University reported in 2013.
Therefore, buying eggs that are from free-range chickens or marketed as high in vitamin D can be a great way to help meet your daily needs.
Excluding fortified foods, mushrooms are the only plant source of vitamin D.
However, it's worth noting that mushrooms contain vitamin D2, whereas animal-based food produce contains vitamin D3.
Although vitamin D2 is thought to help raise blood levels of vitamin D, studies have suggested it may not be as effective as vitamin D3.
Nonetheless, wild mushrooms are a good sources of vitamin D2. Some varieties contain up to 2,300IU per 3.5oz (100g) serving, according to a 2013 study published in the journal Food and Chemical Toxicology.
However, commercially grown mushrooms are often grown in the dark and contain very little vitamin D2.
Yet there is one simple trick you can do to boost your shop-bought mushrooms, according to Penn State University. Popped on a sunny windowsill, the mushrooms will react to the UV light, and produce more antioxidant Vitamin D.
Astonishingly, researchers found in their experiments that white button mushrooms containing essentially no Vitamin D which were exposed for just one second could then contain 824 per cent of your daily value.
VITAMIN D AND LIBIDO
Research has suggested that vitamin D plays a role in libido in both genders.
An Austrian study published in Clinical Endocrinology journal found testosterone is boosted by it.
The analysis of 2,299 men found those with enough of the vitamin had more of the male sex hormone than those with less.
Blood levels of both dipped in the winter and peaked in the summer, said the team from Medical University of Graz, Austria.
A study published in the journal International Urology and Nephrology found women with female sexual dysfunction had lower levels of vitamin D in their blood.
Based on 50 premenopausal women, the research, by Şişli Etfal Training and Research Hospital in Istanbul, suggested the vitamin was linked to low desire, arousal, lubrication, orgasm and satisfaction and pain.