Low-fat diets ‘lower men’s testosterone levels,’ study finds

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Low-fat diets can lower men’s testosterone levels – which can increase the risk of heart disease, diabetes and Alzheimer’s, a new study warns.

In a sample of 206 men, nutritionists at the University of Worcester found that low-fat diets reduced testosterone levels by an average of 10 to 15 percent.

The decrease in testosterone was even higher for men on vegetarian low-fat diets – up to 26 percent, the experts found.

Low-fat diets usually contain mostly whole grains, lean meats such as skinless chicken, fish, fruits, vegetables and legumes.

While these are healthy choices, the experts stress the importance of including fats in men’s diets, which are found in meat, nuts, and dairy products such as cheese and milk.

Men should ideally consume a lot of monounsaturated fats found in olive oil, avocados and nuts to boost their testosterone levels.

While fat is an essential part of a healthy, balanced diet, experts generally do not recommend consuming too much of their intake of saturated fats found in butter, fatty meats, and treats such as cakes and pastries.

Too much fat in your diet, especially saturated fats, can raise your cholesterol, the NHS points out, which also increases your risk of heart disease.

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Low-fat diets usually contain mostly whole grains, lean meats such as skinless chicken, fish, fruits, vegetables, and legumes

Low-fat diets usually contain mostly whole grains, lean meats such as skinless chicken, fish, fruits, vegetables, and legumes

Testosterone is the male sex hormone and is mainly produced in the testicles, but also in the adrenal glands, which are located near the kidneys.

Normal testosterone levels are essential for men’s athletic performance, mental health and sexual health.

LOW FAT DIET

People tend to opt for a low-fat diet to help reduce overall calorie intake and improve cholesterol levels to help them lose weight.

Low-fat diets usually contain mostly whole grains, lean meats such as skinless chicken, fish, fruits, vegetables and legumes.

If people on a low-fat diet consume dairy at all, it is usually dairy with a reduced fat content, such as low-fat milk and low-fat yogurt.

Other foods that are relatively high in fat include salad dressings, certain sauces, and pastry and sponge-based foods.

Source: Diabetes.co.uk

The researchers – who admit that dietary fat is a controversial topic in nutritional science – also found that men of European descent may experience a greater decrease in testosterone in response to a low-fat diet.

While the study suggests that low-fat diets appear to lower testosterone levels in men, further randomized controlled trials are needed to confirm this effect, according to the study’s lead author.

“Ideally, we would like to see a few more studies to confirm our results,” said Joseph Whittaker of the University of Worcester.

However, these studies may never come, normally researchers want to find new results, not replicate old ones.

“In the meantime, men with low testosterone would be wise to avoid low-fat diets.”

Higher testosterone levels have already been linked to a reduced risk of chronic disease and mortality.

In a 2007 studya team of researchers from the University of Cambridge reported a link between low testosterone and a high risk of cardiovascular disease.

However, the relationship between ‘endogenous’ testosterone (produced internally) and health in men is ‘controversial’, they said.

At the other end of the scale, high testosterone has also been linked to a slew of problems listed by Harvard Medical Schoolincluding low sperm count, an increased risk of heart attack and growth retardation in adolescents.

Since the 1970s, there has been a decline in men’s average testosterone levels and hypogonadism (medically low testosterone) has increased, the Worcester authors point out.

3D illustration of a testosterone molecule.  Testosterone is the male sex hormone and is mainly produced in the testicles, but also in the adrenal glands, which are located near the kidneys.

3D illustration of a testosterone molecule.  Testosterone is the male sex hormone and is mainly produced in the testicles, but also in the adrenal glands, which are located near the kidneys.

3D illustration of a testosterone molecule. Testosterone is the male sex hormone and is mainly produced in the testicles, but also in the adrenal glands, which are located near the kidneys.

A normal testosterone range – usually measured by a blood sample – is typically 300 to 1,000 nanograms per deciliter (ng / dL), according to the U.S. Food and Drug Administration, although specifications would vary by age.

For their study, the researchers combined the results of six well-controlled studies involving a total of 206 participants with an average age of 46 years.

These studies first put men on a high-fat diet, consisting of 40 percent fat, and then switched them to a low-fat diet (20 percent fat) to calculate the decrease in testosterone as a percentage.

The authors linked their results to similar studies in humans and mice, which are found that high intakes of monounsaturated fats can stimulate testosterone production.

TESTOSTERONE LEVELS IN HEALTHY MEN

Age

40-49

50-59

60-69

70-79

Testosterone

252-916

215-878

196-859

156-819

Testosterone levels displayed in nanograms per deciliter (ng / dL)

Source: ‘Male Testosterone: What’s Normal?’, Barrett-Conor, Clinical Endocrinology 2005

“The best fats for testosterone were monounsaturated fats and to a lesser extent saturated fat,” Whittaker told MailOnline.

Monounsaturated fats also reduce the risk of heart disease, so increasing monounsaturated fats is a safe way to boost your testosterone levels.

The best sources of monounsaturated fats are olive oil, avocados, hazelnuts and macadamia nuts.

“So men on a low-fat diet could increase their consumption of these foods to boost their testosterone.”

However, omega 6 polyunsaturated fats found mainly in vegetable oils can damage the cells’ ability to produce testosterone, the results suggested.

This is because highly unsaturated fats such as polyunsaturated fats are more sensitive to oxidation, which causes cell damage.

“From the results, polyunsaturated fats appeared to be the worst fats for testosterone,” Whittaker told MailOnline.

These are found in large amounts in vegetable oil commonly used in processed foods such as cakes and cookies.

“So to optimize testosterone, these fats / foods are best avoided.”

Red meat, meanwhile, contains monounsaturated fat, saturated fat, and zinc, all of which likely boost testosterone levels.

“There is some truth to the stereotype of masculine men who eat a lot of red meat,” Whittaker said.

“Grass-fed meat contains more monounsaturated fats than saturated fats, so it’s a safe way to boost your testosterone levels without increasing your risk of heart disease.”

The authors stated that further research should be done with a larger sample of men.

The main limitation of their study, published in the Journal of Steroid Biochemistry and Molecular Biologywas the low number of studies and small total sample size, they admit.

Nonetheless, the researchers in Worcester believe that the benefits of low-fat diets, such as reduced cholesterol levels, should be weighed against the potential downsides, such as reduced testosterone levels.

Traditionally, dietary guidelines have focused on limiting fat intake, while current UK and US guidelines limit fat intake to less than 35 percent of total calories.

Dietary fat is a controversial topic in nutritional science - proponents of high-fat and low-fat diets often disagree.  The NHS says people should eat and drink less high in saturated and trans fats and replace some of them with unsaturated fats.Saturated fats are those in milk, cheese, meat, butter, baked goods, cream and more

Dietary fat is a controversial topic in nutritional science - proponents of high-fat and low-fat diets often disagree.  The NHS says people should eat and drink less high in saturated and trans fats and replace some of them with unsaturated fats.Saturated fats are those in milk, cheese, meat, butter, baked goods, cream and more

Dietary fat is a controversial topic in nutritional science – proponents of high-fat and low-fat diets often disagree. The NHS says people should eat and drink less high in saturated and trans fats and replace some of them with unsaturated fats.Saturated fats are those in milk, cheese, meat, butter, baked goods, cream and more

However, as more research is conducted into the benefits of high-fat, low-carbohydrate diets, this traditional view is increasingly coming under scrutiny, the study authors said.

In recent years, diets high in fat have also been shown to lower triglycerides, lower blood pressure and increase HDL cholesterol (known as ‘good cholesterol’).

Another team of US researchers also reported earlier this year that eating foods rich in saturated fats, found in cakes, fatty meats such as bacon and cheese, can reduce the risk of acute pancreatitis.

The NHS says people should eat fewer foods and drinks rich in saturated fats and trans fats and replace some of them with unsaturated fats.

Saturated fats are those in milk, cheese, meat, butter, pastries, chocolate and cream and a lot more.

“Many researchers and nutritionists don’t think saturated fat is a major player in heart disease, although government guidelines still recommend limiting saturated fat,” Whittaker added.

“They eventually catch up with the investigation.”

SOURCES OF SATURATED AND UNSATURATED FATS

Saturated fat is a natural form of fat found in meat, butter and cheese.

It differs from unsaturated fat in the way that chains of fatty acids are linked together.

Eating a lot of saturated fat can raise cholesterol levels in an unhealthy way and increase the risk of heart disease.

This is because cholesterol builds up on the walls of the arteries, narrowing them and increasing pressure on the heart, while restricting blood and oxygen flow.

Foods high in saturated fat include:

  • Fatty red meats such as pork and beef
  • Butter and products made from butter, including pastries and pies
  • Pastries and biscuits
  • Cheese, cream and ice cream
  • Chocolate

The British Heart Foundation advises people to exchange saturated fats for unsaturated fats whenever possible.

  • Unsaturated fats are those found in:
  • Nuts and seeds
  • Fish such as salmon and mackerel
  • Vegetable oils, including olive oil
  • peanut butter
  • Avocados