Although weight-loss diets traditionally suggest avoiding foods with too much fat, there are good and bad types of fat. Nearly all modern dietary guides encourage eating moderate amounts of good fat, both for weight loss and general health. Researchers generally consider CLA a healthful fat.

The main dietary sources of CLA are dairy products and beef. People believe that this particular fatty acid has a range of health benefits. However, while CLA seems to be safe, researchers disagree about its benefits for health.

In this article, we take a close look at the uses, benefits, and risks of CLA in the diet and in supplements.

What is conjugated linoleic acid?

A person can include CLA in their diet or take supplements.

CLAs are a family of fatty acids originating in animal products, including meat and dairy. CLAs contain omega-6 fatty acids. They are polyunsaturated fat, which the American Heart Association (AHA) say can have beneficial effects on the heart.

CLAs are also technically trans fats, which, in most cases, are unhealthful fats. However, CLA is a natural form of trans fat and does not seem to have the same negative health effects as artificially produced, industrial trans fats. The AHA has linked artificial trans fats to a higher risk of heart disease.

While there is a large amount of evidence to show that industrial trans fats are harmful, the research on natural trans fats and their effects is limited and inconclusive.

Possible health benefits

Many people use CLA supplements, believing that they have benefits for weight loss and heart health. The evidence is mixed, however, and many of the studies involve animals instead of humans. Consequently, the research is not yet clear about the exact health benefits of CLA.

The following sections discuss the possible benefits of CLA and what the current research suggests.

Weight loss

According to the Office of Dietary Supplements (ODS), “CLA may help you lose a very small amount of weight and body fat.“

A 2015 review paper states that CLA plays a major role in breaking down fats in the body. This may be why people believe CLA can help with weight loss.

While many studies have shown substantial weight loss in animals, a 2015 review study says that these results do not necessarily apply to humans.

Several studies show that CLA promotes slight weight loss when researchers compare it with placebo groups. However, these examples say that the evidence is inconsistent across the studies.

Bodybuilding

There are no studies looking at the effects of CLA on bodybuilding specifically. A 2015 review of available research suggests that the benefits of taking CLA supplements alongside exercising vary.

The researchers, however, do include several studies that showed CLA supplements could reduce body fat and improve lean body mass, which is the ratio of fat to body weight.

In one study, participants who took 1.8 mg of CLA for 12 weeks and went to the gym for 90 minutes three times per week reduced their body fat but not their body weight when the researchers compared them with a placebo group. The authors said that CLA might reduce fat deposition.

Weight loss but with fewer benefits?

Recent studies have questioned whether CLA-induced weight loss has the same benefits as traditional methods of weight loss, the latter being calorie restriction and exercise.

One 2017 study compared two groups of obese mice with characteristics of human metabolic syndrome. To test weight loss, the researchers gave the first group of animals CLA supplements while putting the second group on a calorie-restriction diet.

The scientists studied the physical changes between the two groups. Both groups lost equal amounts of weight, though they had different physical changes:

• The mice that took CLA supplements lost subcutaneous fat, which is a protective, healthy form of fat, without losing harmful visceral fat.
• The calorie restriction group improved markers of diabetes, such as reduced fasting blood glucose levels, while the CLA group did not. This makes sense as visceral fat is a major contributor to insulin resistance.

The study concluded that calorie restriction was a healthier form of weight loss than taking CLA supplements.

Heart health

Atherosclerosis, or hardening of the arteries, is when plaque builds up in the arteries. This is a risk factor for heart disease.

One 2018 study on obese mice suggested that taking CLA supplements could protect against atherosclerosis.

However, researchers need to do further studies before they know the true effects of CLA on atherosclerosis in humans.

Sources

People can get CLA from their diet by eating foods naturally rich in CLA or by taking CLA supplements.

Meat and dairy

Consuming CLA-rich butter is a way of benefiting from the fatty acid.

Animal products from ruminants, such as cows, goats, sheep, and deer contain CLA. These products include meat, milk, and cheese.

The amount of CLA in animal products depends on farming techniques. Products from grass-fed animals contain more CLA than those from grain-fed animals.

Over recent decades, numerous studies have shown that grass-based diets improve fatty acid ratios, specifically increasing CLA and omega-3 content, and also increase the healthful antioxidant content in beef.

Feeding animals plant sources of linoleic acid, such as sunflower, soybean or linseed oil, can also increase the amount of CLA in their milk fat.

A popular method of consuming CLA-rich butter is bulletproof coffee, which combines coffee, oil, and butter.

CLA supplements

The type of CLA in supplements is different from natural forms from animal products. To make supplements, manufacturers create CLA by chemically altering plant sources of linoleic acid.

Several studies recommend getting CLA from natural sources instead of supplements.

Dosage

There are no established guidelines, but past studies show effects from at least 3 g a day. Studies on fat loss used between 3.4 g and 6.8 g a day.

The ODS say CLA seems to be safe when people take up to 6 g per day for a year. Beyond this, studies so far are inconclusive about how much CLA people may consume.

Dramatic results seen in animal studies required mice to consume large amounts of CLA for effects. Also, there are few studies into long-term CLA supplementation.

Risks and side effects

The ODS report that CLA may cause side effects, such as:

Some studies suggest an association between the dosages people must consume to promote weight loss and negative effects, such as systemic inflammation and insulin resistance. One study also suggests that CLA may worsen fatty liver disease.

As a result of these concerns, more research must be done into the possible side effects of CLA in humans.

Summary

CLA is present in food products from ruminants, including cows, goats, and sheep. Products from grass-fed animals contain more CLA than products from grain-fed animals.

Official sources state that CLA seems to be safe, though people may experience mild side effects, such as digestive issues.

While studies show potential for the use of CLA in losing weight and increasing lean body mass, more comprehensive studies are necessary.

Guavas are tropical fruits with yellowish-green skin, and they grow on trees in Central America. The Latin name for the common guava tree is Psidium guajava.

People use guava leaf tea as a treatment for diarrhea in several countries, including India and China. In other countries, such as Mexico, people have traditionally used the flesh of the fruit to heal wounds.

In this article, we explore some potential health benefits and uses of guava. We also describe nutritional information, risks, and how to incorporate guava into the diet.

Type 2 diabetes

Guava fruit may help treat a range of conditions, including type 2 diabetes.

Guava leaf tea may help prevent spikes in blood sugar and improve symptoms in people with type 2 diabetes.

A 2010 review of evidence from clinical trials and animal studies suggests that guava leaf tea may help improve insulin resistance and lower blood sugar levels.

These benefits may result from compounds in guava leaf extract helping to moderate glucose absorption after a person eats a meal.

Menstrual cramps

Taking supplements containing guava leaf extract may reduce menstrual cramps.

The results of a study from 2007 suggest that taking guava leaf extract supplements may relieve menstrual pain in women with primary dysmenorrhea.

Participants who took 6 milligrams (mg) of the extract each day experienced less menstrual pain than those taking ibuprofen or a placebo.

Diarrhea

Guava leaf tea is a traditional remedy for diarrhea in many parts of the world.

Evidence from animal studies suggests that the leaf extract may have the potential to treat infectious diarrhea.

A 2015 study investigated the use of this extract in mice with infectious diarrhea. The infection cleared more quickly in the mice who consumed guava leaf extract than in those who did not. The researchers noted that guava leaf extract shows promise as a treatment for this illness.

Another study from 2015 found that guava leaf extract helped control diarrhea in chickens with Escherichia coli infections.

However, scientists need to carry out more research to confirm these findings in humans.

Flu

Drinking guava leaf tea is an easy way to enjoy the health benefits of the fruit.

Drinking guava leaf tea may help people fight off the flu.

In a 2012 test tube study, guava leaf tea showed promise as an antiviral agent for flu treatment. The researchers found that the tea inhibited the growth of the virus that causes the flu.

The antiviral effect of the tea may result from the leaf’s flavanols, which are a natural antioxidant.

Confirming the effects in humans will require further research.

Blood pressure

Consuming guava leaf extract may help lower high blood pressure.

A 2016 test tube study found that the extract had an antihypertensive effect in rat tissues, which means that it may have the potential to reduce blood pressure.

This effect may be due to the leaf extract’s antioxidant properties. Antioxidants may lower blood pressure by helping to expand blood vessels.

However, scientists need to carry out more studies to determine whether guava leaf extract can reduce high blood pressure in humans.

Osteoarthritis

Some research in animals suggests that guava leaf extract may benefit people with osteoarthritis.

A 2018 study found that consuming the extract protected against cartilage destruction in rats with induced osteoarthritis. However, researchers have yet to confirm this effect in humans.

Cancer

Guava leaf extract may eventually play a role in cancer treatment.

Results of a 2014 test tube, animal, and computer study suggest that compounds in the extract may inhibit the growth of cancer cells.

The researchers believe that the effect may occur because guava leaf compounds act like selective estrogen receptor modulators (SERMs).

SERMs are a class of drugs that doctors use to treat cancer. They work by preventing cancer cells from multiplying.

However, scientists need to conduct clinical trials in humans to better understand the potential for these compounds to combat cancer.

Nutritional information

Guava contains vitamin A and potassium.

Guava fruit is a nutritious and healthful food that is rich in several important nutrients.

According to the United States Department of Agriculture, 100 grams (g) of raw guava fruit contain:

Adverse effects and risks

A 2017 review of research into guava did not highlight any notable adverse effects of eating guava fruit, consuming guava leaf tea, or taking guava leaf extract supplements.

However, there is not enough evidence to rule out the possibility. Any remedies or supplements that do not have Food and Drug Administration (FDA) approval may cause adverse effects.

Anyone who is pregnant or breastfeeding should consult a doctor before taking guava leaf extract.

It is not clear whether this extract can interact with medications. Anyone using medicines on an ongoing basis should speak to a doctor before trying a new remedy.

How to eat guava

Some people enjoy sliced guava, either on its own or with yogurt. Others use the fruit in smoothies or add guava leaves to boiled water to create an herbal tea.

Some recipe ideas for guava include:

Using guava supplements

Many health stores sell dietary supplements that contain guava leaf extract. A person usually takes these daily, but it is important to follow the manufacturer’s instructions.

It is also advisable to speak to a doctor before taking any new dietary supplement, especially when trying to treat a specific health issue.

Various guava dietary supplements are available to purchase online.

Summary

Guava is a traditional remedy for a number of ailments.

Preliminary research suggests that compounds in guava leaf extract may have a positive effect on a range of illnesses and symptoms, including menstrual cramps, diarrhea, the flu, type 2 diabetes, and cancer.

However, scientists need to carry out further studies in humans to confirm and better understand these findings.

Black walnuts contain three main components that make them beneficial when consumed – antioxidants, polyunsaturated fats, and phenolic compounds. The walnuts also contain a range of other nutrients that includes fiber, protein, melatonin, and folate, which is a type of B vitamin.

Whether people eat them in nut form or take them as a supplement, black walnuts have many potential health benefits. It is also important to consider possible drawbacks as well.

Reduced risk for cardiovascular disease

Studies suggest a link between high nut consumption and lower risks for heart disease.

Most experts agree that consuming nuts, including black walnuts, has well-established links to improving heart health.

Nuts, such as black walnuts, are high in fatty acids and antioxidants that can help to improve a person’s overall heart health.

According to the International Journal of Food Properties, numerous major studies have identified a positive correlation between higher nut consumption and lower risks for sudden cardiac death, heart attack, and heart disease.

Lowering blood pressure

Black walnuts contain arginine, which is an amino acid. Arginine turns into nitric acid in the body. Nitric oxide is a vasodilator, which means that it makes blood vessels larger. According to the International Journal of Food Properties, vasodilators can potentially lower blood pressure,.

The journal reports that black walnuts contain 3.62 grams (g) of arginine per 100 g of the food. This is slightly higher than English walnuts, which contain 2.28 g of arginine per 100 g of black walnuts.

Improved cholesterol levels

Walnuts contain phytosterols or plant sterols. Phytosterols are beneficial to the body because they limit the absorption of cholesterol in the body. This effect can help to lower a person’s cholesterol levels.

Black walnuts contain 37 milligrams (mg) more phytosterols than their English walnut counterparts, according to the International Journal of Food Properties.

Because doctors associate high cholesterol levels with greater risks for heart disease, keeping cholesterol levels low is essential for heart health.

Protection against neurological diseases

Black walnuts are rich in ellagitannins, which are a type of polyphenol. Ellagitannins have anti-inflammatory and free-radical-fighting properties in the body.

According to the journal Critical Reviews in Food Science and Nutrition, these compounds help prevent the onset and progression of neurodegenerative diseases in the body. Examples of these diseases include Parkinson’s disease, Alzheimer’s disease, and amyotrophic lateral sclerosis.

Reduced risk for liver cancer

A study in the 2011 issue of Pharmaceutical Biology found that cancer cells exposed to walnut extracts in a laboratory setting were effective in keeping cancer cells from multiplying.

The researchers found that the compounds chloroform and ethyl acetate were particularly effective at preventing liver cancer cells from multiplying. The researchers theorized that black walnut could have preventive and protective effects against liver cancer as well as some other cancer types.

Reduced risk for prostate cancer

Black walnuts are high in the compound y-tocopherol. Researchers have linked this nutrient with inhibiting tumor cell growth in prostate cancer cells, according to the International Journal of Food Properties.

While researchers have not been able to identify a specific dose or amount that has prostate cancer-protective properties, these compounds show promise as a method to reduce prostate cancer risk.

Additional reported benefits

Some researchers believe that black walnuts have many more health benefits. However, scientists have not studied these in any detail, so they are unable to confirm their effectiveness.

Examples of these potential benefits include:

• treating intestinal parasites
• healing skin wounds
• treating yeast infections

Some people believe that topical pastes of black walnut can treat skin conditions, such as warts, psoriasis plaques, and canker sores. However, researchers have not proven these properties to be true.

How to take and add to the diet

People can add black walnuts to entrees, appetizers, and salads.

A person can simply add black walnuts to appetizers, salads, entrees, side dishes, and desserts.

Walnut shells are very thick, and some people may find them difficult to crack. However, shelled black walnuts are available.

Choosing walnuts that have undergone minimal processing and preparation will usually ensure they retain their nutritional profile.

Supplement manufacturers also sell black walnut as a single supplement or incorporate it with other herbs and fruits, such as garlic, cranberry, and Echinacea.

People should always check with their doctor before taking any new supplements. Always read the directions on the package carefully to ensure safe consumption.

Side effects

Doctors generally consider black walnuts safe when people eat them in small amounts or take them as a supplement on a short-term basis.

Doctors do not know the long-term effects of taking black walnut supplements. Also, the U.S. Food and Drug Administration (FDA) do not regulate the supplements industry, so use discretion when buying supplements and always purchase them from a reputable company.

Some people report allergies after consuming black walnuts. Others report stomach irritation and upset after taking black walnut supplements or eating the nuts. Because doctors do not know much about the side effects of black walnut consumption, they recommend that breastfeeding or pregnant women do not take the supplements.

Black walnuts also contain substances called tannins that may decrease the body’s ability to absorb other medications. As a result, a person should not consume or take black walnut supplements at the same time as their regular medications. Waiting 1 to 2 hours between taking the supplement and taking other medicines is the best way to ensure that they will all work effectively.

Summary

Black walnut is a natural food product that has anti-inflammatory properties, which may help fight disease. A person can incorporate the nut into their diet or select a supplement that contains it.

However, always talk to a doctor before taking any new supplement, as it is possible that taking black walnut could interfere with how well the body absorbs certain medications.