There is a lot of conflicting information available about the link between saw palmetto and testosterone. Many people believe that saw palmetto can boost testosterone levels, but others disagree.
Is there any truth to this idea and does saw palmetto affects men's health in any other ways?
Facts and myths
Researchers have looked into a variety of roles that saw palmetto might play in men's health. Here, we look at eight of the facts and myths surrounding saw palmetto.
1. Fact: Saw palmetto is linked to testosterone levels
Experts disagree on whether saw palmetto has any effect on testosterone levels.
Scientists have found that saw palmetto can slow down 5-alpha reductase. This enzyme converts testosterone into a potent androgen hormone called dihydrotestosterone (DHT). Androgen hormones regulate the development of male characteristics.
The production of androgen hormones occurs in the testes, ovaries, and adrenal glands. These hormones are also responsible for the development of primary sex organs in the womb and secondary male characteristics in puberty.
By slowing down 5-alpha reductase, saw palmetto could reduce the effects of DHT as men get older.
While proponents of saw palmetto claim that it helps to regulate testosterone levels, there is little evidence confirming this. Much of the research on the connection between saw palmetto and testosterone levels is also very outdated.
One old report of multiple studies on saw palmetto in the Journal of the International Society of Sports Nutrition did find that men taking saw palmetto over a 2-week period had higher levels of testosterone than those in the placebo control group.
However, there have not been enough studies since to either counter or confirm these findings.
2. Fact: Saw palmetto may help reduce BPH symptoms
Benign prostatic hyperplasia (BPH) is a non-cancerous condition that causes an enlarged prostate. The prostate is a small gland that sits just below the bladder. It is part of the male reproductive system.
An enlarged prostate puts pressure on the urethra, the long tube inside the penis that is responsible for draining urine from the bladder. BPH can be uncomfortable as it makes it harder to urinate even when the need is urgent. It can also make it difficult to empty the bladder completely and can cause leaking after urination.
Several small studies investigating saw palmetto as a treatment for the symptoms of BPH have shown modest results. At least one study shows that saw palmetto is beneficial in combination with other natural therapies to treat these symptoms.
A double-blind, randomized study in 2011 divided 369 men into two groups. One group took up to three times the standard daily dose of saw palmetto while the other group took a placebo. The results showed that saw palmetto was no more effective than the placebo in reducing the lower urinary tract symptoms of BPH.
In addition, a 2012 Cochrane review of 32 randomized controlled studies showed that taking a double or triple dose of saw palmetto did not lead to an improvement in prostate size or urinary symptoms in men with BPH.
A 2014 randomized study of 225 men looked at the effectiveness of using a combination of saw palmetto, lycopene, selenium and tamsulosin to treat symptoms of BPH. The combination therapy was more effective than the single treatments and did not cause any adverse events.
3. Fact: It can improve sex drive
A person's sex drive may improve as a result of saw palmetto.
Low testosterone reduces sex drive, or libido, in both men and women. Some people believe that saw palmetto can improve libido by reducing testosterone breakdown, and there is some evidence to support this.
One study reported in the journal Urologia Internationalis found that men using saw palmetto were experiencing improved sexual function.
In the study, which involved 120 men with enlarged prostate glands, researchers monitored the following over a 2-year period:
- urine flow
- blood prostate-specific antigen (PSA)
- prostate symptoms
- erectile function
- quality of life
They found that saw palmetto improved prostate symptoms and sexual function after 2 years. This improvement was significant, especially in the first year.
4. Fact: Saw palmetto can help prevent prostate cancer
Prostate cancer affects 1 in 9 men in the United States, according to the American Cancer Society. The American Cancer Society estimate that there will be around 29,430 deaths from prostate cancer in 2018.
Research has suggested that DHT may contribute to the development of prostate cancer. Therefore, it is possible that saw palmetto might help to prevent this disease by slowing down the conversion of DHT.
Prescription medications can also slow down this conversion, but they often have severe side effects. Saw palmetto may inhibit DHT without serious side effects.
5. Myth: Saw palmetto improves fertility
Some couples who are unable to conceive have tried taking saw palmetto to improve the likelihood of conception.
The common belief is that saw palmetto increases the sperm count in men and promotes healthier eggs in women.
However, there is no substantial evidence to suggest that saw palmetto can improve fertility.
6. Fact: Saw palmetto can reduce male hair loss
It is normal for hair to fall out and grow back. However, high levels of DHT can reduce hair growth. As a result, some people believe that saw palmetto extracts and supplements may help to prevent hair loss.
The research on saw palmetto and hair growth is varied and somewhat limited, but there are studies indicating that the plant extract might show some promise as a treatment.
One study in mouse models found that saw palmetto promotes hair regeneration and repairs hair loss by activating the signaling pathways responsible for hair growth.
A small 2014 study of 25 men showed positive results when men used topical saw palmetto and 10-percent trichogen as a treatment. The study showed an 11.9 percent hair count increase after 4 months.
7. Myth: It does nothing for women
Saw palmetto research often focuses on men's health, so many people believe that it cannot benefit women.
However, there is some evidence to suggest that saw palmetto may help to regulate specific female hormones. It may have an estrogen-like effect and balance out the effects of testosterone in women.
Saw palmetto may also help to reduce high levels of androgens and prolactin in women with polycystic ovary syndrome (PCOS). Women with PCOS have elevated levels of male hormones. This causes a specific set of symptoms, including irregular and heavy menstrual periods, excess body and facial hair, and acne.
Many of the studies are on animals so they cannot confirm a link between PCOS and saw palmetto in humans. However, they are still helpful as they show that saw palmetto can block prolactin receptors on ovarian cells that are over-expressing them. The regulation of these receptors may reduce the symptoms of PCOS.
8. Myth: Saw palmetto has no side effects because it is a plant
Taking saw palmetto can cause stomach pains and nausea.
Many people believe that because saw palmetto is a plant, it will not cause side effects. Saw palmetto can cause side effects, including:
Saw palmetto may also cause adverse effects in people taking anticoagulants, oral contraceptives, and iron supplements.
Much of the information on saw palmetto safety comes from studies on men. Researchers know little about the side effects of saw palmetto in women and children.
The majority of studies suggest that saw palmetto might be beneficial to prostate health, especially in men with BPH. There is limited research confirming a positive effect on testosterone levels.
As with any supplement, it is a good idea to discuss the use of saw palmetto with a doctor first. While it is safe for most healthy adults, some people have reported side effects. Saw palmetto may also interfere with other medications.
The FDA do not monitor the quality and purity of herbs, so it is possible for marketed herbs to contain toxic metals and other contaminants.