Which supplements specifically increase semen volume and have clinical evidence in older men?

1. Clinical trials named — one small, industry‑sponsored trial

The clearest clinical evidence in these results is an exploratory randomized, double‑blind, placebo‑controlled trial testing a polyherbal dietary supplement sold as Semenax; the study reported a significant increase in ejaculate volume after two months compared to placebo in 78 adult men (described as exploratory) and is cited by multiple marketing and secondary sites ^{[1] [5]}. Independent clinic summaries also note only one such trial dated to the product sponsor ^[6]. Marketing materials amplify the result to “20–30%” volume gains ^{[2] [5]}, but the underlying study is described in the medical report as exploratory, not definitive ^[1].

2. Which single nutrients have clinical support — conditional and context‑dependent

Several individual nutrients recur across the coverage with some clinical associations: zinc, L‑carnitine, L‑arginine, maca, and antioxidants (vitamins C/E, selenium, CoQ10) are mentioned as linked to semen parameters in research summaries ^{[3] [7] [1]}. The systematic/overview article on antioxidants found mixed results: some antioxidant regimens improved concentration, motility or morphology in infertile men, while CoQ10 in one trial produced non‑significant changes in classic semen measures though increased antioxidant capacity ^[3]. The sources stress that benefits are often seen in men with existing deficiencies or fertility problems rather than universally in healthy older men ^{[3] [6]}.

3. Evidence versus marketing — overlapping and sometimes overstated messages

Multiple press releases and commercial reviews repeat the claim that Semenax is “clinically tested” and “clinically validated,” and some copy lists a specific 20–30% increase figure; these appear to rest on the single exploratory trial sponsored by the manufacturer rather than independent large trials ^{[5] [2] [8]}. Independent clinic commentary flags that the product is not FDA‑evaluated for efficacy and that only one small sponsor‑backed trial exists ^[6]. This pattern—marketing citing a small trial while implying broader validation—is visible across the promotional sources ^{[9] [5]}.

4. What about older men specifically? — sparse direct data

Available reporting does not provide trial results explicitly stratified for “older men” or large trials focused on aging populations. The Semenax trial involved adult men but the sources do not present age‑specific efficacy data for older age groups ^{[1] [6]}. General statements in industry copy assert that “men of all ages” can benefit and that semen volume declines with age, but the underlying studies cited do not appear to isolate effects in older men in the material provided ^{[10] [11]}. In short: not found in current reporting that there are robust, age‑targeted clinical trials proving efficacy in older men ^{[1] [6]}.

5. What is reasonable to conclude for clinicians and consumers

From the current material, the most defensible conclusion is that a small, sponsor‑backed trial reported modest ejaculate volume increases for one commercial multi‑ingredient product (Semenax) and that some individual nutrients (notably zinc and certain antioxidants or amino acids) have conditional evidence for improving semen parameters — especially in men with deficiencies or infertility — but not definitive proof of benefit for all older men ^{[1] [3] [4]}. Independent commentators warn supplements are not FDA‑approved for efficacy and advise medical consultation, particularly around documented deficiencies ^[6].

6. How to read future claims — questions to ask

When evaluating a supplement claim, ask: Was the study randomized and placebo‑controlled or industry‑sponsored? How large and how long was it? Were results reproduced by independent researchers? Were participants representative of “older” men or only younger/adult samples? The available sources show one exploratory randomized trial for Semenax (industry‑linked) and mixed evidence for component nutrients — they do not show large, independent, age‑specific trials proving routine benefit for older men ^{[1] [6] [3]}.

Limitations: This analysis relies only on the supplied search results; other peer‑reviewed trials or systematic reviews outside these sources may exist but are not cited here.