This Source Naturals capsule is built around immune support, delivering 125mg of **Transfer Factor Complex** — a fractionated colostrum extract. At one capsule a day you're getting the low end of the range these fractions are typically labeled at (100–600mg); the label's allowance of up to 5 capsules during physiological stress would take you to 625mg.

What matters more than the dose is the evidence: there's no clinical trial establishing a therapeutic amount for transfer-factor fractions, and the core idea you're paying for — that these concentrated fractions transfer immunity better than whole colostrum — hasn't held up under independent research. That weak evidence base is why this scores low, not the milligrams.

So if immune support is your goal, you're buying a proprietary fraction whose active components aren't standardized or independently validated. And skip it entirely if you're dairy-allergic or lactose-intolerant, since colostrum contains both.