This article from the NIH is interesting, especially as to the reason most supplements only contain 99 mg potassium.
https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/
Many dietary supplement manufacturers and distributors limit the amount of potassium in their products to 99 mg (which is only about 3% of the DV) because of two concerns related to potassium-containing drugs. First, the FDA has ruled that some oral drug products that contain potassium chloride and provide more than 99 mg potassium are not safe because they have been associated with small-bowel lesions [21]. Second, the FDA requires some potassium salts containing more than 99 mg potassium per tablet to be labeled with a warning about the reports of small-bowel lesions [22,23]. In accordance with a ruling by Congress, the FDA may not limit the amount of any nutrient, including potassium, in a dietary supplement, except for safety-related reasons [24]. However, the FDA has not issued a ruling about whether dietary supplements containing more than 99 mg potassium must carry a warning label [17,23].
Also of note from the same article:
DV = Daily Value. The DV for potassium used for the values in Table 2 is 3,500 mg for adults and children aged 4 and older [17]. This DV, however, is changing to 4,700 mg as the updated Nutrition and Supplement Facts labels are implemented [18]. The updated labels and DVs must appear on food products and dietary supplements beginning in January 2020, but they can be used now [19].
I bought some potassium citrate powder and I made my own capsules. Trying to get the 4.7 g per day but working up to it slowly.
Potassium will kill you is apparently one of those things āeverybody knowsā that isnāt true. Even the manufacturer I bought from is misinformed. Hereās what they have on the page where theyāre selling it:
This supplement should be taken in servings of exactly 275mg per day; no more, no less. Too much Potassium has the potential to be fatal, so it is always best to measure out amounts of this supplement on an accurate milligram scale. Do not attempt to use anything other than a milligram scale. This supplement should be stirred into a full glass of water and consumed that way.
The FDA recommends taking no more than 100mg elemental Potassium per day. Since this supplement is made up of 36% elemental Potassium, this means that a single serving of 275mg is equal to 99mg, which comes within the recommended daily dosage. If you have any lingering concerns about taking this supplement or your eligibility to take this supplement, it is best to discuss them with a doctor first, as individual needs for Potassium vary greatly.
This is simply not true.