Boric acid from natural food sources?

I've been to an osteopath who recommended me a number of dietary supplements, including boric acid (others were: magnesium with vitamin B6, Omega 3, 6 and 9 fatty acids, and vitaminds D3 with K2).

I'm fine with the other vitamins, but I'm reading about boric acid and seems like it should be easy to get enough from natural food sources. It occurs naturally in fruits and vegetables, as well as beer, wine and some nuts (according to the internets).

The recommendation wasn't based on bloodwork or any other tests. I'm not even sure if it can be tested, or is it just guessing? Seems like it can be overdosed, which is probably easier done with supplements than just diet. Anyway, what would be the healthy natural sources of this?

I think my diet is rather healthy - fruits and veggies local or from my garden, meats and fish from local farmers. I don't have any food allergies. The osteopath didn't discuss my diet at all, just other health issues (mostly muscle pains - I turned entire tree into mulch just two weeks ago...).

If you drink enough beer to increase the boric acid intake, you may not notice the difference for a while.
This document suggests too much ingested is not good for us.
Boric Acid downsides

Not being a medical expert, rather a "googleDuckDuckGo hero", take my comments in the spirit intended as well intentioned, but probably wrong!

I hadn't heard of Boric acid, so my wikipedia trail lead thus: Boric_acid -> Boron_deficiency_(plant_disorder) -> Boron_deficiency_(medicine) -> Osteochondrosis

Osteochondrosis must be what we have been trying to prevent in our young mastiff dog - a disorder of the joints caused (as I simplistically understood) by growing too quickly.  If this is what you have, it seems that the damage may have already been done unless your bones are still forming (we do carry on growing for several years into adulthood). The Boron is needed during the growth phase in fairly small amounts. Although one of the characteristic diseases  also does affect young athletic women apparently.

More research leads to
(US) National Institute of Health

Plant foods—including fruit, tubers, and legumes—contain the largest amounts of boron. Wine, cider, and beer also contain boron

.....

The amount of boron in plant foods depends somewhat on the boron content of the soil and water where they were grown

The same source suggests that extra Boron may help relieve osteoarthritis symptoms although there has not been enough studies to conclusively prove this.

So if you have plenty of fruit and veg in your diet, you are likely to get adequate amounts of Boron, assuming that the plants providing the diet are not themselves deficient due to low Boron in the soil they are grown in.
Hope this helps.

Thanks! I also think there should be enough from fruits and veggies... and occasional beer or wine ;) especially if boric acid is also being used as a food preservative.
I'm definitely too old for my bones to be still forming :D although I had a broken collarbone years ago, but that's healed (and I don't know if healing broken bones / fractures benefit from boric acid, or just growing bones?).
I wonder how it's tested (the amount of boric acid in the body... or boron in the soil).

Do you grow comfrey?

Comfrey contains Vitamins A, B1, B2, B3, B5, B6, B9, B12, C and E, as well as boron, calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, phosphorous, potassium, selenium, sodium and zinc. As comfrey has deep roots, in can draw up minerals that other plants can’t reach, this in turn can benefit plants growing nearby. It’s also used to enrich soils, as a mulch or liquid tea. In a compost pile, it’s considered an activator, similar to manure, in that it will help speed up the process. As a mulch, it’s especially beneficial for potatoes, strawberries and tomatoes, but also useful for fruit trees and other crops as well.

https://www.permaculturenews.org/2019/07/26/all-about-comfrey/

I have not used this product though it might be worth looking into:

https://www.iherb.com/pr/christopher-s-original-formulas-complete-tissue-bone-ointment-4-fl-oz-118-ml/10018

Extra virgin olive oil, wheat germ oil, wildcrafted white oak bark, organic comfrey root, wildcrafted mullein leaf, wildcrafted black walnut leaf,  marshmallow root, wildcrafted gravel root, organic wormwood herb, organic lobelia herb, wildcrafted skullcap herb, and beeswax.