The answer is Japanese diet with plenty of seaweed, almost every day.

Japanese keep dark hair up to 80 years old, but they consume both fish and a lot of seaweed.

I don't know if just vegan diet without fish is enough to prevent hair getting white.

WS

just half a cup of cashews has more than 100 percent of the rda for copper. check this list for zinc sources
Most nutrient dense foods---------------calcium (strong bones, release of neurotransmitters in brain--fortified soymilk/almondmilk/coconutmilk small coffee cup up to 50%, sesame seeds roasted 1 tablespoon 9%, scotch (blue curly) kale 1 cup 14%, most varieties of kale 1 cup 9%, collard greens 1 cup 5% (alot easier to get calcium from fortified drinks like soymilk)....... need vitamin d to absorb, need magnesium to create vitamin d
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iron (red blood cells, needed to make the chemical in the brain called dopamine that makes you feel good----cinnimon life cereal, half a cereal bowl (3/4 cup) 7.4mg, dark chocolate 1/2 bar 6mg ,, medium baked potato with skin .9 , kidney beans boiled 1 cup 5.2mg, lentils 1 cup boiled 6.6mg ,,black beans 1 cup cooked 3.6
((iron from plant foods is much better absorbed with vitamin c, different people need different amounts. for example, adult women 19 to 50 need 18, adult men 19 to 50 need only 8
lpi.oregonstate.edu/mic/minerals/iron#RDA --------------------------------------------------------------------------------------------------------
copper (white blood cells, needed to absorb iron)-- whole sesame seeds roasted 3 tablespoons 35%, , shiitake mushrooms 1/2 cup 288% , dark chocolate 1/2 bar 44%,, cashews 1/2 cup 124% (pyrex measuring cup) cashew butter 2 tablespoons 36% sunflower seeds roasted 1/4 cup 25% lentils 1 cup cooked 25% black beans 1 cup cooked 18%
(copper isn't absorbed as well with vitamin c)
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magnesium (essential for making protein, required to move potassium for a healthy heart rhythm and 300 other things)------hemp seeds 3 tablespoons 45%, pumpkin seeds 4 tablespoons 37% (buy store bought roasted, raw seeds i soaked or roasted didn’t sit well in my stomach) whole brown sesame seeds 4 tablespoons 32% (roast, or soak 8 hours),,black beans cooked 1 cup 30% dark chocolate 1/2 bar 29%,,,cashews 4 tablespoons 20% cashew butter 2 tablespoons 20%, lentils 1 cup cooked 18%,,peanut butter only 9%
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zinc (needed to make the muscle building hormone testosterone, development of cells such as neutrophils, macrophages, and natural killer cells in your immune system,, and 400 other things.))-----1 cup cooked shiitake mushrooms eaten with the broth, maybe with ramen noodles 51% hemp seeds 3 tablespoon 20-25%, nutritional yeast 3 tablespoon 25%, cinnimon life breakfast cereal 3/4 cup 25%,,cashews 1/4 cup 10% (better absorbed soaked and roasted), whole brown sesame seeds 4 tablespoons 19% lentils 1 cup cooked 17%, pumpkin seeds 1/4 cup 15% (better absorbed soaked and roasted) ..black beans 1 cup cooked 13%,,dark chocolate 1/2 bar 11%,, spinach 1 cup boiled with broth 9% sunflower seeds roasted 1/4 up 10%
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potassium (essential for a normal heart rhythm) - large baked potato with skin 46% lentils 1 cup cooked 21%,,pistaccio 1/4 cup 8% large peach 10% medium banana 12% dark chocolate 1/2 bar 10%
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Vitamins A, D, E, K better absorbed with fat such as salad dressing
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soy, broccoli, peanuts, kale and other goitrogens interferere with thyroid function temporarily so best to have them at a differen time than iodized salt or sea vegetables
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thyroid hormone keeps you awake more than coffee. get enough iodine, selenium, zinc. could have 1/2 teaspoon of iodized salt in a fruit shake for the iodine, 2 brazil nuts for the selenium
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oxalic acid and phytic acid limit how much minerals you absorb in beans, wheat, seeds
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The phospholipids of the brain’s gray matter contain high proportions of DHA, suggesting they are important to central nervous system function ,,have flax oil with DHA, or a DHA supplement, or ground flaxseed
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! having too much or too little minerals can cause weird and dangerous symptoms. Dont' take just one mineral, they compete and taking too much of one can cause a deficiency of another one. Taking zinc without also taking copper can cause panic attacks, for example
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find foods highest in vitamins or minerals at http://nutritiondata.self.com/tools/nutrient-search

when the amount of zinc your having is low, the body absorbs more of it.